WorldWideScience

Sample records for grb light curves

  1. a new approach of Analysing GRB light curves

    International Nuclear Information System (INIS)

    Varga, B.; Horvath, I.

    2005-01-01

    We estimated the T xx quantiles of the cumulative GRB light curves using our recalculated background. The basic information of the light curves was extracted by multivariate statistical methods. The possible classes of the light curves are also briefly discussed

  2. The 1.4 GHZ light curve of GRB 970508

    NARCIS (Netherlands)

    Galama, TJ; Wijers, RAMJ; Groot, PJ; Strom, RG; De Bruyn, AG; Kouveliotou, C; Robinson, CR; van Paradus, J

    1998-01-01

    We report on Westerbork 1.4 GHz radio observations of the radio counterpart to gamma-ray burst GRB 970508, between 0.80 and 138 days after this event. The 1.4 GHz light curve shows a transition from optically thick to thin emission between 39 and 54 days after the event. We derive the slope p of the

  3. The host galaxy and optical light curve of the gamma-ray burst GRB 980703

    DEFF Research Database (Denmark)

    Holland, S.; Fynbo, J.P.U.; Hjorth, J.

    2001-01-01

    We present deep HST/STIS and ground-based photometry of the host galaxy of the gamma-ray burst GRB 980703 taken 17, 551, 710, and 716 days after the burst. We find that the host is a blue, slightly over-luminous galaxy with V-gal = 23.00 +/-0.10, (V - R)(gal) = 0.43 +/-0.13, and a centre...... 980703 with any special features in the host. The host galaxy appears to be a typical example of a compact star forming galaxy similar to those found in the Hubble Deep Field North. The R-band light curve of the optical afterglow associated with this gamma-ray burst is consistent with a single power...

  4. Optical light curve of GRB 121011A: a textbook for the onset of GRB afterglow in a mixture of ISM and wind-type medium

    International Nuclear Information System (INIS)

    Xin, Li-Ping; Wei, Jian-Yan; Qiu, Yu-Lei; Deng, Jin-Song; Wang, Jing; Han, Xu-Hui

    2016-01-01

    We report the optical observations of GRB 121011A by the 0.8m TNT facility at Xinglong observatory, China. The light curve of the optical afterglow shows a smooth and featureless bump during the epoch of ∼130 s and ∼5000 s with a rising index of 1.57 ± 0.28 before the break time of 539 ± 44 s, and a decaying index of about 1.29 ± 0.07 up to the end of our observations. Moreover, the X-ray light curve decays in a single power-law with a slope of about 1.51 ± 0.03 observed by XRT onboard Swift from 100 s to about 10 000 s after the burst trigger. The featureless optical light curve could be understood as an onset process under the external-shock model. The typical frequency has been below or near the optical one before the deceleration time, and the cooling frequency is located between the optical and X-ray wavelengths. The external medium density has a transition from a mixed stage of ISM and wind-type medium before the peak time to the ISM at the later phase. The joint-analysis of X-ray and optical light curves shows that the emissions from both frequencies are consistent with the prediction of the standard afterglow model without any energy injections, indicating that the central engine has stopped its activity and does not restart anymore after the prompt phase. (paper)

  5. Radioactive decay of the late-time light curves of GRB-SNe

    Science.gov (United States)

    Misra, Kuntal; Fruchte, Andrew Steven

    2018-04-01

    We present the late-time Hubble Space Telescope observations of two GRB associated supernovae, GRB 030329/SN 2003dh and XRF 060218/SN 2006aj. Using the multi-color data upto ˜ 320 days after the burst, we constrain the late-time decay nature of these supernovae. The decay rates of SN 2003dh are steeper than SN 2006aj. A comparison with two other GRB supernovae, GRB 980425/SN 1998bw and the supernova associated with XRF 020903, shows that the decay rates of SN 2003dh are similar to XRF 020903 and those of SN 2006aj are similar to SN 1998bw. The late-time decay rates are steeper than the 56Co?56Fe radioactive decay rate (0.0098 mag day-1) indicating that there is some leakage of gamma-rays.

  6. GRB060206 and the quandary of achromatic breaks in afterglow light curves

    NARCIS (Netherlands)

    Curran, P.A.; van der Horst, A.J.; Wijers, R.A.M.J.; Starling, R.L.C.; Castro-Tirado, A.J.; Fynbo, J.P.U.; Gorosabel, J.; Järvinen, A.S.; Malesani, D.; Rol, E.; Tanvir, N.R.; Wiersema, K.; Burleigh, M.R.; Casewell, S.L.; Dobbie, P.D.; Guziy, S.; Jakobsson, P.; Jelínek, M.; Laursen, P.; Levan, A.J.; Mundell, C.G.; Näränen, J.; Piranomonte, S.

    2007-01-01

    Gamma-ray burst afterglow observations in the Swift era have a perceived lack of achromatic jet breaks compared with the BeppoSAX era. We present our multi-wavelength analysis of GRB060206 as an illustrative example of how inferences of jet breaks from optical and X-ray data might differ. The

  7. A JET BREAK IN THE X-RAY LIGHT CURVE OF SHORT GRB 111020A: IMPLICATIONS FOR ENERGETICS AND RATES

    International Nuclear Information System (INIS)

    Fong, W.; Berger, E.; Margutti, R.; Zauderer, B. A.; Czekala, I.; Chornock, R.; Troja, E.; Gehrels, N.; Sakamoto, T.; Fox, D. B.; Podsiadlowski, P.

    2012-01-01

    We present broadband observations of the afterglow and environment of the short GRB 111020A. An extensive X-ray light curve from Swift/XRT, XMM-Newton, and Chandra, spanning ∼100 s to 10 days after the burst, reveals a significant break at δt ≈ 2 days with pre- and post-break decline rates of α X,1 ≈ –0.78 and α X,2 ∼ j ≈ 3°-8°. The resulting beaming-corrected γ-ray (10-1000 keV band) and blast-wave kinetic energies are (2-3) × 10 48 erg and (0.3-2) × 10 49 erg, respectively, with the range depending on the unknown redshift of the burst. We report a radio afterglow limit of c X , constrains the circumburst density to n 0 ∼ 0.01-0.1 cm –3 . Optical observations provide an afterglow limit of i ∼> 24.4 mag at 18 hr after the burst and reveal a potential host galaxy with i ≈ 24.3 mag. The subarcsecond localization from Chandra provides a precise offset of 0.''80 ± 0.''11 (1σ) from this galaxy corresponding to an offset of 5-7 kpc for z 0.5-1.5. We find a high excess neutral hydrogen column density of (7.5 ± 2.0) × 10 21 cm –2 (z = 0). Our observations demonstrate that a growing fraction of short gamma-ray bursts (GRBs) are collimated, which may lead to a true event rate of ∼> 100-1000 Gpc –3 yr –1 , in good agreement with the NS-NS merger rate of ≈200-3000 Gpc –3 yr –1 . This consistency is promising for coincident short GRB-gravitational wave searches in the forthcoming era of Advanced LIGO/VIRGO.

  8. Search for the signatures of a new-born black hole from the collapse of a supra-massive millisecond magnetar in short GRB light curves

    Science.gov (United States)

    Zhang, Q.; Lei, W. H.; Zhang, B. B.; Chen, W.; Xiong, S. L.; Song, L. M.

    2018-03-01

    `Internal plateau' followed by a sharp decay is commonly seen in short gamma-ray burst (GRB) light curves. The plateau component is usually interpreted as the dipole emission from a supra-massive magnetar, and the sharp decay may imply the collapse of the magnetar to a black hole (BH). Fall-back accretion on to the new-born BH could produce long-lasting activities via the Blandford-Znajek (BZ) process. The magnetic flux accumulated near the BH would be confined by the accretion discs for a period of time. As the accretion rate decreases, the magnetic flux is strong enough to obstruct gas infall, leading to a magnetically arrested disc. Within this scenario, we show that the BZ process could produce two types of typical X-ray light curves: type I exhibits a long-lasting plateau, followed by a power-law (PL) decay with slopes ranging from 5/3 to 40/9; type II shows roughly a single PL decay with a slope of 5/3. The former requires low magnetic field strength, while the latter corresponds to relatively high values. We search for such signatures of the new-born BH from a sample of short GRBs with an internal plateau, and find two candidates: GRB 101219A and GRB 160821B, corresponding to type II and type I light curves, respectively. It is shown that our model can explain the data very well.

  9. GRB 090313 AND THE ORIGIN OF OPTICAL PEAKS IN GAMMA-RAY BURST LIGHT CURVES: IMPLICATIONS FOR LORENTZ FACTORS AND RADIO FLARES

    International Nuclear Information System (INIS)

    Melandri, A.; Kobayashi, S.; Mundell, C. G.; Guidorzi, C.; Bersier, D.; Steele, I. A.; Smith, R. J.; De Ugarte Postigo, A.; Pooley, G.; Yoshida, M.; Castro-Tirado, A. J.; Gorosabel, J.; Kubanek, P.; Sota, A.; JelInek, M.; Gomboc, A.; Bremer, M.; Winters, J. M.; De Gregorio-Monsalvo, I.; GarcIa-Appadoo, D.

    2010-01-01

    We use a sample of 19 gamma-ray bursts (GRBs) that exhibit single-peaked optical light curves to test the standard fireball model by investigating the relationship between the time of the onset of the afterglow and the temporal rising index. Our sample includes GRBs and X-ray flashes for which we derive a wide range of initial Lorentz factors (40 e and show that values derived from the early time light-curve properties are consistent with published typical values derived from other afterglow studies. We produce expected radio light curves by predicting the temporal evolution of the expected radio emission from forward and reverse shock components, including synchrotron self-absorption effects at early time. Although a number of GRBs in this sample do not have published radio measurements, we demonstrate the effectiveness of this method in the case of Swift GRB 090313, for which millimetric and centimetric observations were available, and conclude that future detections of reverse-shock radio flares with new radio facilities such as the EVLA and ALMA will test the low-frequency model and provide constraints on magnetic models.

  10. A low-latency pipeline for GRB light curve and spectrum using Fermi/GBM near real-time data

    Science.gov (United States)

    Zhao, Yi; Zhang, Bin-Bin; Xiong, Shao-Lin; Long, Xi; Zhang, Qiang; Song, Li-Ming; Sun, Jian-Chao; Wang, Yuan-Hao; Li, Han-Cheng; Bu, Qing-Cui; Feng, Min-Zi; Li, Zheng-Heng; Wen, Xing; Wu, Bo-Bing; Zhang, Lai-Yu; Zhang, Yong-Jie; Zhang, Shuang-Nan; Shao, Jian-Xiong

    2018-05-01

    Rapid response and short time latency are very important for Time Domain Astronomy, such as the observations of Gamma-ray Bursts (GRBs) and electromagnetic (EM) counterparts of gravitational waves (GWs). Based on near real-time Fermi/GBM data, we developed a low-latency pipeline to automatically calculate the temporal and spectral properties of GRBs. With this pipeline, some important parameters can be obtained, such as T 90 and fluence, within ∼ 20 min after the GRB trigger. For ∼ 90% of GRBs, T 90 and fluence are consistent with the GBM catalog results within 2σ errors. This pipeline has been used by the Gamma-ray Bursts Polarimeter (POLAR) and the Insight Hard X-ray Modulation Telescope (Insight-HXMT) to follow up the bursts of interest. For GRB 170817A, the first EM counterpart of GW events detected by Fermi/GBM and INTEGRAL/SPI-ACS, the pipeline gave T 90 and spectral information 21 min after the GBM trigger, providing important information for POLAR and Insight-HXMT observations.

  11. Simulating Supernova Light Curves

    International Nuclear Information System (INIS)

    Even, Wesley Paul; Dolence, Joshua C.

    2016-01-01

    This report discusses supernova light simulations. A brief review of supernovae, basics of supernova light curves, simulation tools used at LANL, and supernova results are included. Further, it happens that many of the same methods used to generate simulated supernova light curves can also be used to model the emission from fireballs generated by explosions in the earth's atmosphere.

  12. Simulating Supernova Light Curves

    Energy Technology Data Exchange (ETDEWEB)

    Even, Wesley Paul [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dolence, Joshua C. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-05-05

    This report discusses supernova light simulations. A brief review of supernovae, basics of supernova light curves, simulation tools used at LANL, and supernova results are included. Further, it happens that many of the same methods used to generate simulated supernova light curves can also be used to model the emission from fireballs generated by explosions in the earth’s atmosphere.

  13. The hidden X-ray breaks in afterglow light curves

    International Nuclear Information System (INIS)

    Curran, P. A.; Wijers, R. A. M. J.; Horst, A. J. van der; Starling, R. L. C.

    2008-01-01

    Gamma-Ray Burst (GRB) afterglow observations in the Swift era have a perceived lack of achromatic jet breaks compared to the BeppoSAX, or pre-Swift era. Specifically, relatively few breaks, consistent with jet breaks, are observed in the X-ray light curves of these bursts. If these breaks are truly missing, it has serious consequences for the interpretation of GRB jet collimation and energy requirements, and the use of GRBs as standard candles.Here we address the issue of X-ray breaks which are possibly 'hidden' and hence the light curves are misinterpreted as being single power-laws. We show how a number of precedents, including GRB 990510 and GRB 060206, exist for such hidden breaks and how, even with the well sampled light curves of the Swift era, these breaks may be left misidentified. We do so by synthesising X-ray light curves and finding general trends via Monte Carlo analysis. Furthermore, in light of these simulations, we discuss how to best identify achromatic breaks in afterglow light curves via multi-wavelength analysis

  14. Light speed variation from gamma ray burst GRB 160509A

    Directory of Open Access Journals (Sweden)

    Haowei Xu

    2016-09-01

    Full Text Available It is postulated in Einstein's relativity that the speed of light in vacuum is a constant for all observers. However, the effect of quantum gravity could bring an energy dependence of light speed. Even a tiny speed variation, when amplified by the cosmological distance, may be revealed by the observed time lags between photons with different energies from astrophysical sources. From the newly detected long gamma ray burst GRB 160509A, we find evidence to support the prediction for a linear form modification of light speed in cosmological space.

  15. Light speed variation from gamma ray burst GRB 160509A

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Haowei [School of Physics, State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871 (China); Ma, Bo-Qiang, E-mail: mabq@pku.edu.cn [School of Physics, State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871 (China); Collaborative Innovation Center of Quantum Matter, Beijing (China); Center for High Energy Physics, Peking University, Beijing 100871 (China); Center for History and Philosophy of Science, Peking University, Beijing 100871 (China)

    2016-09-10

    It is postulated in Einstein's relativity that the speed of light in vacuum is a constant for all observers. However, the effect of quantum gravity could bring an energy dependence of light speed. Even a tiny speed variation, when amplified by the cosmological distance, may be revealed by the observed time lags between photons with different energies from astrophysical sources. From the newly detected long gamma ray burst GRB 160509A, we find evidence to support the prediction for a linear form modification of light speed in cosmological space.

  16. LCC: Light Curves Classifier

    Science.gov (United States)

    Vo, Martin

    2017-08-01

    Light Curves Classifier uses data mining and machine learning to obtain and classify desired objects. This task can be accomplished by attributes of light curves or any time series, including shapes, histograms, or variograms, or by other available information about the inspected objects, such as color indices, temperatures, and abundances. After specifying features which describe the objects to be searched, the software trains on a given training sample, and can then be used for unsupervised clustering for visualizing the natural separation of the sample. The package can be also used for automatic tuning parameters of used methods (for example, number of hidden neurons or binning ratio). Trained classifiers can be used for filtering outputs from astronomical databases or data stored locally. The Light Curve Classifier can also be used for simple downloading of light curves and all available information of queried stars. It natively can connect to OgleII, OgleIII, ASAS, CoRoT, Kepler, Catalina and MACHO, and new connectors or descriptors can be implemented. In addition to direct usage of the package and command line UI, the program can be used through a web interface. Users can create jobs for ”training” methods on given objects, querying databases and filtering outputs by trained filters. Preimplemented descriptors, classifier and connectors can be picked by simple clicks and their parameters can be tuned by giving ranges of these values. All combinations are then calculated and the best one is used for creating the filter. Natural separation of the data can be visualized by unsupervised clustering.

  17. Automated Blazar Light Curves Using Machine Learning

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Spencer James [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-07-27

    This presentation describes a problem and methodology pertaining to automated blazar light curves. Namely, optical variability patterns for blazars require the construction of light curves and in order to generate the light curves, data must be filtered before processing to ensure quality.

  18. Deep-learnt classification of light curves

    DEFF Research Database (Denmark)

    Mahabal, Ashish; Gieseke, Fabian; Pai, Akshay Sadananda Uppinakudru

    2017-01-01

    Astronomy light curves are sparse, gappy, and heteroscedastic. As a result standard time series methods regularly used for financial and similar datasets are of little help and astronomers are usually left to their own instruments and techniques to classify light curves. A common approach is to d...

  19. Light extraction block with curved surface

    Science.gov (United States)

    Levermore, Peter; Krall, Emory; Silvernail, Jeffrey; Rajan, Kamala; Brown, Julia J.

    2016-03-22

    Light extraction blocks, and OLED lighting panels using light extraction blocks, are described, in which the light extraction blocks include various curved shapes that provide improved light extraction properties compared to parallel emissive surface, and a thinner form factor and better light extraction than a hemisphere. Lighting systems described herein may include a light source with an OLED panel. A light extraction block with a three-dimensional light emitting surface may be optically coupled to the light source. The three-dimensional light emitting surface of the block may includes a substantially curved surface, with further characteristics related to the curvature of the surface at given points. A first radius of curvature corresponding to a maximum principal curvature k.sub.1 at a point p on the substantially curved surface may be greater than a maximum height of the light extraction block. A maximum height of the light extraction block may be less than 50% of a maximum width of the light extraction block. Surfaces with cross sections made up of line segments and inflection points may also be fit to approximated curves for calculating the radius of curvature.

  20. Reflected Light Curves of Extrasolar Planets

    Science.gov (United States)

    Green, D.; Matthews, J.; Kuschnig, R.; Seager, S.

    The planned launches of ultra-precise photometric satellites such as MOST, COROT and MONS should provide the first opportunity to study the reflected light curves from extrasolar planets. To predict the capabilities of these missions, we have constructed a series of models of such light curves, improving upon the Monte Carlo simulations by Seager et al. (2000). These models include more realistic features such limb darkening of the star and broad band photometry. For specific models, the resulting planet light curves exhibit unique behavior with the variation of radius, inclination and presence or absence of clouds.

  1. Classification of ASKAP Vast Radio Light Curves

    Science.gov (United States)

    Rebbapragada, Umaa; Lo, Kitty; Wagstaff, Kiri L.; Reed, Colorado; Murphy, Tara; Thompson, David R.

    2012-01-01

    The VAST survey is a wide-field survey that observes with unprecedented instrument sensitivity (0.5 mJy or lower) and repeat cadence (a goal of 5 seconds) that will enable novel scientific discoveries related to known and unknown classes of radio transients and variables. Given the unprecedented observing characteristics of VAST, it is important to estimate source classification performance, and determine best practices prior to the launch of ASKAP's BETA in 2012. The goal of this study is to identify light curve characterization and classification algorithms that are best suited for archival VAST light curve classification. We perform our experiments on light curve simulations of eight source types and achieve best case performance of approximately 90% accuracy. We note that classification performance is most influenced by light curve characterization rather than classifier algorithm.

  2. Light Curve Analysis of SAO23229

    Directory of Open Access Journals (Sweden)

    Ho-Il Kim

    1993-06-01

    Full Text Available We have made UBV light curves of a newly discovered eclipsing binary, SAO23229 at Sobaeksan Astronomy Observatory. We determined a minimum light time of HJD2448636.1170+/-0.0005 that is 3 minutes later than predicted time, and founda peculiar light variation at phase 0.75 that may not be secondary eclipse. Orbital period of SAO23229 would be 4.2 days rather than 2.1 days. Our analysis of the light curves shows that SAO23229 has a detached configuration consisting of two almost identical F type main sequence stars.

  3. Multiwavelength analysis of the intriguing GRB 061126: The reverse shock scenario and magnetization

    NARCIS (Netherlands)

    Gomboc, A.; Kobayashi, S.; Guidorzi, C.; Melandri, A.; Mangano, V.; Sbarufatti, B.; Mundell, C.G.; Schady, P.; Smith, R.J.; Updike, A.C.; Kann, D.A.; Misra, K.; Rol, E.; Pozanenko, A.; Castro-Tirado, A.J.; Anupama, G.C.; Bersier, D.; Bode, M.F.; Carter, D.; Curran, P.; Fruchter, A.; Graham, J.; Hartmann, D.H.; Ibrahimov, M.; Levan, A.; Monfardini, A.; Mottram, C.J.; O'Brien, P.T.; Prema, P.; Sahu, D.K.; Steele, I.A.; Tanvir, N.R.; Wiersema, K.

    2008-01-01

    We present a detailed study of the prompt and afterglow emission from Swift GRB 061126 using BAT, XRT, UVOT data and multicolor optical imaging from 10 ground-based telescopes. GRB 061126 was a long burst (T90 = 191 s) with four overlapping peaks in its γ-ray light curve. The X-ray afterglow,

  4. Multiwavelength light curve parameters of Cepheid variables

    Directory of Open Access Journals (Sweden)

    Bhardwaj Anupam

    2017-01-01

    Full Text Available We present a comparative analysis of theoretical and observed light curves of Cepheid variables using Fourier decomposition. The theoretical light curves at multiple wavelengths are generated using stellar pulsation models for chemical compositions representative of Cepheids in the Galaxy and Magellanic Clouds. The observed light curves at optical (VI, near-infrared (JHKs and mid-infrared (3.6 & 4.5-μm bands are compiled from the literature. We discuss the variation of light curve parameters as a function of period, wavelength and metallicity. Theoretical and observed Fourier amplitude parameters decrease with increase in wavelength while the phase parameters increase with wavelength. We find that theoretical amplitude parameters obtained using canonical mass-luminosity levels exhibit a greater offset with respect to observations when compared to non-canonical relations. We also discuss the impact of variation in convective efficiency on the light curve structure of Cepheid variables. The increase in mixing length parameter results in a zero-point offset in bolometric mean magnitudes and reduces the systematic large difference in theoretical amplitudes with respect to observations.

  5. Deep-learnt classification of light curves

    DEFF Research Database (Denmark)

    Mahabal, Ashish; Gieseke, Fabian; Pai, Akshay Sadananda Uppinakudru

    2017-01-01

    is to derive statistical features from the time series and to use machine learning methods, generally supervised, to separate objects into a few of the standard classes. In this work, we transform the time series to two-dimensional light curve representations in order to classify them using modern deep......Astronomy light curves are sparse, gappy, and heteroscedastic. As a result standard time series methods regularly used for financial and similar datasets are of little help and astronomers are usually left to their own instruments and techniques to classify light curves. A common approach...... learning techniques. In particular, we show that convolutional neural networks based classifiers work well for broad characterization and classification. We use labeled datasets of periodic variables from CRTS survey and show how this opens doors for a quick classification of diverse classes with several...

  6. Discovery of the optical counterpart and early optical observations of GRB 990712

    DEFF Research Database (Denmark)

    Sahu, K.C.; Vreesvijk, P.; Bakos, G.

    2000-01-01

    We present the discovery observations of the optical counterpart of the gamma-ray burst GRB 990712 taken 4.16 hr after the outburst and discuss its light curve observed in the V, R, and I bands during the first similar to 35 days after the outburst. The observed light curves were fitted with a po......We present the discovery observations of the optical counterpart of the gamma-ray burst GRB 990712 taken 4.16 hr after the outburst and discuss its light curve observed in the V, R, and I bands during the first similar to 35 days after the outburst. The observed light curves were fitted...

  7. The sub-energetic gamma-ray burst GRB 031203 as a cosmic analogue to the nearby GRB 980425.

    Science.gov (United States)

    Soderberg, A M; Kulkarni, S R; Berger, E; Fox, D W; Sako, M; Frail, D A; Gal-Yam, A; Moon, D S; Cenko, S B; Yost, S A; Phillips, M M; Persson, S E; Freedman, W L; Wyatt, P; Jayawardhana, R; Paulson, D

    2004-08-05

    Over the six years since the discovery of the gamma-ray burst GRB 980425, which was associated with the nearby (distance approximately 40 Mpc) supernova 1998bw, astronomers have debated fiercely the nature of this event. Relative to bursts located at cosmological distance (redshift z approximately 1), GRB 980425 was under-luminous in gamma-rays by three orders of magnitude. Radio calorimetry showed that the explosion was sub-energetic by a factor of 10. Here we report observations of the radio and X-ray afterglow of the recent GRB 031203 (refs 5-7), which has a redshift of z = 0.105. We demonstrate that it too is sub-energetic which, when taken together with the low gamma-ray luminosity, suggests that GRB 031203 is the first cosmic analogue to GRB 980425. We find no evidence that this event was a highly collimated explosion viewed off-axis. Like GRB 980425, GRB 031203 appears to be an intrinsically sub-energetic gamma-ray burst. Such sub-energetic events have faint afterglows. We expect intensive follow-up of faint bursts with smooth gamma-ray light curves (common to both GRB 031203 and 980425) to reveal a large population of such events.

  8. Aspherical Supernovae: Effects on Early Light Curves

    Science.gov (United States)

    Afsariardchi, Niloufar; Matzner, Christopher D.

    2018-04-01

    Early light from core-collapse supernovae, now detectable in high-cadence surveys, holds clues to a star and its environment just before it explodes. However, effects that alter the early light have not been fully explored. We highlight the possibility of nonradial flows at the time of shock breakout. These develop in sufficiently nonspherical explosions if the progenitor is not too diffuse. When they do develop, nonradial flows limit ejecta speeds and cause ejecta–ejecta collisions. We explore these phenomena and their observational implications using global, axisymmetric, nonrelativistic FLASH simulations of simplified polytropic progenitors, which we scale to representative stars. We develop a method to track photon production within the ejecta, enabling us to estimate band-dependent light curves from adiabatic simulations. Immediate breakout emission becomes hidden as an oblique flow develops. Nonspherical effects lead the shock-heated ejecta to release a more constant luminosity at a higher, evolving color temperature at early times, effectively mixing breakout light with the early light curve. Collisions between nonradial ejecta thermalize a small fraction of the explosion energy; we will address emission from these collisions in a subsequent paper.

  9. SPOTTED STAR LIGHT CURVES WITH ENHANCED PRECISION

    International Nuclear Information System (INIS)

    Wilson, R. E.

    2012-01-01

    The nearly continuous timewise coverage of recent photometric surveys is free of the large gaps that compromise attempts to follow starspot growth and decay as well as motions, thereby giving incentive to improve computational precision for modeled spots. Due to the wide variety of star systems in the surveys, such improvement should apply to light/velocity curve models that accurately include all the main phenomena of close binaries and rotating single stars. The vector fractional area (VFA) algorithm that is introduced here represents surface elements by small sets of position vectors so as to allow accurate computation of circle-triangle overlap by spherical geometry. When computed by VFA, spots introduce essentially no noticeable scatter in light curves at the level of one part in 10,000. VFA has been put into the Wilson-Devinney light/velocity curve program and all logic and mathematics are given so as to facilitate entry into other such programs. Advantages of precise spot computation include improved statistics of spot motions and aging, reduced computation time (intrinsic precision relaxes needs for grid fineness), noise-free illustration of spot effects in figures, and help in guarding against false positives in exoplanet searches, where spots could approximately mimic transiting planets in unusual circumstances. A simple spot growth and decay template quantifies time profiles, and specifics of its utilization in differential corrections solutions are given. Computational strategies are discussed, the overall process is tested in simulations via solutions of synthetic light curve data, and essential simulation results are described. An efficient time smearing facility by Gaussian quadrature can deal with Kepler mission data that are in 30 minute time bins.

  10. GRB 110731A within the IGC paradigm

    Directory of Open Access Journals (Sweden)

    Primorac Daria

    2018-01-01

    Full Text Available Bright gamma-ray burst (GRB 110731A was simultaneously observed by Fermi and Swift observatories, with a follow up optical observation which inferred the redshift of z = 2.83. Thus, available data are spanning from optical to high energy (GeV emission. We analyze these data within the induced gravitational collapse (IGC paradigm, recently introduced to explain temporal coincidence of some long GRBs with type Ic supernovae. The case of binary-driven hypcrnova (BdHN assumes a close system, which starts as an evolved core - neutron star binary. After the core-collapse event, the new NS - black hole system is formed, emitting the GRB in the process. We performed the time-resolved and time-integrated analysis of the Fermi data. Preliminary results gave isotropic energy Eiso = 6.05 × 1053 erg and the total P-GRB energy of Ep–GRB = 3.7 × 1052 erg. At transparency point we found a Lorentz factor Γ ~ 2.17 × 103 laboratory radius of 8.33 x 1013 cm, P-GRB observed temperature of 168 keV and a baryon load B = 4.35 × 10-4. Simulated light-curve and prompt emission spectra showed the average circum burst medium density to be n ~ 0.03 particles per cm3. We reproduced the X-ray light-curve within the rest-frame of the source, finding the common late power-law behavior, with α = –1.22. Considering these results, we interpret GRB 110731A as a member of a BdHNe group.

  11. GRB 110731A within the IGC paradigm

    Science.gov (United States)

    Primorac, Daria; Ruffini, Remo; Pisani, Giovanni Battista; Aimuratov, Yerlan; Biancol, Carlo Luciano; Karlica, Mile; Melon Fuksman, Julio David; Moradi, Rahim; Muccino, Marco; Penacchioni, Ana Virginia; Rueda, Jorge Armando; Wang, Yu

    2018-01-01

    Bright gamma-ray burst (GRB) 110731A was simultaneously observed by Fermi and Swift observatories, with a follow up optical observation which inferred the redshift of z = 2.83. Thus, available data are spanning from optical to high energy (GeV) emission. We analyze these data within the induced gravitational collapse (IGC) paradigm, recently introduced to explain temporal coincidence of some long GRBs with type Ic supernovae. The case of binary-driven hypcrnova (BdHN) assumes a close system, which starts as an evolved core - neutron star binary. After the core-collapse event, the new NS - black hole system is formed, emitting the GRB in the process. We performed the time-resolved and time-integrated analysis of the Fermi data. Preliminary results gave isotropic energy Eiso = 6.05 × 1053 erg and the total P-GRB energy of Ep-GRB = 3.7 × 1052 erg. At transparency point we found a Lorentz factor Γ 2.17 × 103 laboratory radius of 8.33 x 1013 cm, P-GRB observed temperature of 168 keV and a baryon load B = 4.35 × 10-4. Simulated light-curve and prompt emission spectra showed the average circum burst medium density to be n 0.03 particles per cm3. We reproduced the X-ray light-curve within the rest-frame of the source, finding the common late power-law behavior, with α = -1.22. Considering these results, we interpret GRB 110731A as a member of a BdHNe group.

  12. Light Curve Variations of AR Lacertae

    Directory of Open Access Journals (Sweden)

    Il-Seong Nha

    1991-12-01

    Full Text Available Sixteen unitary Light curves of AR Lac in B and V are made at Yonsei University Observatory in the period of 1980-1988. Some overview findings of light variations are made. (1 The light variations outside eclipse follow none of the wave migration patterns reported by previous investigators. (2 Complicated shapes outside eclipse are apparently much reduced in the light curves of 1983-1984. This suggests that, in the future, AR Lac has a chance to attain a normal state with mo complicated interactions. (3 The depths of the primary and the secondary mid-eclipses are changing year-to-year. (4 The K0 star, the larger component, has brightened by 0.m14 V, while the G2 star has shown a fluctuation of about 0.m05 in V. (5 The B-V values at primary mid-eclipse have no correlation with the depth variations. (6 Independently of the increase of maximum brightness, the B-V colors in the non-eclipsed phases changed slightly over the years.

  13. Photoelectic BV Light Curves of Algol and the Interpretations of the Light Curves

    Directory of Open Access Journals (Sweden)

    Ho-Il Kim

    1985-06-01

    Full Text Available Standardized B and V photoelectric light curves of Algol are made with the observations obtained during 1982-84 with the 40-cm and the 61-cm reflectors of Yonsei University Observatory. These light curves show asymmetry between ascending and descending shoulders. The ascending shoulder is 0.02 mag brighter than descending shoulder in V light curve and 0.03 mag in B light curve. These asymmetric light curves are interpreted as the result of inhomogeneous energy distribution on the surface of one star of the eclipsing pair rather than the result of gaseous stream flowing from KOIV to B8V star. The 180-year periodicity, so called great inequality, are most likely the result proposed by Kim et al. (1983 that the abrupt and discrete mass losses of cooler component may be the cause of this orbital change. The amount of mass loss deduced from these discrete period changes turned out to be of the order of 10^(-6 - 10^(-5 Msolar.

  14. Two Early Gamma-ray Bursts Optical Afterglow Detections with TAOS Telescopes--GRB 071010B and GRB 071112C

    International Nuclear Information System (INIS)

    Huang, K. Y.; Wang, S. Y.; Urata, Y.

    2009-01-01

    We present on two early detections of GRB afterglows with the Taiwanese-American Occltation Sruvey (TAOS) telescopes. The robotic TAOS system has been devised so that the routine Kuiper Belt Object (KBO) survey is interrupted when a GRB alert is triggered. Our first detection, GRB 071010B was detected by TAOS 62 s after the burst and showed a weak early brightening during the observations. No significant correction with the prompt gamma-ray emission indicated that our optical emission detected is afterglow emission. The second detection of TAOS, GRB 071112C was detected 96 s after the burst, also showed a possible initial raising then followed a steep decay in the R-band light curve.

  15. ENERGETIC FERMI/LAT GRB 100414A: ENERGETIC AND CORRELATIONS

    International Nuclear Information System (INIS)

    Urata, Yuji; Tsai, Patrick P.; Huang, Kuiyun; Yamaoka, Kazutaka; Tashiro, Makoto S.

    2012-01-01

    This study presents multi-wavelength observational results for energetic GRB 100414A with GeV photons. The prompt spectral fitting using Suzaku/WAM data yielded spectral peak energies of E src peak of 1458.7 +132.6 –106.6 keV and E iso of 34.5 +2.0 –1.8 × 10 52 erg with z = 1.368. The optical afterglow light curves between 3 and 7 days were effectively fitted according to a simple power law with a temporal index of α = –2.6 ± 0.1. The joint light curve with earlier Swift/UVOT observations yields a temporal break at 2.3 ± 0.2 days. This was the first Fermi/LAT detected event that demonstrated the clear temporal break in the optical afterglow. The jet opening angle derived from this temporal break was 5. 0 8, consistent with those of other well-observed long gamma-ray bursts (GRBs). The multi-wavelength analyses in this study showed that GRB 100414A follows E src peak -E iso and E src peak -E γ correlations. The late afterglow revealed a flatter evolution with significant excesses at 27.2 days. The most straightforward explanation for the excess is that GRB 100414A was accompanied by a contemporaneous supernova. The model light curve based on other GRB-SN events is marginally consistent with that of the observed light curve.

  16. SUPERNOVA LIGHT CURVES POWERED BY FALLBACK ACCRETION

    Energy Technology Data Exchange (ETDEWEB)

    Dexter, Jason; Kasen, Daniel, E-mail: jdexter@berkeley.edu [Departments of Physics and Astronomy, University of California, Berkeley, CA 94720 (United States)

    2013-07-20

    Some fraction of the material ejected in a core collapse supernova explosion may remain bound to the compact remnant, and eventually turn around and fall back. We show that the late time ({approx}>days) power potentially associated with the accretion of this 'fallback' material could significantly affect the optical light curve, in some cases producing super-luminous or otherwise peculiar supernovae. We use spherically symmetric hydrodynamical models to estimate the accretion rate at late times for a range of progenitor masses and radii and explosion energies. The accretion rate onto the proto-neutron star or black hole decreases as M-dot {proportional_to}t{sup -5/3} at late times, but its normalization can be significantly enhanced at low explosion energies, in very massive stars, or if a strong reverse shock wave forms at the helium/hydrogen interface in the progenitor. If the resulting super-Eddington accretion drives an outflow which thermalizes in the outgoing ejecta, the supernova debris will be re-energized at a time when photons can diffuse out efficiently. The resulting light curves are different and more diverse than previous fallback supernova models which ignored the input of accretion power and produced short-lived, dim transients. The possible outcomes when fallback accretion power is significant include super-luminous ({approx}> 10{sup 44} erg s{sup -1}) Type II events of both short and long durations, as well as luminous Type I events from compact stars that may have experienced significant mass loss. Accretion power may unbind the remaining infalling material, causing a sudden decrease in the brightness of some long duration Type II events. This scenario may be relevant for explaining some of the recently discovered classes of peculiar and rare supernovae.

  17. Multi-Band Light Curves from Two-Dimensional Simulations of Gamma-Ray Burst Afterglows

    Science.gov (United States)

    MacFadyen, Andrew

    2010-01-01

    The dynamics of gamma-ray burst outflows is inherently multi-dimensional. 1.) We present high resolution two-dimensional relativistic hydrodynamics simulations of GRBs in the afterglow phase using adaptive mesh refinement (AMR). Using standard synchrotron radiation models, we compute multi-band light curves, from the radio to X-ray, directly from the 2D hydrodynamics simulation data. We will present on-axis light curves for both constant density and wind media. We will also present off-axis light curves relevant for searches for orphan afterglows. We find that jet breaks are smoothed due to both off-axis viewing and wind media effects. 2.) Non-thermal radiation mechanisms in GRB afterglows require substantial magnetic field strengths. In turbulence driven by shear instabilities in relativistic magnetized gas, we demonstrate that magnetic field is naturally amplified to half a percent of the total energy (epsilon B = 0.005). We will show high resolution three dimensional relativistic MHD simulations of this process as well as particle in cell (PIC) simulations of mildly relativistic collisionless shocks.

  18. Structure in the early afterglow light curve of the gamma-ray burst of 29 March 2003.

    Science.gov (United States)

    Uemura, Makoto; Kato, Taichi; Ishioka, Ryoko; Yamaoka, Hitoshi; Monard, Berto; Nogami, Daisaku; Maehara, Hiroyuki; Sugie, Atsushi; Takahashi, Susumu

    2003-06-19

    Gamma-ray bursts (GRBs) are energetic explosions that for 0.01-100 s are the brightest gamma-ray sources in the sky. Observations of the early evolution of afterglows are expected to provide clues about the nature of the bursts, but their rapid fading has hampered such studies; some recent rapid localizations of bursts have improved the situation. Here we report an early detection of the very bright afterglow of the burst of 29 March 2003 (GRB030329). Our data show that, even early in the afterglow phase, the light curve shows unexpectedly complicated structures superimposed on the fading background.

  19. Interpretation of photometric observations of R Coronae Borealis. Light curves

    International Nuclear Information System (INIS)

    Pugach, A.F.

    1990-01-01

    The calculations confirm the 'reptive hypothesis' of light variations of R CrB. The central point of the hypothesis is an assertion of infinite expansion of an elementary dust cloud. The calculations for different masses of the dust cloud provide a set of elementary light curves. Superposition of the curves yields a complex light curve. The comparison with the observed minima of 1972 has been performed

  20. Rectification of light refraction in curved waveguide arrays.

    Science.gov (United States)

    Longhi, Stefano

    2009-02-15

    An "optical ratchet" for discretized light in photonic lattices, which enables observing rectification of light refraction at any input beam conditions, is theoretically presented, and a possible experimental implementation based on periodically curved zigzag waveguide arrays is proposed.

  1. Rectification of light refraction in curved waveguide arrays

    OpenAIRE

    Longhi, S.

    2010-01-01

    An 'optical ratchet' for discretized light in photonic lattices, which enables to observe rectification of light refraction at any input beam conditions, is theoretically presented, and a possible experimental implementation based on periodically-curved zigzag waveguide arrays is proposed.

  2. A COMPREHENSIVE ANALYSIS OF SWIFT/X-RAY TELESCOPE DATA. IV. SINGLE POWER-LAW DECAYING LIGHT CURVES VERSUS CANONICAL LIGHT CURVES AND IMPLICATIONS FOR A UNIFIED ORIGIN OF X-RAYS

    International Nuclear Information System (INIS)

    Liang Enwei; Lue Houjun; Hou Shujin; Zhang Binbin; Zhang Bing

    2009-01-01

    By systematically analyzing the Swift/XRT light curves detected before 2009 July, we find 19 light curves that monotonously decay as a single power law (SPL) with an index of 1 ∼ 1.7 from tens (or hundreds) of seconds to ∼10 5 s post the gamma-ray burst (GRB) trigger. They are apparently different from the canonical light curves characterized by a shallow-to-normal decay transition. We compare the observations of the prompt gamma rays and the X-rays for these two samples of GRBs (SPL vs. canonical). No statistical difference is found in the prompt gamma-ray properties for the two samples. The X-ray properties of the two samples are also similar, although the SPL sample tends to have a slightly lower neutral hydrogen absorption column for the host galaxies and a slightly larger energy release compared with the canonical sample. The SPL X-ray Telescope (XRT) light curves in the burst frame gradually merge into a conflux, and their luminosities at 10 5 s are normally distributed at log L/ergs s -1 = 45.6 ± 0.5. The normal decay segment of the canonical XRT light curves has the same feature. Similar to the normal decay segment, the SPL light curves satisfy the closure relations and therefore can be roughly explained with external shock models. In the scenario that the X-rays are the afterglows of the GRB fireball, our results indicate that the shallow decay would be due to energy injection into the fireball and the total energy budget after injection for both samples of GRBs is comparable. More intriguing, we find that a prior X-ray emission model proposed by Yamazaki is more straightforward to interpret the observed XRT data. We show that the zero times (T 0 ) of the X-rays are 10 2 -10 5 s prior to the GRB trigger for the canonical sample, and satisfy a log-normal distribution. The negligible T 0 's of the SPL sample are consistent with being the tail of T 0 distributions at low end, suggesting that the SPL sample and the canonical sample may be from a same

  3. Multi-messenger Light Curves from Gamma-Ray Bursts in the Internal Shock Model

    Energy Technology Data Exchange (ETDEWEB)

    Bustamante, Mauricio [Center for Cosmology and AstroParticle Physics (CCAPP), The Ohio State University, Columbus, OH 43210 (United States); Heinze, Jonas; Winter, Walter [Deutsches Elektronen-Synchrotron (DESY), Platanenallee 6, D-15738 Zeuthen (Germany); Murase, Kohta, E-mail: bustamanteramirez.1@osu.edu, E-mail: walter.winter@desy.de, E-mail: jonas.heinze@desy.de, E-mail: murase@psu.edu [Center for Particle and Gravitational Astrophysics, The Pennsylvania State University, University Park, PA16802 (United States)

    2017-03-01

    Gamma-ray bursts (GRBs) are promising as sources of neutrinos and cosmic rays. In the internal shock scenario, blobs of plasma emitted from a central engine collide within a relativistic jet and form shocks, leading to particle acceleration and emission. Motivated by present experimental constraints and sensitivities, we improve the predictions of particle emission by investigating time-dependent effects from multiple shocks. We produce synthetic light curves with different variability timescales that stem from properties of the central engine. For individual GRBs, qualitative conclusions about model parameters, neutrino production efficiency, and delays in high-energy gamma-rays can be deduced from inspection of the gamma-ray light curves. GRBs with fast time variability without additional prominent pulse structure tend to be efficient neutrino emitters, whereas GRBs with fast variability modulated by a broad pulse structure can be inefficient neutrino emitters and produce delayed high-energy gamma-ray signals. Our results can be applied to quantitative tests of the GRB origin of ultra-high-energy cosmic rays, and have the potential to impact current and future multi-messenger searches.

  4. Multi-messenger light curves from gamma-ray bursts in the internal shock model

    Energy Technology Data Exchange (ETDEWEB)

    Bustamante, Mauricio [Ohio State Univ., Columbus, OH (United States). Center for Cosmology and AstroParticle Physics (CCAPP); Ohio State Univ., Columbus, OH (United States). Dept. of Physics; Murase, Kohta [Pennsylvania State Univ., University Park, PA (United States). Center for Particle and Gravitational Astrophysics; Pennsylvania State Univ., University Park, PA (United States). Dept. of Astronomy and Astrophysics; Winter, Walter [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)

    2016-06-15

    Gamma-ray bursts (GRBs) are promising as sources of neutrinos and cosmic rays. In the internal shock scenario, blobs of plasma emitted from a central engine collide within a relativistic jet and form shocks, leading to particle acceleration and emission. Motivated by present experimental constraints and sensitivities, we improve the predictions of particle emission by investigating time-dependent effects from multiple shocks. We produce synthetic light curves with different variability timescales that stem from properties of the central engine. For individual GRBs, qualitative conclusions about model parameters, neutrino production efficiency, and delays in high-energy gamma rays can be deduced from inspection of the gamma-ray light curves. GRBs with fast time variability without additional prominent pulse structure tend to be efficient neutrino emitters, whereas GRBs with fast variability modulated by a broad pulse structure tend to be inefficient neutrino emitters and produce delayed high-energy gamma-ray signals. Our results can be applied to quantitative tests of the GRB origin of ultra-high-energy cosmic rays, and have the potential to impact current and future multi-messenger searches.

  5. An Alternate Light Curve Solution of AR Lacertae

    Directory of Open Access Journals (Sweden)

    Hong Suh Park

    1984-09-01

    Full Text Available Photoelectric UBV light curves of AR Lacertae made in one season during 1981-82 are presented. Although the shape of the light curves in the outside eclipses show a strong distortion, the scatter of observations as well as phase coverage are better than those previously available. Fourier coefficients are derived from the V-light curve and observed curve successfully rectified to the Russell model. Light curve solutions are computed and the geometrical and physical parameters of AR Lac are derived as as = 0.812, ag = 0.341, j = 86°3, Ls = 0.372, Lg = 0.628, k = 0.53, Xs = 0.85, Xg = 0.4.

  6. Temporal Evolution of the Gamma-ray Burst Afterglow Spectrum for an Observer: GeV–TeV Synchrotron Self-Compton Light Curve

    Energy Technology Data Exchange (ETDEWEB)

    Fukushima, Takuma; Fujita, Yutaka [Department of Earth and Space Science, Osaka University, Osaka, 560-0043 (Japan); To, Sho; Asano, Katsuaki, E-mail: fukushima@vega.ess.sci.osaka-u.ac.jp, E-mail: fujita@vega.ess.sci.osaka-u.ac.jp, E-mail: tosho@icrr.u-tokyo.ac.jp, E-mail: asanok@icrr.u-tokyo.ac.jp [Institute for Cosmic Ray Research, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8582 (Japan)

    2017-08-01

    We numerically simulate the gamma-ray burst (GRB) afterglow emission with a one-zone time-dependent code. The temporal evolutions of the decelerating shocked shell and energy distributions of electrons and photons are consistently calculated. The photon spectrum and light curves for an observer are obtained taking into account the relativistic propagation of the shocked shell and the curvature of the emission surface. We find that the onset time of the afterglow is significantly earlier than the previous analytical estimate. The analytical formulae of the shock propagation and light curve for the radiative case are also different from our results. Our results show that even if the emission mechanism is switching from synchrotron to synchrotron self-Compton, the gamma-ray light curves can be a smooth power law, which agrees with the observed light curve and the late detection of a 32 GeV photon in GRB 130427A. The uncertainty of the model parameters obtained with the analytical formula is discussed, especially in connection with the closure relation between spectral index and decay index.

  7. A tale of two GRB-SNe at a common redshift of ζ = 0.54

    International Nuclear Information System (INIS)

    Cano, Z.; Bersier, D.; Kobayashi, S.; Clay, N.; Mottram, C.; Mundell, C.G.; Small, E.; Smith, R.J.; Steele, I.; Guidorzi, C.; Curran, P.A.

    2011-01-01

    We present ground-based and Hubble Space Telescope optical observations of the optical transients (OTs) of long-duration Gamma Ray Bursts (GRBs) 060729 and 090618, both at a redshift of z=0.54. For GRB 060729, bumps are seen in the optical light curves (LCs), and the late-time broad-band spectral energy distributions (SEDs) of the OT resemble those of local Type Ic supernovae (SNe). For GRB 090618, the dense sampling of our optical observations has allowed us to detect well-defined bumps in the optical LCs, as well as a change in colour, that are indicative of light coming from a core-collapse SN. The accompanying SNe for both events are individually compared with SN1998bw, a known GRB supernova, and SN1994I, a typical Type Ic supernova without a known GRB counterpart, and in both cases the brightness and temporal evolution more closely resemble SN1998bw. We also exploit our extensive optical and radio data for GRB 090618, as well as the publicly available Swift-XRT data, and discuss the properties of the afterglow at early times. In the context of a simple jet-like model, the afterglow of GRB 090618 is best explained by the presence of a jet-break at t - t 0 ≥ 0.5 d. We then compare the rest-frame, peak V-band absolute magnitudes of all of the GRB and X-Ray Flash (XRF)-associated SNe with a large sample of local Type Ibc SNe, concluding that, when host extinction is considered, the peak magnitudes of the GRB/XRF-SNe cannot be distinguished from the peak magnitudes of non-GRB/XRF SNe. (authors)

  8. Explosions and light curves of supernovae

    International Nuclear Information System (INIS)

    Gaffet, B.

    1975-01-01

    The models developed to explain supernovae explosions are reviewed. The first one is thermonuclear explosion (simple or preceded by an implosion phase); the neutrino emission which results of such an explosion can have an important dynamical effect, according as the star is opaque or transparent to them; another theory involves the radiation pressure of the pulsar which is formed in the center of the star. The origin of the supernovae brightness is also uncertain: the initial heat due to the explosion does not seem to be sufficient; the brightness can result from the diffusion of the heat through the ejected matter or can be transported more rapidly by a shock wave. A model in which the heat is produced by the pulsar seems compatible with most observations (shapes of the brightness curves and the continuum spectra, expansion velocities, temperature and luminosity at the peak, total kinetic energy) [fr

  9. Light Curve Solution of the Contact Binary AW UMa

    Directory of Open Access Journals (Sweden)

    J. H. Jeong

    1997-12-01

    Full Text Available A total of 1088 observations (272 in B,272 in V, 272 in R, and 272 in I were made from January to February in 1995 at Chungbuk National University observatory(CbNUO. We constructed BVRI light curves with our data. The photometric solution of these light curves was obtained by means of the Wilson-Devinney method. Our result was compared with those by previous investigators.

  10. EVEREST: Pixel Level Decorrelation of K2 Light Curves

    Science.gov (United States)

    Luger, Rodrigo; Agol, Eric; Kruse, Ethan; Barnes, Rory; Becker, Andrew; Foreman-Mackey, Daniel; Deming, Drake

    2016-10-01

    We present EPIC Variability Extraction and Removal for Exoplanet Science Targets (EVEREST), an open-source pipeline for removing instrumental noise from K2 light curves. EVEREST employs a variant of pixel level decorrelation to remove systematics introduced by the spacecraft’s pointing error and a Gaussian process to capture astrophysical variability. We apply EVEREST to all K2 targets in campaigns 0-7, yielding light curves with precision comparable to that of the original Kepler mission for stars brighter than {K}p≈ 13, and within a factor of two of the Kepler precision for fainter targets. We perform cross-validation and transit injection and recovery tests to validate the pipeline, and compare our light curves to the other de-trended light curves available for download at the MAST High Level Science Products archive. We find that EVEREST achieves the highest average precision of any of these pipelines for unsaturated K2 stars. The improved precision of these light curves will aid in exoplanet detection and characterization, investigations of stellar variability, asteroseismology, and other photometric studies. The EVEREST pipeline can also easily be applied to future surveys, such as the TESS mission, to correct for instrumental systematics and enable the detection of low signal-to-noise transiting exoplanets. The EVEREST light curves and the source code used to generate them are freely available online.

  11. Optical and IR light curves of VV Puppis

    International Nuclear Information System (INIS)

    Szkody, P.; Bailey, J.A.; Hough, J.H.

    1983-01-01

    We present optical (0.36 to 0.6 μm) light curves with time resolutions of seconds and infrared (IR) (1.25 to 2.2 μm) light curves with time resolutions of minutes for VV Puppis during a high state. The optical light curves show a single hump with largest amplitude in the V filter, while the IR light curves show a double hump sinusoidal variation. Flickering is evident in both the optical and IR light curves, with the largest amplitude in optical B light. Through subtraction of the low state fluxes from our high state values, we obtain a flux distribution of the accretion column which peaks at 0.55 μm and becomes #betta# 2 in the IR, consistent with current cyclotron models. Comparison of the observed IR variations throughout the orbit with the expected variations due to an M4 star heated by an accretion column at an inclination of 66 0 suggests that the IR light is a combination of the secondary star plus contributions from two emitting poles. (author)

  12. Early GRB optical and infrared afterglow observations with the 2-m robotic Liverpool Telescope

    International Nuclear Information System (INIS)

    Gomboc, A.; Ljubljana Univ., Ljubljana; Mundell, C.G.; Guidorzi, C.

    2005-01-01

    We present the first optical observations of a Gamma Ray Burst IGRB) afterglow using the 2-m robotic Liverpool Telescope (LT), which is owned and operated by Liverpool John Moores University and situated on La Palma. We briefly discuss the capabilities of LT and its suitability for rapid follow-up observations of early optical and infrared GRB light curves. In particular, the combination of aperture, site, instrumentation and rapid response (robotic over-ride mode aided by telescope's rapid slew and fully-opening enclosure) makes the LT ideal for investigating the nature of short bursts, optically-dark bursts, and GRB blast-wave physics in general. We briefly describe the LT's key position in the RoboNet-1.0 network of robotic telescopes. We present the LT observations of GRB041006 and use its gamma-ray properties to predict the time of the break in optical light curve, a prediction consistent with the observations

  13. ENERGETIC FERMI/LAT GRB 100414A: ENERGETIC AND CORRELATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Urata, Yuji; Tsai, Patrick P. [Institute of Astronomy, National Central University, Chung-Li 32054, Taiwan (China); Huang, Kuiyun [Academia Sinica Institute of Astronomy and Astrophysics, Taipei 106, Taiwan (China); Yamaoka, Kazutaka [Department of Physics and Mathematics, Aoyama Gakuin University, 5-10-1, Fuchinobe, Sayamihara 229-8558 (Japan); Tashiro, Makoto S., E-mail: urata@astro.ncu.edu.tw [Department of Physics, Saitama University, Shimo-Okubo, Saitama 338-8570 (Japan)

    2012-03-20

    This study presents multi-wavelength observational results for energetic GRB 100414A with GeV photons. The prompt spectral fitting using Suzaku/WAM data yielded spectral peak energies of E{sup src}{sub peak} of 1458.7{sup +132.6}{sub -106.6} keV and E{sub iso} of 34.5{sup +2.0}{sub -1.8} Multiplication-Sign 10{sup 52} erg with z = 1.368. The optical afterglow light curves between 3 and 7 days were effectively fitted according to a simple power law with a temporal index of {alpha} = -2.6 {+-} 0.1. The joint light curve with earlier Swift/UVOT observations yields a temporal break at 2.3 {+-} 0.2 days. This was the first Fermi/LAT detected event that demonstrated the clear temporal break in the optical afterglow. The jet opening angle derived from this temporal break was 5.{sup 0}8, consistent with those of other well-observed long gamma-ray bursts (GRBs). The multi-wavelength analyses in this study showed that GRB 100414A follows E{sup src}{sub peak}-E{sub iso} and E{sup src}{sub peak}-E{sub {gamma}} correlations. The late afterglow revealed a flatter evolution with significant excesses at 27.2 days. The most straightforward explanation for the excess is that GRB 100414A was accompanied by a contemporaneous supernova. The model light curve based on other GRB-SN events is marginally consistent with that of the observed light curve.

  14. Closed Paths of Light Trapped in a Closed Fermat Curve

    Science.gov (United States)

    Dana-Picard, Thierry; Naiman, Aaron

    2002-01-01

    Geometric constructions have previously been shown that can be interpreted as rays of light trapped either in polygons or in conics, by successive reflections. The same question, trapping light in closed Fermat curves, is addressed here. Numerical methods are used to study the behaviour of the reflection points of a triangle when the degree of the…

  15. Automated Blazar Light Curves Using Machine Learning

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Spencer James [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-07-27

    Every night in a remote clearing called Fenton Hill high in the Jemez Mountains of central New Mexico, a bank of robotically controlled telescopes tilt their lenses to the sky for another round of observation through digital imaging. Los Alamos National Laboratory’s Thinking Telescopes project is watching for celestial transients including high-power cosmic flashes called, and like all science, it can be messy work. To keep the project clicking along, Los Alamos scientists routinely install equipment upgrades, maintain the site, and refine the sophisticated machinelearning computer programs that process those images and extract useful data from them. Each week the system amasses 100,000 digital images of the heavens, some of which are compromised by clouds, wind gusts, focus problems, and so on. For a graduate student at the Lab taking a year’s break between master’s and Ph.D. studies, working with state-of-the-art autonomous telescopes that can make fundamental discoveries feels light years beyond the classroom.

  16. Implications of the Early X-Ray Afterglow Light Curves of Swift GRBs

    Energy Technology Data Exchange (ETDEWEB)

    Granot, Jonathan; /KIPAC, Menlo Park; Konigl, Arieh; /Chicago U., Astron. Astrophys. Ctr. /Chicago U., EFI; Piran, Tsvi; /Hebrew U.

    2006-01-17

    According to current models, gamma-ray bursts (GRBs) are produced when the energy carried by a relativistic outflow is dissipated and converted into radiation. The efficiency of this process, {epsilon}{sub {gamma}}, is one of the critical factors in any GRB model. The X-ray afterglow light curves of Swift GRBs show an early stage of flattish decay. This has been interpreted as reflecting energy injection. When combined with previous estimates, which have concluded that the kinetic energy of the late ({approx}> 10 hr) afterglow is comparable to the energy emitted in {gamma}-rays, this interpretation implies very high values of {epsilon}{sub {gamma}}, corresponding to {approx}> 90% of the initial energy being converted into {gamma}-rays. Such a high efficiency is hard to reconcile with most models, including in particular the popular internal-shocks model. We re-analyze the derivation of the kinetic energy from the afterglow X-ray flux and re-examine the resulting estimates of the efficiency. We confirm that, if the flattish decay arises from energy injection and the pre-Swift broad-band estimates of the kinetic energy are correct, then {epsilon}{sub {gamma}} {approx}> 0.9. We discuss various issues related to this result, including an alternative interpretation of the light curve in terms of a two-component outflow model, which we apply to the X-ray observations of GRB 050315. We point out, however, that another interpretation of the flattish decay--a variable X-ray afterglow efficiency (e.g., due to a time dependence of afterglow shock microphysical parameters)--is possible. We also show that direct estimates of the kinetic energy from the late X-ray afterglow flux are sensitive to the assumed values of the shock microphysical parameters and suggest that broad-band afterglow fits might have underestimated the kinetic energy (e.g., by overestimating the fraction of electrons that are accelerated to relativistic energies). Either one of these possibilities implies a

  17. SPITZER SPACE TELESCOPE MID-IR LIGHT CURVES OF NEPTUNE

    Energy Technology Data Exchange (ETDEWEB)

    Stauffer, John; Rebull, Luisa; Carey, Sean J.; Krick, Jessica; Ingalls, James G.; Lowrance, Patrick; Glaccum, William [Spitzer Science Center (SSC), California Institute of Technology, Pasadena, CA 91125 (United States); Marley, Mark S. [NASA Ames Research Center, Space Sciences and Astrobiology Division, MS245-3, Moffett Field, CA 94035 (United States); Gizis, John E. [Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States); Kirkpatrick, J. Davy [Infrared Processing and Analysis Center, MS 100-22, California Institute of Technology, Pasadena, CA 91125 (United States); Simon, Amy A. [NASA Goddard Space Flight Center, Solar System Exploration Division (690.0), 8800 Greenbelt Road, Greenbelt, MD 20771 (United States); Wong, Michael H. [University of California, Department of Astronomy, Berkeley CA 94720-3411 (United States)

    2016-11-01

    We have used the Spitzer Space Telescope in 2016 February to obtain high cadence, high signal-to-noise, 17 hr duration light curves of Neptune at 3.6 and 4.5 μ m. The light curve duration was chosen to correspond to the rotation period of Neptune. Both light curves are slowly varying with time, with full amplitudes of 1.1 mag at 3.6 μ m and 0.6 mag at 4.5 μ m. We have also extracted sparsely sampled 18 hr light curves of Neptune at W1 (3.4 μ m) and W2 (4.6 μ m) from the Wide-feld Infrared Survey Explorer ( WISE )/ NEOWISE archive at six epochs in 2010–2015. These light curves all show similar shapes and amplitudes compared to the Spitzer light curves but with considerable variation from epoch to epoch. These amplitudes are much larger than those observed with Kepler / K 2 in the visible (amplitude ∼0.02 mag) or at 845 nm with the Hubble Space Telescope ( HST ) in 2015 and at 763 nm in 2016 (amplitude ∼0.2 mag). We interpret the Spitzer and WISE light curves as arising entirely from reflected solar photons, from higher levels in Neptune’s atmosphere than for K 2. Methane gas is the dominant opacity source in Neptune’s atmosphere, and methane absorption bands are present in the HST 763 and 845 nm, WISE W1, and Spitzer 3.6 μ m filters.

  18. A tale of two GRB-SNe at a common redshift of z=0.54

    NARCIS (Netherlands)

    Cano, Z.; Bersier, D.; Guidorzi, C.; Margutti, R.; Svensson, K.M.; Kobayashi, S.; Melandri, A.; Wiersema, K.; Pozanenko, A.; van der Horst, A.J.; Pooley, G.G.; Fernandez-Soto, A.; Castro-Tirado, A.J.; de Ugarte Postigo, A.; Im, M.; Kamble, A.P.; Sahu, D.; Alonso-Lorite, J.; Anupama, G.; Bibby, J.L.; Burgdorf, M.J.; Clay, N.; Curran, P.A.; Fatkhullin, T.A.; Fruchter, A.S.; Garnavich, P.; Gomboc, A.; Gorosabel, J.; Graham, J.F.; Gurugubelli, U.; Haislip, J.; Huang, K.; Huxor, A.; Ibrahimov, M.; Jeon, Y.; Jeon, Y.B.; Ivarsen, K.; Kasen, D.; Klunko, E.; Kouveliotou, C.; Lacluyze, A.; Levan, A.J.; Loznikov, V.; Mazzali, P.A.; Moskvitin, A.S.; Mottram, C.; Mundell, C.G.; Nugent, P.E.; Nysewander, M.; O'Brien, P.T.; Park, W.K.; Peris, V.; Pian, E.; Reichart, D.; Rhoads, J.E.; Rol, E.; Rumyantsev, V.; Scowcroft, V.; Shakhovskoy, D.; Small, E.; Smith, R.J.; Sokolov, V.V.; Starling, R.L.C.; Steele, I.; Strom, R.G.; Tanvir, N.R.; Tsapras, Y.; Urata, Y.; Vaduvescu, O.; Volnova, A.; Volvach, A.; Wijers, R.A.M.J.; Woosley, S.E.; Young, D.R.

    2011-01-01

    We present ground-based and Hubble Space Telescope optical observations of the optical transients (OTs) of long-duration Gamma Ray Bursts (GRBs) 060729 and 090618, both at a redshift of z= 0.54. For GRB 060729, bumps are seen in the optical light curves (LCs), and the late-time broad-band spectral

  19. The rapidly flaring afterglow of the very bright and energetic GRB 070125

    NARCIS (Netherlands)

    Updike, A.C.; Haislip, J.B.; Nysewander, M.C.; Fruchter, A.S.; Kann, D.A.; Klose, S.; Milne, P.A.; Williams, G.G.; Zheng, W.; Hergenrother, C.W.; Prochaska, J.X.; Halpern, J.P.; Mirabal, N.; Thorstensen, J.R.; van der Horst, A.J.; Starling, R.L.C.; Racusin, J.L.; Burrows, D.N.; Kuin, N.P.M.; Roming, P.W.A.; Bellm, E.; Hurley, K.; Li, W.; Filippenko, A.V.; Blake, C.; Starr, D.; Falco, E.E.; Brown, W.R.; Dai, X.; Deng, J.; Xin, L.; Qiu, Y.; Wei, J.; Urata, Y.; Nanni, D.; Maiorano, E.; Palazzi, E.; Greco, G.; Bartolini, C.; Guarnieri, A.; Piccioni, A.; Pizzichini, G.; Terra, F.; Misra, K.; Bhatt, B.C.; Anupama, G.C.; Fan, X.; Jiang, L.; Wijers, R.A.M.J.; Reichart, D.E.; Eid, H.A.; Bryngelson, G.; Puls, J.; Goldthwaite, R.C.; Hartmann, D.H.

    2008-01-01

    We report on multiwavelength observations, ranging from X-ray to radio wave bands, of the IPN-localized gamma-ray burst GRB 070125. Spectroscopic observations reveal the presence of absorption lines due to O I, Si II, and C IV, implying a likely redshift of z = 1.547. The well-sampled light curves,

  20. GRB 051008

    DEFF Research Database (Denmark)

    Volnova, A. A.; Pozanenko, A. S.; Gorosabel, J.

    2014-01-01

    due to the presence of a clear, strong Lyman-break feature. The host galaxy is a small starburst galaxy with moderate intrinsic extinction (AV = 0.3) and has a star formation rate of ∼60 M⊙ yr−1 typical for LBGs. It is one of the few cases where a GRB host has been found to be a classical LBG. Using...

  1. The bright optical afterglow of the long GRB 001007

    DEFF Research Database (Denmark)

    Ceron, J.M.C.; Castro-Tirado, A.J.; Gorosabel, J.

    2002-01-01

    We present optical follow up observations of the long GRB 001007 between 6.14 hours and similar to468 days after the event. An unusually bright optical afterglow (OA) was seen to decline following a steep power law decay with index alpha = -2.03 +/- 0.11, possibly indicating a break in the light...... curve at t - t(0) hours after the gamma ray event provide tentative (1.2σ) evidence for a break in the optical light curve. The spectral index β of the OA yields -1.24 +/- 0.57. These values may be explained both...

  2. Exploring Algorithms for Stellar Light Curves With TESS

    Science.gov (United States)

    Buzasi, Derek

    2018-01-01

    The Kepler and K2 missions have produced tens of thousands of stellar light curves, which have been used to measure rotation periods, characterize photometric activity levels, and explore phenomena such as differential rotation. The quasi-periodic nature of rotational light curves, combined with the potential presence of additional periodicities not due to rotation, complicates the analysis of these time series and makes characterization of uncertainties difficult. A variety of algorithms have been used for the extraction of rotational signals, including autocorrelation functions, discrete Fourier transforms, Lomb-Scargle periodograms, wavelet transforms, and the Hilbert-Huang transform. In addition, in the case of K2 a number of different pipelines have been used to produce initial detrended light curves from the raw image frames.In the near future, TESS photometry, particularly that deriving from the full-frame images, will dramatically further expand the number of such light curves, but details of the pipeline to be used to produce photometry from the FFIs remain under development. K2 data offers us an opportunity to explore the utility of different reduction and analysis tool combinations applied to these astrophysically important tasks. In this work, we apply a wide range of algorithms to light curves produced by a number of popular K2 pipeline products to better understand the advantages and limitations of each approach and provide guidance for the most reliable and most efficient analysis of TESS stellar data.

  3. QUEST1 Variability Survey. III. Light Curve Catalog Update

    Science.gov (United States)

    Rengstorf, A. W.; Thompson, D. L.; Mufson, S. L.; Andrews, P.; Honeycutt, R. K.; Vivas, A. K.; Abad, C.; Adams, B.; Bailyn, C.; Baltay, C.; Bongiovanni, A.; Briceño, C.; Bruzual, G.; Coppi, P.; Della Prugna, F.; Emmet, W.; Ferrín, I.; Fuenmayor, F.; Gebhard, M.; Hernández, J.; Magris, G.; Musser, J.; Naranjo, O.; Oemler, A.; Rosenzweig, P.; Sabbey, C. N.; Sánchez, Ge.; Sánchez, Gu.; Schaefer, B.; Schenner, H.; Sinnott, J.; Snyder, J. A.; Sofia, S.; Stock, J.; van Altena, W.

    2009-03-01

    This paper reports an update to the QUEST1 (QUasar Equatorial Survey Team, Phase 1) Variability Survey (QVS) light curve catalog, which links QVS instrumental magnitude light curves to Sloan Digital Sky Survey (SDSS) objects and photometry. In the time since the original QVS catalog release, the overlap between publicly available SDSS data and QVS data has increased by 8% in sky coverage and 16,728 in number of matched objects. The astrometric matching and the treatment of SDSS masks have been refined for the updated catalog. We report on these improvements and present multiple bandpass light curves, global variability information, and matched SDSS photometry for 214,941 QUEST1 objects. Based on observations obtained at the Llano del Hato National Astronomical Observatory, operated by the Centro de Investigaciones de Astronomía for the Ministerio de Ciencia y Tecnologia of Venezuela.

  4. THE FIRST SYSTEMATIC STUDY OF TYPE Ibc SUPERNOVA MULTI-BAND LIGHT CURVES

    International Nuclear Information System (INIS)

    Drout, Maria R.; Soderberg, Alicia M.; Gal-Yam, Avishay; Arcavi, Iair; Green, Yoav; Cenko, S. Bradley; Fox, Derek B.; Leonard, Douglas C.; Sand, David J.; Moon, Dae-Sik

    2011-01-01

    We present detailed optical photometry for 25 Type Ibc supernovae (SNe Ibc) within d ≈ 150 Mpc obtained with the robotic Palomar 60 inch telescope in 2004-2007. This study represents the first uniform, systematic, and statistical sample of multi-band SNe Ibc light curves available to date. We correct the light curves for host galaxy extinction using a new technique based on the photometric color evolution, namely, we show that the (V – R) color of extinction-corrected SNe Ibc at Δt ≈ 10 days after V-band maximum is tightly distributed, ((V – R) V10 ) = 0.26 ± 0.06 mag. Using this technique, we find that SNe Ibc typically suffer from significant host galaxy extinction, (E(B – V)) ≈ 0.4 mag. A comparison of the extinction-corrected light curves for helium-rich (Type Ib) and helium-poor (Type Ic) SNe reveals that they are statistically indistinguishable, both in luminosity and decline rate. We report peak absolute magnitudes of (M R ) = –17.9 ± 0.9 mag and (M R ) = –18.3 ± 0.6 mag for SNe Ib and Ic, respectively. Focusing on the broad-lined (BL) SNe Ic, we find that they are more luminous than the normal SNe Ibc sample, (M R ) = –19.0 ± 1.1 mag, with a probability of only 1.6% that they are drawn from the same population of explosions. By comparing the peak absolute magnitudes of SNe Ic-BL with those inferred for local engine-driven explosions (GRB-SN 1998bw, XRF-SN 2006aj, and SN 2009bb) we find a 25% probability that relativistic SNe are drawn from the overall SNe Ic-BL population. Finally, we fit analytic models to the light curves to derive typical 56 Ni masses of M Ni ≈ 0.2 and 0.5 M ☉ for SNe Ibc and SNe Ic-BL, respectively. With reasonable assumptions for the photospheric velocities, we further extract kinetic energy and ejecta mass values of M ej ≈ 2 M ☉ and E K ≈ 10 51 erg for SNe Ibc, while for SNe Ic-BL we find higher values, M ej ≈ 5 M ☉ and E K ≈ 10 52 erg. We discuss the implications for the progenitors of SNe Ibc

  5. Multiperiodicity in the light curve of Alpha Orionis

    International Nuclear Information System (INIS)

    Karovska, M.

    1987-01-01

    Alpha Ori, a supergiant star classified as M2 Iab, is characterized by pronounced variability encompassing most of its observed parameters. Variability on two different time scales has been observed in the light and velocity curves: a long period variation of about 6 years and superposed on this, irregular fluctuations having a time scale of several hundred days. This paper reports the results of Fourier analysis of more than 60- years of AAVSO (American Association of Variable Stars Observers) data which suggest a multiperiodicity in the light curve of α Ori

  6. On Some Statistical Properties of GRBs with Measured Redshifts Having Peaks in Optical Light Curves

    Directory of Open Access Journals (Sweden)

    Grigorii Beskin

    2013-01-01

    Full Text Available We studied the subset of optical light curves of gamma-ray bursts with measured redshifts and well-sampled R band data that have clearly detected peaks. Among 43 such events, 11 are promptoptical peaks (P, coincident with gamma-ray activity, 22 are purely afterglows (A, and 10 more carrythe signatures of an underlying activity (A(U. We studied pair correlations of their gamma-ray andoptical parameters, e.g. total energetics, peak optical luminosities, and durations. The main outcomeof our study is the detection of source frame correlations between both optical peak luminosity and total energy and the redshift for classes A and A(U, and the absence of such a correlation for class Pevents. This result seems to provide evidence of the cosmological evolution of a medium around the burst defining class A and A(U energetics, and the absence of cosmological evolution of the internal properties of GRB engines. We also discuss some other prominent correlations.

  7. Characterizing high-energy light curves of Fermi/Lat GRBs

    Energy Technology Data Exchange (ETDEWEB)

    Gillette, Jarred [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-08-21

    A systematic analysis of the light curves of Gamma-Ray Burst (GRBs) with redshift and detected at high-energy (> 100 MeV) by Fermi/LAT has never been done before our work, because there were only a handful of detections. Now we have 20 of those, which we can use to characterize the GRBs in their rest frame. We compared a characteristic decay times Tc of GRBs with redshifts using the new “Pass 8” data, and used a Crystal Ball function to parametrize GRB characteristics. An unexpected anti-correlation between Tc and the peak flux was observed. This means that brighter peaked GRBs have shorter durations. There is also no correlation between the Tc and the decay index, which makes the anti-correlation with brightness more clear. This results appears to be consistent with the External Shock model, which is one of the competing hypothesis on the origin of the high-energy emission. We did not observe any bimodality, which is seen in GRBs at lower energies.

  8. Gamma-ray Burst X-ray Flares Light Curve Fitting

    Science.gov (United States)

    Aubain, Jonisha

    2018-01-01

    Gamma Ray Bursts (GRBs) are the most luminous explosions in the Universe. These electromagnetic explosions produce jets demonstrated by a short burst of prompt gamma-ray emission followed by a broadband afterglow. There are sharp increases of flux in the X-ray light curves known as flares that occurs in about 50% of the afterglows. In this study, we characterized all of the X-ray afterglows that were detected by the Swift X-ray Telescope (XRT), whether with flares or without. We fit flares to the Norris function (Norris et al. 2005) and power laws with breaks where necessary (Racusin et al. 2009). After fitting the Norris function and power laws, we search for the residual pattern detected in prompt GRB pulses (Hakkila et al. 2014, 2015, 2017), that may indicate a common signature of shock physics. If we find the same signature in flares and prompt pulses, it provides insight into what causes them, as well as, how these flares are produced.

  9. The Kepler Light Curves of AGN: A Detailed Analysis

    Science.gov (United States)

    Smith, Krista Lynne; Mushotzky, Richard F.; Boyd, Patricia T.; Malkan, Matt; Howell, Steve B.; Gelino, Dawn M.

    2018-04-01

    We present a comprehensive analysis of 21 light curves of Type 1 active galactic nuclei (AGN) from the Kepler spacecraft. First, we describe the necessity and development of a customized pipeline for treating Kepler data of stochastically variable sources like AGN. We then present the light curves, power spectral density functions (PSDs), and flux histograms. The light curves display an astonishing variety of behaviors, many of which would not be detected in ground-based studies, including switching between distinct flux levels. Six objects exhibit PSD flattening at characteristic timescales that roughly correlate with black hole mass. These timescales are consistent with orbital timescales or free-fall accretion timescales. We check for correlations of variability and high-frequency PSD slope with accretion rate, black hole mass, redshift, and luminosity. We find that bolometric luminosity is anticorrelated with both variability and steepness of the PSD slope. We do not find evidence of the linear rms–flux relationships or lognormal flux distributions found in X-ray AGN light curves, indicating that reprocessing is not a significant contributor to optical variability at the 0.1%–10% level.

  10. Orbital Signatures from Observed Light Curves of Blazars

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... Variability in active galactic nuclei is observed in UV to X-ray emission based light curves. This could be attributed to orbital signatures of the plasma that constitutes the accretion flow on the putative disk or in the developing jet close to the inner region of the central black hole. We discuss some theoretical ...

  11. The GO Cygni system: photoelectric observations and light curves analysis

    International Nuclear Information System (INIS)

    Rovithis, P.; Rovithis-Livaniou, H.; Niarchos, P.G.

    1990-01-01

    Photoelectric observations, in B and V, of the system GO Cygni obtained during 1985 at the Kryonerion Astronomical Station of the National Observatory of Greece are given. The corresponding light curves (typical β Lyrae) are analysed using Frequency Domain techniques. New photoelectric and absolute elements for the system are given, and its period was found to continue its increasing

  12. Photometric Observation and Light Curve Analysis of Binary System ...

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... Photometric Observation and Light Curve Analysis of Binary System ER-Orionis ... February to April 2008 with the 51 cm telescope of Biruni Observatory of Shiraz University in U, B and V filters (Johnson system) and an RCA 4509 photomultiplier. ... Articles are also visible in Web of Science immediately.

  13. Photometric Observation and Light Curve Analysis of Binary System ...

    Indian Academy of Sciences (India)

    Abstract. Photometric observations of the over-contact binary ER ORI were performed during November 2007 and February to April 2008 with the 51cm telescope of Biruni Observatory of Shiraz University in U, B and V filters (Johnson system) and an RCA 4509 photomultiplier. We used these data to obtain the light curves ...

  14. UNSUPERVISED TRANSIENT LIGHT CURVE ANALYSIS VIA HIERARCHICAL BAYESIAN INFERENCE

    Energy Technology Data Exchange (ETDEWEB)

    Sanders, N. E.; Soderberg, A. M. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Betancourt, M., E-mail: nsanders@cfa.harvard.edu [Department of Statistics, University of Warwick, Coventry CV4 7AL (United Kingdom)

    2015-02-10

    Historically, light curve studies of supernovae (SNe) and other transient classes have focused on individual objects with copious and high signal-to-noise observations. In the nascent era of wide field transient searches, objects with detailed observations are decreasing as a fraction of the overall known SN population, and this strategy sacrifices the majority of the information contained in the data about the underlying population of transients. A population level modeling approach, simultaneously fitting all available observations of objects in a transient sub-class of interest, fully mines the data to infer the properties of the population and avoids certain systematic biases. We present a novel hierarchical Bayesian statistical model for population level modeling of transient light curves, and discuss its implementation using an efficient Hamiltonian Monte Carlo technique. As a test case, we apply this model to the Type IIP SN sample from the Pan-STARRS1 Medium Deep Survey, consisting of 18,837 photometric observations of 76 SNe, corresponding to a joint posterior distribution with 9176 parameters under our model. Our hierarchical model fits provide improved constraints on light curve parameters relevant to the physical properties of their progenitor stars relative to modeling individual light curves alone. Moreover, we directly evaluate the probability for occurrence rates of unseen light curve characteristics from the model hyperparameters, addressing observational biases in survey methodology. We view this modeling framework as an unsupervised machine learning technique with the ability to maximize scientific returns from data to be collected by future wide field transient searches like LSST.

  15. UNSUPERVISED TRANSIENT LIGHT CURVE ANALYSIS VIA HIERARCHICAL BAYESIAN INFERENCE

    International Nuclear Information System (INIS)

    Sanders, N. E.; Soderberg, A. M.; Betancourt, M.

    2015-01-01

    Historically, light curve studies of supernovae (SNe) and other transient classes have focused on individual objects with copious and high signal-to-noise observations. In the nascent era of wide field transient searches, objects with detailed observations are decreasing as a fraction of the overall known SN population, and this strategy sacrifices the majority of the information contained in the data about the underlying population of transients. A population level modeling approach, simultaneously fitting all available observations of objects in a transient sub-class of interest, fully mines the data to infer the properties of the population and avoids certain systematic biases. We present a novel hierarchical Bayesian statistical model for population level modeling of transient light curves, and discuss its implementation using an efficient Hamiltonian Monte Carlo technique. As a test case, we apply this model to the Type IIP SN sample from the Pan-STARRS1 Medium Deep Survey, consisting of 18,837 photometric observations of 76 SNe, corresponding to a joint posterior distribution with 9176 parameters under our model. Our hierarchical model fits provide improved constraints on light curve parameters relevant to the physical properties of their progenitor stars relative to modeling individual light curves alone. Moreover, we directly evaluate the probability for occurrence rates of unseen light curve characteristics from the model hyperparameters, addressing observational biases in survey methodology. We view this modeling framework as an unsupervised machine learning technique with the ability to maximize scientific returns from data to be collected by future wide field transient searches like LSST

  16. The Supercritical Pile GRB Model: The Prompt to Afterglow Evolution

    Science.gov (United States)

    Mastichiadis, A.; Kazanas, D.

    2009-01-01

    The "Supercritical Pile" is a very economical GRB model that provides for the efficient conversion of the energy stored in the protons of a Relativistic Blast Wave (RBW) into radiation and at the same time produces - in the prompt GRB phase, even in the absence of any particle acceleration - a spectral peak at energy approx. 1 MeV. We extend this model to include the evolution of the RBW Lorentz factor Gamma and thus follow its spectral and temporal features into the early GRB afterglow stage. One of the novel features of the present treatment is the inclusion of the feedback of the GRB produced radiation on the evolution of Gamma with radius. This feedback and the presence of kinematic and dynamic thresholds in the model can be the sources of rich time evolution which we have began to explore. In particular. one can this may obtain afterglow light curves with steep decays followed by the more conventional flatter afterglow slopes, while at the same time preserving the desirable features of the model, i.e. the well defined relativistic electron source and radiative processes that produce the proper peak in the (nu)F(sub nu), spectra. In this note we present the results of a specific set of parameters of this model with emphasis on the multiwavelength prompt emission and transition to the early afterglow.

  17. Human Adolescent Phase Response Curves to Bright White Light.

    Science.gov (United States)

    Crowley, Stephanie J; Eastman, Charmane I

    2017-08-01

    Older adolescents are particularly vulnerable to circadian misalignment and sleep restriction, primarily due to early school start times. Light can shift the circadian system and could help attenuate circadian misalignment; however, a phase response curve (PRC) to determine the optimal time for receiving light and avoiding light is not available for adolescents. We constructed light PRCs for late pubertal to postpubertal adolescents aged 14 to 17 years. Participants completed 2 counterbalanced 5-day laboratory sessions after 8 or 9 days of scheduled sleep at home. Each session included phase assessments to measure the dim light melatonin onset (DLMO) before and after 3 days of free-running through an ultradian light-dark (wake-sleep) cycle (2 h dim [~20 lux] light, 2 h dark). In one session, intermittent bright white light (~5000 lux; four 20-min exposures) was alternated with 10 min of dim room light once per day for 3 consecutive days. The time of light varied among participants to cover the 24-h day. For each individual, the phase shift to bright light was corrected for the free-run derived from the other laboratory session with no bright light. One PRC showed phase shifts in response to light start time relative to the DLMO and another relative to home sleep. Phase delay shifts occurred around the hours corresponding to home bedtime. Phase advances occurred during the hours surrounding wake time and later in the afternoon. The transition from delays to advances occurred at the midpoint of home sleep. The adolescent PRCs presented here provide a valuable tool to time bright light in adolescents.

  18. Observation of the prompt and early afterglow of GRB 050904 by TAROT

    International Nuclear Information System (INIS)

    Boeer, M.; Damerdji, Y.; Atteia, J. L.; Stratta, G.; Gendre, B.; Klotz, A.

    2006-01-01

    We present the recent observation of the very high redshift burst source GRB 050904 made by the TAROT robotized telescope. We have compared our data with the SWIFT XRT light curve to analyze the broad ban spectrum. We show that the luminosity and the behavior of this event is comparable with that of GRB 990123, suggesting the existence of very bright events. They can be detected at very high redshifts, even with small or moderate aperture telescopes, and they may constitute a powerful means for the exploration of the young universe. An update of the last TAROT observations performed as a response from SWIFT alerts is made

  19. Interpretation of eclipsing light curves of dwarf novae

    International Nuclear Information System (INIS)

    Matvienko, A.N.; Cherepashchuk, A.M.; Yagola, A.G.

    1988-01-01

    The method for interpretation of eclipsing light curves of dwarf novae is proposed, taking into account the influence of the hot spot situated in the outer part of the disk-like envelope surrounding a white dwarf. This method is applied to the analysis of the eclipsing light curves of the system Z Cha in the quiet and active stages. It is shown that the optical luminosity of the hot spot in the system Z Cha in the active stage is 3-5 times greater than that in the quiet stage. Radius of the disk-like envelope in the active stage is more than twice greater than that in the quiet stage

  20. Light and velocity curve bumps for BW Vulpeculae

    International Nuclear Information System (INIS)

    Pesnell, W.D.; Cox, A.N.

    1980-01-01

    Bumps in the light and radial velocity curves of the Beta Cephei star BW Vulpeculae were modeled. Two mechanisms, a resonance phenomena and non-linear pulsations, were investigated. The resonance condition was clearly not fulfilled, the calculated period ratio being approximately 0.60, where a value of 0.50 L +- 0.03 is required for resonance. In the non-linear calculation, the bump appears, with the correct phase, but was found at an amplitude that is too large. Further, the light curve does not show any bump-like feature. The cause of the bump is the large spurious boost given the star's velocity field by the solution methods. The calculated periods of the stellar models are shorter than those of previous calculations, enhancing the possibility that these stars pulsate in a radial fundamental mode

  1. Preparation of Kepler light curves for asteroseismic analyses

    DEFF Research Database (Denmark)

    García, R.A.; Hekker, Saskia; Stello, Dennis

    2011-01-01

    The Kepler mission is providing photometric data of exquisite quality for the asteroseismic study of different classes of pulsating stars. These analyses place particular demands on the pre-processing of the data, over a range of time-scales from minutes to months. Here, we describe processing...... procedures developed by the Kepler Asteroseismic Science Consortium to prepare light curves that are optimized for the asteroseismic study of solar-like oscillating stars in which outliers, jumps and drifts are corrected....

  2. SIMULATIONS OF GAMMA-RAY BURST JETS IN A STRATIFIED EXTERNAL MEDIUM: DYNAMICS, AFTERGLOW LIGHT CURVES, JET BREAKS, AND RADIO CALORIMETRY

    International Nuclear Information System (INIS)

    De Colle, Fabio; Ramirez-Ruiz, Enrico; Granot, Jonathan; Lopez-Camara, Diego

    2012-01-01

    The dynamics of gamma-ray burst (GRB) jets during the afterglow phase is most reliably and accurately modeled using hydrodynamic simulations. All published simulations so far, however, have considered only a uniform external medium, while a stratified external medium is expected around long duration GRB progenitors. Here, we present simulations of the dynamics of GRB jets and the resulting afterglow emission for both uniform and stratified external media with ρ ext ∝r –k for k = 0, 1, 2. The simulations are performed in two dimensions using the special relativistic version of the Mezcal code. Common to all calculations is the initiation of the GRB jet as a conical wedge of half-opening angle θ 0 = 0.2 whose radial profile is taken from the self-similar Blandford-McKee solution. The dynamics for stratified external media (k = 1, 2) are broadly similar to those derived for expansion into a uniform external medium (k = 0). The jet half-opening angle is observed to start increasing logarithmically with time (or radius) once the Lorentz factor Γ drops below θ –1 0 . For larger k values, however, the lateral expansion is faster at early times (when Γ > θ –1 0 ) and slower at late times with the jet expansion becoming Newtonian and slowly approaching spherical symmetry over progressively longer timescales. We find that, contrary to analytic expectations, there is a reasonably sharp jet break in the light curve for k = 2 (a wind-like external medium), although the shape of the break is affected more by the viewing angle (for θ obs ≤ θ 0 ) than by the slope of the external density profile (for 0 ≤ k ≤ 2). Steeper density profiles (i.e., increasing k values) are found to produce more gradual jet breaks while larger viewing angles cause smoother and later appearing jet breaks. The counterjet becomes visible as it becomes sub-relativistic, and for k = 0 this results in a clear bump-like feature in the light curve. However, for larger k values the jet

  3. Simulations of Gamma-Ray Burst Jets in a Stratified External Medium: Dynamics, Afterglow Light Curves, Jet Breaks, and Radio Calorimetry

    Science.gov (United States)

    De Colle, Fabio; Ramirez-Ruiz, Enrico; Granot, Jonathan; Lopez-Camara, Diego

    2012-05-01

    The dynamics of gamma-ray burst (GRB) jets during the afterglow phase is most reliably and accurately modeled using hydrodynamic simulations. All published simulations so far, however, have considered only a uniform external medium, while a stratified external medium is expected around long duration GRB progenitors. Here, we present simulations of the dynamics of GRB jets and the resulting afterglow emission for both uniform and stratified external media with ρextvpropr -k for k = 0, 1, 2. The simulations are performed in two dimensions using the special relativistic version of the Mezcal code. Common to all calculations is the initiation of the GRB jet as a conical wedge of half-opening angle θ0 = 0.2 whose radial profile is taken from the self-similar Blandford-McKee solution. The dynamics for stratified external media (k = 1, 2) are broadly similar to those derived for expansion into a uniform external medium (k = 0). The jet half-opening angle is observed to start increasing logarithmically with time (or radius) once the Lorentz factor Γ drops below θ-1 0. For larger k values, however, the lateral expansion is faster at early times (when Γ > θ-1 0) and slower at late times with the jet expansion becoming Newtonian and slowly approaching spherical symmetry over progressively longer timescales. We find that, contrary to analytic expectations, there is a reasonably sharp jet break in the light curve for k = 2 (a wind-like external medium), although the shape of the break is affected more by the viewing angle (for θobs <= θ0) than by the slope of the external density profile (for 0 <= k <= 2). Steeper density profiles (i.e., increasing k values) are found to produce more gradual jet breaks while larger viewing angles cause smoother and later appearing jet breaks. The counterjet becomes visible as it becomes sub-relativistic, and for k = 0 this results in a clear bump-like feature in the light curve. However, for larger k values the jet decelerates more

  4. SIMULATIONS OF GAMMA-RAY BURST JETS IN A STRATIFIED EXTERNAL MEDIUM: DYNAMICS, AFTERGLOW LIGHT CURVES, JET BREAKS, AND RADIO CALORIMETRY

    Energy Technology Data Exchange (ETDEWEB)

    De Colle, Fabio; Ramirez-Ruiz, Enrico [TASC, Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Granot, Jonathan [Racah Institute of Physics, The Hebrew University, Jerusalem 91904 (Israel); Lopez-Camara, Diego [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Ap. 70-543, 04510 D.F. (Mexico)

    2012-05-20

    The dynamics of gamma-ray burst (GRB) jets during the afterglow phase is most reliably and accurately modeled using hydrodynamic simulations. All published simulations so far, however, have considered only a uniform external medium, while a stratified external medium is expected around long duration GRB progenitors. Here, we present simulations of the dynamics of GRB jets and the resulting afterglow emission for both uniform and stratified external media with {rho}{sub ext}{proportional_to}r{sup -k} for k = 0, 1, 2. The simulations are performed in two dimensions using the special relativistic version of the Mezcal code. Common to all calculations is the initiation of the GRB jet as a conical wedge of half-opening angle {theta}{sub 0} = 0.2 whose radial profile is taken from the self-similar Blandford-McKee solution. The dynamics for stratified external media (k = 1, 2) are broadly similar to those derived for expansion into a uniform external medium (k = 0). The jet half-opening angle is observed to start increasing logarithmically with time (or radius) once the Lorentz factor {Gamma} drops below {theta}{sup -1}{sub 0}. For larger k values, however, the lateral expansion is faster at early times (when {Gamma} > {theta}{sup -1}{sub 0}) and slower at late times with the jet expansion becoming Newtonian and slowly approaching spherical symmetry over progressively longer timescales. We find that, contrary to analytic expectations, there is a reasonably sharp jet break in the light curve for k = 2 (a wind-like external medium), although the shape of the break is affected more by the viewing angle (for {theta}{sub obs} {<=} {theta}{sub 0}) than by the slope of the external density profile (for 0 {<=} k {<=} 2). Steeper density profiles (i.e., increasing k values) are found to produce more gradual jet breaks while larger viewing angles cause smoother and later appearing jet breaks. The counterjet becomes visible as it becomes sub-relativistic, and for k = 0 this results

  5. Candidate Binary Trojan and Hilda Asteroids from Rotational Light Curves

    Science.gov (United States)

    Sonnett, Sarah M.; Mainzer, Amy K.; Grav, Tommy; Masiero, Joseph R.; Bauer, James M.; Kramer, Emily A.

    2017-10-01

    Jovian Trojans (hereafter, Trojans) are asteroids in stable orbits at Jupiter's L4 and L5 Lagrange points, and Hilda asteroids are inwards of the Trojans in 3:2 mean-motion resonance with Jupiter. Due to their special dynamical properties, observationally constraining the formation location and dynamical histories of Trojans and HIldas offers key input for giant planet migration models. A fundamental parameter in assessing formation location is the bulk density - with low-density objects associated with an ice-rich formation environment in the outer solar system and high-density objects typically linked to the warmer inner solar system. Bulk density can only be directly measured during a close fly-by or by determining the mutual orbits of binary asteroid systems. With the aim of determining densities for a statistically significant sample of Trojans and Hildas, we are undertaking an observational campaign to confirm and characterize candidate binary asteroids published in Sonnett et al. (2015). These objects were flagged as binary candidates because their large NEOWISE brightness variations imply shapes so elongated that they are not likely explained by a singular equilibrium rubble pile and instead may be two elongated, gravitationally bound asteroids. We are obtaining densely sampled rotational light curves of these possible binaries to search for light curve features diagnostic of binarity and to determine the orbital properties of any confirmed binary systems by modeling the light curve. We compare the We present an update on this follow-up campaign and comment on future steps.

  6. Pre-nebular Light Curves of SNe I

    Energy Technology Data Exchange (ETDEWEB)

    Arnett, W. David [Steward Observatory, University of Arizona, 933 N. Cherry Avenue, Tucson, AZ 85721 (United States); Fryer, Christopher [Los Alamos National Laboratory, Los Alamos, NM (United States); Matheson, Thomas [National Optical Astronomy Observatory, Tucson, AZ (United States)

    2017-09-01

    We compare analytic predictions of supernova light curves with recent high-quality data from SN2011fe (Ia), KSN2011b (Ia), and the Palomar Transient Factory and the La Silla-QUEST variability survey (LSQ) (Ia). Because of the steady, fast cadence of observations, KSN2011b provides unique new information on SNe Ia: the smoothness of the light curve, which is consistent with significant large-scale mixing during the explosion, possibly due to 3D effects (e.g., Rayleigh–Taylor instabilities), and provides support for a slowly varying leakage (mean opacity). For a more complex light curve (SN2008D, SN Ib), we separate the luminosity due to multiple causes and indicate the possibility of a radioactive plume. The early rise in luminosity is shown to be affected by the opacity (leakage rate) for thermal and non-thermal radiation. A general derivation of Arnett’s rule again shows that it depends upon all processes heating the plasma, not just radioactive ones, so that SNe Ia will differ from SNe Ibc if the latter have multiple heating processes.

  7. Fourier analysis of the light curves of eclipsing variables. XV

    International Nuclear Information System (INIS)

    Demircan, O.

    1978-01-01

    A new general expression for the theoretical moments Asub(2m) of the light curves of eclipsing systems has been presented in the form of infinite series expansion. In this expansion, the terms have been given as the product of two different polynomials which satisfy certain three-term recursion formulae, and the coefficients diminish rapidly with increasing number of terms. Thus, the numerical values of the theoretical moments Asub(2m) can be generated recursively up to four significant figures for any given set of eclipse elements. This can be utilized to solve the eclipse elements in two ways: (i) with an indirect method, (ii) with a direct method as minimization to the observational moments Asub(2m) (area fitting). The procedures for obtaining the elements of any eclipsing system consisting of spherical stars have been automated by making use of the new expression for the moments Asub(2m) of the light curves. The theoretical functions f 0 , f 2 , f 4 , f 6 , g 2 and g 4 which are the functions of a and c 0 , have been used to solve the eclipse elements from the observed photometric data. The closed-form expressions for the functions f 2 , f 4 and f 6 have also been derived in terms of Kopal's I-integrals. The automated methods for obtaining the eclipse elements from one minimum alone have been tested on the light curves of YZ (21) Cassiopeiae under the spherical model assumptions. The results of these applications are given. (Auth.)

  8. Early light curves for Type Ia supernova explosion models

    Science.gov (United States)

    Noebauer, U. M.; Kromer, M.; Taubenberger, S.; Baklanov, P.; Blinnikov, S.; Sorokina, E.; Hillebrandt, W.

    2017-12-01

    Upcoming high-cadence transient survey programmes will produce a wealth of observational data for Type Ia supernovae. These data sets will contain numerous events detected very early in their evolution, shortly after explosion. Here, we present synthetic light curves, calculated with the radiation hydrodynamical approach STELLA for a number of different explosion models, specifically focusing on these first few days after explosion. We show that overall the early light curve evolution is similar for most of the investigated models. Characteristic imprints are induced by radioactive material located close to the surface. However, these are very similar to the signatures expected from ejecta-CSM or ejecta-companion interaction. Apart from the pure deflagration explosion models, none of our synthetic light curves exhibit the commonly assumed power-law rise. We demonstrate that this can lead to substantial errors in the determination of the time of explosion. In summary, we illustrate with our calculations that even with very early data an identification of specific explosion scenarios is challenging, if only photometric observations are available.

  9. PAIR INSTABILITY SUPERNOVAE: LIGHT CURVES, SPECTRA, AND SHOCK BREAKOUT

    International Nuclear Information System (INIS)

    Kasen, Daniel; Woosley, S. E.; Heger, Alexander

    2011-01-01

    For the initial mass range (140 M sun sun ) stars die in a thermonuclear runaway triggered by the pair-production instability. The supernovae they make can be remarkably energetic (up to ∼10 53 erg) and synthesize considerable amounts of radioactive isotopes. Here we model the evolution, explosion, and observational signatures of representative pair instability supernovae (PI SNe) spanning a range of initial masses and envelope structures. The predicted light curves last for hundreds of days and range in luminosity from very dim to extremely bright (L ∼ 10 44 erg s -1 ). The most massive events are bright enough to be seen at high redshift, but the extended light curve duration (∼1 yr)-prolonged by cosmological time-dilation-may make it difficult to detect them as transients. A more promising approach may be to search for the brief and luminous outbreak occurring when the explosion shock wave first reaches the stellar surface. Using a multi-wavelength radiation-hydrodynamics code we calculate that, in the rest frame, the shock breakout transients of PI SNe reach luminosities of 10 45 -10 46 erg s -1 , peak at wavelengths ∼30-170 A, and last for several hours. We discuss how observations of the light curves, spectra, and breakout emission can be used to constrain the mass, radius, and metallicity of the progenitor.

  10. REM observations of GRB060418 and GRB060607A: the onset of the afterglow and the initial fireball Lorentz factor determination

    Energy Technology Data Exchange (ETDEWEB)

    Molinari, E.; Covino, S.; D' Avanzo, P.; Chincarini, G.; Zerbi, F.M.; Conconi, P.; Malaspina, G.; Campana, S.; Rizzuto, D.; Tagliaferri, G. [Osserv Astron Brera, INAF, I-23807 Merate, LC, (Italy); Vergani, S.D.; Meurs, E.J.A.; Ward, P.A. [DIAS, Dunsink Observ, Dublin 15, (Ireland); Vergani, S.D.; Norci, L. [Dublin City Univ, Sch Phys Sci, NCPST, Dublin 9, (Ireland); Malesani, D. [SISSA, ISAS, I-34014 Trieste, (Italy); Malesani, D. [Univ Copenhagen, Niels Bohr Inst, Dark Cosmol Ctr, DK-2100 Copenhagen, (Denmark); D' Avanzo, P. [Univ Insubria, Dipartimento Matemat and Fis, I-22100 Como, (Italy); Chincarini, G.; Rizzuto, D. [Univ Milan, I-20126 Milan, (Italy); Antonelli, L.A.; Testa, V.; Vitali, F.; D' Alessio, F.; Guetta, D.; Piranomonte, S.; Stella, L. [Osserv Astron Roma, INAF, I-00040 Monte Porzio Catone, (Italy); Tosti, G. [Univ Perugia, Dipartimento Fis, Osservatorio Astron, I-06123 Perugia, (Italy); Nicastro, L.; Palazzi, E.; Masetti, N. [IASF Bologna, INAF, I-40129 Bologna, (Italy); Goldoni, P. [APC, Lab Astroparticule and Cosmol, UMR 7164, F-75231 Paris 05, (France); Goldoni, P. [CEA Saclay, DSM, DAPNIA, Serv Astrophys, F-91191 Gif Sur Yvette, (France)] (and others)

    2007-07-01

    Context. Gamma-ray burst (GRB) emission is believed to originate in highly relativistic fireballs. Aims. Currently, only lower limits were securely set to the initial fireball Lorentz factor {gamma}{sub 0}. We aim to provide a direct measure of {gamma}{sub 0}. Methods. The early-time afterglow light curve carries information about {gamma}{sub 0}, which determines the time of the afterglow peak. We have obtained early observations of the near-infrared afterglows of GRB060418 and GRB060607A with the REM robotic telescope. Results. For both events, the afterglow peak could be clearly singled out, allowing a firm determination of the fireball Lorentz of {gamma}{sub 0} similar to 400, fully confirming the highly relativistic nature of GRB fireballs. The deceleration radius was inferred to be R-dec approximate to 10{sup 17} cm. This is much larger than the internal shocks radius (believed to power the prompt emission), thus providing further evidence for a different origin of the prompt and afterglow stages of the GRB. (authors)

  11. UBVRIz LIGHT CURVES OF 51 TYPE II SUPERNOVAE

    International Nuclear Information System (INIS)

    Galbany, Lluis; Hamuy, Mario; Jaeger, Thomas de; Moraga, Tania; González-Gaitán, Santiago; Gutiérrez, Claudia P.; Phillips, Mark M.; Morrell, Nidia I.; Thomas-Osip, Joanna; Suntzeff, Nicholas B.; Maza, José; González, Luis; Antezana, Roberto; Wishnjewski, Marina; Krisciunas, Kevin; Krzeminski, Wojtek; McCarthy, Patrick; Anderson, Joseph P.; Stritzinger, Maximilian; Folatelli, Gastón

    2016-01-01

    We present a compilation of UBVRIz light curves of 51 type II supernovae discovered during the course of four different surveys during 1986–2003: the Cerro Tololo Supernova Survey, the Calán/Tololo Supernova Program (C and T), the Supernova Optical and Infrared Survey (SOIRS), and the Carnegie Type II Supernova Survey (CATS). The photometry is based on template-subtracted images to eliminate any potential host galaxy light contamination, and calibrated from foreground stars. This work presents these photometric data, studies the color evolution using different bands, and explores the relation between the magnitude at maximum brightness and the brightness decline parameter (s) from maximum light through the end of the recombination phase. This parameter is found to be shallower for redder bands and appears to have the best correlation in the B band. In addition, it also correlates with the plateau duration, being shorter (longer) for larger (smaller) s values

  12. UBVRIz LIGHT CURVES OF 51 TYPE II SUPERNOVAE

    Energy Technology Data Exchange (ETDEWEB)

    Galbany, Lluis; Hamuy, Mario; Jaeger, Thomas de; Moraga, Tania; González-Gaitán, Santiago; Gutiérrez, Claudia P. [Millennium Institute of Astrophysics, Universidad de Chile (Chile); Phillips, Mark M.; Morrell, Nidia I.; Thomas-Osip, Joanna [Carnegie Observatories, Las Campanas Observatory, Casilla 60, La Serena (Chile); Suntzeff, Nicholas B. [Department of Physics and Astronomy, Texas A and M University, College Station, TX 77843 (United States); Maza, José; González, Luis; Antezana, Roberto; Wishnjewski, Marina [Departamento de Astronomía, Universidad de Chile, Camino El Observatorio 1515, Las Condes, Santiago (Chile); Krisciunas, Kevin [George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Texas A. and M. University, Department of Physics and Astronomy, 4242 TAMU, College Station, TX 77843 (United States); Krzeminski, Wojtek [N. Copernicus Astronomical Center, ul. Bartycka 18, 00-716 Warszawa (Poland); McCarthy, Patrick [The Observatories of the Carnegie Institution for Science, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Anderson, Joseph P. [European Southern Observatory, Alonso de Cordova 3107, Vitacura, Casilla 19001, Santiago (Chile); Stritzinger, Maximilian [Department of Physics and Astronomy, Aarhus University (Denmark); Folatelli, Gastón, E-mail: lgalbany@das.uchile.cl [Instituto de Astrofísica de La Plata (IALP, CONICET) (Argentina); and others

    2016-02-15

    We present a compilation of UBVRIz light curves of 51 type II supernovae discovered during the course of four different surveys during 1986–2003: the Cerro Tololo Supernova Survey, the Calán/Tololo Supernova Program (C and T), the Supernova Optical and Infrared Survey (SOIRS), and the Carnegie Type II Supernova Survey (CATS). The photometry is based on template-subtracted images to eliminate any potential host galaxy light contamination, and calibrated from foreground stars. This work presents these photometric data, studies the color evolution using different bands, and explores the relation between the magnitude at maximum brightness and the brightness decline parameter (s) from maximum light through the end of the recombination phase. This parameter is found to be shallower for redder bands and appears to have the best correlation in the B band. In addition, it also correlates with the plateau duration, being shorter (longer) for larger (smaller) s values.

  13. THE LATE PEAKING AFTERGLOW OF GRB 100418A

    International Nuclear Information System (INIS)

    Marshall, F. E.; Holland, S. T.; Sakamoto, T.; Antonelli, L. A.; Burrows, D. N.; Siegel, M. H.; Covino, S.; Fugazza, D.; De Pasquale, M.; Oates, S. R.; Evans, P. A.; O'Brien, P. T.; Osborne, J. P.; Pagani, C.; Liang, E. W.; Wu, X. F.; Zhang, B.

    2011-01-01

    GRB 100418A is a long gamma-ray burst (GRB) at redshift z = 0.6235 discovered with the Swift Gamma-ray Burst Explorer with unusual optical and X-ray light curves. After an initial short-lived, rapid decline in X-rays, the optical and X-ray light curves observed with Swift are approximately flat or rising slightly out to at least ∼7 x 10 3 s after the trigger, peak at ∼5 x 10 4 s, and then follow an approximately power-law decay. Such a long optical plateau and late peaking is rarely seen in GRB afterglows. Observations with Rapid Eye Mount during a gap in the Swift coverage indicate a bright optical flare at ∼2.5 x 10 4 s. The long plateau phase of the afterglow is interpreted using either a model with continuous injection of energy into the forward shock of the burst or a model in which the jet of the burst is viewed off-axis. In both models the isotropic kinetic energy in the late afterglow after the plateau phase is ≥10 2 times the 10 51 erg of the prompt isotropic gamma-ray energy release. The energy injection model is favored because the off-axis jet model would require the intrinsic T 90 for the GRB jet viewed on-axis to be very short, ∼10 ms, and the intrinsic isotropic gamma-ray energy release and the true jet energy to be much higher than the typical values of known short GRBs. The non-detection of a jet break up to t ∼ 2 x 10 6 s indicates a jet half-opening angle of at least ∼14 0 , and a relatively high-collimation-corrected jet energy of E jet ≥ 10 52 erg.

  14. The Supercritical Pile Gamma-Ray Burst Model: The GRB Afterglow Steep Decline and Plateau Phase

    Science.gov (United States)

    Sultana, Joseph; Kazanas, D.; Mastichiadis, A.

    2013-01-01

    We present a process that accounts for the steep decline and plateau phase of the Swift X-Ray Telescope (XRT) light curves, vexing features of gamma-ray burst (GRB) phenomenology. This process is an integral part of the "supercritical pile" GRB model, proposed a few years ago to account for the conversion of the GRB kinetic energy into radiation with a spectral peak at E(sub pk) is approx. m(sub e)C(exp 2). We compute the evolution of the relativistic blast wave (RBW) Lorentz factor Gamma to show that the radiation-reaction force due to the GRB emission can produce an abrupt, small (approx. 25%) decrease in Gamma at a radius that is smaller (depending on conditions) than the deceleration radius R(sub D). Because of this reduction, the kinematic criticality criterion of the "supercritical pile" is no longer fulfilled. Transfer of the proton energy into electrons ceases and the GRB enters abruptly the afterglow phase at a luminosity smaller by approx. m(sub p)/m(sub e) than that of the prompt emission. If the radius at which this slow-down occurs is significantly smaller than R(sub D), the RBW internal energy continues to drive the RBW expansion at a constant (new) Gamma and its X-ray luminosity remains constant until R(sub D) is reached, at which point it resumes its more conventional decay, thereby completing the "unexpected" XRT light curve phase. If this transition occurs at R is approx. equal to R(sub D), the steep decline is followed by a flux decrease instead of a "plateau," consistent with the conventional afterglow declines. Besides providing an account of these peculiarities, the model suggests that the afterglow phase may in fact begin before the RBW reaches R is approx. equal to R(sub D), thus providing novel insights into GRB phenomenology.

  15. GRB 080503 LATE AFTERGLOW RE-BRIGHTENING: SIGNATURE OF A MAGNETAR-POWERED MERGER-NOVA

    International Nuclear Information System (INIS)

    Gao, He; Ding, Xuan; Wu, Xue-Feng; Dai, Zi-Gao; Zhang, Bing

    2015-01-01

    GRB 080503 is a short gamma-ray burst (GRB) detected by Swift and has been classified as a GRB originating from a compact star merger. The soft extended emission and the simultaneous late re-brightening in both the X-ray and optical afterglow light curves raise interesting questions regarding its physical origin. We show that the broadband data of GRB 080503 can be well explained within the framework of the double neutron star merger model, provided that the merger remnant is a rapidly rotating massive neutron star with an extremely high magnetic field (i.e., a millisecond magnetar). We show that the late optical re-brightening is consistent with the emission from a magnetar-powered “merger-nova.” This adds one more case to the growing sample of merger-novae associated with short GRBs. The soft extended emission and the late X-ray excess emission are well connected through a magnetar dipole spin-down luminosity evolution function, suggesting that direct magnetic dissipation is the mechanism to produce these X-rays. The X-ray emission initially leaks from a hole in the merger ejecta pierced by the short GRB jet. The hole subsequently closes after the magnetar spins down and the magnetic pressure drops below ram pressure. The X-ray photons are then trapped behind the merger-nova ejecta until the ejecta becomes optically thin at a later time. This explains the essentially simultaneous re-brightening in both the optical and X-ray light curves. Within this model, future gravitational-wave sources could be associated with a bright X-ray counterpart along with the merger-nova, even if the short GRB jet beams away from Earth

  16. Marginalizing Instrument Systematics in HST WFC3 Transit Light Curves

    Science.gov (United States)

    Wakeford, H. R.; Sing, D. K.; Evans, T.; Deming, D.; Mandell, A.

    2016-03-01

    Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) infrared observations at 1.1-1.7 μm probe primarily the H2O absorption band at 1.4 μm, and have provided low-resolution transmission spectra for a wide range of exoplanets. We present the application of marginalization based on Gibson to analyze exoplanet transit light curves obtained from HST WFC3 to better determine important transit parameters such as Rp/R*, which are important for accurate detections of H2O. We approximate the evidence, often referred to as the marginal likelihood, for a grid of systematic models using the Akaike Information Criterion. We then calculate the evidence-based weight assigned to each systematic model and use the information from all tested models to calculate the final marginalized transit parameters for both the band-integrated and spectroscopic light curves to construct the transmission spectrum. We find that a majority of the highest weight models contain a correction for a linear trend in time as well as corrections related to HST orbital phase. We additionally test the dependence on the shift in spectral wavelength position over the course of the observations and find that spectroscopic wavelength shifts {δ }λ (λ ) best describe the associated systematic in the spectroscopic light curves for most targets while fast scan rate observations of bright targets require an additional level of processing to produce a robust transmission spectrum. The use of marginalization allows for transparent interpretation and understanding of the instrument and the impact of each systematic evaluated statistically for each data set, expanding the ability to make true and comprehensive comparisons between exoplanet atmospheres.

  17. Orbital Light Curves of UU Aquarii in Stunted Outburst

    Science.gov (United States)

    Robertson, J. W.; Honeycutt, R. K.; Henden, A. A.; Campbell, R. T.

    2018-02-01

    Stunted outbursts are ∼0.ͫ6 eruptions, typically lasting 5–10 days, which are found in some novalike cataclysmic variables, including UU Aqr. The mechanism responsible for stunted outbursts is uncertain but is likely related to an accretion disk instability or to variations in the mass transfer rate. A campaign to monitor the eclipse light curves in UU Aqr has been conducted in order to detect any light curve distortions due to the appearance of a hot spot on the disk at the location of the impact point of the accretion stream. If stunted outbursts are due to a temporary mass transfer enhancement, then predictable deformations of the orbital light curve are expected to occur during such outbursts. This study used 156 eclipses on 135 nights during the years 2000–2012. During this interval, random samples found the system to be in stunted outbursts 4%–5% of the time, yielding ∼7 eclipses obtained during some stage of stunted outburst. About half of the eclipses obtained during stunted outbursts showed clear evidence for hot spot enhancement, providing strong evidence that the stunted outbursts in UU Aqr are associated with mass transfer variations. The other half of the eclipses during stunted outburst showed little or no evidence for hot spot enhancement. Furthermore, there were no systematic changes in the hot spot signature as stunted outbursts progressed. Therefore, we have tentatively attributed the changes in hot spot visibility during stunted outburst to random blobby accretion, which likely further modulates the strength of the accretion stream on orbital timescales.

  18. DETERMINISTIC COMPONENTS IN THE LIGHT CURVE AMPLITUDE OF Y OPH

    International Nuclear Information System (INIS)

    Pop, Alexandru; Turcu, Vlad; Vamos, Calin

    2010-01-01

    About two decades after the discovery of the amplitude decline of the light curve of the classical Cepheid Y Oph, its study is resumed using an increased amount of homogenized data and an extended time base. In our approach, the investigation of different time series concerning the light curve amplitude of Y Oph is not only the reason for the present study, but also a stimulus for developing a coherent methodology for studying long- and short-term variability phenomena in variable stars, taking into account the details of concrete observing conditions: amount of data, data sampling, time base, and individual errors of observational data. The statistical significance of this decreasing trend was estimated by assuming its linearity. We approached the decision-making process by formulating adequate null and alternative hypotheses, and testing the value of the regression line slope for different data sets via Monte Carlo simulations. A variability analysis, through various methods, of the original data and of the residuals obtained after removing the linear trend was performed. We also proposed a new statistical test, based on amplitude spectrum analysis and Monte Carlo simulations, intended to evaluate how detectible is a given (linear) trend in well-defined observing conditions: the trend detection probability. The main conclusion of our study on Y Oph is that, even if the false alarm probability is low enough to consider the decreasing trend to be statistically significant, the available data do not allow us to obtain a reasonably powerful test. We are able to confirm the light curve amplitude decline, and the order of magnitude of its slope with a better statistical substantiation. According to the obtained values of the trend detection probability, it seems that the trend we are dealing with is marked by a low detectibility. Our attempt to find signs of possible variability phenomena at shorter timescales ended by emphasizing the relative constancy of our data

  19. Testing the stationarity of white dwarf light-curves

    International Nuclear Information System (INIS)

    Molnar, L; Kollath, Z; Plachy, E; Paparo, M

    2009-01-01

    Long period white dwarfs show changes in their frequency spectra from one observing season to another, i.e. their light-curves cannot be considered as stationary multiperiodic variations on long timescales. However, due to the complex frequency spectra of these stars and the narrow frequency spacing, it is still unknown, what the shortest time scale is, where real physical modulation exists. We present tests on artificial data, resembling the observations, using time-frequency distributions (TFDs), Fourier-analysis and the analytical signal method.

  20. Dependence on supernovae light-curve processing in void models

    Energy Technology Data Exchange (ETDEWEB)

    Bengochea, Gabriel R., E-mail: gabriel@iafe.uba.ar [Instituto de Astronomía y Física del Espacio (IAFE), UBA-CONICET, CC 67, Suc. 28, 1428 Buenos Aires (Argentina); De Rossi, Maria E., E-mail: derossi@iafe.uba.ar [Instituto de Astronomía y Física del Espacio (IAFE), UBA-CONICET, CC 67, Suc. 28, 1428 Buenos Aires (Argentina); Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires (Argentina)

    2014-06-02

    In this work, we show that when supernova Ia (SN Ia) data sets are used to put constraints on the free parameters of inhomogeneous models, certain extra information regarding the light-curve fitter used in the supernovae Ia luminosity fluxes processing should be taken into account. We found that the size of the void as well as other parameters of these models might be suffering extra degenerations or additional systematic errors due to the fitter. A recent proposal to relieve the tension between the results from Planck satellite and SNe Ia is re-analyzed in the framework of these subjects.

  1. Statistical analysis of the W Cyg light curve

    International Nuclear Information System (INIS)

    Klyus, I.A.

    1983-01-01

    A statistical analysis of the light curve of W Cygni has been carried out. The process of brightness variations brightness of the star is shown to be a stationary stochastic one. The hypothesis of stationarity of the process was checked at the significance level of α=0.05. Oscillations of the brightness with average durations of 131 and 250 days have been found. It is proved that oscillations are narrow-band noise, i.e. cycles. Peaks on the power spectrum corresponding to these cycles exceed 99% confidence interval. It has been stated that the oscillations are independent

  2. A new approach to the analysis of Mira light curves

    International Nuclear Information System (INIS)

    Mennessier, M.O.; Barthes, D.; Mattei, J.A.

    1990-01-01

    Two different but complementary methods for predicting Mira luminosities are presented. One method is derived from a Fourier analysis, it requires performing deconvolution, and its results are not certain due to the inherent instability of deconvolution problems. The other method is a learning method utilizing artificial intelligence techniques where a light curve is presented as an ordered sequence of pseudocycles, and rules are learned by linking the characteristics of several consecutive pseudocycles to one characteristic of the future cycle. It is observed that agreement between these methods is obtainable when it is possible to eliminate similar false frequencies from the preliminary power spectrum and to improve the degree of confidence in the rules

  3. Flare Characteristics from X-ray Light Curves

    Science.gov (United States)

    Gryciuk, M.; Siarkowski, M.; Sylwester, J.; Gburek, S.; Podgorski, P.; Kepa, A.; Sylwester, B.; Mrozek, T.

    2017-06-01

    A new methodology is given to determine basic parameters of flares from their X-ray light curves. Algorithms are developed from the analysis of small X-ray flares occurring during the deep solar minimum of 2009, between Solar Cycles 23 and 24, observed by the Polish Solar Photometer in X-rays (SphinX) on the Complex Orbital Observations Near-Earth of Activity of the Sun-Photon (CORONAS- Photon) spacecraft. One is a semi-automatic flare detection procedure that gives start, peak, and end times for single ("elementary") flare events under the assumption that the light curve is a simple convolution of a Gaussian and exponential decay functions. More complex flares with multiple peaks can generally be described by a sum of such elementary flares. Flare time profiles in the two energy ranges of SphinX (1.16 - 1.51 keV, 1.51 - 15 keV) are used to derive temperature and emission measure as a function of time during each flare. The result is a comprehensive catalogue - the SphinX Flare Catalogue - which contains 1600 flares or flare-like events and is made available for general use. The methods described here can be applied to observations made by Geosynchronous Operational Environmental Satellites (GOES), the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) and other broad-band spectrometers.

  4. SIMULATED PERFORMANCE OF TIMESCALE METRICS FOR APERIODIC LIGHT CURVES

    Energy Technology Data Exchange (ETDEWEB)

    Findeisen, Krzysztof; Hillenbrand, Lynne [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, MC 249-17, Pasadena, CA 91125 (United States); Cody, Ann Marie, E-mail: krzys@astro.caltech.edu [Spitzer Science Center, California Institute of Technology, MC 314-6, Pasadena, CA 91125 (United States)

    2015-01-10

    Aperiodic variability is a characteristic feature of young stars, massive stars, and active galactic nuclei. With the recent proliferation of time-domain surveys, it is increasingly essential to develop methods to quantify and analyze aperiodic variability. We develop three timescale metrics that have been little used in astronomy—Δm-Δt plots, peak-finding, and Gaussian process regression—and present simulations comparing their effectiveness across a range of aperiodic light curve shapes, characteristic timescales, observing cadences, and signal to noise ratios. We find that Gaussian process regression is easily confused by noise and by irregular sampling, even when the model being fit reflects the process underlying the light curve, but that Δm-Δt plots and peak-finding can coarsely characterize timescales across a broad region of parameter space. We make public the software we used for our simulations, both in the spirit of open research and to allow others to carry out analogous simulations for their own observing programs.

  5. Machine Learning Techniques for Stellar Light Curve Classification

    Science.gov (United States)

    Hinners, Trisha A.; Tat, Kevin; Thorp, Rachel

    2018-07-01

    We apply machine learning techniques in an attempt to predict and classify stellar properties from noisy and sparse time-series data. We preprocessed over 94 GB of Kepler light curves from the Mikulski Archive for Space Telescopes (MAST) to classify according to 10 distinct physical properties using both representation learning and feature engineering approaches. Studies using machine learning in the field have been primarily done on simulated data, making our study one of the first to use real light-curve data for machine learning approaches. We tuned our data using previous work with simulated data as a template and achieved mixed results between the two approaches. Representation learning using a long short-term memory recurrent neural network produced no successful predictions, but our work with feature engineering was successful for both classification and regression. In particular, we were able to achieve values for stellar density, stellar radius, and effective temperature with low error (∼2%–4%) and good accuracy (∼75%) for classifying the number of transits for a given star. The results show promise for improvement for both approaches upon using larger data sets with a larger minority class. This work has the potential to provide a foundation for future tools and techniques to aid in the analysis of astrophysical data.

  6. Fourier analysis of the light curves of eclipsing variables, XXIV

    International Nuclear Information System (INIS)

    Edalati, M.T.

    1978-01-01

    The aim of the present paper will be to evaluate numerically Jacobian and other functions which have been discussed in more detail in a previous paper of this series, and also choose the most convenient moments to obtain a good determination for the unknown eclipse parameters a and c 0 . More than 12 different pairs of g-functions for real values of m have been investigated numerically and diagrammatically. The behaviour of g-functions depends but very little on different combination of the moments, and related diagrams are approximately the same as g 2 and g 4 . The behaviour of the vanishing Jacobian, arising from different pairs of g-functions for real values of m>= 0 . Accordingly, the author obtains the optimum combination of the moments (i.e., A 6 , A 7 , A 8 and A 9 ) in g-functions g 7 and g 8 . It has been noted that the behaviour of the g-functions which depend on the combinations of the higher order moments (i.e., m>= 5) have been ruled out, because the proportional error of the moments Asub(2m) increases with increasing values of real m. The automated method has been tested successfully on the light curve of RT Per. Finally, a comparison is given of the elements of RT Per arising from two different pairs of g-functions, i.e. g 2 , g 4 and g 7 , g 8 for the light curves analysis. (Auth.)

  7. A Semiautomatic Pipeline for Be Star Light Curves

    Science.gov (United States)

    Rímulo, L. R.; Carciofi, A. C.; Rivinius, T.; Okazaki, A.

    2016-11-01

    Observational and theoretical studies from the last decade have shown that the Viscous Decretion Disk (VDD) scenario, in which turbulent viscosity is the physical mechanism responsible for the transport of material and angular momentum ejected from the star to the outer regions of the disk, is the only viable model for explaining the circumstellar disks of Be stars. In the α-disk approach applied to the VDD, the dimensionless parameter α is a measure of the turbulent viscosity. Recently, combining the time-dependent evolution of a VDD α-disk with non-LTE radiative transfer calculations, the first measurement of the α parameter was made, for the disk dissipation of the Be star ω CMa. It was found that α≍ 1 for that Be disk. The main motivation of this present work is the statistical determination of the α parameter. For this purpose, we present a pipeline that will allow the semiautomatic determination of the α parameter of several dozens of light curves of Be stars available from photometric surveys, In this contribution, we describe the pipeline, outlining the main staps required for the semiautomatic analysis of light curves

  8. SIMULATED PERFORMANCE OF TIMESCALE METRICS FOR APERIODIC LIGHT CURVES

    International Nuclear Information System (INIS)

    Findeisen, Krzysztof; Hillenbrand, Lynne; Cody, Ann Marie

    2015-01-01

    Aperiodic variability is a characteristic feature of young stars, massive stars, and active galactic nuclei. With the recent proliferation of time-domain surveys, it is increasingly essential to develop methods to quantify and analyze aperiodic variability. We develop three timescale metrics that have been little used in astronomy—Δm-Δt plots, peak-finding, and Gaussian process regression—and present simulations comparing their effectiveness across a range of aperiodic light curve shapes, characteristic timescales, observing cadences, and signal to noise ratios. We find that Gaussian process regression is easily confused by noise and by irregular sampling, even when the model being fit reflects the process underlying the light curve, but that Δm-Δt plots and peak-finding can coarsely characterize timescales across a broad region of parameter space. We make public the software we used for our simulations, both in the spirit of open research and to allow others to carry out analogous simulations for their own observing programs

  9. Common Envelope Light Curves. I. Grid-code Module Calibration

    Energy Technology Data Exchange (ETDEWEB)

    Galaviz, Pablo; Marco, Orsola De; Staff, Jan E.; Iaconi, Roberto [Department of Physics and Astronomy, Macquarie University, Sydney, NSW (Australia); Passy, Jean-Claude, E-mail: Pablo.Galaviz@me.com [Argelander-Institut für Astronomie, Auf dem Hügel 71, D-53121 Bonn (Germany)

    2017-04-01

    The common envelope (CE) binary interaction occurs when a star transfers mass onto a companion that cannot fully accrete it. The interaction can lead to a merger of the two objects or to a close binary. The CE interaction is the gateway of all evolved compact binaries, all stellar mergers, and likely many of the stellar transients witnessed to date. CE simulations are needed to understand this interaction and to interpret stars and binaries thought to be the byproduct of this stage. At this time, simulations are unable to reproduce the few observational data available and several ideas have been put forward to address their shortcomings. The need for more definitive simulation validation is pressing and is already being fulfilled by observations from time-domain surveys. In this article, we present an initial method and its implementation for post-processing grid-based CE simulations to produce the light curve so as to compare simulations with upcoming observations. Here we implemented a zeroth order method to calculate the light emitted from CE hydrodynamic simulations carried out with the 3D hydrodynamic code Enzo used in unigrid mode. The code implements an approach for the computation of luminosity in both optically thick and optically thin regimes and is tested using the first 135 days of the CE simulation of Passy et al., where a 0.8  M {sub ⊙} red giant branch star interacts with a 0.6  M {sub ⊙} companion. This code is used to highlight two large obstacles that need to be overcome before realistic light curves can be calculated. We explain the nature of these problems and the attempted solutions and approximations in full detail to enable the next step to be identified and implemented. We also discuss our simulation in relation to recent data of transients identified as CE interactions.

  10. Ultraviolet light curves of U Geminorum and VW Hydri

    International Nuclear Information System (INIS)

    Wu, C.-C.; Panek, R.J.; Holm, A.V.; Schiffer, F.H. III

    1982-01-01

    Ultraviolet light curves have been obtained for the quiescent dwarf novae U Gem and VW Hyi. The amplitude of the hump associated with the accretion hot spot is much smaller in the UV than in the visible. This implies that the bright spot temperature is roughly 12000 K if it is optically thick. A hotter spot would have to be optically thin in the near UV. The flux distribution of U Gem in quiescence cannot be fitted by model spectra of steady state, viscous accretion disks. The absolute luminosity, the flux distribution, and the far UV spectrum suggest that the primary star is visible in the far UV. The optical-UV flux distribution of VW Hyi could be matched roughly by the authors' model accretion disks, but the fitting is poorly constrained due to the uncertainty in its distance. (Auth.)

  11. Supernova light-curve fitters and dark energy

    Energy Technology Data Exchange (ETDEWEB)

    Bengochea, Gabriel R., E-mail: gabriel@iafe.uba.a [Instituto de Astronomia y Fisica del Espacio (IAFE), CC 67, Suc. 28, 1428 Buenos Aires (Argentina)

    2011-01-24

    We show that when a procedure is made to remove the tension between a supernova Ia (SN Ia) data set and observations from BAO and CMB, there might be the case where the same SN Ia set built with two different light-curve fitters behaves as two separate and distinct supernova sets, and the tension found by some authors between supernova sets actually could be due to tension or inconsistency between fitters. We also show that the information of the fitter used in an SN Ia data set could be relevant to determine whether phantom type models are favored or not when such a set is combined with the BAO/CMB joint parameter.

  12. Secondary eclipses in the CoRoT light curves

    Directory of Open Access Journals (Sweden)

    Belmonte Juan Antonio

    2013-04-01

    Full Text Available We identify and characterize secondary eclipses in the original light curves of published CoRoT planets using uniform detection and evaluation criteria. Our analysis is based on a Bayesian statistics: the eclipse search is carried out using Bayesian model selection, and the characterization of the plausible eclipse candidates using Bayesian parameter estimation. We discover statistically significant eclipse events for two planets, CoRoT-6b and CoRoT-11b, and for one brown dwarf, CoRoT-15b. We also find marginally significant eclipse events passing our plausibility criteria for CoRoT-3b, 13b, 18b, and 21b, and confirm the previously published CoRoT-1b and CoRoT-2b eclipses.

  13. Supernova light-curve fitters and dark energy

    International Nuclear Information System (INIS)

    Bengochea, Gabriel R.

    2011-01-01

    We show that when a procedure is made to remove the tension between a supernova Ia (SN Ia) data set and observations from BAO and CMB, there might be the case where the same SN Ia set built with two different light-curve fitters behaves as two separate and distinct supernova sets, and the tension found by some authors between supernova sets actually could be due to tension or inconsistency between fitters. We also show that the information of the fitter used in an SN Ia data set could be relevant to determine whether phantom type models are favored or not when such a set is combined with the BAO/CMB joint parameter.

  14. Low mass SN Ia and the late light curve

    International Nuclear Information System (INIS)

    Colgate, S.A.; Fryer, C.L.

    1995-01-01

    The late bolometric light curves of type Ia supernovae, when measured accurately over several years, show an exponential decay with a 56d half-life over a drop in luminosity of 8 magnitudes (10 half-lives). The late-time light curve is thought to be governed by the decay of Co 56 , whose 77d half-life must then be modified to account for the observed decay time. Two mechanisms, both relying upon the positron fraction of the Co 56 decay, have been proposed to explain this modification. One explanation requires a large amount of emission at infra-red wavelengths where it would not be detected. The other explanation has proposed a progressive transparency or leakage of the high energy positrons (Colgate, Petschek and Kriese, 1980). For the positrons to leak out of the expanding nebula at the required rate necessary to produce the modified 56d exponential, the mass of the ejecta from a one foe (10 51 erg in kinetic energy) explosion must be small, M ejec = 0.4M circle-dot with M ejec ∝ KE 0.5 . Thus, in this leakage explanation, any reasonable estimate of the total energy of the explosion requires that the ejected mass be very much less than the Chandrasekhar mass of 1.4M circle-dot . This is very difficult to explain with the ''canonical'' Chandrasekhar-mass thermonuclear explosion that disintegrates the original white dwarf star. This result leads us to pursue alternate mechanisms of type Ia supernovae. These mechanisms include sub-Chandrasekhar thermonuclear explosions and the accretion induced collapse of Chandrasekhar mass white dwarfs. We will summarize the advantages and disadvantages of both mechanisms with considerable detail spent on our new accretion induced collapse simulations. These mechanisms lead to lower Ni 56 production and hence result in type Ia supernovae with luminosities decreased down to ∼ 50% that predicted by the ''standard'' model

  15. VizieR Online Data Catalog: V346 Cen multiwavelength light curves (Mayer+, 2016)

    Science.gov (United States)

    Mayer, P.; Harmanec, P.; Wolf, M.; Nemravova, J.; Prsa, A.; Fremat, Y.; Zejda, M.; Liska, J.; Jurysek, J.; Honkova, K.; Masek, M.

    2016-06-01

    We present photographic light curves from O'Connell (1939, Publications of the Riverview College Observatory, 2, 5), uvby light curves from Gimenez et al. (1986A&AS...66...45G), BVR light curves from 0.6 m reflector with a CCD camera, Mt. John, New Zealand, green light curve from Sonnar 4/135mm telephoto lens with a CCD ATIK16IC camera, Sutherland, South Africa and BVRI light curves from 0.3m Meade Schmidt-Cassegrain reflector with a CCD camera. (5 data files).

  16. Detailed optical and near-infrared polarimetry, spectroscopy and broad-band photometry of the afterglow of GRB 091018: polarization evolution

    NARCIS (Netherlands)

    Wiersema, K.; Curran, P.; Krühler, T.; Melandri, A.; Rol, E.; Starling, R.L.C.; Tanvir, N.R.; van der Horst, A.J.; Covino, S.; Fynbo, J.P.U.; Goldoni, P.; Gorosabel, J.; Hjorth, J.; Klose, S.; Mundell, C.G.; O'Brien, P.T.; Palazzi, E.; Wijers, R.A.M.J.; D'Elia, V.; Evans, P.A.; Filgas, R.; Gomboc, A.; Greiner, J.; Guidorzi, C.; Kaper, L.; Kobayashi, S.; Kouveliotou, C.; Levan, A.J.; Rossi, A..; Rowlinson, A.; Steele, I.A.; de Ugarte Postigo, A.; Vergani, S.D.

    2012-01-01

    Follow-up observations of large numbers of gamma-ray burst (GRB) afterglows, facilitated by the Swift satellite, have produced a large sample of spectral energy distributions and light curves, from which their basic micro- and macro-physical parameters can in principle be derived. However, a number

  17. Supervised detection of anomalous light curves in massive astronomical catalogs

    International Nuclear Information System (INIS)

    Nun, Isadora; Pichara, Karim; Protopapas, Pavlos; Kim, Dae-Won

    2014-01-01

    The development of synoptic sky surveys has led to a massive amount of data for which resources needed for analysis are beyond human capabilities. In order to process this information and to extract all possible knowledge, machine learning techniques become necessary. Here we present a new methodology to automatically discover unknown variable objects in large astronomical catalogs. With the aim of taking full advantage of all information we have about known objects, our method is based on a supervised algorithm. In particular, we train a random forest classifier using known variability classes of objects and obtain votes for each of the objects in the training set. We then model this voting distribution with a Bayesian network and obtain the joint voting distribution among the training objects. Consequently, an unknown object is considered as an outlier insofar it has a low joint probability. By leaving out one of the classes on the training set, we perform a validity test and show that when the random forest classifier attempts to classify unknown light curves (the class left out), it votes with an unusual distribution among the classes. This rare voting is detected by the Bayesian network and expressed as a low joint probability. Our method is suitable for exploring massive data sets given that the training process is performed offline. We tested our algorithm on 20 million light curves from the MACHO catalog and generated a list of anomalous candidates. After analysis, we divided the candidates into two main classes of outliers: artifacts and intrinsic outliers. Artifacts were principally due to air mass variation, seasonal variation, bad calibration, or instrumental errors and were consequently removed from our outlier list and added to the training set. After retraining, we selected about 4000 objects, which we passed to a post-analysis stage by performing a cross-match with all publicly available catalogs. Within these candidates we identified certain known

  18. Supervised Detection of Anomalous Light Curves in Massive Astronomical Catalogs

    Science.gov (United States)

    Nun, Isadora; Pichara, Karim; Protopapas, Pavlos; Kim, Dae-Won

    2014-09-01

    The development of synoptic sky surveys has led to a massive amount of data for which resources needed for analysis are beyond human capabilities. In order to process this information and to extract all possible knowledge, machine learning techniques become necessary. Here we present a new methodology to automatically discover unknown variable objects in large astronomical catalogs. With the aim of taking full advantage of all information we have about known objects, our method is based on a supervised algorithm. In particular, we train a random forest classifier using known variability classes of objects and obtain votes for each of the objects in the training set. We then model this voting distribution with a Bayesian network and obtain the joint voting distribution among the training objects. Consequently, an unknown object is considered as an outlier insofar it has a low joint probability. By leaving out one of the classes on the training set, we perform a validity test and show that when the random forest classifier attempts to classify unknown light curves (the class left out), it votes with an unusual distribution among the classes. This rare voting is detected by the Bayesian network and expressed as a low joint probability. Our method is suitable for exploring massive data sets given that the training process is performed offline. We tested our algorithm on 20 million light curves from the MACHO catalog and generated a list of anomalous candidates. After analysis, we divided the candidates into two main classes of outliers: artifacts and intrinsic outliers. Artifacts were principally due to air mass variation, seasonal variation, bad calibration, or instrumental errors and were consequently removed from our outlier list and added to the training set. After retraining, we selected about 4000 objects, which we passed to a post-analysis stage by performing a cross-match with all publicly available catalogs. Within these candidates we identified certain known

  19. Vaporization of comet nuclei: Light curves and life times

    Energy Technology Data Exchange (ETDEWEB)

    Cowan, J J [Harvard Univ., Cambridge, MA (USA). Center for Astrophysics; A' Hearn, M F [Maryland Univ., College Park (USA)

    1979-10-01

    The authors have examined the effects of vaporization from the nucleus of a comet and show that a latitude dependence of vaporization can, in some cases, explain asymmetries in commetary light curves. They also find that a non-uniform distribution of solar radiation over a comet can considerably shorten the vaporization lifetime compared to the results normally obtained by assuming that the nuclear surface is isothermal. Independent of any latitude effects, comets with CO/sub 2/-dominated nuclei and with periherlion distances less than 0.5 AU have vaporization lifetimes less than or comparable to their dynamical ejection times. This may explain the observed deficit of comets with small perihelion distances. Similarly comets with CO/sub 2/-dominated nuclei and perihelia near Jupiter's orbit have vaporization lifetimes that are shorter than the time for capture into short-period orbits. They suggest, therefore, that at least some new comets are composed in large part of CO/sub 2/, while only H/sub 2/O-dominated comets, with lower vaporization rates, can survive to be captured into short-period orbits.

  20. SWIFT GRB GRB071010B: OUTLIER OF THE E srcpeak - E γ AND E iso - E srcpeak - t srcjet CORRELATIONS

    International Nuclear Information System (INIS)

    Urata, Yuji; Lee, Induk; Ip, Wing Huen; Huang, Kuiyun; Im, Myungshin; Deng Jinsong; Liping Xin; Qiu Yulei; Wei Jianyan; Zheng Weikang; Krimm, Hans; Ohno, Masanori; Sugita, Satoshi; Tashiro, Makoto; Yamaoka, Kazutaka

    2009-01-01

    We present multi-band results for GRB071010B based on Swift, Suzaku, and ground-based optical observations. This burst is an ideal target to evaluate the robustness of the E src peak - E iso and E src peak - E γ relations, whose studies have been in stagnation due to the lack of the combined estimation of E src peak and long-term optical monitoring. The joint prompt spectral fitting using Swift/Burst Alert Telescope and Suzaku/Wide-band All-sky Monitor data yielded the spectral peak energy as E src peak of 86.5 +6.4 -6.3 keV and E iso of 2.25 +0.19 -0.16 x 10 52 erg with z = 0.947. The optical afterglow light curve is well fitted by a simple power law with temporal index α = -0.60 ± 0.02. The lower limit of temporal break in the optical light curve is 9.8 days. Our multi-wavelength analysis reveals that GRB071010B follows E src peak - E iso but violates the E src peak - E γ and E iso - E src peak - t src jet at more than the 3σ level.

  1. RADIOACTIVELY POWERED RISING LIGHT CURVES OF TYPE Ia SUPERNOVAE

    International Nuclear Information System (INIS)

    Piro, Anthony L.

    2012-01-01

    The rising luminosity of the recent, nearby supernova 2011fe shows a quadratic dependence with time during the first ≈0.5-4 days. In addition, studies of the composite light curves formed from stacking together many Type Ia supernovae (SNe Ia) have found similar power-law indices for the rise, but may also show some dispersion that may indicate diversity. I explore what range of power-law rises are possible due to the presence of radioactive material near the surface of the exploding white dwarf (WD). I summarize what constraints such a model places on the structure of the progenitor and the distribution and velocity of ejecta. My main conclusion is that for the inferred explosion time for SN 2011fe, its rise requires an increasing mass fraction X 56 ≈ (4-6) × 10 –2 of 56 Ni distributed between a depth of ≈10 –2 and 0.3 M ☉ below the WD's surface. Radioactive elements this shallow are not found in simulations of a single C/O detonation. Scenarios that may produce this material include helium-shell burning during a double-detonation ignition, a gravitationally confined detonation, and a subset of deflagration to detonation transition models. In general, the power-law rise can differ from quadratic depending on the details of the velocity, density, and radioactive deposition gradients in a given event. Therefore, comparisons of this work with observed bolometric rises of SNe Ia would place strong constraints on the properties of the shallow outer layers, providing important clues for identifying the elusive progenitors of SNe Ia.

  2. Intensive Monitoring Survey of Nearby Galaxies (IMSNG): Catching Early Light Curves of Supernovae

    Science.gov (United States)

    Im, Myungshin; IMSNG Team

    2018-01-01

    SNe light curves have been used to study the expansion history of the universe, and a lot of efforts have gone into understanding the overall shape of the radioactively powered light curve. However, we still have little direct observational evidence for the theorized SN progenitor systems. Recent studies suggest that the light curve of a supernova shortly after its explosion (world. Through this survey, we expect to catch the very early precursor emission as faint as R=21 mag (~0.1 Rsun for the progenitor). This poster outlines this project, and present a few scientific highlights, such as the early light curve of SN 2015F in NGC 2442.

  3. Exquisite Nova Light Curves from the Solar Mass Ejection Imager (SMEI)

    OpenAIRE

    Hounsell, R.; Bode, M. F.; Hick, P. P.; Buffington, A.; Jackson, B. V.; Clover, J. M.; Shafter, A. W.; Darnley, M. J.; Mawson, N. R.; Steele, I. A.; Evans, A.; Eyres, S. P. S.; O'Brien, T. J.

    2010-01-01

    We present light curves of three classical novae (KT Eridani, V598 Puppis, V1280 Scorpii) and one recurrent nova (RS Ophiuchi) derived from data obtained by the Solar Mass Ejection Imager (SMEI) on board the Coriolis satellite. SMEI provides near complete sky-map coverage with precision visible-light photometry at 102-minute cadence. The light curves derived from these sky maps offer unprecedented temporal resolution around, and especially before, maximum light, a phase of the nova eruption n...

  4. Fourier techniques for an analysis of eclipsing binary light curves. Pt. 6b

    International Nuclear Information System (INIS)

    Demircan, O.

    1980-01-01

    This is a continuation of a previous paper which appeared in this journal (Demircan, 1980b) and aims at ascertaining some other relations between the integral transforms of the light curves of eclipsing binary systems. The appropriate use of these relations should facilitate the numerical computations for an analysis of eclipsing binary light curves by different Fourier techniques. (orig.)

  5. Infrared and optical light curves of EX Hydrae and VW Hydri

    International Nuclear Information System (INIS)

    Sherrington, M.R.; Lawson, P.A.; King, A.R.; Jameson, R.F.

    1980-01-01

    Optical and infrared light curves of EX Hya (V and K) and VW Hyi (J and K) are presented. The infrared colours imply very large discs for these systems. It is also found for EX Hya that the structure of the light curves is non-repeatable. (author)

  6. Application of Geodetic VLBI Data to Obtaining Long-Term Light Curves for Astrophysics

    Science.gov (United States)

    Kijima, Masachika

    2010-01-01

    The long-term light curve is important to research on binary black holes and disk instability in AGNs. The light curves have been drawn mainly using single dish data provided by the University of Michigan Radio Observatory and the Metsahovi Radio Observatory. Hence, thus far, we have to research on limited sources. I attempt to draw light curves using VLBI data for those sources that have not been monitored by any observatories with single dish. I developed software, analyzed all geodetic VLBI data available at the IVS Data Centers, and drew the light curves at 8 GHz. In this report, I show the tentative results for two AGNs. I compared two light curves of 4C39.25, which were drawn based on single dish data and on VLBI data. I confirmed that the two light curves were consistent. Furthermore, I succeeded in drawing the light curve of 0454-234 with VLBI data, which has not been monitored by any observatory with single dish. In this report, I suggest that the geodetic VLBI archive data is useful to obtain the long-term light curves at radio bands for astrophysics.

  7. Four-colour photometry of eclipsing binaries. XXXII. Light curves of V1031 Orionis

    Energy Technology Data Exchange (ETDEWEB)

    Clausen, J V; Nordstroem, B; Andersen, J [Copenhagen Univ. Observatory, (DK); Nordstroem, B; Andersen, J [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (US)

    1989-12-01

    Complete uvby light curves are presented for the bright, southern, A-type triple system V1031 Orionis which consists of two well-separated eclipsing components in a circular orbit and a third component at an angular distance of about 0.16 sec. The light curves contain 1280 points in each colour, obtained from 1980 to 1983.

  8. Four-colour photometry of eclipsing binaries. XXXII. Light curves of V1031 Orionis

    International Nuclear Information System (INIS)

    Clausen, J.V.; Nordstroem, B.; Andersen, J.; Nordstroem, B.; Andersen, J.

    1989-01-01

    Complete uvby light curves are presented for the bright, southern, A-type triple system V1031 Orionis which consists of two well-separated eclipsing components in a circular orbit and a third component at an angular distance of about 0.16 sec. The light curves contain 1280 points in each colour, obtained from 1980 to 1983

  9. Evolution of the polarization of the optical afterglow of the gamma-ray burst GRB030329.

    Science.gov (United States)

    Greiner, Jochen; Klose, Sylvio; Reinsch, Klaus; Schmid, Hans Martin; Sari, Re'em; Hartmann, Dieter H; Kouveliotou, Chryssa; Rau, Arne; Palazzi, Eliana; Straubmeier, Christian; Stecklum, Bringfried; Zharikov, Sergej; Tovmassian, Gaghik; Bärnbantner, Otto; Ries, Christoph; Jehin, Emmanuel; Henden, Arne; Kaas, Anlaug A; Grav, Tommy; Hjorth, Jens; Pedersen, Holger; Wijers, Ralph A M J; Kaufer, Andreas; Park, Hye-Sook; Williams, Grant; Reimer, Olaf

    2003-11-13

    The association of a supernova with GRB030329 strongly supports the 'collapsar' model of gamma-ray bursts, where a relativistic jet forms after the progenitor star collapses. Such jets cannot be spatially resolved because gamma-ray bursts lie at cosmological distances; their existence is instead inferred from 'breaks' in the light curves of the afterglows, and from the theoretical desire to reduce the estimated total energy of the burst by proposing that most of it comes out in narrow beams. Temporal evolution of the polarization of the afterglows may provide independent evidence for the jet structure of the relativistic outflow. Small-level polarization ( approximately 1-3 per cent) has been reported for a few bursts, but its temporal evolution has yet to be established. Here we report polarimetric observations of the afterglow of GRB030329. We establish the polarization light curve, detect sustained polarization at the per cent level, and find significant variability. The data imply that the afterglow magnetic field has a small coherence length and is mostly random, probably generated by turbulence, in contrast with the picture arising from the high polarization detected in the prompt gamma-rays from GRB021206 (ref. 18).

  10. Multicolour modelling of SN 2013dx associated with GRB 130702A★

    Science.gov (United States)

    Volnova, A. A.; Pruzhinskaya, M. V.; Pozanenko, A. S.; Blinnikov, S. I.; Minaev, P. Yu.; Burkhonov, O. A.; Chernenko, A. M.; Ehgamberdiev, Sh. A.; Inasaridze, R.; Jelinek, M.; Khorunzhev, G. A.; Klunko, E. V.; Krugly, Yu. N.; Mazaeva, E. D.; Rumyantsev, V. V.; Volvach, A. E.

    2017-05-01

    We present optical observations of SN 2013dx, related to the Fermi burst GRB 130702A, which occurred at red shift z = 0.145. It is the second-best sampled gamma-ray burst (GRB)/supernova (SN) after SN 1998bw. The observational light curves contain more than 280 data points in the uBgrRiz filters until 88 d after the burst, and the data were collected from our observational collaboration (Maidanak Observatory, Abastumani Observatory, Crimean Astrophysical Observatory, Mondy Observatory, National Observatory of Turkey and Observatorio del Roque de los Muchachos) and from the literature. We model numerically the multicolour light curves using the one-dimensional radiation hydrodynamical code stella, previously widely implemented for modelling typical non-GRB SNe. The best-fitting model has the following parameters: pre-SN star mass M = 25 M⊙; mass of the compact remnant MCR = 6 M⊙; total energy of the outburst Eoburst = 3.5 × 1052 erg; pre-supernova star radius R = 100 R⊙; M_^{56Ni} = 0.2 M_{⊙}, which is totally mixed through the ejecta; MO = 16.6 M⊙; MSi = 1.2 M⊙ and MFe = 1.2 M⊙, and the radiative efficiency of the SN is 0.1 per cent.

  11. Long-term continuous energy injection in the afterglow of GRB 060729

    International Nuclear Information System (INIS)

    Xu Ming; Huang Yongfeng; Lu Tan

    2009-01-01

    A long plateau phase and an amazing level of brightness have been observed in the X-ray afterglow of GRB 060729. This peculiar light curve is likely due to long-term energy injection in external shock. Here, we present a detailed numerical study of the energy injection process of magnetic dipole radiation from a strongly magnetized millisecond pulsar and model the multi-band afterglow observations. It is found that this model can successfully explain the long plateaus in the observed X-ray and optical afterglow light curves. The sharp break following the plateaus could be due to the rapid decline of the emission power of the central pulsar. At an even later time (∼ 5 x 10 6 s), an obvious jet break appears, which implies a relatively large half opening angle of θ ∼ 0.3 for the GRB ejecta. Due to the energy injection, the Lorentz factor of the outflow is still larger than two even at 10 7 s after the GRB trigger, making the X-ray afterglow of this burst detectable by Chandra even 642 d after the burst.

  12. Generalized Fermat's principle and action for light rays in a curved spacetime

    Science.gov (United States)

    Frolov, Valeri P.

    2013-09-01

    We start with formulation of the generalized Fermat’s principle for light propagation in a curved spacetime. We apply Pontryagin’s minimum principle of the optimal control theory and obtain an effective Hamiltonian for null geodesics in a curved spacetime. We explicitly demonstrate that dynamical equations for this Hamiltonian correctly reproduce null geodesic equations. Other forms of the action for light rays in a curved spacetime are also discussed.

  13. CSI 2264: CHARACTERIZING YOUNG STARS IN NGC 2264 WITH STOCHASTICALLY VARYING LIGHT CURVES

    Energy Technology Data Exchange (ETDEWEB)

    Stauffer, John; Rebull, Luisa; Carey, Sean [Spitzer Science Center, California Institute of Technology, Pasadena, CA 91125 (United States); Cody, Ann Marie [NASA Ames Research Center, Kepler Science Office, Mountain View, CA 94035 (United States); Hillenbrand, Lynne A.; Carpenter, John [Astronomy Department, California Institute of Technology, Pasadena, CA 91125 (United States); Turner, Neal J. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Terebey, Susan [Department of Physics and Astronomy, 5151 State University Drive, California State University at Los Angeles, Los Angeles, CA 90032 (United States); Morales-Calderón, Maria [Centro de Astrobiología, Dpto. de Astrofísica, INTA-CSIC, P.O. BOX 78, E-28691, ESAC Campus, Villanueva de la Cañada, Madrid (Spain); Alencar, Silvia H. P.; McGinnis, Pauline; Sousa, Alana [Departamento de Física—ICEx—UFMG, Av. Antônio Carlos, 6627, 30270-901, Belo Horizonte, MG (Brazil); Bouvier, Jerome; Venuti, Laura [Université de Grenoble, Institut de Planétologie et d’Astrophysique de Grenoble (IPAG), F-38000 Grenoble (France); Hartmann, Lee; Calvet, Nuria [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI:48105 (United States); Micela, Giusi; Flaccomio, Ettore [INAF—Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, I-90134, Palermo (Italy); Song, Inseok [Department of Physics and Astronomy, The University of Georgia, Athens, GA 30602-2451 (United States); Gutermuth, Rob, E-mail: stauffer@ipac.caltech.edu [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States); and others

    2016-03-15

    We provide CoRoT and Spitzer light curves and other supporting data for 17 classical T Tauri stars in NGC 2264 whose CoRoT light curves exemplify the “stochastic” light curve class as defined in 2014 by Cody et al. The most probable physical mechanism to explain the optical variability within this light curve class is time-dependent mass accretion onto the stellar photosphere, producing transient hot spots. Where we have appropriate spectral data, we show that the veiling variability in these stars is consistent in both amplitude and timescale with the optical light curve morphology. The veiling variability is also well-correlated with the strength of the He i 6678 Å emission line, predicted by models to arise in accretion shocks on or near the stellar photosphere. Stars with accretion burst light curve morphology also have variable mass accretion. The stochastic and accretion burst light curves can both be explained by a simple model of randomly occurring flux bursts, with the stochastic light curve class having a higher frequency of lower amplitude events. Members of the stochastic light curve class have only moderate mass accretion rates. Their Hα profiles usually have blueshifted absorption features, probably originating in a disk wind. The lack of periodic signatures in the light curves suggests that little of the variability is due to long-lived hot spots rotating into or out of our line of sight; instead, the primary driver of the observed photometric variability is likely to be instabilities in the inner disk that lead to variable mass accretion.

  14. UBV Light Curves of ζ AUR Star 32 Cygni

    Directory of Open Access Journals (Sweden)

    Il-Seong Nha

    1992-12-01

    Full Text Available UBV ovservation of ζ Aur star 32 Cyg have been at the Yonsei University Observatory suing the 60-cm Goto reflector and five years, 1988-1992. Observations made during these years cover outside of eclipse phase only. No significant light variation which would represent the secondary eclipse of red supergiant by a hot main sequence star is found. The light levels in three passbands do not show any evidence of the proximate effect of this binary system. Some strong light variations, particularly in U, are discussed with no successful explanation.

  15. MODELING THE EARLY AFTERGLOW IN THE SHORT AND HARD GRB 090510

    Energy Technology Data Exchange (ETDEWEB)

    Fraija, N.; Lee, W. H. [Instituto de Astronomía, Universidad Nacional Autónoma de México, Apdo. Postal 70-264, Cd. Universitaria, 04510 Ciudad de México, DF (Mexico); Veres, P. [Center for Space Plasma and Aeronomic Research (CSPAR), University of Alabama in Huntsville, Huntsville, AL 35899 (United States); Duran, R. Barniol, E-mail: nifraija@astro.unam.mx, E-mail: wlee@astro.unam.mx, E-mail: pv0004@uah.edu, E-mail: rbarniol@purdue.edu [Department of Physics and Astronomy, Purdue University, 525 Northwestern Avenue, West Lafayette, IN 47907 (United States)

    2016-11-01

    The bright, short, and hard GRB 090510 was detected by all instruments aboard the Fermi and Swift satellites. The multiwavelength observations of this burst presented similar features to the Fermi -LAT-detected gamma-ray bursts. In the framework of the external shock model of early afterglow, a leptonic scenario that evolves in a homogeneous medium is proposed to revisit GRB 090510 and explain the multiwavelength light curve observations presented in this burst. These observations are consistent with the evolution of a jet before and after the jet break. The long-lasting LAT, X-ray, and optical fluxes are explained in the synchrotron emission from the adiabatic forward shock. Synchrotron self-Compton emission from the reverse shock is consistent with the bright LAT peak provided that the progenitor environment is entrained with strong magnetic fields. It could provide compelling evidence of magnetic field amplification in the neutron star merger.

  16. LONG-TERM LIGHT CURVE OF HIGHLY VARIABLE PROTOSTELLAR STAR GM CEP

    International Nuclear Information System (INIS)

    Xiao Limin; Kroll, Peter; Henden, Arne A.

    2010-01-01

    We present data from the archival plates at Harvard College Observatory and Sonneberg Observatory showing the field of the solar-type pre-main-sequence star GM Cep. A total of 186 magnitudes of GM Cep have been measured on these archival plates, with 176 in blue sensitivity, six in visible, and four in red. We combine our data with data from the literature and from the American Association of Variable Star Observers to depict the long-term light curves of GM Cep in both B and V wavelengths. The light curves span from 1895 until now, with two densely sampled regions (1935-1945 in the B band, and 2006 until now in the V band). The long-term light curves do not show any fast rise behavior as predicted by an accretion mechanism. Both the light curves and the magnitude histograms confirm the conclusion that the light curves are dominated by dips (possibly from extinction) superposed on some quiescence state, instead of outbursts caused by accretion flares. Our result excludes the possibility of GM Cep being a FUor, EXor, or McNeil's Nebula-type star. Several special cases of T Tauri stars were checked, but none of these light curves were compatible with that of GM Cep. The lack of periodicity in the light curve excludes the possibility of GM Cep being a KH 15D system.

  17. NEPTUNE'S DYNAMIC ATMOSPHERE FROM KEPLER K2 OBSERVATIONS: IMPLICATIONS FOR BROWN DWARF LIGHT CURVE ANALYSES.

    Science.gov (United States)

    Simon, Amy A; Rowe, Jason F; Gaulme, Patrick; Hammel, Heidi B; Casewell, Sarah L; Fortney, Jonathan J; Gizis, John E; Lissauer, Jack J; Morales-Juberias, Raul; Orton, Glenn S; Wong, Michael H; Marley, Mark S

    2016-02-01

    Observations of Neptune with the Kepler Space Telescope yield a 49 day light curve with 98% coverage at a 1 minute cadence. A significant signature in the light curve comes from discrete cloud features. We compare results extracted from the light curve data with contemporaneous disk-resolved imaging of Neptune from the Keck 10-m telescope at 1.65 microns and Hubble Space Telescope visible imaging acquired nine months later. This direct comparison validates the feature latitudes assigned to the K2 light curve periods based on Neptune's zonal wind profile, and confirms observed cloud feature variability. Although Neptune's clouds vary in location and intensity on short and long timescales, a single large discrete storm seen in Keck imaging dominates the K2 and Hubble light curves; smaller or fainter clouds likely contribute to short-term brightness variability. The K2 Neptune light curve, in conjunction with our imaging data, provides context for the interpretation of current and future brown dwarf and extrasolar planet variability measurements. In particular we suggest that the balance between large, relatively stable, atmospheric features and smaller, more transient, clouds controls the character of substellar atmospheric variability. Atmospheres dominated by a few large spots may show inherently greater light curve stability than those which exhibit a greater number of smaller features.

  18. Gamma-Ray Light Curves from Pulsar Magnetospheres with Finite Conductivity

    Science.gov (United States)

    Harding, A. K.; Kalapotharakos, C.; Kazanas, D.; Contopoulos, I.

    2012-01-01

    The Fermi Large Area Telescope has provided an unprecedented database for pulsar emission studies that includes gamma-ray light curves for over 100 pulsars. Modeling these light curves can reveal and constrain the geometry of the particle accelerator, as well as the pulsar magnetic field structure. We have constructed 3D magnetosphere models with finite conductivity, that bridge the extreme vacuum and force-free solutions used in previous light curves modeling. We are investigating the shapes of pulsar gamma-ray light curves using these dissipative solutions with two different approaches: (l) assuming geometric emission patterns of the slot gap and outer gap, and (2) using the parallel electric field provided by the resistive models to compute the trajectories and . emission of the radiating particles. The light curves using geometric emission patterns show a systematic increase in gamma-ray peak phase with increasing conductivity, introducing a new diagnostic of these solutions. The light curves using the model electric fields are very sensitive to the conductivity but do not resemble the observed Fermi light curves, suggesting that some screening of the parallel electric field, by pair cascades not included in the models, is necessary

  19. DETERMINATION OF THE LIGHT CURVE OF THE ARTIFICIAL SATELLITE BY ITS ROTATION PATH AS PREPARATION TO THE INVERSE PROBLEM SOLUTION

    OpenAIRE

    Pavlenko, Daniil

    2012-01-01

    Developing the algorithm of estimation of the rotational parameters of the artificial satellite by its light curve, we face the necessity to compute test light curves for various initially given types of rotation and specific features of lighting of the satellite. In the present study the algorithm of creation of such light curves with the simulation method and the obtained result are described.

  20. TYPE Ia SUPERNOVA LIGHT-CURVE INFERENCE: HIERARCHICAL BAYESIAN ANALYSIS IN THE NEAR-INFRARED

    International Nuclear Information System (INIS)

    Mandel, Kaisey S.; Friedman, Andrew S.; Kirshner, Robert P.; Wood-Vasey, W. Michael

    2009-01-01

    We present a comprehensive statistical analysis of the properties of Type Ia supernova (SN Ia) light curves in the near-infrared using recent data from Peters Automated InfraRed Imaging TELescope and the literature. We construct a hierarchical Bayesian framework, incorporating several uncertainties including photometric error, peculiar velocities, dust extinction, and intrinsic variations, for principled and coherent statistical inference. SN Ia light-curve inferences are drawn from the global posterior probability of parameters describing both individual supernovae and the population conditioned on the entire SN Ia NIR data set. The logical structure of the hierarchical model is represented by a directed acyclic graph. Fully Bayesian analysis of the model and data is enabled by an efficient Markov Chain Monte Carlo algorithm exploiting the conditional probabilistic structure using Gibbs sampling. We apply this framework to the JHK s SN Ia light-curve data. A new light-curve model captures the observed J-band light-curve shape variations. The marginal intrinsic variances in peak absolute magnitudes are σ(M J ) = 0.17 ± 0.03, σ(M H ) = 0.11 ± 0.03, and σ(M Ks ) = 0.19 ± 0.04. We describe the first quantitative evidence for correlations between the NIR absolute magnitudes and J-band light-curve shapes, and demonstrate their utility for distance estimation. The average residual in the Hubble diagram for the training set SNe at cz > 2000kms -1 is 0.10 mag. The new application of bootstrap cross-validation to SN Ia light-curve inference tests the sensitivity of the statistical model fit to the finite sample and estimates the prediction error at 0.15 mag. These results demonstrate that SN Ia NIR light curves are as effective as corrected optical light curves, and, because they are less vulnerable to dust absorption, they have great potential as precise and accurate cosmological distance indicators.

  1. Characterization of Type Ia Supernova Light Curves Using Principal Component Analysis of Sparse Functional Data

    Science.gov (United States)

    He, Shiyuan; Wang, Lifan; Huang, Jianhua Z.

    2018-04-01

    With growing data from ongoing and future supernova surveys, it is possible to empirically quantify the shapes of SNIa light curves in more detail, and to quantitatively relate the shape parameters with the intrinsic properties of SNIa. Building such relationships is critical in controlling systematic errors associated with supernova cosmology. Based on a collection of well-observed SNIa samples accumulated in the past years, we construct an empirical SNIa light curve model using a statistical method called the functional principal component analysis (FPCA) for sparse and irregularly sampled functional data. Using this method, the entire light curve of an SNIa is represented by a linear combination of principal component functions, and the SNIa is represented by a few numbers called “principal component scores.” These scores are used to establish relations between light curve shapes and physical quantities such as intrinsic color, interstellar dust reddening, spectral line strength, and spectral classes. These relations allow for descriptions of some critical physical quantities based purely on light curve shape parameters. Our study shows that some important spectral feature information is being encoded in the broad band light curves; for instance, we find that the light curve shapes are correlated with the velocity and velocity gradient of the Si II λ6355 line. This is important for supernova surveys (e.g., LSST and WFIRST). Moreover, the FPCA light curve model is used to construct the entire light curve shape, which in turn is used in a functional linear form to adjust intrinsic luminosity when fitting distance models.

  2. Light-Curve Diagnosis of a Hot Spot for Accretion-Disk Models

    OpenAIRE

    FUKUE, Jun

    2003-01-01

    Light curves of a hot spot rotating in a relativistic Keplerian disk were found to be periodic with typically two peaks, originating from a gravitational focusing effect and a Doppler boost. On the other hand, we found that light curves of a hot spot spirally infalling in a sub-Keplerian advective disk are aperiodic with typically a single peak, originating from a gravitational focusing effect or a Doppler boost. Such a difference in the light curves of a hot spot can discriminate background ...

  3. New Light Curves and Analysis of the Overcontact Binaries PP Lac and DK Sge

    Science.gov (United States)

    Sanders, S. J.; Hargis, J. R.; Bradstreet, D. H.

    2004-12-01

    As a by-product of the ongoing work with the Catalog and AtLas of Eclipsing Binaries database (CALEB; Bradstreet et al. 2004), several hundred eclipsing binary systems have been identified that have either unpublished or poor quality light curves. We present new V & Rc light curves for the overcontact systems PP Lac and DK Sge, both chosen because their deep eclipses (peak-to-peak amplitudes of nearly 0.7 mag) help constrain the light curve modelling. Data were obtained using the 41-cm telescope at the Eastern University Observatory equipped with an SBIG ST-10XME CCD. PP Lac (P= 0.40116 d) is a W-type contact binary with only one previously published light curve (Dumont & Maraziti 1990), but the data are sparse and almost non-existent at primary eclipse. Modelling of these data gave varying results; the published mass ratios differ by nearly 0.3. Our data confirms the noted differing eclipse depths but we find the primary eclipse to be total. We present a new light curve solution using Binary Maker 3 (Bradstreet & Steelman 2002) and Wilson-Devinney, finding the mass ratio to be well-constrained by the duration of total eclipse. A period study will be presented using previously existing and newly derived times of minimum light. DK Sge (P=0.62182 d) appears to be an A-type contact binary with no published light curve. The eclipses are partial, with the primary eclipse being deeper by about 0.08 mag. The maxima show evidence of a slight asymmetry, although the light curve appears to be repeatable over the 1 month of observations. We present the first light curve solution using Binary Maker 3 and Wilson-Devinney, but have limited mass ratio constraints due to the absence of radial velocity data. A period study will be presented using previously existing and newly derived times of minimum light.

  4. Fourier analysis of the light curves of eclipsing variables. XI

    International Nuclear Information System (INIS)

    Kopal, Z.

    1977-01-01

    The aim of the present paper is to introduce a new definition of the loss of light suffered by mutual eclipses of the components of close binary systems: namely, as a cross-correlation of two apertures representing the eclipsing and eclipsed discs. The advantages of such a strategy over the more conventional (geometrical) approach are (a) greater symmetry of the respective expressions; (b) greater affinity of expressions arising from distortion with those expressing the light changes due to eclipses of spherical stars; and (c) greater freedom in dealing with the effects of particular distribution of brightness over the disc of the star undergoing eclipse (generalized limb-darkening), as well as of possible semi-transparency of the eclipsing component (Wolf-Rayet stars). In point of fact, none of these tasks could be handled with equal ease by any other technique; nor could the corresponding loss of light be so automated by any other approach. (Auth.)

  5. A method for the rapid generation of nonsequential light-response curves of chlorophyll fluorescence.

    Science.gov (United States)

    Serôdio, João; Ezequiel, João; Frommlet, Jörg; Laviale, Martin; Lavaud, Johann

    2013-11-01

    Light-response curves (LCs) of chlorophyll fluorescence are widely used in plant physiology. Most commonly, LCs are generated sequentially, exposing the same sample to a sequence of distinct actinic light intensities. These measurements are not independent, as the response to each new light level is affected by the light exposure history experienced during previous steps of the LC, an issue particularly relevant in the case of the popular rapid light curves. In this work, we demonstrate the proof of concept of a new method for the rapid generation of LCs from nonsequential, temporally independent fluorescence measurements. The method is based on the combined use of sample illumination with digitally controlled, spatially separated beams of actinic light and a fluorescence imaging system. It allows the generation of a whole LC, including a large number of actinic light steps and adequate replication, within the time required for a single measurement (and therefore named "single-pulse light curve"). This method is illustrated for the generation of LCs of photosystem II quantum yield, relative electron transport rate, and nonphotochemical quenching on intact plant leaves exhibiting distinct light responses. This approach makes it also possible to easily characterize the integrated dynamic light response of a sample by combining the measurement of LCs (actinic light intensity is varied while measuring time is fixed) with induction/relaxation kinetics (actinic light intensity is fixed and the response is followed over time), describing both how the response to light varies with time and how the response kinetics varies with light intensity.

  6. GRB 120422A: a Low-Luminosity Gamma-Ray Burst Driven by a Central Engine

    Science.gov (United States)

    Zhang, Bin-Bin; Fan, Yi-Zhong; Shen, Rong-Feng; Xu, Dong; Zhang, Fu-Wen; Wei, Da-Ming; Burrows, David N.; Zhang, Bing; Gehrels, Neil

    2012-01-01

    GRB 120422A is a low-luminosity gamma-ray burst (GRB) associated with a bright supernova, which distinguishesitself by its relatively short T(sub 90) (approximately 5 s) and an energetic and steep-decaying X-ray tail. We analyze the Swift BurstAlert Telescope and X-ray Telescope data and discuss the physical implications. We show that the steep declineearly in the X-ray light curve can be interpreted as the curvature tail of a late emission episode around 58-86 s,with a curved instantaneous spectrum at the end of the emission episode. Together with the main activity in thefirst 20 s and the weak emission from 40 s to 60 s, the prompt emission is variable, which points to a centralengine origin in contrast to a shock-breakout origin, which is used to interpret some other nearby low-luminosity supernova GRBs. Both the curvature effect model and interpreting the early shallow decay as the coasting externalforward shock emission in a wind medium provide a constraint on the bulk Lorentz factor to be around several.Comparing the properties ofGRB 120422A and other supernova GRBs,we find that themain criterion to distinguish engine-driven GRBs from shock-breakout GRBs is the time-averaged -ray luminosity. Engine-driven GRBs likelyhave a luminosity above approximately 10(sup 48) erg s(sup -1).

  7. Swift captures the spectrally evolving prompt emission of GRB070616

    Science.gov (United States)

    Starling, R. L. C.; O'Brien, P. T.; Willingale, R.; Page, K. L.; Osborne, J. P.; de Pasquale, M.; Nakagawa, Y. E.; Kuin, N. P. M.; Onda, K.; Norris, J. P.; Ukwatta, T. N.; Kodaka, N.; Burrows, D. N.; Kennea, J. A.; Page, M. J.; Perri, M.; Markwardt, C. B.

    2008-02-01

    The origins of gamma-ray burst (GRB) prompt emission are currently not well understood and in this context long, well-observed events are particularly important to study. We present the case of GRB070616, analysing the exceptionally long-duration multipeaked prompt emission, and later afterglow, captured by all the instruments on-board Swift and by Suzaku Wide-Band All-Sky Monitor (WAM). The high-energy light curve remained generally flat for several hundred seconds before going into a steep decline. Spectral evolution from hard to soft is clearly taking place throughout the prompt emission, beginning at 285s after the trigger and extending to 1200s. We track the movement of the spectral peak energy, whilst observing a softening of the low-energy spectral slope. The steep decline in flux may be caused by a combination of this strong spectral evolution and the curvature effect. We investigate origins for the spectral evolution, ruling out a superposition of two power laws and considering instead an additional component dominant during the late prompt emission. We also discuss origins for the early optical emission and the physics of the afterglow. The case of GRB070616 clearly demonstrates that both broad-band coverage and good time resolution are crucial to pin down the origins of the complex prompt emission in GRBs. This paper is dedicated to the memory of Dr Francesca Tamburelli who died during its production. Francesca played a fundamental role within the team which is in charge of the development of the Swift X-Ray Telescope (XRT) data analysis software at the Italian Space Agency's Science Data Centre in Frascati. She is sadly missed. E-mail: rlcs1@star.le.ac.uk

  8. Light curves for ''bump Cepheids'' computed with a dynamically zoned pulsation code

    International Nuclear Information System (INIS)

    Adams, T.F.; Castor, J.E.; Davis, C.G.

    1978-01-01

    The dynamically zoned pulsation code developed by Castor, Davis, and Davison has been used to recalculate the Goddard model and to calculate three other Cepheid models with the same period (9.8 days). This family of models shows how the bumps and other features of the light and velocity curves change as the mass is varied at constant period. This study, with a code that is capable of producing reliable light curves, shows again that the light and velocity curves for 9.8-day Cepheid models with standard homogeneous compositions do not show bumps like those that are observed unless the mass is significantly lower than the ''evolutionary mass.'' The light and velocity curves for the Goddard model presented here are similar to those computed independently by Fischel, Sparks, and Karp. They should be useful as standards for future investigators

  9. Eclipsing binary stars with extreme light curve asymmetries mined from large astronomical surveys

    Directory of Open Access Journals (Sweden)

    Papageorgiou Athanasios

    2017-01-01

    Full Text Available The O’Connell effect is one of the most perplexing challenges in binary studies as it has not been convincingly explained. Furthermore, a simple method to obtain essential parameters for eclipsing binaries exhibiting this effect and to extract information describing the asymmetry in the light curve maxima is needed. We have developed an automated program that characterizes the morphology of light curves by depth of both minima, height of both maxima and curvature outside the eclipses.

  10. The GRB coordinates network (GCN): A status report

    International Nuclear Information System (INIS)

    Barthelmy, S. D.; Takeshima, T.; Butterworth, P.; Cline, T. L.; Gehrels, N.; Marshall, F.; Connaughton, V.; Kippen, R. M.; Kouveliotou, C.; Robinson, C. R.

    1998-01-01

    A review of the GRB Coordinates Network (GCN) will be given. The GCN has recently replaced the BATSE Coordinates Distribution Network (BACODINE), maintaining all of BACODINE's original capabilities and services, but also providing new sources of GRB location information. These are: (1) source locations using the MSFC LOCBURST algorithm, (2) the Rossi-XTE detections (PCA and ASM), (3) the Interplanetary Network (IPN) locations, and (4) CGRO-COMPTEL locations. These new sources of locations are available for distribution in the minutes-to-hours-to-days time delay ranges, and they also have increasingly and significantly reduced error boxes, thus providing a broad range of time delays and error box sizes to fit within the observing capabilities of a broad range of follow-up instruments in the radio, optical, and TeV gamma-ray bands. Extreme-UV transients from ALEXIS are also now distributed. For all sources of location information, all the distribution methods are available (Internet Socket, E-mail, Alpha-numeric and Numeric Pagers, and Phone/modem) and several filters. Sites can choose which sources to receive and what filters to be applied. The GCN web site has been expanded to include a globally inclusive table of locations, light-curves, and fluence information which is automatically updated in real-time

  11. Colour variations in the GRB 120327A afterglow

    Science.gov (United States)

    Melandri, A.; Covino, S.; Zaninoni, E.; Campana, S.; Bolmer, J.; Cobb, B. E.; Gorosabel, J.; Kim, J.-W.; Kuin, P.; Kuroda, D.; Malesani, D.; Mundell, C. G.; Nappo, F.; Sbarufatti, B.; Smith, R. J.; Steele, I. A.; Topinka, M.; Trotter, A. S.; Virgili, F. J.; Bernardini, M. G.; D'Avanzo, P.; D'Elia, V.; Fugazza, D.; Ghirlanda, G.; Gomboc, A.; Greiner, J.; Guidorzi, C.; Haislip, J. B.; Hanayama, H.; Hanlon, L.; Im, M.; Ivarsen, K. M.; Japelj, J.; Jelínek, M.; Kawai, N.; Kobayashi, S.; Kopac, D.; LaCluyzé, A. P.; Martin-Carrillo, A.; Murphy, D.; Reichart, D. E.; Salvaterra, R.; Salafia, O. S.; Tagliaferri, G.; Vergani, S. D.

    2017-10-01

    Aims: We present a comprehensive temporal and spectral analysis of the long Swift GRB 120327A afterglow data to investigate possible causes of the observed early-time colour variations. Methods: We collected data from various instruments and telescopes in X-ray, ultraviolet, optical, and near-infrared bands, and determined the shapes of the afterglow early-time light curves. We studied the overall temporal behaviour and the spectral energy distributions from early to late times. Results: The ultraviolet, optical, and near-infrared light curves can be modelled with a single power-law component between 200 and 2 × 104 s after the burst event. The X-ray light curve shows a canonical steep-shallow-steep behaviour that is typical of long gamma-ray bursts. At early times a colour variation is observed in the ultraviolet/optical bands, while at very late times a hint of a re-brightening is visible. The observed early-time colour change can be explained as a variation in the intrinsic optical spectral index, rather than an evolution of the optical extinction. Table 2 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/607/A29

  12. REFLECTED LIGHT CURVES, SPHERICAL AND BOND ALBEDOS OF JUPITER- AND SATURN-LIKE EXOPLANETS

    Energy Technology Data Exchange (ETDEWEB)

    Dyudina, Ulyana; Kopparla, Pushkar; Ingersoll, Andrew P.; Yung, Yuk L. [Division of Geological and Planetary Sciences, 150-21 California Institute of Technology, Pasadena, CA 91125 (United States); Zhang, Xi [University of California Santa Cruz 1156 High Street, Santa Cruz, CA 95064 (United States); Li, Liming [Department of Physics, University of Houston, Houston, TX 77204 (United States); Dones, Luke [Southwest Research Institute, 1050 Walnut Street, Suite 300, Boulder CO 80302 (United States); Verbiscer, Anne, E-mail: ulyana@gps.caltech.edu [Department of Astronomy, University of Virginia, Charlottesville, VA 22904-4325 (United States)

    2016-05-10

    Reflected light curves observed for exoplanets indicate that a few of them host bright clouds. We estimate how the light curve and total stellar heating of a planet depends on forward and backward scattering in the clouds based on Pioneer and Cassini spacecraft images of Jupiter and Saturn. We fit analytical functions to the local reflected brightnesses of Jupiter and Saturn depending on the planet’s phase. These observations cover broadbands at 0.59–0.72 and 0.39–0.5 μ m, and narrowbands at 0.938 (atmospheric window), 0.889 (CH4 absorption band), and 0.24–0.28 μ m. We simulate the images of the planets with a ray-tracing model, and disk-integrate them to produce the full-orbit light curves. For Jupiter, we also fit the modeled light curves to the observed full-disk brightness. We derive spherical albedos for Jupiter and Saturn, and for planets with Lambertian and Rayleigh-scattering atmospheres. Jupiter-like atmospheres can produce light curves that are a factor of two fainter at half-phase than the Lambertian planet, given the same geometric albedo at transit. The spherical albedo is typically lower than for a Lambertian planet by up to a factor of ∼1.5. The Lambertian assumption will underestimate the absorption of the stellar light and the equilibrium temperature of the planetary atmosphere. We also compare our light curves with the light curves of solid bodies: the moons Enceladus and Callisto. Their strong backscattering peak within a few degrees of opposition (secondary eclipse) can lead to an even stronger underestimate of the stellar heating.

  13. Searching for transits in the Wide Field Camera Transit Survey with difference-imaging light curves

    NARCIS (Netherlands)

    Zendejas, Dominguez J.; Koppenhoefer, J.; Saglia, R.; Birkby, J.L.; Hodgkin, S.; Kovács, G.; Pinfield, D.; Sipocz, B.; Barrado, D.; Bender, R.; Burgo, del C.; Cappetta, M.; Martín, E.; Nefs, B.; Riffeser, A.; Steele, P.

    2013-01-01

    The Wide Field Camera Transit Survey is a pioneer program aiming at for searching extra-solar planets in the near-infrared. The images from the survey are processed by a data reduction pipeline, which uses aperture photometry to construct the light curves. We produce an alternative set of light

  14. X-ray heating and the optical light curve of HZ Herculis

    International Nuclear Information System (INIS)

    Perrenod, S.C.; Shields, G.A.

    1975-01-01

    We discuss theoretically the optical light curve of HZ Her, the binary companion of the pulsed X-ray source Her X-1. Using model stellar atmospheres, we construct light curves that are in agreement with UBV photometry of HZ Her except for the sharpness of the minimum. Unlike previous authors, we find that heating of the photosphere of HZ Her by the observed X-ray flux is sufficient to explain the amplitude of the light variations in each color, if the X-ray emission persists at HZ Her throughout the 35-day ON-OFF CYCLE. We rule out a corona surrounding HZ Her as the source of the extra light near minimum, and we also rule out a model wherein the extra light is caused by a stellar wind that electron-scatters optical light emitted by the photosphere of the hot side of the star

  15. Gamma-Ray Pulsar Light Curves as Probes of Magnetospheric Structure

    Science.gov (United States)

    Harding, A. K.

    2016-01-01

    The large number of gamma-ray pulsars discovered by the Fermi Gamma-Ray Space Telescope since its launch in 2008 dwarfs the handful that were previously known. The variety of observed light curves makes possible a tomography of both the ensemble-averaged field structure and the high-energy emission regions of a pulsar magnetosphere. Fitting the gamma-ray pulsar light curves with model magnetospheres and emission models has revealed that most of the high-energy emission, and the particles acceleration, takes place near or beyond the light cylinder, near the current sheet. As pulsar magnetosphere models become more sophisticated, it is possible to probe magnetic field structure and emission that are self-consistently determined. Light curve modeling will continue to be a powerful tool for constraining the pulsar magnetosphere physics.

  16. SEARCH FOR GAMMA-RAYS FROM THE UNUSUALLY BRIGHT GRB 130427A WITH THE HAWC GAMMA-RAY OBSERVATORY

    Energy Technology Data Exchange (ETDEWEB)

    Abeysekara, A. U. [Department of Physics and Astronomy, Michigan State University, East Lansing, MI (United States); Alfaro, R. [Instituto de Física, Universidad Nacional Autónoma de México, México D. F. (Mexico); Alvarez, C.; Arceo, R. [CEFyMAP, Universidad Autónoma de Chiapas, Tuxtla Gutiérrez, Chiapas (Mexico); Álvarez, J. D.; Arteaga-Velázquez, J. C.; Cotti, U.; De León, C. [Universidad Michoacana de San Nicolás de Hidalgo, Morelia, Michoacán (Mexico); Solares, H. A. Ayala [Department of Physics, Michigan Technological University, Houghton, MI (United States); Barber, A. S. [Department of Physics and Astronomy, University of Utah, Salt Lake City, UT (United States); Baughman, B. M.; Braun, J. [Department of Physics, University of Maryland, College Park, MD (United States); Bautista-Elivar, N. [Universidad Politécnica de Pachuca, Municipio de Zempoala, Hidalgo (Mexico); BenZvi, S. Y. [Department of Physics and Astronomy, University of Rochester, Rochester, NY (United States); Rosales, M. Bonilla; Carramiñana, A. [Instituto Nacional de Astrofísica, Óptica y Electrónica, Tonantzintla, Puebla (Mexico); Caballero-Mora, K. S. [Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México D. F. (Mexico); Castillo, M.; Cotzomi, J. [Facultad de Ciencias Físico Matemáticas, Benemérita Universidad Autónoma de Puebla, Ciudad Universitaria, Puebla (Mexico); De la Fuente, E., E-mail: dirk.lennarz@gatech.edu [Departamento de Física, Centro Universitario de Ciencias Exactas e Ingenierías, Universidad de Guadalajara, Guadalajara (Mexico); Collaboration: HAWC collaboration; and others

    2015-02-20

    The first limits on the prompt emission from the long gamma-ray burst (GRB) 130427A in the >100 GeV energy band are reported. GRB 130427A was the most powerful burst ever detected with a redshift z ≲ 0.5 and featured the longest lasting emission above 100 MeV. The energy spectrum extends at least up to 95 GeV, clearly in the range observable by the High Altitude Water Cherenkov (HAWC) Gamma-Ray Observatory, a new extensive air shower detector currently under construction in central Mexico. The burst occurred under unfavorable observation conditions, low in the sky and when HAWC was running 10% of the final detector. Based on the observed light curve at MeV-GeV energies, eight different time periods have been searched for prompt and delayed emission from this GRB. In all cases, no statistically significant excess of counts has been found and upper limits have been placed. It is shown that a similar GRB close to zenith would be easily detected by the full HAWC detector, which will be completed soon. The detection rate of the full HAWC detector may be as high as one to two GRBs per year. A detection could provide important information regarding the high energy processes at work and the observation of a possible cut-off beyond the Fermi Large Area Telescope energy range could be the signature of gamma-ray absorption, either in the GRB or along the line of sight due to the extragalactic background light.

  17. Timescale stretch parameterization of Type Ia supernova B-band light curves

    International Nuclear Information System (INIS)

    Goldhaber, G.; Groom, D.E.; Kim, A.; Aldering, G.; Astier, P.; Conley, A.; Deustua, S.E.; Ellis, R.; Fabbro, S.; Fruchter, A.S.; Goobar, A.; Hook, I.; Irwin, M.; Kim, M.; Knop, R.A.; Lidman, C.; McMahon, R.; Nugent, P.E.; Pain, R.; Panagia, N.; Pennypacker, C.R.; Perlmutter, S.; Ruiz-Lapuente, P.; Schaefer, B.; Walton, N.A.; York, T.

    2001-01-01

    R-band intensity measurements along the light curve of Type Ia supernovae discovered by the Cosmology Project (SCP) are fitted in brightness to templates allowing a free parameter the time-axis width factor w identically equal to s times (1+z). The data points are then individually aligned in the time-axis, normalized and K-corrected back to the rest frame, after which the nearly 1300 normalized intensity measurements are found to lie on a well-determined common rest-frame B-band curve which we call the ''composite curve.'' The same procedure is applied to 18 low-redshift Calan/Tololo SNe with Z < 0.11; these nearly 300 B-band photometry points are found to lie on the composite curve equally well. The SCP search technique produces several measurements before maximum light for each supernova. We demonstrate that the linear stretch factor, s, which parameterizes the light-curve timescale appears independent of z, and applies equally well to the declining and rising parts of the light curve. In fact, the B band template that best fits this composite curve fits the individual supernova photometry data when stretched by a factor s with chi 2/DoF ∼ 1, thus as well as any parameterization can, given the current data sets. The measurement of the data of explosion, however, is model dependent and not tightly constrained by the current data. We also demonstrate the 1 + z light-cure time-axis broadening expected from cosmological expansion. This argues strongly against alternative explanations, such as tired light, for the redshift of distant objects

  18. KEPLER ECLIPSING BINARY STARS. III. CLASSIFICATION OF KEPLER ECLIPSING BINARY LIGHT CURVES WITH LOCALLY LINEAR EMBEDDING

    International Nuclear Information System (INIS)

    Matijevič, Gal; Prša, Andrej; Orosz, Jerome A.; Welsh, William F.; Bloemen, Steven; Barclay, Thomas

    2012-01-01

    We present an automated classification of 2165 Kepler eclipsing binary (EB) light curves that accompanied the second Kepler data release. The light curves are classified using locally linear embedding, a general nonlinear dimensionality reduction tool, into morphology types (detached, semi-detached, overcontact, ellipsoidal). The method, related to a more widely used principal component analysis, produces a lower-dimensional representation of the input data while preserving local geometry and, consequently, the similarity between neighboring data points. We use this property to reduce the dimensionality in a series of steps to a one-dimensional manifold and classify light curves with a single parameter that is a measure of 'detachedness' of the system. This fully automated classification correlates well with the manual determination of morphology from the data release, and also efficiently highlights any misclassified objects. Once a lower-dimensional projection space is defined, the classification of additional light curves runs in a negligible time and the method can therefore be used as a fully automated classifier in pipeline structures. The classifier forms a tier of the Kepler EB pipeline that pre-processes light curves for the artificial intelligence based parameter estimator.

  19. Human phase response curve to a 1 h pulse of bright white light

    Science.gov (United States)

    St Hilaire, Melissa A; Gooley, Joshua J; Khalsa, Sat Bir S; Kronauer, Richard E; Czeisler, Charles A; Lockley, Steven W

    2012-01-01

    The phase resetting response of the human circadian pacemaker to light depends on the timing of exposure and is described by a phase response curve (PRC). The current study aimed to construct a PRC for a 1 h exposure to bright white light (∼8000 lux) and to compare this PRC to a dim background light PRC. These data were also compared to a previously completed 6.7 h bright white light PRC and a dim background light PRC constructed under similar conditions. Participants were randomized for exposure to 1 h of either bright white light (n= 18) or dim background light (n= 18) scheduled at 1 of 18 circadian phases. Participants completed constant routine (CR) procedures in dim light (light exposure to assess circadian phase. Phase shifts were calculated as the difference in timing of dim light melatonin onset (DLMO) during pre- and post-stimulus CRs. Exposure to 1 h of bright white light induced a Type 1 PRC with a fitted peak-to-trough amplitude of 2.20 h. No discernible PRC was observed in the dim background light PRC. The fitted peak-to-trough amplitude of the 1 h bright light PRC was ∼40% of that for the 6.7 h PRC despite representing only 15% of the light exposure duration, consistent with previous studies showing a non-linear duration–response function for the effects of light on circadian resetting. PMID:22547633

  20. GRB 110205A: ANATOMY OF A LONG GAMMA-RAY BURST

    International Nuclear Information System (INIS)

    Gendre, B.; Stratta, G.; Atteia, J. L.; Klotz, A.; Boër, M.; Colas, F.; Vachier, F.; Kugel, F.; Rinner, C.; Laas-Bourez, M.; Strajnic, J.

    2012-01-01

    The Swift burst GRB 110205A was a very bright burst visible in the Northern Hemisphere. GRB 110205A was intrinsically long and very energetic and it occurred in a low-density interstellar medium environment, leading to delayed afterglow emission and a clear temporal separation of the main emitting components: prompt emission, reverse shock, and forward shock. Our observations show several remarkable features of GRB 110205A: the detection of prompt optical emission strongly correlated with the Burst Alert Telescope light curve, with no temporal lag between the two; the absence of correlation of the X-ray emission compared to the optical and high-energy gamma-ray ones during the prompt phase; and a large optical re-brightening after the end of the prompt phase, that we interpret as a signature of the reverse shock. Beyond the pedagogical value offered by the excellent multi-wavelength coverage of a gamma-ray burst with temporally separated radiating components, we discuss several questions raised by our observations: the nature of the prompt optical emission and the spectral evolution of the prompt emission at high energies (from 0.5 keV to 150 keV); the origin of an X-ray flare at the beginning of the forward shock; and the modeling of the afterglow, including the reverse shock, in the framework of the classical fireball model.

  1. GRB 091024A and the nature of ultra-long gamma-ray bursts

    International Nuclear Information System (INIS)

    Virgili, F. J.; Mundell, C. G.; Harrison, R.; Kobayashi, S.; Steele, I. A.; Mottram, C. J.; Clay, N. R.; Pal'shin, V.; Guidorzi, C.; Margutti, R.; Chornock, R.; Melandri, A.; Henden, A.; Updike, A. C.; Cenko, S. B.; Tanvir, N. R.; Cucchiara, A.; Gomboc, A.; Levan, A.; Cano, Z.

    2013-01-01

    We present a broadband study of gamma-ray burst (GRB) 091024A within the context of other ultra-long-duration GRBs. An unusually long burst detected by Konus-Wind (KW), Swift, and Fermi, GRB 091024A has prompt emission episodes covering ∼1300 s, accompanied by bright and highly structured optical emission captured by various rapid-response facilities, including the 2 m autonomous robotic Faulkes North and Liverpool Telescopes, KAIT, S-LOTIS, and the Sonoita Research Observatory. We also observed the burst with 8 and 10 m class telescopes and determine the redshift to be z = 1.0924 ± 0.0004. We find no correlation between the optical and γ-ray peaks and interpret the optical light curve as being of external origin, caused by the reverse and forward shock of a highly magnetized jet (R B ≈ 100-200). Low-level emission is detected throughout the near-background quiescent period between the first two emission episodes of the KW data, suggesting continued central-engine activity; we discuss the implications of this ongoing emission and its impact on the afterglow evolution and predictions. We summarize the varied sample of historical GRBs with exceptionally long durations in gamma-rays (≳1000 s) and discuss the likelihood of these events being from a separate population; we suggest ultra-long GRBs represent the tail of the duration distribution of the long GRB population.

  2. A Composite Light Curve Model of the Symbiotic Nova PU Vul (1979

    Directory of Open Access Journals (Sweden)

    Kato M.

    2012-06-01

    Full Text Available PU Vul (1979 is a symbiotic nova that shows a long-lasting flat optical peak followed by a slow decline. We made a quasi-evolution model for outbursts on a 0.6 M⊙ white dwarf consisting of a series of static solutions with optically-thin winds. Our theoretical models reproduce well the observed visual/UV light curves as well as the new estimates of the temperature and radius of the hot component. We also modeled the light curve of the 1980 and 1994 eclipses as the total eclipse occulted by a pulsating M-giant companion star. In the second eclipse, the visual magnitude is dominated by nebular emission which is possibly ejected from the hot component between 1990 to 2000. We have quantitatively estimated three components of emission, i.e., the white dwarf, companion and nebular, and made a composite light curve that represents well the evolution of the PU Vul outburst.

  3. Light Curve Simulation Using Spacecraft CAD Models and Empirical Material Spectral BRDFS

    Science.gov (United States)

    Willison, A.; Bedard, D.

    This paper presents a Matlab-based light curve simulation software package that uses computer-aided design (CAD) models of spacecraft and the spectral bidirectional reflectance distribution function (sBRDF) of their homogenous surface materials. It represents the overall optical reflectance of objects as a sBRDF, a spectrometric quantity, obtainable during an optical ground truth experiment. The broadband bidirectional reflectance distribution function (BRDF), the basis of a broadband light curve, is produced by integrating the sBRDF over the optical wavelength range. Colour-filtered BRDFs, the basis of colour-filtered light curves, are produced by first multiplying the sBRDF by colour filters, and integrating the products. The software package's validity is established through comparison of simulated reflectance spectra and broadband light curves with those measured of the CanX-1 Engineering Model (EM) nanosatellite, collected during an optical ground truth experiment. It is currently being extended to simulate light curves of spacecraft in Earth orbit, using spacecraft Two-Line-Element (TLE) sets, yaw/pitch/roll angles, and observer coordinates. Measured light curves of the NEOSSat spacecraft will be used to validate simulated quantities. The sBRDF was chosen to represent material reflectance as it is spectrometric and a function of illumination and observation geometry. Homogeneous material sBRDFs were obtained using a goniospectrometer for a range of illumination and observation geometries, collected in a controlled environment. The materials analyzed include aluminum alloy, two types of triple-junction photovoltaic (TJPV) cell, white paint, and multi-layer insulation (MLI). Interpolation and extrapolation methods were used to determine the sBRDF for all possible illumination and observation geometries not measured in the laboratory, resulting in empirical look-up tables. These look-up tables are referenced when calculating the overall sBRDF of objects, where

  4. The two-component afterglow of Swift GRB 050802

    Science.gov (United States)

    Oates, S. R.; de Pasquale, M.; Page, M. J.; Blustin, A. J.; Zane, S.; McGowan, K.; Mason, K. O.; Poole, T. S.; Schady, P.; Roming, P. W. A.; Page, K. L.; Falcone, A.; Gehrels, N.

    2007-09-01

    This paper investigates GRB 050802, one of the best examples of a Swift gamma-ray burst afterglow that shows a break in the X-ray light curve, while the optical counterpart decays as a single power law. This burst has an optically bright afterglow of 16.5 mag, detected throughout the 170-650nm spectral range of the Ultraviolet and Optical Telescope (UVOT) onboard Swift. Observations began with the X-ray Telescope and UVOT telescopes 286s after the initial trigger and continued for 1.2 ×106s. The X-ray light curve consists of three power-law segments: a rise until 420s, followed by a slow decay with α =0.63 +/-0.03 until 5000s, after which, the light curve decays faster with a slope of α3 =1.59 +/-0.03. The optical light curve decays as a single power law with αO =0.82 +/-0.03 throughout the observation. The X-ray data on their own are consistent with the break at 5000s being due to the end of energy injection. Modelling the optical to X-ray spectral energy distribution, we find that the optical afterglow cannot be produced by the same component as the X-ray emission at late times, ruling out a single-component afterglow. We therefore considered two-component jet models and find that the X-ray and optical emission is best reproduced by a model in which both components are energy injected for the duration of the observed afterglow and the X-ray break at 5000s is due to a jet break in the narrow component. This bright, well-observed burst is likely a guide for interpreting the surprising finding of Swift that bursts seldom display achromatic jet breaks.

  5. Light curve analysis of the late type binary V523 Cassiopeiae

    Directory of Open Access Journals (Sweden)

    Latković O.

    2009-01-01

    Full Text Available We present the analysis of V and R light curves of the late type contact binary V523 Cas for the season of 2006. These observations make part of the monitoring program aimed at studying the long-term light curve variability in this system. Our results confirm that the system is in an over contact configuration, and include a bright spot in the neck region of the cooler and larger primary. We compare these results with the previous solution, obtained for the season 2005 dataset and discuss the differences.

  6. Using Light Curves to Characterize Size and Shape of Pseudo-Debris

    Science.gov (United States)

    Rodriquez, Heather M.; Abercromby, Kira J.; Jarvis, Kandy S.; Barker, Edwin

    2006-01-01

    Photometric measurements were collected for a new study aimed at estimating orbital debris sizes based on object brightness. To obtain a size from optical measurements the current practice is to assume an albedo and use a normalized magnitude to calculate optical size. However, assuming a single albedo value may not be valid for all objects or orbit types; material type and orientation can mask an object s true optical cross section. This experiment used a CCD camera to record data, a 300 W Xenon, Ozone Free collimated light source to simulate solar illumination, and a robotic arm with five degrees of freedom to move the piece of simulated debris through various orientations. The pseudo-debris pieces used in this experiment originate from the European Space Operations Centre s ESOC2 ground test explosion of a mock satellite. A uniformly illuminated white ping-pong ball was used as a zero-magnitude reference. Each debris piece was then moved through specific orientations and rotations to generate a light curve. This paper discusses the results of five different object-based light curves as measured through an x-rotation. Intensity measurements, from which each light curve was generated, were recorded in five degree increments from zero to 180 degrees. Comparing light curves of different shaped and sized pieces against their characteristic length establishes the start of a database from which an optical size estimation model will be derived in the future.

  7. The Prompt-afterglow Connection in Gamma-ray Bursts: a Comprehensive Statistical Analysis of Swift X-ray Light-curves

    Science.gov (United States)

    Margutti, R.; Zaninoni, E.; Bernardini, M. G.; Chincarini, G.; Pasotti, F.; Guidorzi, C.; Angelini, Lorella; Burrows, D. N.; Capalbi, M.; Evans, P. A.; hide

    2012-01-01

    We present a comprehensive statistical analysis of Swift X-ray light-curves of Gamma- Ray Bursts (GRBs) collecting data from more than 650 GRBs discovered by Swift and other facilities. The unprecedented sample size allows us to constrain the rest-frame X-ray properties of GRBs from a statistical perspective, with particular reference to intrinsic time scales and the energetics of the different light-curve phases in a common rest-frame 0.3-30 keV energy band. Temporal variability episodes are also studied and their properties constrained. Two fundamental questions drive this effort: i) Does the X-ray emission retain any kind of "memory" of the prompt ?-ray phase? ii) Where is the dividing line between long and short GRB X-ray properties? We show that short GRBs decay faster, are less luminous and less energetic than long GRBs in the X-rays, but are interestingly characterized by similar intrinsic absorption. We furthermore reveal the existence of a number of statistically significant relations that link the X-ray to prompt ?-ray parameters in long GRBs; short GRBs are outliers of the majority of these 2-parameter relations. However and more importantly, we report on the existence of a universal 3-parameter scaling that links the X-ray and the ?-ray energy to the prompt spectral peak energy of both long and short GRBs: E(sub X,iso)? E(sup 1.00+/-0.06)(sub ?,iso) /E(sup 0.60+/-0.10)(sub pk).

  8. LATE-TIME LIGHT CURVES OF TYPE II SUPERNOVAE: PHYSICAL PROPERTIES OF SUPERNOVAE AND THEIR ENVIRONMENT

    Energy Technology Data Exchange (ETDEWEB)

    Otsuka, Masaaki; Meixner, Margaret; Panagia, Nino [Space Telescope Science Institute, 3700 San Martin Dr., Baltimore, MD 21218 (United States); Fabbri, Joanna; Barlow, Michael J.; Wesson, Roger [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom); Clayton, Geoffrey C.; Andrews, Jennifer E. [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803 (United States); Gallagher, Joseph S. [Department of Mathematics, Physics, and Computer Science, Raymond Walters College, 9555 Plain field Rd., Blue Ash, OH 45236 (United States); Sugerman, Ben E. K. [Department of Physics and Astronomy, Goucher College, 1021 Dulaney Valley Road, Baltimore, MD 21204 (United States); Ercolano, Barbara [Universitaets-Sternwarte Muenchen, Scheinerstr. 1, 81679 Muenchen (Germany); Welch, Douglas, E-mail: otsuka@stsci.edu, E-mail: otsuka@asiaa.sinica.edu.tw [Department of Physics and Astronomy, McMaster University, Hamilton, Ontario L8S 4M1 (Canada)

    2012-01-01

    We present BVRIJHK-band photometry of six core-collapse supernovae, SNe 1999bw, 2002hh, 2003gd, 2004et, 2005cs, and 2006bc, measured at late epochs (>2 yr) based on the Hubble Space Telescope (HST), and the Gemini North, and WIYN telescopes. We also show the JHK light curves of supernova impostor SN 2008S up to day 575 because it was serendipitously in our SN 2002hh field of view. Of our 43 HST observations in total, 36 observations are successful in detecting the light from the SNe alone and measuring magnitudes of all the targets. HST observations show a resolved scattered light echo around SN 2003gd at day 1520 and around SN 2002hh at day 1717. Our Gemini and WIYN observations detected SNe 2002hh and 2004et as well. Combining our data with previously published data, we show VRIJHK-band light curves and estimate decline magnitude rates at each band in four different phases. Our prior work on these light curves and other data indicate that dust is forming in our targets from days {approx}300 to 400, supporting SN dust formation theory. In this paper we focus on other physical properties derived from late-time light curves. We estimate {sup 56}Ni masses for our targets (0.5-14 Multiplication-Sign 10{sup -2} M{sub Sun }) from the bolometric light curve of each of days {approx}150-300 using SN 1987A as a standard (7.5 Multiplication-Sign 10{sup -2} M{sub Sun }). The flattening or sometimes increasing fluxes in the late-time light curves of SNe 2002hh, 2003gd, 2004et, and 2006bc indicate the presence of light echoes. We estimate the circumstellar hydrogen density of the material causing the light echo and find that SN 2002hh is surrounded by relatively dense materials (n(H) >400 cm{sup -3}) and SNe 2003gd and 2004et have densities more typical of the interstellar medium ({approx}1 cm{sup -3}). We analyze the sample as a whole in the context of physical properties derived in prior work. The {sup 56}Ni mass appears well correlated with progenitor mass with a slope of 0

  9. Surprise in simplicity: an unusual spectral evolution of a single pulse GRB 151006A

    Science.gov (United States)

    Basak, R.; Iyyani, S.; Chand, V.; Chattopadhyay, T.; Bhattacharya, D.; Rao, A. R.; Vadawale, S. V.

    2017-11-01

    We present a detailed analysis of GRB 151006A, the first gamma-ray burst (GRB) detected by AstroSat Cadmium-Zinc-Telluride Imager (CZTI). We study the long-term spectral evolution by exploiting the capabilities of Fermi and Swift satellites at different phases, which is complemented by the polarization measurement with the CZTI. While the light curve of the GRB in different energy bands shows a simple pulse profile, the spectrum shows an unusual evolution. The first phase exhibits a hard-to-soft evolution until ∼16-20 s, followed by a sudden increase in the spectral peak reaching a few MeV. Such a dramatic change in the spectral evolution in the case of a single pulse burst is reported for the first time. This is captured by all models we used namely, Band function, blackbody+Band and two blackbodies+power law. Interestingly, the Fermi Large Area Telescope also detects its first photon (>100 MeV) during this time. This new injection of energy may be associated with either the beginning of afterglow phase, or a second hard pulse of the prompt emission itself that, however, is not seen in the otherwise smooth pulse profile. By constructing Bayesian blocks and studying the hardness evolution we find a good evidence for a second hard pulse. The Swift data at late epochs (>T90 of the GRB) also show a significant spectral evolution consistent with the early second phase. The CZTI data (100-350 keV), though having low significance (1σ), show high values of polarization in the two epochs (77-94 per cent), in agreement with our interpretation.

  10. DISCOVERY OF THE BROAD-LINED TYPE Ic SN 2013cq ASSOCIATED WITH THE VERY ENERGETIC GRB 130427A

    Energy Technology Data Exchange (ETDEWEB)

    Xu, D.; Krühler, T.; Hjorth, J.; Malesani, D.; Fynbo, J. P. U.; Watson, D. J.; Geier, S. [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 København Ø (Denmark); De Ugarte Postigo, A.; Thöne, C. C.; Sánchez-Ramírez, R. [Instituto de Astrofísica de Andalucía, CSIC, Glorieta de la Astronomía s/n, E-18008 Granada (Spain); Leloudas, G. [The Oskar Klein Centre, Department of Physics, Stockholm University, AlbaNova, SE-10691 Stockholm (Sweden); Cano, Z.; Jakobsson, P. [Centre for Astrophysics and Cosmology, Science Institute, University of Iceland, Dunhagi 5, IS-107 Reykjavik (Iceland); Schulze, S. [Departamento de Astronomía y Astrofísica, Pontificia Universidad Católica de Chile, Casilla 306, Santiago 22 (Chile); Kaper, L. [Astronomical Institute Anton Pannekoek, University of Amsterdam, Science Park 904, NL-1098 XH Amsterdam (Netherlands); Sollerman, J. [The Oskar Klein Centre, Department of Astronomy, Stockholm University, AlbaNova, SE-10691 Stockholm (Sweden); Cabrera-Lavers, A. [Instituto de Astrofísica de Canarias, E-38205 La Laguna, Tenerife (Spain); Cao, C. [Department of Space Science and Physics, Shandong University at Weihai, Weihai, Shandong 264209 (China); Covino, S. [INAF/Brera Astronomical Observatory, via Bianchi 46, I-23807 Merate (Italy); Flores, H., E-mail: dong@dark-cosmology.dk [Laboratoire Galaxies Etoiles Physique et Instrumentation, Observatoire de Paris, 5 place Jules Janssen, F-92195 Meudon (France); and others

    2013-10-20

    Long-duration gamma-ray bursts (GRBs) at z < 1 are found in most cases to be accompanied by bright, broad-lined Type Ic supernovae (SNe Ic-BL). The highest-energy GRBs are mostly located at higher redshifts, where the associated SNe are hard to detect observationally. Here, we present early and late observations of the optical counterpart of the very energetic GRB 130427A. Despite its moderate redshift, z = 0.3399 ± 0.0002, GRB 130427A is at the high end of the GRB energy distribution, with an isotropic-equivalent energy release of E{sub iso} ∼ 9.6 × 10{sup 53} erg, more than an order of magnitude more energetic than other GRBs with spectroscopically confirmed SNe. In our dense photometric monitoring, we detect excess flux in the host-subtracted r-band light curve, consistent with that expected from an emerging SN, ∼0.2 mag fainter than the prototypical SN 1998bw. A spectrum obtained around the time of the SN peak (16.7 days after the GRB) reveals broad undulations typical of SNe Ic-BL, confirming the presence of an SN, designated SN 2013cq. The spectral shape and early peak time are similar to those of the high expansion velocity SN 2010bh associated with GRB 100316D. Our findings demonstrate that high-energy, long-duration GRBs, commonly detected at high redshift, can also be associated with SNe Ic-BL, pointing to a common progenitor mechanism.

  11. THE PROPERTIES OF THE 2175 Å EXTINCTION FEATURE DISCOVERED IN GRB AFTERGLOWS

    International Nuclear Information System (INIS)

    Zafar, Tayyaba; Watson, Darach; Elíasdóttir, Árdís; Fynbo, Johan P. U.; Krühler, Thomas; Leloudas, Giorgos; Schady, Patricia; Greiner, Jochen; Jakobsson, Páll; Thöne, Christina C.; Perley, Daniel A.; Morgan, Adam N.; Bloom, Joshua

    2012-01-01

    The unequivocal, spectroscopic detection of the 2175 Å bump in extinction curves outside the Local Group is rare. To date, the properties of the bump have been examined in only two gamma-ray burst (GRB) afterglows (GRB 070802 and GRB 080607). In this work, we analyze in detail the detections of the 2175 Å extinction bump in the optical spectra of two further GRB afterglows: GRB 080605 and 080805. We gather all available optical/near-infrared photometric, spectroscopic, and X-ray data to construct multi-epoch spectral energy distributions (SEDs) for both GRB afterglows. We fit the SEDs with the Fitzpatrick and Massa model with a single or broken power law. We also fit a sample of 38 GRB afterglows, known to prefer a Small Magellanic Cloud (SMC)-type extinction curve, with the same model. We find that the SEDs of GRB 080605 and GRB 080805 at two epochs are fit well with a single power law with a derived extinction of A V = 0.52 +0.13 –0.16 and 0.50 +0.13 –0.10 , and 2.1 +0.7 –0.6 and 1.5 ± 0.2, respectively. While the slope of the extinction curve of GRB 080805 is not well constrained, the extinction curve of GRB 080605 has an unusual very steep far-UV rise together with the 2175 Å bump. Such an extinction curve has previously been found in only a small handful of sightlines in the Milky Way. One possible explanation of such an extinction curve may be dust arising from two different regions with two separate grain populations, however we cannot distinguish the origin of the curve. We finally compare the four 2175 Å bump sightlines to the larger GRB afterglow sample and to Local Group sightlines. We find that while the width and central positions of the bumps are consistent with what is observed in the Local Group, the relative strength of the detected bump (A bump ) for GRB afterglows is weaker for a given A V than for almost any Local Group sightline. Such dilution of the bump strength may offer tentative support to a dual dust-population scenario.

  12. SHOCK BREAKOUT AND EARLY LIGHT CURVES OF TYPE II-P SUPERNOVAE OBSERVED WITH KEPLER

    International Nuclear Information System (INIS)

    Garnavich, P. M.; Tucker, B. E.; Rest, A.; Shaya, E. J.; Olling, R. P.; Kasen, D; Villar, A.

    2016-01-01

    We discovered two transient events in the Kepler field with light curves that strongly suggest they are type II-P supernovae (SNe II-P). Using the fast cadence of the Kepler observations we precisely estimate the rise time to maximum for KSN2011a and KSN2011d as 10.5 ± 0.4 and 13.3 ± 0.4 rest-frame days, respectively. Based on fits to idealized analytic models, we find the progenitor radius of KSN2011a (280 ± 20 R ⊙ ) to be significantly smaller than that for KSN2011d (490 ± 20 R ⊙ ), but both have similar explosion energies of 2.0 ± 0.3 × 10 51 erg. The rising light curve of KSN2011d is an excellent match to that predicted by simple models of exploding red supergiants (RSG). However, the early rise of KSN2011a is faster than the models predict, possibly due to the supernova shock wave moving into pre-existing wind or mass-loss from the RSG. A mass-loss rate of 10 −4 M ⊙ yr −1 from the RSG can explain the fast rise without impacting the optical flux at maximum light or the shape of the post-maximum light curve. No shock breakout emission is seen in KSN2011a, but this is likely due to the circumstellar interaction suspected in the fast rising light curve. The early light curve of KSN2011d does show excess emission consistent with model predictions of a shock breakout. This is the first optical detection of a shock breakout from a SNe II-P

  13. Steep extinction towards GRB 140506A reconciled from host galaxy observations: Evidence that steep reddening laws are local

    Science.gov (United States)

    Heintz, K. E.; Fynbo, J. P. U.; Jakobsson, P.; Krühler, T.; Christensen, L.; Watson, D.; Ledoux, C.; Noterdaeme, P.; Perley, D. A.; Rhodin, H.; Selsing, J.; Schulze, S.; Tanvir, N. R.; Møller, P.; Goldoni, P.; Xu, D.; Milvang-Jensen, B.

    2017-05-01

    We present the spectroscopic and photometric late-time follow-up of the host galaxy of the long-duration Swift γ-ray burst GRB 140506A at z = 0.889. The optical and near-infrared afterglow of this GRB had a peculiar spectral energy distribution (SED) with a strong flux-drop at 8000 Å (4000 Å rest-frame) suggesting an unusually steep extinction curve. By analysing the contribution and physical properties of the host galaxy, we here aim at providing additional information on the properties and origin of this steep, non-standard extinction. We find that the strong flux-drop in the GRB afterglow spectrum at contamination by the host galaxy light at short wavelengths so that the scenario with an extreme 2175 Å extinction bump can be excluded. We localise the GRB to be at a projected distance of approximately 4 kpc from the centre of the host galaxy. Based on emission-line diagnostics of the four detected nebular lines, Hα, Hβ, [O II] and [O III], we find the host to be a modestly star forming (SFR = 1.34 ± 0.04 M⊙ yr-1) and relatively metal poor (Z=0.35+0.15-0.11 Z⊙) galaxy with a large dust content, characterised by a measured visual attenuation of AV = 1.74 ± 0.41 mag. We compare the host to other GRB hosts at similar redshifts and find that it is unexceptional in all its physical properties. We model the extinction curve of the host-corrected afterglow and show that the standard dust properties causing the reddening seen in the Local Group are inadequate in describing the steep drop. We thus conclude that the steep extinction curve seen in the afterglow towards the GRB is of exotic origin and issightline-dependent only, further confirming that this type of reddening is present only at very local scales and that it is solely a consequence of the circumburst environment. Based on observations carried out under programme IDs 095.D-0043(A, C) and 095.A-0045(A) with the X-shooter spectrograph and the FOcal Reducer and low dispersion Spectrograph 2 (FORS2

  14. Light Curve Stability and Period Behavior of the Contact Binary TZ ...

    Indian Academy of Sciences (India)

    J. Astrophys. Astr. (2013) 34, 329–339 c Indian Academy of Sciences. Light Curve Stability and Period Behavior of the Contact. Binary TZ Boo. M. M. Elkhateeb1,2 & M. I. Nouh1,2,∗. 1National Research Institute of Astronomy and Geophysics, 11421 Helwan, Cairo, Egypt. 2Physics Department, College of Science, Northern ...

  15. New methods for deriving cometary secular light curves: C/1995 O1 (Hale-Bopp) revisited

    Science.gov (United States)

    Womack, Maria; Lastra, Nathan; Harrington, Olga; Curtis, Anthony; Wierzchos, Kacper; Ruffini, Nicholas; Charles, Mentzer; Rabson, David; Cox, Timothy; Rivera, Isabel; Micciche, Anthony

    2017-10-01

    We present an algorithm for reducing scatter and increasing precision in a comet light curve. As a demonstration, we processed apparent magnitudes of comet Hale-Bopp from 16 highly experienced observers (archived with the International Comet Quarterly), correcting for distance from Earth and phase angle. Different observers tend to agree on the difference in magnitudes of an object at different distances, but the magnitude reported by observer is shifted relative to that of another for an object at a fixed distance. We estimated the shifts using a self-consistent statistical approach, leading to a sharper light curve and improving the precision of the measured slopes. The final secular lightcurve for comet Hale-Bopp ranges from -7 au (pre-perihelion) to +8 au (post-perihelion) and is the best secular light curve produced to date for this “great” comet. We discuss Hale-Bopp’s lightcurve evolution and possibly related physical implications, and potential usefulness of this light curve for comparisons with other future bright comets. We also assess the appropriateness of using secular lightcurves to characterize dust production rates in Hale-Bopp and other dust-rich comets. M.W. acknowledges support from NSF grant AST-1615917.

  16. EXPLORING THE POTENTIAL DIVERSITY OF EARLY TYPE IA SUPERNOVA LIGHT CURVES

    Energy Technology Data Exchange (ETDEWEB)

    Piro, Anthony L. [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Morozova, Viktoriya S., E-mail: piro@obs.carnegiescience.edu [Theoretical Astrophysics, California Institute of Technology, 1200 E California Boulevard, M/C 350-17, Pasadena, CA 91125 (United States)

    2016-07-20

    During the first several days after explosion, Type Ia supernova light curves probe the outer layers of the exploding star, and therefore provide important clues for identifying their progenitors. We investigate how both the shallow {sup 56}Ni distribution and the presence of circumstellar material shape these early light curves. This is performed using a series of numerical experiments with parameterized properties for systematic exploration. Although not all of the considered models may be realized in nature (and indeed there are arguments why some of them should not occur), the spirit of this work is to provide a broader exploration of the diversity of possibilities. We find that shallower {sup 56}Ni leads to steeper, bluer light curves. Differences in the shape of the rise can introduce errors in estimating the explosion time, and thus impact efforts to infer upper limits on the progenitor or companion radius from a lack of observed shock cooling emission. Circumstellar material can lead to significant luminosity during the first few days, but its presence can be difficult to identify depending on the degree of nickel mixing. In some cases, the hot emission of circumstellar material may even lead to a signature similar to an interaction with a companion, and thus in the future additional diagnostics should be gathered for properly assessing early light curves.

  17. Fractal Property in the Light Curve of BL Lac Object S5 0716+714

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... In this paper, we compile the historical R-band data of S5 0716+714 from literature and obtain its fractal dimension by using a fractal method and then simulate the data with the Weierstrass–Mandelbrot (W–M) function. It is considered that the light curve has a fractal property.

  18. Light Curve Periodic Variability of Cyg X-1 using Jurkevich Method ...

    Indian Academy of Sciences (India)

    Abstract. The Jurkevich method is a useful method to explore periodic- ity in the unevenly sampled observational data. In this work, we adopted the method to the light curve of Cyg X-1 from 1996 to 2012, and found that there is an interesting period of 370 days, which appears in both low/hard and high/soft states.

  19. Light Curve Periodic Variability of Cyg X-1 using Jurkevich Method

    Indian Academy of Sciences (India)

    The Jurkevich method is a useful method to explore periodicity in the unevenly sampled observational data. In this work, we adopted the method to the light curve of Cyg X-1 from 1996 to 2012, and found that there is an interesting period of 370 days, which appears in both low/hard and high/soft states. That period may be ...

  20. Characterizing the V-band light-curves of hydrogen-rich type II supernovae

    DEFF Research Database (Denmark)

    Anderson, Joseph P.; González-Gaitán, Santiago; Hamuy, Mario

    2014-01-01

    a dispersion of 0.56 mag, offering the prospect of using type II supernovae as purely photometric distance indicators. Our analysis suggests that the type II population spans a continuum from low-luminosity events which have flat light-curves during the "plateau" stage, through to the brightest events which...

  1. Photometric light curves for ten rapidly rotating stars in Alpha Persei, the Pleiades, and the field

    Science.gov (United States)

    Prosser, Charles F.; Schild, Rudolph E.; Stauffer, John R.; Jones, Burton F.

    1993-01-01

    We present the results from a photometric monitoring program of ten rapidly rotating stars observed during 1991 using the FLWO 48-in. telescope. Brightness variations for an additional six cluster stars observed with the Lick 40-in. telescope are also given. The periods and light curves for seven Alpha Persei members, two Pleiades members, and one naked T Tauri field star are reported.

  2. UBV Light Curves of AR Lacertae During 1980-'81 and 1981-'82

    Directory of Open Access Journals (Sweden)

    Il-Seong Nha

    1985-12-01

    Full Text Available The UBV observations of the brightest RE CVn-type eclipsing binary star AR Lac were made at four observatories, two in Korea and two in the U.S. in the 1980-81 and 1981-82 seasons. As a result of the cooperation, two light curves in the yellow and in the blue were completed for each observing seasons. Ultraviolet observations were also made at three of the four observatories. The orbital period of AR Lac apparantly decreased around 1977. An analysis of our yellow light curves together with five other yellow curves available in the literature since 1975 shows that there seems no periodicity in the migration of the distortion waves. There is a gradual decrease of at least 0.m1 between 1976 and 1982 in the brightness of the cooler component if one assumes that the hotter component is constant.

  3. Exquisite Nova Light Curves from the Solar Mass Ejection Imager (SMEI)

    Science.gov (United States)

    Hounsell, R.; Bode, M. F.; Hick, P. P.; Buffington, A.; Jackson, B. V.; Clover, J. M.; Shafter, A. W.; Darnley, M. J.; Mawson, N. R.; Steele, I. A.; Evans, A.; Eyres, S. P. S.; O'Brien, T. J.

    2010-11-01

    We present light curves of three classical novae (CNe; KT Eridani, V598 Puppis, V1280 Scorpii) and one recurrent nova (RS Ophiuchi) derived from data obtained by the Solar Mass Ejection Imager (SMEI) on board the Coriolis satellite. SMEI provides near complete skymap coverage with precision visible-light photometry at 102 minute cadence. The light curves derived from these skymaps offer unprecedented temporal resolution around, and especially before, maximum light, a phase of the eruption normally not covered by ground-based observations. They allow us to explore fundamental parameters of individual objects including the epoch of the initial explosion, the reality and duration of any pre-maximum halt (found in all three fast novae in our sample), the presence of secondary maxima, speed of decline of the initial light curve, plus precise timing of the onset of dust formation (in V1280 Sco) leading to estimation of the bolometric luminosity, white dwarf mass, and object distance. For KT Eri, Liverpool Telescope SkyCamT data confirm important features of the SMEI light curve and overall our results add weight to the proposed similarities of this object to recurrent rather than to CNe. In RS Oph, comparison with hard X-ray data from the 2006 outburst implies that the onset of the outburst coincides with extensive high-velocity mass loss. It is also noted that two of the four novae we have detected (V598 Pup and KT Eri) were only discovered by ground-based observers weeks or months after maximum light, yet these novae reached peak magnitudes of 3.46 and 5.42, respectively. This emphasizes the fact that many bright novae per year are still overlooked, particularly those of the very fast speed class. Coupled with its ability to observe novae in detail even when relatively close to the Sun in the sky, we estimate that as many as five novae per year may be detectable by SMEI.

  4. GRB 170817A: a short GRB seen off-axis

    Science.gov (United States)

    He, Xin-Bo; Tam, Pak-Hin Thomas; Shen, Rong-Feng

    2018-04-01

    The angular distribution of gamma-ray burst (GRB) jets is not yet clear. The observed luminosity of GRB 170817A is the lowest among all known short GRBs, which is best explained by the fact that our line of sight is outside of the jet opening angle, θ obs > θ j , where θ obs is the angle between our line of sight and the jet axis. As inferred by gravitational wave observations, as well as radio and X-ray afterglow modeling of GRB 170817A, it is likely that θ obs ∼ 20° – 28°. In this work, we quantitatively consider two scenarios of angular energy distribution of GRB ejecta: a top-hat jet and a structured jet with a power law index s. For the top-hat jet model, we get a large θ j (e.g., θ j > 10°), a rather high local (i.e., z 7.5 × 104, keV (∼500, keV for a typical short GRB). For the structured jet model, we use θ obs to give limits on s and θj for typical on-axis luminosity of a short GRB (e.g., 1049 erg s‑1 ∼ 1051 erg s‑1), and a low on-axis luminosity case (e.g., 1049 erg s‑1) gives more reasonable values of s. The structured jet model is more feasible for GRB 170817A than the top-hat jet model due to the rather high local short GRB rate, and the extremely high on-axis E peak,0 almost rules out the top-hat jet model. GRB 170817A is likely a low on-axis luminosity GRB (1049 erg s‑1) with a structured jet.

  5. EXPLORING THE VARIABLE SKY WITH LINEAR. III. CLASSIFICATION OF PERIODIC LIGHT CURVES

    Energy Technology Data Exchange (ETDEWEB)

    Palaversa, Lovro; Eyer, Laurent; Rimoldini, Lorenzo [Observatoire Astronomique de l' Université de Genève, 51 chemin des Maillettes, CH-1290 Sauverny (Switzerland); Ivezić, Željko; Loebman, Sarah; Hunt-Walker, Nicholas; VanderPlas, Jacob; Westman, David; Becker, Andrew C. [Department of Astronomy, University of Washington, P.O. Box 351580, Seattle, WA 98195-1580 (United States); Ruždjak, Domagoj; Sudar, Davor; Božić, Hrvoje [Hvar Observatory, Faculty of Geodesy, Kačićeva 26, 10000 Zagreb (Croatia); Galin, Mario [Faculty of Geodesy, Kačićeva 26, 10000 Zagreb (Croatia); Kroflin, Andrea; Mesarić, Martina; Munk, Petra; Vrbanec, Dijana [Department of Physics, Faculty of Science, University of Zagreb, Bijenička cesta 32, 10000 Zagreb (Croatia); Sesar, Branimir [Division of Physics, Mathematics, and Astronomy, Caltech, Pasadena, CA 91125 (United States); Stuart, J. Scott [Lincoln Laboratory, Massachusetts Institute of Technology, 244 Wood Street, Lexington, MA 02420-9108 (United States); Srdoč, Gregor, E-mail: lovro.palaversa@unige.ch [Saršoni 90, 51216 Viškovo (Croatia); and others

    2013-10-01

    We describe the construction of a highly reliable sample of ∼7000 optically faint periodic variable stars with light curves obtained by the asteroid survey LINEAR across 10,000 deg{sup 2} of the northern sky. The majority of these variables have not been cataloged yet. The sample flux limit is several magnitudes fainter than most other wide-angle surveys; the photometric errors range from ∼0.03 mag at r = 15 to ∼0.20 mag at r = 18. Light curves include on average 250 data points, collected over about a decade. Using Sloan Digital Sky Survey (SDSS) based photometric recalibration of the LINEAR data for about 25 million objects, we selected ∼200,000 most probable candidate variables with r < 17 and visually confirmed and classified ∼7000 periodic variables using phased light curves. The reliability and uniformity of visual classification across eight human classifiers was calibrated and tested using a catalog of variable stars from the SDSS Stripe 82 region and verified using an unsupervised machine learning approach. The resulting sample of periodic LINEAR variables is dominated by 3900 RR Lyrae stars and 2700 eclipsing binary stars of all subtypes and includes small fractions of relatively rare populations such as asymptotic giant branch stars and SX Phoenicis stars. We discuss the distribution of these mostly uncataloged variables in various diagrams constructed with optical-to-infrared SDSS, Two Micron All Sky Survey, and Wide-field Infrared Survey Explorer photometry, and with LINEAR light-curve features. We find that the combination of light-curve features and colors enables classification schemes much more powerful than when colors or light curves are each used separately. An interesting side result is a robust and precise quantitative description of a strong correlation between the light-curve period and color/spectral type for close and contact eclipsing binary stars (β Lyrae and W UMa): as the color-based spectral type varies from K4 to F5, the

  6. PANCHROMATIC OBSERVATIONS OF THE TEXTBOOK GRB 110205A: CONSTRAINING PHYSICAL MECHANISMS OF PROMPT EMISSION AND AFTERGLOW

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, W. [Department of Physics, University of Michigan, 450 Church Street, Ann Arbor, MI 48109 (United States); Shen, R. F. [Department of Astronomy and Astrophysics, University of Toronto, Toronto, Ontario M5S 3H4 (Canada); Sakamoto, T. [Center for Research and Exploration in Space Science and Technology (CRESST), NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Beardmore, A. P. [Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH (United Kingdom); De Pasquale, M. [Mullard Space Science Laboratory, University College London, Holmbury Road, Holmbury St. Mary, Dorking RH5 6NT (United Kingdom); Wu, X. F.; Zhang, B. [Department of Physics and Astronomy, University of Nevada Las Vegas, Las Vegas, NV 89154 (United States); Gorosabel, J. [Instituto de Astrofisica de Andalucia (IAA-CSIC), 18008 Granada (Spain); Urata, Y. [Institute of Astronomy, National Central University, Chung-Li 32054, Taiwan (China); Sugita, S. [EcoTopia Science Institute, Nagoya University, Furo-cho, chikusa, Nagoya 464-8603 (Japan); Pozanenko, A. [Space Research Institute (IKI), 84/32 Profsoyuznaya St., Moscow 117997 (Russian Federation); Nissinen, M. [Taurus Hill Observatory, Haerkaemaeentie 88, 79480 Kangaslampi (Finland); Sahu, D. K. [CREST, Indian Institute of Astrophysics, Koramangala, Bangalore 560034 (India); Im, M. [Center for the Exploration of the Origin of the Universe, Department of Physics and Astronomy, FPRD, Seoul National University, Shillim-dong, San 56-1, Kwanak-gu, Seoul (Korea, Republic of); Ukwatta, T. N. [Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Andreev, M. [Terskol Branch of Institute of Astronomy of RAS, Kabardino-Balkaria Republic 361605 (Russian Federation); Klunko, E., E-mail: zwk@umich.edu, E-mail: rfshen@astro.utoronto.ca, E-mail: zhang@physics.unlv.edu [Institute of Solar-Terrestrial Physics, Lermontov St., 126a, Irkutsk 664033 (Russian Federation); and others

    2012-06-01

    We present a comprehensive analysis of a bright, long-duration (T{sub 90} {approx} 257 s) GRB 110205A at redshift z = 2.22. The optical prompt emission was detected by Swift/UVOT, ROTSE-IIIb, and BOOTES telescopes when the gamma-ray burst (GRB) was still radiating in the {gamma}-ray band, with optical light curve showing correlation with {gamma}-ray data. Nearly 200 s of observations were obtained simultaneously from optical, X-ray, to {gamma}-ray (1 eV to 5 MeV), which makes it one of the exceptional cases to study the broadband spectral energy distribution during the prompt emission phase. In particular, we clearly identify, for the first time, an interesting two-break energy spectrum, roughly consistent with the standard synchrotron emission model in the fast cooling regime. Shortly after prompt emission ({approx}1100 s), a bright (R = 14.0) optical emission hump with very steep rise ({alpha} {approx} 5.5) was observed, which we interpret as the reverse shock (RS) emission. It is the first time that the rising phase of an RS component has been closely observed. The full optical and X-ray afterglow light curves can be interpreted within the standard reverse shock (RS) + forward shock (FS) model. In general, the high-quality prompt and afterglow data allow us to apply the standard fireball model to extract valuable information, including the radiation mechanism (synchrotron), radius of prompt emission (R{sub GRB} {approx} 3 Multiplication-Sign 10{sup 13} cm), initial Lorentz factor of the outflow ({Gamma}{sub 0} {approx} 250), the composition of the ejecta (mildly magnetized), the collimation angle, and the total energy budget.

  7. The Discovery of Ellipsoidal Variations in the Kepler Light Curve of HAT-P-7

    OpenAIRE

    Welsh, William F.; Orosz, Jerome A.; Seager, Sara; Fortney, Jonathan J.; Jenkins, Jon; Rowe, Jason F.; Koch, David; Borucki, William J.

    2010-01-01

    We present an analysis of the early Kepler observations of the previously discovered transiting planet HAT-P-7b. The light curve shows the transit of the star, the occultation of the planet, and the orbit phase-dependent light from the planet. In addition, phase-dependent light from the star is present, known as "ellipsoidal variations". The very nearby planet (only 4 stellar radii away) gravitationally distorts the star and results in a flux modulation twice per orbit. The ellipsoidal variat...

  8. GRB 090902B: AFTERGLOW OBSERVATIONS AND IMPLICATIONS

    International Nuclear Information System (INIS)

    Pandey, S. B.; Akerlof, C.; McKay, T. A.; Swenson, C. A.; Perley, D. A.; Kleiser, I. K. W.; Guidorzi, C.; Wiersema, K.; Malesani, D.; Ashley, M. C. B.; Bersier, D.; Cano, Z.; Kobayashi, S.; Melandri, A.; Mottram, C. J.; Gomboc, A.; Ilyin, I.; Jakobsson, P.; Kouveliotou, C.; Levan, A. J.

    2010-01-01

    The optical-infrared afterglow of the Large Area Telescope (LAT)-detected long-duration burst, GRB 090902B, has been observed by several instruments. The earliest detection by ROTSE-IIIa occurred 80 minutes after detection by the Gamma-ray Burst Monitor instrument on board the Fermi Gamma-Ray Space Telescope, revealing a bright afterglow and a decay slope suggestive of a reverse shock origin. Subsequent optical-IR observations followed the light curve for 6.5 days. The temporal and spectral behavior at optical-infrared frequencies is consistent with synchrotron fireball model predictions; the cooling break lies between optical and XRT frequencies ∼1.9 days after the burst. The inferred electron energy index is p = 1.8 ± 0.2, which would however imply an X-ray decay slope flatter than observed. The XRT and LAT data have similar spectral indices and the observed steeper value of the LAT temporal index is marginally consistent with the predicted temporal decay in the radiative regime of the forward shock model. Absence of a jet break during the first 6 days implies a collimation-corrected γ-ray energy E γ > 2.2 x 10 52 erg, one of the highest ever seen in a long-duration gamma-ray bursts. More events combining GeV photon emission with multiwavelength observations will be required to constrain the nature of the central engine powering these energetic explosions and to explore the correlations between energetic quanta and afterglow emission.

  9. GRB follow-up observations in the East-Asian region

    International Nuclear Information System (INIS)

    Tamagawa, T.; Urata, Y.; Tokyo Institute of Technology, Tokyo; Huang, K. Y.; Ip, W.H.; Qiu, Y.; Hu, J.Y.; Zhou, Xn.; Onda, K.; Tokyo Univ. of Sciences, Tokyo; Makishima, K.; Tokyo Univ., Tokyo

    2005-01-01

    In 2004, we established a Japan-Taiwan-China collaboration for GBR study in the East-Asian region. This serves as a valuable addiction to the world-wide optical and infrared follow-up network, because the East-Asia region would otherwise be blank. We have been carrying out imaging and spectroscopy follow-up observations at Lulin (Taiwan), Kiso (Japan), WIDGET (Japan) and Xinglong (China). From Xinglong and Kiso, we can locate candidates and obtain early time spectra for afterglows. While WIDGET provides early time observations before the bursts, the high-time resolution for multi-band light curves can be obtained at Lulin. With the data from these sites, we can obtain detailed information about the light curve and redshift of GRBs, which are important to understand the mechanism of the afterglows. Up to March 2005, ten follow-up observations have been provided by this East-Asia cooperation. Two optical afterglows were detected, GRB 040924 and GRB 041006. The results of the two detected afterglows are reported in this paper

  10. GRB follow-up observations in the East-Asian region

    Energy Technology Data Exchange (ETDEWEB)

    Tamagawa, T. [RIKEN, Saitama (Japan); Urata, Y. [RIKEN, Saitama (Japan); Tokyo Institute of Technology, Tokyo (Japan). Department of Physics; Huang, K. Y.; Ip, W.H. [National Centre University, Tokyo (Japan). Institute of Astronomy; Qiu, Y.; Hu, J.Y.; Zhou, Xn. [Chinese Academy of Sciences, Beijing (China). National Astronomical Observatoires; Onda, K. [RIKEN, Saitama (Japan); Tokyo Univ. of Sciences, Tokyo (Japan). Department of Physics; Makishima, K. [RIKEN, Saitama (Japan); Tokyo Univ., Tokyo (Japan). Department of Physics

    2005-07-15

    In 2004, we established a Japan-Taiwan-China collaboration for GBR study in the East-Asian region. This serves as a valuable addiction to the world-wide optical and infrared follow-up network, because the East-Asia region would otherwise be blank. We have been carrying out imaging and spectroscopy follow-up observations at Lulin (Taiwan), Kiso (Japan), WIDGET (Japan) and Xinglong (China). From Xinglong and Kiso, we can locate candidates and obtain early time spectra for afterglows. While WIDGET provides early time observations before the bursts, the high-time resolution for multi-band light curves can be obtained at Lulin. With the data from these sites, we can obtain detailed information about the light curve and redshift of GRBs, which are important to understand the mechanism of the afterglows. Up to March 2005, ten follow-up observations have been provided by this East-Asia cooperation. Two optical afterglows were detected, GRB 040924 and GRB 041006. The results of the two detected afterglows are reported in this paper.

  11. SUPERLUMINOUS SUPERNOVAE POWERED BY MAGNETARS: LATE-TIME LIGHT CURVES AND HARD EMISSION LEAKAGE

    International Nuclear Information System (INIS)

    Wang, S. Q.; Wang, L. J.; Dai, Z. G.; Wu, X. F.

    2015-01-01

    Recently, research performed by two groups has revealed that the magnetar spin-down energy injection model with full energy trapping can explain the early-time light curves of SN 2010gx, SN 2013dg, LSQ12dlf, SSS120810, and CSS121015 but fails to fit the late-time light curves of these superluminous supernovae (SLSNe). These results imply that the original magnetar-powered model is challenged in explaining these SLSNe. Our paper aims to simultaneously explain both the early- and late-time data/upper limits by considering the leakage of hard emissions. We incorporate quantitatively the leakage effect into the original magnetar-powered model and derive a new semianalytical equation. Comparing the light curves reproduced by our revised magnetar-powered model with the observed data and/or upper limits of these five SLSNe, we found that the late-time light curves reproduced by our semianalytical equation are in good agreement with the late-time observed data and/or upper limits of SN 2010gx, CSS121015, SN 2013dg, and LSQ12dlf and the late-time excess of SSS120810, indicating that the magnetar-powered model might be responsible for these SLSNe and that the gamma-ray and X-ray leakages are unavoidable when the hard photons were down-Comptonized to softer photons. To determine the details of the leakage effect and unveil the nature of SLSNe, more high-quality bolometric light curves and spectra of SLSNe are required

  12. The effect of lunarlike satellites on the orbital infrared light curves of Earth-analog planets.

    Science.gov (United States)

    Moskovitz, Nicholas A; Gaidos, Eric; Williams, Darren M

    2009-04-01

    We have investigated the influence of lunarlike satellites on the infrared orbital light curves of Earth-analog extrasolar planets. Such light curves will be obtained by NASA's Terrestrial Planet Finder (TPF) and ESA's Darwin missions as a consequence of repeat observations to confirm the companion status of a putative planet and determine its orbit. We used an energy balance model to calculate disk-averaged infrared (bolometric) fluxes from planet-satellite systems over a full orbital period (one year). The satellites are assumed to lack an atmosphere, have a low thermal inertia like that of the Moon, and span a range of plausible radii. The planets are assumed to have thermal and orbital properties that mimic those of Earth, while their obliquities and orbital longitudes of inferior conjunction remain free parameters. Even if the gross thermal properties of the planet can be independently constrained (e.g., via spectroscopy or visible-wavelength detection of specular glint from a surface ocean), only the largest (approximately Mars-sized) lunarlike satellites can be detected by light curve data from a TPF-like instrument (i.e., one that achieves a photometric signal-to-noise ratio of 10 to 20 at infrared wavelengths). Nondetection of a lunarlike satellite can obfuscate the interpretation of a given system's infrared light curve so that it may resemble a single planet with high obliquity, different orbital longitude of vernal equinox relative to inferior conjunction, and in some cases drastically different thermal characteristics. If the thermal properties of the planet are not independently established, then the presence of a lunarlike satellite cannot be inferred from infrared data, which would thus demonstrate that photometric light curves alone can only be used for preliminary study, and the addition of spectroscopic data will be necessary.

  13. The Peculiar Light Curve of J1415+1320: A Case Study in Extreme Scattering Events

    Science.gov (United States)

    Vedantham, H. K.; Readhead, A. C. S.; Hovatta, T.; Koopmans, L. V. E.; Pearson, T. J.; Blandford, R. D.; Gurwell, M. A.; Lähteenmäki, A.; Max-Moerbeck, W.; Pavlidou, V.; Ravi, V.; Reeves, R. A.; Richards, J. L.; Tornikoski, M.; Zensus, J. A.

    2017-08-01

    The radio light curve of J1415+1320 (PKS 1413+135) shows time-symmetric and recurring U-shaped features across the centimeter-wave and millimeter-wave bands. The symmetry of these features points to lensing by an intervening object as the cause. U-shaped events in radio light curves in the centimeter-wave band have previously been attributed to Extreme scattering events (ESE). ESEs are thought to be the result of lensing by compact plasma structures in the Galactic interstellar medium, but the precise nature of these plasma structures remains unknown. Since the strength of a plasma lens evolves with wavelength λ as {λ }2, the presence of correlated variations at over a wide wavelength range casts doubt on the canonical ESE interpretation for J1415+1320. In this paper, we critically examine the evidence for plasma lensing in J1415+1320. We compute limits on the lensing strength and the associated free-free opacity of the putative plasma lenses. We compare the observed and model ESE light curves, and also derive a lower limit on the lens distance based on the effects of parallax due to the Earth’s orbit around the Sun. We conclude that plasma lensing is not a viable interpretation for J1415+1320's light curves and that symmetric U-shaped features in the radio light curves of extragalactic sources do not present prima facie evidence for ESEs. The methodology presented here is generic enough to be applicable to any plasma-lensing candidate.

  14. Devil in the Details: Investigating Astrophysical Phenomena with Kepler Light Curves

    Science.gov (United States)

    Jenkins, Jon Michael; SOC, Kepler; SO, Kepler; Kepler Science Team

    2011-05-01

    The light curves produced by the Kepler photometer are unprecedented in their photometric precision, completeness, and contiguity. Moreover, although Kepler was designed to detect 100 ppm changes in brightness corresponding to transits of Earth-size planets crossing Sun-size stars, the Kepler light curves preserve intrinsic intensity variations across a large dynamic range, including those of RR Lyrae stars, which can increase their brightness by more than a factor of two over a few hours. The large dynamic range and phenomenal photometric precision of Kepler promises to revolutionize the study of intrinsic stellar variability and a wide variety of variable stars on timescales from minutes to several years. In this paper, we describe the science pipeline processing that produces the uncorrected and the systematic error-corrected light curves, and give examples of residual instrumental artifacts that can be found in the data, such as those caused by thermal changes due to the position of the spacecraft with relation to the sun or heaters cycling on and off on various spacecraft components (which can change the shape of the telescope and alter its focus), as well as examples of processing artifacts that can occur. We also describe algorithms in development that promise to improve our ability to identify and remove instrumental signatures and further reduce the incidence of processing artifacts in the archival light curves, thereby increasing the usability of the corrected light curves for astrophysical investigations. Kepler was selected as the 10th mission of the Discovery Program. Funding for this mission is provided by the NASA Science Mission Directorate.

  15. Type IIP supernova light curves affected by the acceleration of red supergiant winds

    Science.gov (United States)

    Moriya, Takashi J.; Förster, Francisco; Yoon, Sung-Chul; Gräfener, Götz; Blinnikov, Sergei I.

    2018-05-01

    We introduce the first synthetic light-curve model set of Type IIP supernovae exploded within circumstellar media in which the acceleration of the red supergiant winds is taken into account. Because wind acceleration makes the wind velocities near the progenitors low, the density of the immediate vicinity of the red supergiant supernova progenitors can be higher than that extrapolated by using a constant terminal wind velocity. Therefore, even if the mass-loss rate of the progenitor is relatively low, it can have a dense circumstellar medium at the immediate stellar vicinity and the early light curves of Type IIP supernovae are significantly affected by it. We adopt a simple β velocity law to formulate the wind acceleration. We provide bolometric and multicolour light curves of Type IIP supernovae exploding within such accelerated winds from the combinations of three progenitors, 12-16 M⊙; five β, 1-5; seven mass-loss rates, 10-5-10-2 M⊙ yr-1; and four explosion energies, (0.5-2) × 1051 erg. All the light-curve models are available at https://goo.gl/o5phYb. When the circumstellar density is sufficiently high, our models do not show a classical shock breakout as a consequence of the interaction with the dense and optically thick circumstellar media. Instead, they show a delayed `wind breakout', substantially affecting early light curves of Type IIP supernovae. We find that the mass-loss rates of the progenitors need to be 10-3-10-2 M⊙ yr-1 to explain typical rise times of 5-10 d in Type IIP supernovae assuming a dense circumstellar radius of 1015 cm.

  16. THE INFORMATION CONTENT IN ANALYTIC SPOT MODELS OF BROADBAND PRECISION LIGHT CURVES

    Energy Technology Data Exchange (ETDEWEB)

    Walkowicz, Lucianne M. [Department of Astrophysical Sciences, Princeton University, Peyton Hall, 4 Ivy Lane, Princeton, NJ 08534 (United States); Basri, Gibor [Astronomy Department, University of California at Berkeley, Hearst Field Annex, Berkeley, CA 94720 (United States); Valenti, Jeff A. [Space Telescope Science Institute, 3700 San Martin Dr., Baltimore, MD 21218 (United States)

    2013-04-01

    We present the results of numerical experiments to assess degeneracies in light curve models of starspots. Using synthetic light curves generated with the Cheetah starspot modeling code, we explore the extent to which photometric light curves constrain spot model parameters, including spot latitudes and stellar inclination. We also investigate the effects of spot parameters and differential rotation on one's ability to correctly recover rotation periods and differential rotation in the Kepler light curves. We confirm that in the absence of additional constraints on the stellar inclination, such as spectroscopic measurements of vsin i or occultations of starspots by planetary transits, the spot latitude and stellar inclination are difficult to determine uniquely from the photometry alone. We find that for models with no differential rotation, spots that appear on opposite hemispheres of the star may cause one to interpret the rotation period to be half of the true period. When differential rotation is included, the changing longitude separation between spots breaks the symmetry of the hemispheres and the correct rotation period is more likely to be found. The dominant period found via periodogram analysis is typically that of the largest spot. Even when multiple spots with periods representative of the star's differential rotation exist, if one spot dominates the light curve the signal of differential rotation may not be detectable from the periodogram alone. Starspot modeling is applicable to stars with a wider range of rotation rates than other surface imaging techniques (such as Doppler imaging), allows subtle signatures of differential rotation to be measured, and may provide valuable information on the distribution of stellar spots. However, given the inherent degeneracies and uncertainty present in starspot models, caution should be exercised in their interpretation.

  17. THE INFORMATION CONTENT IN ANALYTIC SPOT MODELS OF BROADBAND PRECISION LIGHT CURVES

    International Nuclear Information System (INIS)

    Walkowicz, Lucianne M.; Basri, Gibor; Valenti, Jeff A.

    2013-01-01

    We present the results of numerical experiments to assess degeneracies in light curve models of starspots. Using synthetic light curves generated with the Cheetah starspot modeling code, we explore the extent to which photometric light curves constrain spot model parameters, including spot latitudes and stellar inclination. We also investigate the effects of spot parameters and differential rotation on one's ability to correctly recover rotation periods and differential rotation in the Kepler light curves. We confirm that in the absence of additional constraints on the stellar inclination, such as spectroscopic measurements of vsin i or occultations of starspots by planetary transits, the spot latitude and stellar inclination are difficult to determine uniquely from the photometry alone. We find that for models with no differential rotation, spots that appear on opposite hemispheres of the star may cause one to interpret the rotation period to be half of the true period. When differential rotation is included, the changing longitude separation between spots breaks the symmetry of the hemispheres and the correct rotation period is more likely to be found. The dominant period found via periodogram analysis is typically that of the largest spot. Even when multiple spots with periods representative of the star's differential rotation exist, if one spot dominates the light curve the signal of differential rotation may not be detectable from the periodogram alone. Starspot modeling is applicable to stars with a wider range of rotation rates than other surface imaging techniques (such as Doppler imaging), allows subtle signatures of differential rotation to be measured, and may provide valuable information on the distribution of stellar spots. However, given the inherent degeneracies and uncertainty present in starspot models, caution should be exercised in their interpretation.

  18. Hierarchical Models for Type Ia Supernova Light Curves in the Optical and Near Infrared

    Science.gov (United States)

    Mandel, Kaisey; Narayan, G.; Kirshner, R. P.

    2011-01-01

    I have constructed a comprehensive statistical model for Type Ia supernova optical and near infrared light curves. Since the near infrared light curves are excellent standard candles and are less sensitive to dust extinction and reddening, the combination of near infrared and optical data better constrains the host galaxy extinction and improves the precision of distance predictions to SN Ia. A hierarchical probabilistic model coherently accounts for multiple random and uncertain effects, including photometric error, intrinsic supernova light curve variations and correlations across phase and wavelength, dust extinction and reddening, peculiar velocity dispersion and distances. An improved BayeSN MCMC code is implemented for computing probabilistic inferences for individual supernovae and the SN Ia and host galaxy dust populations. I use this hierarchical model to analyze nearby Type Ia supernovae with optical and near infared data from the PAIRITEL, CfA3, and CSP samples and the literature. Using cross-validation to test the robustness of the model predictions, I find that the rms Hubble diagram scatter of predicted distance moduli is 0.11 mag for SN with optical and near infrared data versus 0.15 mag for SN with only optical data. Accounting for the dispersion expected from random peculiar velocities, the rms intrinsic prediction error is 0.08-0.10 mag for SN with both optical and near infrared light curves. I discuss results for the inferred intrinsic correlation structures of the optical-NIR SN Ia light curves and the host galaxy dust distribution captured by the hierarchical model. The continued observation and analysis of Type Ia SN in the optical and near infrared is important for improving their utility as precise and accurate cosmological distance indicators.

  19. CSI 2264: characterizing accretion-burst dominated light curves for young stars in NGC 2264

    International Nuclear Information System (INIS)

    Stauffer, John; Cody, Ann Marie; Rebull, Luisa; Carey, Sean; Baglin, Annie; Alencar, Silvia; Hillenbrand, Lynne A.; Carpenter, John; Findeisen, Krzysztof; Venuti, Laura; Bouvier, Jerome; Turner, Neal J.; Plavchan, Peter; Terebey, Susan; Morales-Calderón, María; Micela, Giusi; Flaccomio, Ettore; Song, Inseok; Gutermuth, Rob; Hartmann, Lee

    2014-01-01

    Based on more than four weeks of continuous high-cadence photometric monitoring of several hundred members of the young cluster NGC 2264 with two space telescopes, NASA's Spitzer and the CNES CoRoT (Convection, Rotation, and planetary Transits), we provide high-quality, multi-wavelength light curves for young stellar objects whose optical variability is dominated by short-duration flux bursts, which we infer are due to enhanced mass accretion rates. These light curves show many brief—several hours to one day—brightenings at optical and near-infrared wavelengths with amplitudes generally in the range of 5%-50% of the quiescent value. Typically, a dozen or more of these bursts occur in a 30 day period. We demonstrate that stars exhibiting this type of variability have large ultraviolet (UV) excesses and dominate the portion of the u – g versus g – r color-color diagram with the largest UV excesses. These stars also have large Hα equivalent widths, and either centrally peaked, lumpy Hα emission profiles or profiles with blueshifted absorption dips associated with disk or stellar winds. Light curves of this type have been predicted for stars whose accretion is dominated by Rayleigh-Taylor instabilities at the boundary between their magnetosphere and inner circumstellar disk, or where magneto-rotational instabilities modulate the accretion rate from the inner disk. Among the stars with the largest UV excesses or largest Hα equivalent widths, light curves with this type of variability greatly outnumber light curves with relatively smooth sinusoidal variations associated with long-lived hot spots. We provide quantitative statistics for the average duration and strength of the accretion bursts and for the fraction of the accretion luminosity associated with these bursts.

  20. The Physics of Type Ia Supernova Light Curves. I. Analytic Results and Time Dependence

    International Nuclear Information System (INIS)

    Pinto, Philip A.; Eastman, Ronald G.

    2000-01-01

    We develop an analytic solution of the radiation transport problem for Type Ia supernovae (SNe Ia) and show that it reproduces bolometric light curves produced by more detailed calculations under the assumption of a constant-extinction coefficient. This model is used to derive the thermal conditions in the interior of SNe Ia and to study the sensitivity of light curves to various properties of the underlying supernova explosions. Although the model is limited by simplifying assumptions, it is adequate for demonstrating that the relationship between SNe Ia maximum-light luminosity and rate of decline is most easily explained if SNe Ia span a range in mass. The analytic model is also used to examine the size of various terms in the transport equation under conditions appropriate to maximum light. For instance, the Eulerian and advective time derivatives are each shown to be of the same order of magnitude as other order v/c terms in the transport equation. We conclude that a fully time-dependent solution to the transport problem is needed in order to compute SNe Ia light curves and spectra accurate enough to distinguish subtle differences of various explosion models. (c) 2000 The American Astronomical Society

  1. Relativistic Hydrodynamics and Spectral Evolution of GRB Jets

    Science.gov (United States)

    Cuesta-Martínez, C.

    2017-09-01

    dynamical details of the jet propagation and connect them to the generation of thermal radiation in GRB events akin to that of the Christmas burst. A comprehensive parameter study of the jet/environment interaction has been performed and synthetic light curves are confronted with the observational data. The thermal emission in our models originates from the interaction between the jet and the hydrogen envelope ejected during the neutron star/He core merger. We find that the lack of a classical afterglow and the accompanying thermal emission in BBD-GRBs can be explained by the interaction of an ultrarelativistic jet with a toroidally shaped ejecta whose axis coincides with the binary rotation axis. We also find that the synchrotron emission of the forward shock of the jet is dominant during the early phases of the evolution, along which that shock is still moderately relativistic. The contribution of the reverse shock is of the same magnitude as that of the forward shock during the first 80 min after the GRB. Later, it quickly fades because the jet/environment interaction chokes the ultrarelativistic jet beam and effectively dumps the reverse shock. We highlight that, in agreement with observations, we obtain rather flat light curves during the first 2 days after the GRB, and a spectral evolution consistent with the observed reddening of the system. Besides, we obtain that this spectral inversion and reddening happening at about 2 days in the Christmas burst can be related to the time at which the massive shell, ejected in an early phase of the common-envelope evolution of the progenitor system, is completely ablated by the ultrarelativistic jet. In the second part of this thesis, we study more canonical progenitor systems of GRBs, namely single massive stars on the brink of collapse. Motivated by the many associations of GRBs with energetic SN explosions, we study the propagation of relativistic jets within the progenitor star and the circumstellar medium. Particular

  2. Phase shifts and nonellipsoidal light curves: Challenges from mass determinations in x-ray binary stars

    Science.gov (United States)

    Cantrell, Andrew Glenn

    We consider two types of anomalous observations which have arisen from efforts to measure dynamical masses of X-ray binary stars: (1) Radial velocity curves which seemingly show the primary and the secondary out of antiphase in most systems, and (2) The observation of double-waved light curves which deviate significantly from the ellipsoidal modulations expected for a Roche lobe filling star. We consider both problems with the joint goals of understanding the physical origins of the anomalous observations, and using this understanding to allow robust dynamical determinations of mass in X-ray binary systems. In our analysis of phase-shifted radial velocity curves, we discuss a comprehensive sample of X-ray binaries with published phase-shifted radial velocity curves. We show that the most commonly adopted explanation for phase shifts is contradicted by many observations, and consider instead a generalized form of a model proposed by Smak in 1970. We show that this model is well supported by a range of observations, including some systems which had previously been considered anomalous. We lay the groundwork for the derivation of mass ratios based on our explanation for phase shifts, and we discuss the work necessary to produce more detailed physical models of the phase shift. In our analysis of non-ellipsoidal light curves, we focus on the very well-studied system A0620-00. We present new VIH SMARTS photometry spanning 1999-2007, and supplement this with a comprehensive collection of archival data obtained since 1981. We show that A0620-00 undergoes optical state changes within X-ray quiescence and argue that not all quiescent data should be used for determinations of the inclination. We identify twelve light curves which may reliably be used for determining the inclination. We show that the accretion disk contributes significantly to all twelve curves and is the dominant source of nonellipsoidal variations. We derive the disk fraction for each of the twelve curves

  3. Mass estimates from optical-light curves for binary X-ray sources

    International Nuclear Information System (INIS)

    Avni, Y.

    1978-01-01

    The small amplitude variations with orbital phase of the optical light from X-ray binaries are caused by the changing geometrical aspect of the primary as seen by a fixed observer. The shape and the amplitude of the light curve depends on the stellar masses and on the orbital elements. The light curve can, therefore, be used to determine, or set limits on, the parameters of the binary system. A self-consistent procedure for the calculation of the light curve can be formulated if the primary is formulated if the primary is uniformly rotating at an angular velocity equal to the angular velocity of its orbital revolution in a circular orbit, and if the primary is in a hydrostatic and radiative equilibrium in the co-rotating frame. When the primary is further approximated to be centrally condensed, the above set of assumptions is called the standard picture. The standard picture is described, its validity discussed and its application to various systems reviewed. (C.F.)

  4. Searching for transits in the WTS with the difference imaging light curves

    Science.gov (United States)

    Zendejas Dominguez, Jesus

    2013-12-01

    The search for exo-planets is currently one of the most exiting and active topics in astronomy. Small and rocky planets are particularly the subject of intense research, since if they are suitably located from their host star, they may be warm and potentially habitable worlds. On the other hand, the discovery of giant planets in short-period orbits provides important constraints on models that describe planet formation and orbital migration theories. Several projects are dedicated to discover and characterize planets outside of our solar system. Among them, the Wide-Field Camera Transit Survey (WTS) is a pioneer program aimed to search for extra-solar planets, that stands out for its particular aims and methodology. The WTS has been in operation since August 2007 with observations from the United Kingdom Infrared Telescope, and represents the first survey that searches for transiting planets in the near-infrared wavelengths; hence the WTS is designed to discover planets around M-dwarfs. The survey was originally assigned about 200 nights, observing four fields that were selected seasonally (RA = 03, 07, 17 and 19h) during a year. The images from the survey are processed by a data reduction pipeline, which uses aperture photometry to construct the light curves. For the most complete field (19h-1145 epochs) in the survey, we produce an alternative set of light curves by using the method of difference imaging, which is a photometric technique that has shown important advantages when used in crowded fields. A quantitative comparison between the photometric precision achieved with both methods is carried out in this work. We remove systematic effects using the sysrem algorithm, scale the error bars on the light curves, and perform a comparison of the corrected light curves. The results show that the aperture photometry light curves provide slightly better precision for objects with J detect transits in the WTS light curves, we use a modified version of the box

  5. Corot 310266512: A Light Curve With Primary, Secondary And Tertiary Eclipses

    Directory of Open Access Journals (Sweden)

    Fernández Fernández Javier

    2015-01-01

    Full Text Available We present the photometric study of an interesting target in the CoRoT exoplanet database: CoRoT 310266512. Its light curve shows primary, secondary and tertiary eclipses that suggests the presence of at least three celestial bodies. The primary and secondary eclipses have the same orbital period, 7.42 days, and the tertiary eclipse has an orbital period of 3.27 days. Two of the tertiary eclipses fall within a primary eclipse and a secondary eclipse. The properties of the light curve indicate the presence of two physically separated systems. The primary and secondary eclipses corresponds to a binary system (System I. The tertiary eclipses correspond to a star-planet system or a star-dwarf system (System II. Some parameters of these two systems are obtained from JKTEBOP [1] program.

  6. BINARY CANDIDATES IN THE JOVIAN TROJAN AND HILDA POPULATIONS FROM NEOWISE LIGHT CURVES

    Energy Technology Data Exchange (ETDEWEB)

    Sonnett, S.; Mainzer, A.; Masiero, J.; Bauer, J. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Grav, T., E-mail: Sarah.Sonnett@jpl.nasa.gov [Planetary Science Institute, Tucson, AZ (United States)

    2015-02-01

    Determining the binary fraction for a population of asteroids, particularly as a function of separation between the two components, helps describe the dynamical environment at the time the binaries formed, which in turn offers constraints on the dynamical evolution of the solar system. We searched the NEOWISE archival data set for close and contact binary Trojans and Hildas via their diagnostically large light curve amplitudes. We present 48 out of 554 Hilda and 34 out of 953 Trojan binary candidates in need of follow-up to confirm their large light curve amplitudes and subsequently constrain the binary orbit and component sizes. From these candidates, we calculate a preliminary estimate of the binary fraction without confirmation or debiasing of 14%-23% for Trojans larger than ∼12 km and 30%-51% for Hildas larger than ∼4 km. Once the binary candidates have been confirmed, it should be possible to infer the underlying, debiased binary fraction through estimation of survey biases.

  7. VizieR Online Data Catalog: Praesepe members light curves (Kovacs+, 2014)

    Science.gov (United States)

    Kovacs, G.; Hartman, J. D.; Bakos, G. A.; Quinn, S. N.; Penev, K.; Latham, D. W.; Bhatti, W.; Csubry, Z.; de Val-Borro, M.

    2014-07-01

    Light curves used in the time series analysis of Praesepe are presented. There are 381 light curves on instrumental Sloan r' magnitude scale with the zero points determined by the 2MASS magnitudes according to Eq. (1) of the paper. We present two types of magnitudes: a) external parameter decorrelated (EPD) and b), the ones obtained after the application of a trend filtering algorithm (TFA) on the EPD time series. These two methods are briefly described in the paper and in detail in the references therein. Here we just note that both methods are intended to filter out systematics due to environmental effects (instrumental, weather, etc.). For TFA filtering we used 600 templates and did not apply signal reconstruction. (5 data files).

  8. Spotted star light curve numerical modeling technique and its application to HII 1883 surface imaging

    Science.gov (United States)

    Kolbin, A. I.; Shimansky, V. V.

    2014-04-01

    We developed a code for imaging the surfaces of spotted stars by a set of circular spots with a uniform temperature distribution. The flux from the spotted surface is computed by partitioning the spots into elementary areas. The code takes into account the passing of spots behind the visible stellar limb, limb darkening, and overlapping of spots. Modeling of light curves includes the use of recent results of the theory of stellar atmospheres needed to take into account the temperature dependence of flux intensity and limb darkening coefficients. The search for spot parameters is based on the analysis of several light curves obtained in different photometric bands. We test our technique by applying it to HII 1883.

  9. EXTRASOLAR STORMS: PRESSURE-DEPENDENT CHANGES IN LIGHT-CURVE PHASE IN BROWN DWARFS FROM SIMULTANEOUS HST AND SPITZER OBSERVATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Hao; Apai, Dániel; Karalidi, Theodora [Department of Astronomy, University of Arizona, 933 N. Cherry Ave., Tucson, AZ 85721 (United States); Marley, Mark S. [NASA Ames Research Center, Naval Air Station, Moffett Field, Mountain View, CA 94035 (United States); Flateau, Davin [Department of Planetary Sciences, 1629 E. University Blvd., Tucson, AZ 85721 (United States); Showman, Adam P. [Department of Planetary Sciences, University of Arizona, 1629 University Blvd., Tucson, AZ 85721 (United States); Metchev, Stanimir [The University of Western Ontario, Department of Physics and Astronomy, Centre for Planetary Science and Exploration, 1151 Richmond St., London, ON N6A 3K7 (Canada); Buenzli, Esther [Institute for Astronomy, ETH Zürich Wolfgang-Pauli-Str. 27, 8093 Zürich (Switzerland); Radigan, Jacqueline [Space Telescope Science Institute, 3700 San Martin Dr., Baltimore, MD 21218 (United States); Artigau, Étienne [Département de Physique, Université de Montréal, C.P. 6128 Succ. Centre-ville, Montréal, QC H3C 3J7 (Canada); Lowrance, Patrick J. [Infrared Processing and Analysis Center, MS 100-22, California Institute of Technology, Pasadena, CA 91125 (United States); Burgasser, Adam J., E-mail: haoyang@email.arizona.edu, E-mail: apai@arizona.edu [Center for Astrophysics and Space Science, University of California, San Diego, La Jolla, CA 92093 (United States)

    2016-07-20

    We present Spitzer /Infrared Array Camera Ch1 and Ch2 monitoring of six brown dwarfs during eight different epochs over the course of 20 months. For four brown dwarfs, we also obtained simulataneous Hubble Space Telescope ( HST )/WFC3 G141 grism spectra during two epochs and derived light curves in five narrowband filters. Probing different pressure levels in the atmospheres, the multiwavelength light curves of our six targets all exhibit variations, and the shape of the light curves evolves over the timescale of a rotation period, ranging from 1.4 to 13 hr. We compare the shapes of the light curves and estimate the phase shifts between the light curves observed at different wavelengths by comparing the phase of the primary Fourier components. We use state-of-the-art atmosphere models to determine the flux contribution of different pressure layers to the observed flux in each filter. We find that the light curves that probe higher pressures are similar and in phase, but are offset and often different from the light curves that probe lower pressures. The phase differences between the two groups of light curves suggest that the modulations seen at lower and higher pressures may be introduced by different cloud layers.

  10. A Simple yet Accurate Method for Students to Determine Asteroid Rotation Periods from Fragmented Light Curve Data

    Science.gov (United States)

    Beare, R. A.

    2008-01-01

    Professional astronomers use specialized software not normally available to students to determine the rotation periods of asteroids from fragmented light curve data. This paper describes a simple yet accurate method based on Microsoft Excel[R] that enables students to find periods in asteroid light curve and other discontinuous time series data of…

  11. CfA3: 185 TYPE Ia SUPERNOVA LIGHT CURVES FROM THE CfA

    International Nuclear Information System (INIS)

    Hicken, Malcolm; Challis, Peter; Kirshner, Robert P.; Bakos, Gaspar; Berlind, Perry; Brown, Warren R.; Caldwell, Nelson; Calkins, Mike; Cho, Richard; Contreras, Maria; Jha, Saurabh; Matheson, Tom; Modjaz, Maryam; Rest, Armin; Michael Wood-Vasey, W.; Barton, Elizabeth J.; Bragg, Ann; Briceno, Cesar; Ciupik, Larry; Dendy, Kristi-Concannon

    2009-01-01

    We present multiband photometry of 185 type-Ia supernovae (SNe Ia), with over 11,500 observations. These were acquired between 2001 and 2008 at the F. L. Whipple Observatory of the Harvard-Smithsonian Center for Astrophysics (CfA). This sample contains the largest number of homogeneously observed and reduced nearby SNe Ia (z ∼< 0.08) published to date. It more than doubles the nearby sample, bringing SN Ia cosmology to the point where systematic uncertainties dominate. Our natural system photometry has a precision of ∼<0.02 mag in BVRIr'i' and ∼<0.04 mag in U for points brighter than 17.5 mag. We also estimate a systematic uncertainty of 0.03 mag in our SN Ia standard system BVRIr'i' photometry and 0.07 mag for U. Comparisons of our standard system photometry with published SN Ia light curves and comparison stars, where available for the same SN, reveal agreement at the level of a few hundredths mag in most cases. We find that 1991bg-like SNe Ia are sufficiently distinct from other SNe Ia in their color and light-curve-shape/luminosity relation that they should be treated separately in light-curve/distance fitter training samples. The CfA3 sample will contribute to the development of better light-curve/distance fitters, particularly in the few dozen cases where near-infrared photometry has been obtained and, together, can help disentangle host-galaxy reddening from intrinsic supernova color, reducing the systematic uncertainty in SN Ia distances due to dust.

  12. VizieR Online Data Catalog: Ji light curves of WTS-2 (Birkby+, 2014)

    Science.gov (United States)

    Birkby, J. L.; Cappetta, M.; Cruz, P.; Koppenhoefer, J.; Ivanyuk, O.; Mustill, A. J.; Hodgkin, S. T.; Pinfield, D. J.; Sipocz, B.; Kovacs, G.; Saglia, R.; Pavlenko, Y.; Barrado, D.; Bayo, A.; Campbell, D.; Catalan, S.; Fossati, L.; Galvez-Ortiz, M.-C.; Kenworthy, M.; Lillo-Box, J.; Martin, E. L.; Mislis, D.; de Mooij, E. J. W.; Nefs, S. V.; Snellen, I. A. G.; Stoev, H.; Zendejas, J.; Del Burgo, C.; Barnes, J.; Goulding, N.; Haswell, C. A.; Kuznetsov, M.; Lodieu, N.; Murgas, F.; Palle, E.; Solano, E.; Steele, P.; Tata, R.

    2015-07-01

    The infrared light curves of the WTS were generated from time series photometry taken with the WFCAM imager mounted at the prime focus of UKIRT. In order to confirm the transit of WTS-2 b and to help constrain the transit model, on 2010 July 18 we obtained further time series photometry in the Sloan i band using the Wide Field Camera (WFC) on the 2.5m Isaac Newton Telescope (INT) at Roque de Los Muchachos, La Palma. (2 data files).

  13. Ensemble Learning Method for Outlier Detection and its Application to Astronomical Light Curves

    Science.gov (United States)

    Nun, Isadora; Protopapas, Pavlos; Sim, Brandon; Chen, Wesley

    2016-09-01

    Outlier detection is necessary for automated data analysis, with specific applications spanning almost every domain from financial markets to epidemiology to fraud detection. We introduce a novel mixture of the experts outlier detection model, which uses a dynamically trained, weighted network of five distinct outlier detection methods. After dimensionality reduction, individual outlier detection methods score each data point for “outlierness” in this new feature space. Our model then uses dynamically trained parameters to weigh the scores of each method, allowing for a finalized outlier score. We find that the mixture of experts model performs, on average, better than any single expert model in identifying both artificially and manually picked outliers. This mixture model is applied to a data set of astronomical light curves, after dimensionality reduction via time series feature extraction. Our model was tested using three fields from the MACHO catalog and generated a list of anomalous candidates. We confirm that the outliers detected using this method belong to rare classes, like Novae, He-burning, and red giant stars; other outlier light curves identified have no available information associated with them. To elucidate their nature, we created a website containing the light-curve data and information about these objects. Users can attempt to classify the light curves, give conjectures about their identities, and sign up for follow up messages about the progress made on identifying these objects. This user submitted data can be used further train of our mixture of experts model. Our code is publicly available to all who are interested.

  14. Spotted star mapping by light curve inversion: Tests and application to HD 12545

    Science.gov (United States)

    Kolbin, A. I.; Shimansky, V. V.

    2013-06-01

    A code for mapping the surfaces of spotted stars is developed. The concept of the code is to analyze rotational-modulated light curves. We simulate the process of reconstruction for the star surface and the results of simulation are presented. The reconstruction atrifacts caused by the ill-posed nature of the problem are deduced. The surface of the spotted component of system HD 12545 is mapped using the procedure.

  15. Use of supernovae light curves for testing the expansion hypothesis and other cosmological relations

    International Nuclear Information System (INIS)

    Rust, B.W.

    1974-01-01

    This thesis is primarily concerned with a test of the expansion hypothesis based on the relation Δt/sub obs/ = (1 + V/sub r//c)Δt/sub int/ where Δt/sub int/ is the time lapse characterizing some phenomenon in a distant galaxy, Δt/sub obs/ is the observed time lapse and V/sub r/ is the symbolic velocity of recession. If the red shift is a Doppler effect, the observed time lapse should be lengthened by the same factor as the wave length of the light. Many authors have suggested type I supernovae for such a test because of their great luminosity and the uniformity of their light curves, but apparently the test has heretofore never actually been performed. Thirty-six light curves were gathered from the literature and one (SN1971i) was measured. All of the light curves were reduced to a common (m/sub pg/) photometric system. The comparison time lapse, Δt/sub c/, was taken to be the time required for the brightness to fall from 0.5 m below peak to 2.5 m below peak. The straight line regression of Δt/sub c/ on V/sub r/ gives a correlation coefficient significant at the 93 percent level, and the simple static Euclidean hypothesis is rejected at that level. The regression line also deviates from the prediction of the classical expansion hypothesis. Better agreement was obtained using the chronogeometric theory of I. E. Segal ( []972 Astron. and Astrophys. 18, 143), but the scatter in the present data makes it impossible to distinguish between these alternate hypotheses at the 95 percent confidence level. The question of how many additional light curves would be needed to give definite tests is addressed. It is shown that at the present rate of supernova discoveries, only a few more years would be required to obtain the necessary data if light curves are systematically measured for the more distant supernovae. (Diss. Abstr. Int., B)

  16. A powerful test for weak periodic signals with unknown light curve shape in sparse data

    International Nuclear Information System (INIS)

    Jager De, O.C.; Raubenheimer, B.C.; Swanepoel, J.W.H.

    1989-01-01

    A problem with most tests for periodicity is that they are powerful enough to detect only certain kinds of periodic shapes in the case of weak signals. This causes a selection effect with the identification of weak periodic signals. A new test for uniformity called the H-test is derived for which the probability distribution is an exponential function. This test is shown to have a very good power against most light curve shapes encountered in X- and γ-ray Astronomy and therefore makes the detection of sources with a larger variety of shapes possible. The use of the H-test is suggested if no a priori information about the light curve shape is available. It is also shown how the probability distribution of the test statistics changes when a periodicity search is conducted using very small steps in the period or frequency range. The flux sensitivity for various light curve shapes is also derived for a few tests and this flux is on average a minimum for the H-test

  17. New limb-darkening coefficients for modeling binary star light curves

    Science.gov (United States)

    Van Hamme, W.

    1993-01-01

    We present monochromatic, passband-specific, and bolometric limb-darkening coefficients for a linear as well as nonlinear logarithmic and square root limb-darkening laws. These coefficients, including the bolometric ones, are needed when modeling binary star light curves with the latest version of the Wilson-Devinney light curve progam. We base our calculations on the most recent ATLAS stellar atmosphere models for solar chemical composition stars with a wide range of effective temperatures and surface gravitites. We examine how well various limb-darkening approximations represent the variation of the emerging specific intensity across a stellar surface as computed according to the model. For binary star light curve modeling purposes, we propose the use of a logarithmic or a square root law. We design our tables in such a manner that the relative quality of either law with respect to another can be easily compared. Since the computation of bolometric limb-darkening coefficients first requires monochromatic coefficients, we also offer tables of these coefficients (at 1221 wavelength values between 9.09 nm and 160 micrometer) and tables of passband-specific coefficients for commonly used photometric filters.

  18. Absolute Distances to Nearby Type Ia Supernovae via Light Curve Fitting Methods

    Science.gov (United States)

    Vinkó, J.; Ordasi, A.; Szalai, T.; Sárneczky, K.; Bányai, E.; Bíró, I. B.; Borkovits, T.; Hegedüs, T.; Hodosán, G.; Kelemen, J.; Klagyivik, P.; Kriskovics, L.; Kun, E.; Marion, G. H.; Marschalkó, G.; Molnár, L.; Nagy, A. P.; Pál, A.; Silverman, J. M.; Szakáts, R.; Szegedi-Elek, E.; Székely, P.; Szing, A.; Vida, K.; Wheeler, J. C.

    2018-06-01

    We present a comparative study of absolute distances to a sample of very nearby, bright Type Ia supernovae (SNe) derived from high cadence, high signal-to-noise, multi-band photometric data. Our sample consists of four SNe: 2012cg, 2012ht, 2013dy and 2014J. We present new homogeneous, high-cadence photometric data in Johnson–Cousins BVRI and Sloan g‧r‧i‧z‧ bands taken from two sites (Piszkesteto and Baja, Hungary), and the light curves are analyzed with publicly available light curve fitters (MLCS2k2, SNooPy2 and SALT2.4). When comparing the best-fit parameters provided by the different codes, it is found that the distance moduli of moderately reddened SNe Ia agree within ≲0.2 mag, and the agreement is even better (≲0.1 mag) for the highest signal-to-noise BVRI data. For the highly reddened SN 2014J the dispersion of the inferred distance moduli is slightly higher. These SN-based distances are in good agreement with the Cepheid distances to their host galaxies. We conclude that the current state-of-the-art light curve fitters for Type Ia SNe can provide consistent absolute distance moduli having less than ∼0.1–0.2 mag uncertainty for nearby SNe. Still, there is room for future improvements to reach the desired ∼0.05 mag accuracy in the absolute distance modulus.

  19. THREE FUNDAMENTAL PERIODS IN AN 87 YEAR LIGHT CURVE OF THE SYMBIOTIC STAR MWC 560

    Energy Technology Data Exchange (ETDEWEB)

    Leibowitz, Elia M.; Formiggini, Liliana, E-mail: elia@astro.tau.ac.il [The Wise Observatory and the School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978 (Israel)

    2015-08-15

    We construct a visual light curve of the symbiotic star MWC covering the last 87 years of its history. The data were assembled from the literature and from the AAVSO data bank. Most of the periodic components of the system brightness variation can be accounted for by the operation of three basic clocks of the periods P1 = 19,000 days, P2 = 1943 days, and P3 = 722 days. These periods can plausibly, and consistently with the observations, be attributed to three physical mechanisms in the system: the working of a solar-like magnetic dynamo cycle in the outer layers of the giant star of the system, the binary orbit cycle, and the sidereal rotation cycle of the giant star. MWC 560 is the seventh symbiotic star with historical light curves that reveal similar basic characteristics of the systems. The light curves of all these stars are well interpreted on the basis of the current understanding of the physical processes that are the major sources of the optical luminosity of these symbiotic systems.

  20. IMAGING STARSPOT EVOLUTION ON KEPLER TARGET KIC 5110407 USING LIGHT-CURVE INVERSION

    International Nuclear Information System (INIS)

    Roettenbacher, Rachael M.; Monnier, John D.; Harmon, Robert O.; Barclay, Thomas; Still, Martin

    2013-01-01

    The Kepler target KIC 5110407, a K-type star, shows strong quasi-periodic light curve fluctuations likely arising from the formation and decay of spots on the stellar surface rotating with a period of 3.4693 days. Using an established light-curve inversion algorithm, we study the evolution of the surface features based on Kepler space telescope light curves over a period of two years (with a gap of .25 years). At virtually all epochs, we detect at least one large spot group on the surface causing a 1%-10% flux modulation in the Kepler passband. By identifying and tracking spot groups over a range of inferred latitudes, we measured the surface differential rotation to be much smaller than that found for the Sun. We also searched for a correlation between the 17 stellar flares that occurred during our observations and the orientation of the dominant surface spot at the time of each flare. No statistically significant correlation was found except perhaps for the very brightest flares, suggesting that most flares are associated with regions devoid of spots or spots too small to be clearly discerned using our reconstruction technique. While we may see hints of long-term changes in the spot characteristics and flare statistics within our current data set, a longer baseline of observation will be needed to detect the existence of a magnetic cycle in KIC 5110407.

  1. THE LICK AGN MONITORING PROJECT: PHOTOMETRIC LIGHT CURVES AND OPTICAL VARIABILITY CHARACTERISTICS

    International Nuclear Information System (INIS)

    Walsh, Jonelle L.; Bentz, Misty C.; Barth, Aaron J.; Minezaki, Takeo; Sakata, Yu; Yoshii, Yuzuru; Baliber, Nairn; Bennert, Vardha Nicola; Street, Rachel A.; Treu, Tommaso; Li Weidong; Filippenko, Alexei V.; Stern, Daniel; Brown, Timothy M.; Canalizo, Gabriela; Gates, Elinor L.; Greene, Jenny E.; Malkan, Matthew A.; Woo, Jong-Hak

    2009-01-01

    The Lick AGN Monitoring Project targeted 13 nearby Seyfert 1 galaxies with the intent of measuring the masses of their central black holes using reverberation mapping. The sample includes 12 galaxies selected to have black holes with masses roughly in the range 10 6 -10 7 M sun , as well as the well-studied active galactic nucleus (AGN) NGC 5548. In conjunction with a spectroscopic monitoring campaign, we obtained broadband B and V images on most nights from 2008 February through 2008 May. The imaging observations were carried out by four telescopes: the 0.76 m Katzman Automatic Imaging Telescope, the 2 m Multicolor Active Galactic Nuclei Monitoring telescope, the Palomar 60 inch (1.5 m) telescope, and the 0.80 m Tenagra II telescope. Having well-sampled light curves over the course of a few months is useful for obtaining the broad-line reverberation lag and black hole mass, and also allows us to examine the characteristics of the continuum variability. In this paper, we discuss the observational methods and the photometric measurements, and present the AGN continuum light curves. We measure various variability characteristics of each of the light curves. We do not detect any evidence for a time lag between the B- and V-band variations, and we do not find significant color variations for the AGNs in our sample.

  2. THREE FUNDAMENTAL PERIODS IN AN 87 YEAR LIGHT CURVE OF THE SYMBIOTIC STAR MWC 560

    International Nuclear Information System (INIS)

    Leibowitz, Elia M.; Formiggini, Liliana

    2015-01-01

    We construct a visual light curve of the symbiotic star MWC covering the last 87 years of its history. The data were assembled from the literature and from the AAVSO data bank. Most of the periodic components of the system brightness variation can be accounted for by the operation of three basic clocks of the periods P1 = 19,000 days, P2 = 1943 days, and P3 = 722 days. These periods can plausibly, and consistently with the observations, be attributed to three physical mechanisms in the system: the working of a solar-like magnetic dynamo cycle in the outer layers of the giant star of the system, the binary orbit cycle, and the sidereal rotation cycle of the giant star. MWC 560 is the seventh symbiotic star with historical light curves that reveal similar basic characteristics of the systems. The light curves of all these stars are well interpreted on the basis of the current understanding of the physical processes that are the major sources of the optical luminosity of these symbiotic systems

  3. How Special Is GRB 170817A?

    Science.gov (United States)

    Yue, Chuan; Hu, Qian; Zhang, Fu-Wen; Liang, Yun-Feng; Jin, Zhi-Ping; Zou, Yuan-Chuan; Fan, Yi-Zhong; Wei, Da-Ming

    2018-01-01

    GRB 170817A is the first short gamma-ray burst (GRB) with direct detection of the gravitational-wave radiation and also the spectroscopically identified macronova emission (i.e., AT 2017gfo). The prompt emission of this burst, however, is underluminous in comparison with the other short GRBs with known redshift. In this work, we examine whether GRB 170817A is indeed unique. We first show that GRB 130603B/macronova may be the on-axis “analogs” of GRB 170817A/AT 2017gfo, and the extremely dim but long-lasting afterglow emission of GRB 170817A may suggest a low number density (∼ {10}-5 {{cm}}-3) of its circumburst medium and a structured outflow. We then discuss whether GRB 070923, GRB 080121, GRB 090417A, GRB 111005A, and GRB 170817A form a new group of very nearby underluminous GRBs originated from neutron star mergers. If the short events GRB 070923, GRB 080121, and GRB 090417A are indeed at a redshift of ∼ 0.076, 0.046, 0.088, respectively, their isotropic energies of the prompt emission are ∼ {10}47 erg and thus comparable to the other two events. The non-detection of optical counterparts of GRB 070923, GRB 080121, GRB 090417A, and GRB 111005A, however, strongly suggests that the macronovae from neutron star mergers are significantly diverse in luminosities or, alternatively, there is another origin channel (for instance, the white dwarf and black hole mergers). We finally suggest that GW170817/GRB 170817A are likely not alone and similar events will be detected by the upgraded/upcoming gravitational-wave detectors and the electromagnetic monitors.

  4. The Carnegie Supernova Project I. Analysis of stripped-envelope supernova light curves

    Science.gov (United States)

    Taddia, F.; Stritzinger, M. D.; Bersten, M.; Baron, E.; Burns, C.; Contreras, C.; Holmbo, S.; Hsiao, E. Y.; Morrell, N.; Phillips, M. M.; Sollerman, J.; Suntzeff, N. B.

    2018-02-01

    Stripped-envelope (SE) supernovae (SNe) include H-poor (Type IIb), H-free (Type Ib), and He-free (Type Ic) events thought to be associated with the deaths of massive stars. The exact nature of their progenitors is a matter of debate with several lines of evidence pointing towards intermediate mass (MinitCarnegie Supernova Project (CSP-I) that are unparalleled in terms of photometric accuracy and wavelength range. Light-curve parameters are estimated through the fits of an analytical function and trends are searched for among the resulting fit parameters. Detailed inspection of the dataset suggests a tentative correlation between the peak absolute B-band magnitude and Δm15(B), while the post maximum light curves reveals a correlation between the late-time linear slope and Δm15. Making use of the full set of optical and near-IR photometry, combined with robust host-galaxy extinction corrections, comprehensive bolometric light curves are constructed and compared to both analytic and hydrodynamical models. This analysis finds consistent results among the two different modeling techniques and from the hydrodynamical models we obtained ejecta masses of 1.1-6.2M⊙, 56Ni masses of 0.03-0.35M⊙, and explosion energies (excluding two SNe Ic-BL) of 0.25-3.0 × 1051 erg. Our analysis indicates that adopting κ = 0.07 cm2 g-1 as the mean opacity serves to be a suitable assumption when comparing Arnett-model results to those obtained from hydrodynamical calculations. We also find that adopting He I and O I line velocities to infer the expansion velocity in He-rich and He-poor SNe, respectively, provides ejecta masses relatively similar to those obtained by using the Fe II line velocities, although the use of Fe II as a diagnostic does imply higher explosion energies. The inferred range of ejecta masses are compatible with intermediate mass (MZAMS ≤ 20M⊙) progenitor stars in binary systems for the majority of SE SNe. Furthermore, our hydrodynamical modeling of the

  5. Spectral optimization simulation of white light based on the photopic eye-sensitivity curve

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Qi, E-mail: qidai@tongji.edu.cn [College of Architecture and Urban Planning, Tongji University, 1239 Siping Road, Shanghai 200092 (China); Institute for Advanced Study, Tongji University, 1239 Siping Road, Shanghai 200092 (China); Key Laboratory of Ecology and Energy-saving Study of Dense Habitat (Tongji University), Ministry of Education, 1239 Siping Road, Shanghai 200092 (China); Hao, Luoxi; Lin, Yi; Cui, Zhe [College of Architecture and Urban Planning, Tongji University, 1239 Siping Road, Shanghai 200092 (China); Key Laboratory of Ecology and Energy-saving Study of Dense Habitat (Tongji University), Ministry of Education, 1239 Siping Road, Shanghai 200092 (China)

    2016-02-07

    Spectral optimization simulation of white light is studied to boost maximum attainable luminous efficacy of radiation at high color-rendering index (CRI) and various color temperatures. The photopic eye-sensitivity curve V(λ) is utilized as the dominant portion of white light spectra. Emission spectra of a blue InGaN light-emitting diode (LED) and a red AlInGaP LED are added to the spectrum of V(λ) to match white color coordinates. It is demonstrated that at the condition of color temperature from 2500 K to 6500 K and CRI above 90, such white sources can achieve spectral efficacy of 330–390 lm/W, which is higher than the previously reported theoretical maximum values. We show that this eye-sensitivity-based approach also has advantages on component energy conversion efficiency compared with previously reported optimization solutions.

  6. Spectral optimization simulation of white light based on the photopic eye-sensitivity curve

    International Nuclear Information System (INIS)

    Dai, Qi; Hao, Luoxi; Lin, Yi; Cui, Zhe

    2016-01-01

    Spectral optimization simulation of white light is studied to boost maximum attainable luminous efficacy of radiation at high color-rendering index (CRI) and various color temperatures. The photopic eye-sensitivity curve V(λ) is utilized as the dominant portion of white light spectra. Emission spectra of a blue InGaN light-emitting diode (LED) and a red AlInGaP LED are added to the spectrum of V(λ) to match white color coordinates. It is demonstrated that at the condition of color temperature from 2500 K to 6500 K and CRI above 90, such white sources can achieve spectral efficacy of 330–390 lm/W, which is higher than the previously reported theoretical maximum values. We show that this eye-sensitivity-based approach also has advantages on component energy conversion efficiency compared with previously reported optimization solutions

  7. Red light-induced shift of the fluence-response curve for first positive curvature of maize [Zea mays] coleoptiles

    International Nuclear Information System (INIS)

    Hofmann, E.; Schäfer, E.

    1987-01-01

    The fluence-response curve for first positive phototropic curvture of dark-grown maize coleoptiles is shifted to ten-fold higher fluences if the coieoptiles are irradiated with red light 2 h prior to the phototropic induction with blue light. Fluence-response curves for this red-induced shift were obtained with unilateral red irradiations 2 h prior to inductive blue pulses of different fluences. They differ significantly depending on whether the red light was given from the same side as or the opposite side to the respective inductive blue pulse, thus demonstrating that the red light effect is a local response of the coleoptile. The fluence-response curves for an inductive blue pulse in the ascending part were compared with those for an inductive blue pulse in the descending part of the fluence-response curve for blue light induced phototropism. They are quite different in threshold of red light sensitivity and shape for irradiations from both the same and the opposite sides. This offers evidence for the hypothesis that at least two different photosystems are involved in phototropism, and that they are modulated differently by a red light preirradiation. All these fluence-response curves indicate that it is possible to increase the response in the coleoptile, if the red light preirradiation is given opposite to the inductive blue pulse. This is supported by blue light fluence-response curves obtained after a weak unilateral red preirradiation. (author)

  8. Estimation of error on the cross-correlation, phase and time lag between evenly sampled light curves

    Science.gov (United States)

    Misra, R.; Bora, A.; Dewangan, G.

    2018-04-01

    Temporal analysis of radiation from Astrophysical sources like Active Galactic Nuclei, X-ray Binaries and Gamma-ray bursts provides information on the geometry and sizes of the emitting regions. Establishing that two light-curves in different energy bands are correlated, and measuring the phase and time-lag between them is an important and frequently used temporal diagnostic. Generally the estimates are done by dividing the light-curves into large number of adjacent intervals to find the variance or by using numerically expensive simulations. In this work we have presented alternative expressions for estimate of the errors on the cross-correlation, phase and time-lag between two shorter light-curves when they cannot be divided into segments. Thus the estimates presented here allow for analysis of light-curves with relatively small number of points, as well as to obtain information on the longest time-scales available. The expressions have been tested using 200 light curves simulated from both white and 1 / f stochastic processes with measurement errors. We also present an application to the XMM-Newton light-curves of the Active Galactic Nucleus, Akn 564. The example shows that the estimates presented here allow for analysis of light-curves with relatively small (∼ 1000) number of points.

  9. The diverse broad-band light-curves of Swift GRBs reproduced with the cannonball model

    CERN Document Server

    Dado, Shlomo; De Rújula, A

    2009-01-01

    Two radiation mechanisms, inverse Compton scattering (ICS) and synchrotron radiation (SR), suffice within the cannonball (CB) model of long gamma ray bursts (LGRBs) and X-ray flashes (XRFs) to provide a very simple and accurate description of their observed prompt emission and afterglows. Simple as they are, the two mechanisms and the burst environment generate the rich structure of the light curves at all frequencies and times. This is demonstrated for 33 selected Swift LGRBs and XRFs, which are well sampled from early time until late time and well represent the entire diversity of the broad band light curves of Swift LGRBs and XRFs. Their prompt gamma-ray and X-ray emission is dominated by ICS of glory light. During their fast decline phase, ICS is taken over by SR which dominates their broad band afterglow. The pulse shape and spectral evolution of the gamma-ray peaks and the early-time X-ray flares, and even the delayed optical `humps' in XRFs, are correctly predicted. The canonical and non-canonical X-ra...

  10. APSIDAL MOTION AND A LIGHT CURVE SOLUTION FOR 13 LMC ECCENTRIC ECLIPSING BINARIES

    Energy Technology Data Exchange (ETDEWEB)

    Zasche, P.; Wolf, M.; Vraštil, J.; Pilarcik, L. [Astronomical Institute, Charles University in Prague, Faculty of Mathematics and Physics, CZ-180 00 Praha 8, V Holešovičkách 2 (Czech Republic)

    2015-12-15

    New CCD observations for 13 eccentric eclipsing binaries from the Large Magellanic Cloud were carried out using the Danish 1.54 m telescope located at the La Silla Observatory in Chile. These systems were observed for their times of minimum and 56 new minima were obtained. These are needed for accurate determination of the apsidal motion. Besides that, in total 436 times of minimum were derived from the photometric databases OGLE and MACHO. The O – C diagrams of minimum timings for these B-type binaries were analyzed and the parameters of the apsidal motion were computed. The light curves of these systems were fitted using the program PHOEBE, giving the light curve parameters. We derived for the first time relatively short periods of the apsidal motion ranging from 21 to 107 years. The system OGLE-LMC-ECL-07902 was also analyzed using the spectra and radial velocities, resulting in masses of 6.8 and 4.4 M{sub ⊙} for the eclipsing components. For one system (OGLE-LMC-ECL-20112), the third-body hypothesis was also used to describe the residuals after subtraction of the apsidal motion, resulting in a period of about 22 years. For several systems an additional third light was also detected, which makes these systems suspect for triplicity.

  11. ELECTROMAGNETIC EMISSION FROM LONG-LIVED BINARY NEUTRON STAR MERGER REMNANTS. II. LIGHT CURVES AND SPECTRA

    Energy Technology Data Exchange (ETDEWEB)

    Siegel, Daniel M. [Max Planck Institute for Gravitational Physics (Albert Einstein Institute), Am Mühlenberg 1, D-14476 Potsdam-Golm (Germany); Ciolfi, Riccardo, E-mail: daniel.siegel@aei.mpg.de, E-mail: riccardo.ciolfi@unitn.it [Physics Department, University of Trento, Via Sommarive 14, I-38123 Trento (Italy)

    2016-03-01

    Recent observations indicate that in a large fraction of binary neutron star (BNS) mergers a long-lived neutron star (NS) may be formed rather than a black hole. Unambiguous electromagnetic (EM) signatures of such a scenario would strongly impact our knowledge on how short gamma-ray bursts (SGRBs) and their afterglow radiation are generated. Furthermore, such EM signals would have profound implications for multimessenger astronomy with joint EM and gravitational-wave (GW) observations of BNS mergers, which will soon become reality thanks to the ground-based advanced LIGO/Virgo GW detector network. Here we explore such EM signatures based on the model presented in a companion paper, which provides a self-consistent evolution of the post-merger system and its EM emission up to ∼10{sup 7} s. Light curves and spectra are computed for a wide range of post-merger physical properties. We present X-ray afterglow light curves corresponding to the “standard” and the “time-reversal” scenario for SGRBs (prompt emission associated with the merger or with the collapse of the long-lived NS). The light curve morphologies include single and two-plateau features with timescales and luminosities that are in good agreement with Swift observations. Furthermore, we compute the X-ray signal that should precede the SGRB in the time-reversal scenario, the detection of which would represent smoking-gun evidence for this scenario. Finally, we find a bright, highly isotropic EM transient peaking in the X-ray band at ∼10{sup 2}–10{sup 4} s after the BNS merger with luminosities of L{sub X} ∼ 10{sup 46}–10{sup 48} erg s{sup −1}. This signal represents a very promising EM counterpart to the GW emission from BNS mergers.

  12. A GLOBAL MODEL OF THE LIGHT CURVES AND EXPANSION VELOCITIES OF TYPE II-PLATEAU SUPERNOVAE

    Energy Technology Data Exchange (ETDEWEB)

    Pejcha, Ondřej [Department of Astrophysical Sciences, Princeton University, 4 Ivy Lane, Princeton, NJ 08540 (United States); Prieto, Jose L., E-mail: pejcha@astro.princeton.edu [Núcleo de Astronomía de la Facultad de Ingeniería, Universidad Diego Portales, Av. Ejército 441 Santiago (Chile)

    2015-02-01

    We present a new self-consistent and versatile method that derives photospheric radius and temperature variations of Type II-Plateau supernovae based on their expansion velocities and photometric measurements. We apply the method to a sample of 26 well-observed, nearby supernovae with published light curves and velocities. We simultaneously fit ∼230 velocity and ∼6800 mag measurements distributed over 21 photometric passbands spanning wavelengths from 0.19 to 2.2 μm. The light-curve differences among the Type II-Plateau supernovae are well modeled by assuming different rates of photospheric radius expansion, which we explain as different density profiles of the ejecta, and we argue that steeper density profiles result in flatter plateaus, if everything else remains unchanged. The steep luminosity decline of Type II-Linear supernovae is due to fast evolution of the photospheric temperature, which we verify with a successful fit of SN 1980K. Eliminating the need for theoretical supernova atmosphere models, we obtain self-consistent relative distances, reddenings, and nickel masses fully accounting for all internal model uncertainties and covariances. We use our global fit to estimate the time evolution of any missing band tailored specifically for each supernova, and we construct spectral energy distributions and bolometric light curves. We produce bolometric corrections for all filter combinations in our sample. We compare our model to the theoretical dilution factors and find good agreement for the B and V filters. Our results differ from the theory when the I, J, H, or K bands are included. We investigate the reddening law toward our supernovae and find reasonable agreement with standard R{sub V}∼3.1 reddening law in UBVRI bands. Results for other bands are inconclusive. We make our fitting code publicly available.

  13. SiFTO: An Empirical Method for Fitting SN Ia Light Curves

    Science.gov (United States)

    Conley, A.; Sullivan, M.; Hsiao, E. Y.; Guy, J.; Astier, P.; Balam, D.; Balland, C.; Basa, S.; Carlberg, R. G.; Fouchez, D.; Hardin, D.; Howell, D. A.; Hook, I. M.; Pain, R.; Perrett, K.; Pritchet, C. J.; Regnault, N.

    2008-07-01

    We present SiFTO, a new empirical method for modeling Type Ia supernova (SN Ia) light curves by manipulating a spectral template. We make use of high-redshift SN data when training the model, allowing us to extend it bluer than rest-frame U. This increases the utility of our high-redshift SN observations by allowing us to use more of the available data. We find that when the shape of the light curve is described using a stretch prescription, applying the same stretch at all wavelengths is not an adequate description. SiFTO therefore uses a generalization of stretch which applies different stretch factors as a function of both the wavelength of the observed filter and the stretch in the rest-frame B band. We compare SiFTO to other published light-curve models by applying them to the same set of SN photometry, and demonstrate that SiFTO and SALT2 perform better than the alternatives when judged by the scatter around the best-fit luminosity distance relationship. We further demonstrate that when SiFTO and SALT2 are trained on the same data set the cosmological results agree. Based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii. This work is based in part on data products produced at the Canadian Astronomy Data Centre as part of the Canada-France-Hawaii Telescope Legacy Survey, a collaborative project of NRC and CNRS.

  14. Type II Supernova Light Curves and Spectra from the CfA

    Science.gov (United States)

    Hicken, Malcolm; Friedman, Andrew S.; Blondin, Stephane; Challis, Peter; Berlind, Perry; Calkins, Mike; Esquerdo, Gil; Matheson, Thomas; Modjaz, Maryam; Rest, Armin; Kirshner, Robert P.

    2017-11-01

    We present multiband photometry of 60 spectroscopically confirmed supernovae (SNe): 39 SNe II/IIP, 19 IIn, 1 IIb, and 1 that was originally classified as a IIn but later as a Ibn. Of these, 46 have only optical photometry, 6 have only near-infrared (NIR) photometry, and 8 have both optical and NIR. The median redshift of the sample is 0.016. We also present 195 optical spectra for 48 of the 60 SN. There are 26 optical and 2 NIR light curves of SNe II/IIP with redshifts z> 0.01, some of which may give rise to useful distances for cosmological applications. All photometry was obtained between 2000 and 2011 at the Fred Lawrence Whipple Observatory (FLWO), via the 1.2 m and 1.3 m PAIRITEL telescopes for the optical and NIR, respectively. Each SN was observed in a subset of the u\\prime {UBVRIr}\\prime I\\prime {{JHK}}s bands. There are a total of 2932 optical and 816 NIR light curve points. Optical spectra were obtained using the FLWO 1.5 m Tillinghast telescope with the FAST spectrograph and the MMT Telescope with the Blue Channel Spectrograph. Our photometry is in reasonable agreement with select samples from the literature: two-thirds of our star sequences have average V offsets within ±0.02 mag and roughly three-quarters of our light curves have average differences within ±0.04 mag. The data from this work and the literature will provide insight into SN II explosions, help with developing methods for photometric SN classification, and contribute to their use as cosmological distance indicators.

  15. Probing Millisecond Pulsar Emission Geometry Using Light Curves From the Fermi Large Area Telescope

    Science.gov (United States)

    Venter, Christo; Harding, Alice; Guillemot, L.

    2009-01-01

    An interesting new high-energy pulsar sub-population is emerging following early discoveries of gamma-ray millisecond pulsars (MSPs) by the Fermi Large Area Telescope (LAT). We present results from 3D emission modeling, including the Special Relativistic effects of aberration and time-of-flight delays and also rotational sweepback of 13-field lines, in the geometric context of polar cap (PC), slot gap (SG), outer gap (OG), and two-pole caustic (TPC) pulsar models. In contrast to the general belief that these very old, rapidly-rotating neutron stars (NSs) should have largely pair-starved magnetospheres due to the absence of significant pair production, we find that most of the light curves are best fit by SG and OG models, which indicates the presence of narrow accelerating gaps limited by robust pair production -- even in these pulsars with very low spin-down luminosities. The gamma-ray pulse shapes and relative phase lags with respect to the radio pulses point to high-altitude emission being dominant for all geometries. We also find exclusive differentiation of the current gamma-ray MSP population into two MSP sub-classes: light curve shapes and lags across wavebands impose either pair-starved PC (PSPC) or SG / OG-type geometries. In the first case, the radio pulse has a small lag with respect to the single gamma-ray pulse, while the (first) gamma-ray peak usually trails the radio by a large phase offset in the latter case. Finally, we find that the flux correction factor as a function of magnetic inclination and observer angles is typically of order unity for all models. Our calculation of light curves and flux correction factor f(_, _, P) for the case of MSPs is therefore complementary to the "ATLAS paper" of Watters et al. for younger pulsars.

  16. IMPROVED DARK ENERGY CONSTRAINTS FROM ∼100 NEW CfA SUPERNOVA TYPE Ia LIGHT CURVES

    International Nuclear Information System (INIS)

    Hicken, Malcolm; Challis, Peter; Kirshner, Robert P.; Wood-Vasey, W. Michael; Blondin, Stephane; Jha, Saurabh; Kelly, Patrick L.; Rest, Armin

    2009-01-01

    We combine the CfA3 supernovae Type Ia (SN Ia) sample with samples from the literature to calculate improved constraints on the dark energy equation of state parameter, w. The CfA3 sample is added to the Union set of Kowalski et al. to form the Constitution set and, combined with a BAO prior, produces 1 + w = 0.013 +0.066 -0.068 (0.11 syst), consistent with the cosmological constant. The CfA3 addition makes the cosmologically useful sample of nearby SN Ia between 2.6 and 2.9 times larger than before, reducing the statistical uncertainty to the point where systematics play the largest role. We use four light-curve fitters to test for systematic differences: SALT, SALT2, MLCS2k2 (R V = 3.1), and MLCS2k2 (R V = 1.7). SALT produces high-redshift Hubble residuals with systematic trends versus color and larger scatter than MLCS2k2. MLCS2k2 overestimates the intrinsic luminosity of SN Ia with 0.7 V = 3.1 overestimates host-galaxy extinction while R V ∼ 1.7 does not. Our investigation is consistent with no Hubble bubble. We also find that, after light-curve correction, SN Ia in Scd/Sd/Irr hosts are intrinsically fainter than those in E/S0 hosts by 2σ, suggesting that they may come from different populations. We also find that SN Ia in Scd/Sd/Irr hosts have low scatter (0.1 mag) and reddening. Current systematic errors can be reduced by improving SN Ia photometric accuracy, by including the CfA3 sample to retrain light-curve fitters, by combining optical SN Ia photometry with near-infrared photometry to understand host-galaxy extinction, and by determining if different environments give rise to different intrinsic SN Ia luminosity after correction for light-curve shape and color.

  17. VizieR Online Data Catalog: Lick AGN monitoring 2011: light curves (Barth+, 2015)

    Science.gov (United States)

    Barth, A. J.; Bennert, V. N.; Canalizo, G.; Filippenko, A. V.; Gates, E. L.; Greene, J. E.; Li, W.; Malkan, M. A.; Pancoast, A.; Sand, D. J.; Stern, D.; Treu, T.; Woo, J.-H.; Assef, R. J.; Bae, H.-J.; Brewer, B. J.; Cenko, S. B.; Clubb, K. I.; Cooper, M. C.; Diamond-Stanic, A. M.; Hiner, K. D.; Honig, S. F.; Hsiao, E.; Kandrashoff, M. T.; Lazarova, M. S.; Nierenberg, A. M.; Rex, J.; Silverman, J. M.; Tollerud, E. J.; Walsh, J. L.

    2015-05-01

    This project was allocated 69 nights at the Lick 3m Shane telescope, distributed between 2011 March 27 and June 13. Observations were conducted using the Kast double spectrograph (3440-5515Å on the blue side and 5410-8200Å on the red side). In order to extend our light curves for two AGNs, we also requested additional observations from other observers using the Kast spectrograph: Mrk 50 from 2011 January through March, and Zw 229-015 in June and July. For Zw 229-015, three additional observations were taken 20-23 days after the end of our main campaign. See section 3. (2 data files).

  18. EARLY-TIME VLA OBSERVATIONS AND BROADBAND AFTERGLOW ANALYSIS OF THE FERMI/LAT DETECTED GRB 130907A

    International Nuclear Information System (INIS)

    Veres, Péter; Corsi, Alessandra; Frail, Dale A.; Cenko, S. Bradley; Perley, Daniel A.

    2015-01-01

    We present multi-wavelength observations of the hyper-energetic gamma-ray burst (GRB) 130907A, a Swift-discovered burst with early radio observations starting at ≈4 hr after the γ-ray trigger. GRB 130907A was also detected by the Fermi/LAT instrument and at late times showed a strong spectral evolution in X-rays. We focus on the early-time radio observations, especially at >10 GHz, to attempt to identify reverse shock signatures. While our radio follow-up of GRB 130907A ranks among the earliest observations of a GRB with the Karl G. Jansky Very Large Array, we did not see an unambiguous signature of a reverse shock. While a model with both reverse and forward shock can correctly describe the observations, the data is not constraining enough to decide upon the presence of the reverse-shock component. We model the broadband data using a simple forward-shock synchrotron scenario with a transition from a wind environment to a constant density interstellar medium (ISM) in order to account for the observed features. Within the confines of this model, we also derive the underlying physical parameters of the fireball, which are within typical ranges except for the wind density parameter (A * ), which is higher than those for bursts with wind-ISM transition, but typical for the general population of bursts. We note the importance of early-time radio observations of the afterglow (and of well-sampled light curves) for unambiguously identifying the potential contribution of the reverse shock

  19. Emergence of curved light-cones in a class of inhomogeneous Luttinger liquids

    Directory of Open Access Journals (Sweden)

    Jérôme Dubail, Jean-Marie Stéphan, Pasquale Calabrese

    2017-09-01

    Full Text Available The light-cone spreading of entanglement and correlation is a fundamental and ubiquitous feature of homogeneous extended quantum systems. Here we point out that a class of inhomogenous Luttinger liquids (those with a uniform Luttinger parameter $K$ at low energy display the universal phenomenon of curved light cones: gapless excitations propagate along the geodesics of the metric $ds^2=dx^2+v(x^2 d\\tau^2$, with $v(x$ being the calculable spatial dependent velocity induced by the inhomogeneity. We confirm our findings with explicit analytic and numerical calculations both in- and out-of-equilibrium for a Tonks-Girardeau gas in a harmonic potential and in lattice systems with artificially tuned hamiltonian density.

  20. A UNIFORM SEARCH FOR SECONDARY ECLIPSES OF HOT JUPITERS IN KEPLER Q2 LIGHT CURVES

    International Nuclear Information System (INIS)

    Coughlin, J. L.; López-Morales, M.

    2012-01-01

    In this paper, we present the results of searching the Kepler Q2 public data set for the secondary eclipses of 76 hot Jupiter planet candidates from the list of 1235 candidates published by Borucki et al. This search has been performed by modeling both the Kepler pre-search data conditioned light curves and new light curves produced via our own photometric pipeline. We derive new stellar and planetary parameters for each system, while calculating robust errors for both. We find 16 systems with 1σ-2σ, 14 systems with 2σ-3σ, and 6 systems with >3σ confidence level secondary eclipse detections in at least one light curve produced via the Kepler pre-search data conditioned light curve or our own pipeline; however, results can vary depending on the light curve modeled and whether eccentricity is allowed to vary or not. We estimate false alarm probabilities of 31%, 10%, and 6% for the 1σ-2σ, 2σ-3σ, and >3σ confidence intervals, respectively. Comparing each secondary eclipse result to theoretical expectations, we find that the majority of detected planet candidates emit more light than expected owing to thermal blackbody emission in the optical Kepler bandpass, and present a trend of increasing excess emission with decreasing maximum effective planetary temperature. These results agree with previously published optical secondary eclipse data for other hot Jupiters. We explore modeling biases, significant planetary albedos, non-local thermodynamic equilibrium or other thermal emission, significant internal energy generation, and misidentification of brown dwarfs, low-mass stars, or stellar blends as possible causes of both the excess emission and its correlation with expected planetary temperature. Although we find that no single cause is able to explain all of the planet candidates, significant planetary albedos, with a general trend of increasing planetary albedos with decreasing atmospheric temperatures, are able to explain most of the systems. Identifying

  1. Detection of Time Lags between Quasar Continuum Emission Bands Based On Pan-STARRS Light Curves

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Yan-Fei [Kavli Institute for Theoretical Physics, University of California, Santa Barbara, CA 93106 (United States); Green, Paul J.; Pancoast, Anna; MacLeod, Chelsea L. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Greene, Jenny E. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Morganson, Eric; Shen, Yue [Department of Astronomy, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States); Anderson, Scott F.; Ruan, John J. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Brandt, W. N.; Grier, C. J. [Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802 (United States); Rix, H.-W. [Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany); Protopapas, Pavlos [Institute for Applied Computational Science, John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138 (United States); Scott, Caroline [Astrophysics, Imperial College London, Blackett Laboratory, London SW7 2AZ (United Kingdom); Burgett, W. S.; Hodapp, K. W.; Huber, M. E.; Kaiser, N.; Kudritzki, R. P.; Magnier, E. A. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu HI 96822 (United States); and others

    2017-02-20

    We study the time lags between the continuum emission of quasars at different wavelengths, based on more than four years of multi-band ( g , r , i , z ) light curves in the Pan-STARRS Medium Deep Fields. As photons from different bands emerge from different radial ranges in the accretion disk, the lags constrain the sizes of the accretion disks. We select 240 quasars with redshifts of z ≈ 1 or z ≈ 0.3 that are relatively emission-line free. The light curves are sampled from day to month timescales, which makes it possible to detect lags on the scale of the light crossing time of the accretion disks. With the code JAVELIN , we detect typical lags of several days in the rest frame between the g band and the riz bands. The detected lags are ∼2–3 times larger than the light crossing time estimated from the standard thin disk model, consistent with the recently measured lag in NGC 5548 and microlensing measurements of quasars. The lags in our sample are found to increase with increasing luminosity. Furthermore, the increase in lags going from g − r to g − i and then to g − z is slower than predicted in the thin disk model, particularly for high-luminosity quasars. The radial temperature profile in the disk must be different from what is assumed. We also find evidence that the lags decrease with increasing line ratios between ultraviolet Fe ii lines and Mg ii, which may point to changes in the accretion disk structure at higher metallicity.

  2. A unique UV flare in the optical light curve of the quasar J004457.9+412344

    Directory of Open Access Journals (Sweden)

    Hatzidimitriou D.

    2012-12-01

    Full Text Available We found that the nova candidate J004457.9+412344 is a radio-quiet quasar at z ∼ 2. Its optical long-term light curve, covering more than half a century, shows quasar typical flux variations superimposed by a spectacular single flare lasting more than one year (observer frame. We could not find comparable light curves among the several thousand catalogued radio-quiet quasars in the stripe 82 of the Sloan Digital Sky Survey. The decreasing part of the flare light curve roughly follows a power law t−5/3. The quasar spectrum, the total energy of the flare, and the decline of the light curve are consistent with the tidal disruption of a ∼10 Mʘ giant star by a supermassive black hole of a few 108 Mʘ. We argue that the alternative explanation by gravitational microlensing is less likely, though it cannot be definitely excluded.

  3. The GRB-SLSN connection: misaligned magnetars, weak jet emergence, and observational signatures

    Science.gov (United States)

    Margalit, Ben; Metzger, Brian D.; Thompson, Todd A.; Nicholl, Matt; Sukhbold, Tuguldur

    2018-04-01

    Multiple lines of evidence support a connection between hydrogen-poor superluminous supernovae (SLSNe) and long-duration gamma-ray bursts (GRBs). Both classes of events require a powerful central energy source, usually attributed to a millisecond magnetar or an accreting black hole. The GRB-SLSN link raises several theoretical questions: What distinguishes the engines responsible for these different phenomena? Can a single engine power both a GRB and a luminous SN in the same event? We propose a unifying model for magnetar thermalization and jet formation: misalignment between the rotation (Ω) and magnetic dipole (μ) axes dissipates a fraction of the spin-down power by reconnection in the striped equatorial wind, providing a guaranteed source of `thermal' emission to power the supernova. The remaining unthermalized power energizes a relativistic jet. We show that even weak relativistic jets of luminosity ˜1046 erg s-1 can escape the expanding SN ejecta implying that escaping relativistic jets may accompany many SLSNe. We calculate the observational signature of these jets. We show that they may produce transient ultraviolet (UV) cocoon emission lasting a few hours when the jet breaks out of the ejecta surface. A longer lived optical/UV signal may originate from a mildly relativistic wind driven from the interface between the jet and the ejecta walls, which could explain the secondary early-time maximum observed in some SLSNe light curves, such as LSQ14bdq. Our scenario predicts a population of GRB from on-axis jets with extremely long durations, potentially similar to the population of `jetted-tidal disruption events', in coincidence with a small subset of SLSNe.

  4. Measuring the beaming angle of GRB 030329 by fitting the rebrightenings in its multiband afterglow

    International Nuclear Information System (INIS)

    Deng Wei; Huang Yongfeng; Kong Siwei

    2010-01-01

    Multiple rebrightenings have been observed in the multiband afterglow of GRB 030329. In particular, a marked and quick rebrightening occurred at about t ∼ 1.2 x 10 5 s. Energy injection from late and slow shells seems to be the best interpretation for these rebrightenings. Usually it is assumed that the energy is injected into the whole external shock. However, in the case of GRB 030329, the rebrightenings are so quick that the usual consideration fails to give a satisfactory fit to the observed light curves. Actually, since these late/slow shells freely coast in the wake of the external shock, they should be cold and may not expand laterally. The energy injection then should only occur at the central region of the external shock. Considering this effect, we numerically re-fit the quick rebrightenings observed in GRB 030329. By doing this, we were able to derive the beaming angle of the energy injection process. Our result, with a relative residual of only 5% - 10% during the major rebrightening, is better than any previous modeling. The derived energy injection angle is about 0.035. We assume that these late shells are ejected by the central engine via the same mechanism as those early shells that produce the prompt gamma-ray burst. The main difference is that their velocities are much slower, so that they catch up with the external shock relatively late and are manifested as the observed quick rebrightenings. If this were true, then the derived energy injection angle can give a good measure of the beaming angle of the prompt γ-ray emission. Our study may hopefully provide a novel method to measure the beaming angle of gamma-ray bursts. (research papers)

  5. The latest two GRB detected by Hete-2: GRB 051022 and GRB 051028

    International Nuclear Information System (INIS)

    Castro-Tirado, A. J.; Jelinek, M.; Pandey, S. B.; Ugarte Postigo, A. de; Gorosabel, J.; McBreen, S.; Bremer, M.; Guziy, S.; Bihain, G.; Caballero, J. A.; Ferrero, P.; Jong, J de; Misra, K.; Sahu, D. K.

    2006-01-01

    We present multiwavelength observations of the latest two GRB detected by Hete-2 in 2005. For GRB 051022, no optical/nIR afterglow has been detected, in spite of the strong gamma-ray emission and the reported X-ray afterglow discovered by Swift. A mm afterglow was discovered at PdB confirming the association of this event with a luminous (MV = - 21.5) galaxy within the X-ray error box. Spectroscopy of this galaxy shows strong a strong [O II] emission line at z = 0.807, besides weaker [O III] emission. The X-ray spectrum showed evidence of considerable absorption by neutral gas with NH,X-ray = 4.5 x 1022 cm2 (at rest frame). ISM absorption by dust in the host galaxy at z = 0.807 cannot certainly account for the non-detection of the optical afterglow, unless the dust-to-gas ratio is quite different than that seen in our Galaxy. It is possible then that GRB 051022 was produced in an obscured, stellar forming region in its parent host galaxy.For GRB 051028, the data can be interpreted by collimated emission (a jet model with p = 2.4) moving in an homogeneous ISM and with a cooling frequency vc still above the X-rays at 0.5 days after the burst onset. GRB 051028 can be classified as a 'gray' or 'potentially dark' GRB. The Swift/XRT data are consistent with the interpretation that the reason for the optical dimness is not extra absorption in the host galaxy, but rather the GRB taking place at high-redshift

  6. Recurrence network measures for hypothesis testing using surrogate data: Application to black hole light curves

    Science.gov (United States)

    Jacob, Rinku; Harikrishnan, K. P.; Misra, R.; Ambika, G.

    2018-01-01

    Recurrence networks and the associated statistical measures have become important tools in the analysis of time series data. In this work, we test how effective the recurrence network measures are in analyzing real world data involving two main types of noise, white noise and colored noise. We use two prominent network measures as discriminating statistic for hypothesis testing using surrogate data for a specific null hypothesis that the data is derived from a linear stochastic process. We show that the characteristic path length is especially efficient as a discriminating measure with the conclusions reasonably accurate even with limited number of data points in the time series. We also highlight an additional advantage of the network approach in identifying the dimensionality of the system underlying the time series through a convergence measure derived from the probability distribution of the local clustering coefficients. As examples of real world data, we use the light curves from a prominent black hole system and show that a combined analysis using three primary network measures can provide vital information regarding the nature of temporal variability of light curves from different spectroscopic classes.

  7. SNaX: A Database of Supernova X-Ray Light Curves

    Energy Technology Data Exchange (ETDEWEB)

    Ross, Mathias; Dwarkadas, Vikram V., E-mail: Mathias_Ross@msn.com, E-mail: vikram@oddjob.uchicago.edu [Astronomy and Astrophysics, University of Chicago, 5640 S Ellis Avenue, ERC 569, Chicago, IL 60637 (United States)

    2017-06-01

    We present the Supernova X-ray Database (SNaX), a compilation of the X-ray data from young supernovae (SNe). The database includes the X-ray fluxes and luminosities of young SNe, from days to years after outburst. The original goal and intent of this study was to present a database of Type IIn SNe (SNe IIn), which we have accomplished. Our ongoing goal is to expand the database to include all SNe for which published data are available. The database interface allows one to search for SNe using various criteria, plot all or selected data points, and download both the data and the plot. The plotting facility allows for significant customization. There is also a facility for the user to submit data that can be directly incorporated into the database. We include an option to fit the decay of any given SN light curve with a power-law. The database includes a conversion of most data points to a common 0.3–8 keV band so that SN light curves may be directly compared with each other. A mailing list has been set up to disseminate information about the database. We outline the structure and function of the database, describe its various features, and outline the plans for future expansion.

  8. EXTRACTING PERIODIC TRANSIT SIGNALS FROM NOISY LIGHT CURVES USING FOURIER SERIES

    Energy Technology Data Exchange (ETDEWEB)

    Samsing, Johan [Department of Astrophysical Sciences, Princeton University, Peyton Hall, 4 Ivy Lane, Princeton, NJ 08544 (United States)

    2015-07-01

    We present a simple and powerful method for extracting transit signals associated with a known transiting planet from noisy light curves. Assuming the orbital period of the planet is known and the signal is periodic, we illustrate that systematic noise can be removed in Fourier space at all frequencies by only using data within a fixed time frame with a width equal to an integer number of orbital periods. This results in a reconstruction of the full transit signal, which on average is unbiased despite no prior knowledge of either the noise or the transit signal itself being used in the analysis. The method therefore has clear advantages over standard phase folding, which normally requires external input such as nearby stars or noise models for removing systematic components. In addition, we can extract the full orbital transit signal (360°) simultaneously, and Kepler-like data can be analyzed in just a few seconds. We illustrate the performance of our method by applying it to a dataset composed of light curves from Kepler with a fake injected signal emulating a planet with rings. For extracting periodic transit signals, our presented method is in general the optimal and least biased estimator and could therefore lead the way toward the first detections of, e.g., planet rings and exo-trojan asteroids.

  9. Cosmological parameter uncertainties from SALT-II type Ia supernova light curve models

    International Nuclear Information System (INIS)

    Mosher, J.; Sako, M.; Guy, J.; Astier, P.; Betoule, M.; El-Hage, P.; Pain, R.; Regnault, N.; Kessler, R.; Frieman, J. A.; Marriner, J.; Biswas, R.; Kuhlmann, S.; Schneider, D. P.

    2014-01-01

    We use simulated type Ia supernova (SN Ia) samples, including both photometry and spectra, to perform the first direct validation of cosmology analysis using the SALT-II light curve model. This validation includes residuals from the light curve training process, systematic biases in SN Ia distance measurements, and a bias on the dark energy equation of state parameter w. Using the SN-analysis package SNANA, we simulate and analyze realistic samples corresponding to the data samples used in the SNLS3 analysis: ∼120 low-redshift (z < 0.1) SNe Ia, ∼255 Sloan Digital Sky Survey SNe Ia (z < 0.4), and ∼290 SNLS SNe Ia (z ≤ 1). To probe systematic uncertainties in detail, we vary the input spectral model, the model of intrinsic scatter, and the smoothing (i.e., regularization) parameters used during the SALT-II model training. Using realistic intrinsic scatter models results in a slight bias in the ultraviolet portion of the trained SALT-II model, and w biases (w input – w recovered ) ranging from –0.005 ± 0.012 to –0.024 ± 0.010. These biases are indistinguishable from each other within the uncertainty; the average bias on w is –0.014 ± 0.007.

  10. THE CARNEGIE SUPERNOVA PROJECT: LIGHT-CURVE FITTING WITH SNooPy

    International Nuclear Information System (INIS)

    Burns, Christopher R.; Persson, S. E.; Madore, Barry F.; Freedman, Wendy L.; Stritzinger, Maximilian; Phillips, M. M.; Boldt, Luis; Campillay, Abdo; Folatelli, Gaston; Gonzalez, Sergio; Krzeminski, Wojtek; Morrell, Nidia; Salgado, Francisco; Kattner, ShiAnne; Contreras, Carlos; Suntzeff, Nicholas B.

    2011-01-01

    In providing an independent measure of the expansion history of the universe, the Carnegie Supernova Project (CSP) has observed 71 high-z Type Ia supernovae (SNe Ia) in the near-infrared bands Y and J. These can be used to construct rest-frame i-band light curves which, when compared to a low-z sample, yield distance moduli that are less sensitive to extinction and/or decline-rate corrections than in the optical. However, working with NIR observed and i-band rest-frame photometry presents unique challenges and has necessitated the development of a new set of observational tools in order to reduce and analyze both the low-z and high-z CSP sample. We present in this paper the methods used to generate uBVgriYJH light-curve templates based on a sample of 24 high-quality low-z CSP SNe. We also present two methods for determining the distances to the hosts of SN Ia events. A larger sample of 30 low-z SNe Ia in the Hubble flow is used to calibrate these methods. We then apply the method and derive distances to seven galaxies that are so nearby that their motions are not dominated by the Hubble flow.

  11. The Origin and Evolution of the Infrared Light Curve of SN2010jl

    Science.gov (United States)

    Dwek, Eli; Sarangi, Arkaprabha; Arendt, Richard; Fox, Ori; Kallman, Timothy; Kazanas, Demosthenes

    2018-01-01

    SN2010jl is a luminous core-collapse supernova (CCSN) of Type IIn that is surrounded by a dense circumstellar medium (CSM). The supernova (SN) luminosity vastly exceeds the available power from radiactive elements in the ejecta, and is powered by the interaction of the SN shock wave with the ambient medium. Upper limits on the UV and near-IR (NIR) emission from pre-explosion images of the region suggest that any progenitor star was hidden by pre-existing CSM dust. After day ~80, the SN spectrum shows the development of an IR excess above the extrapolated UVO emission arising from the shocked CSM. This IR component is attributed to thermal emission from dust.After day ~300, the light curve exhibits a rise in the NIR luminosity, concurrent with a steep decline at UVO wavelengths. Ruling out any possible contribution of SN-condensed dust to the IR light curve, we show that the early IR emission arises from the pre-existing CSM dust that survived the flash of radiation from the shock breakout. The late IR emission arises from newly-formed CSM dust that condensed in the cooling dust-free postshock gas of the advancing SN shock wave. Our analysis presents the first detailed modeling of dust formation in a cooling postshock environment, and provides important insights into the interaction of the SN shock wave with the CSM.

  12. PERIOD ESTIMATION FOR SPARSELY SAMPLED QUASI-PERIODIC LIGHT CURVES APPLIED TO MIRAS

    Energy Technology Data Exchange (ETDEWEB)

    He, Shiyuan; Huang, Jianhua Z.; Long, James [Department of Statistics, Texas A and M University, College Station, TX (United States); Yuan, Wenlong; Macri, Lucas M., E-mail: lmacri@tamu.edu [George P. and Cynthia W. Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics and Astronomy, Texas A and M University, College Station, TX (United States)

    2016-12-01

    We develop a nonlinear semi-parametric Gaussian process model to estimate periods of Miras with sparsely sampled light curves. The model uses a sinusoidal basis for the periodic variation and a Gaussian process for the stochastic changes. We use maximum likelihood to estimate the period and the parameters of the Gaussian process, while integrating out the effects of other nuisance parameters in the model with respect to a suitable prior distribution obtained from earlier studies. Since the likelihood is highly multimodal for period, we implement a hybrid method that applies the quasi-Newton algorithm for Gaussian process parameters and search the period/frequency parameter space over a dense grid. A large-scale, high-fidelity simulation is conducted to mimic the sampling quality of Mira light curves obtained by the M33 Synoptic Stellar Survey. The simulated data set is publicly available and can serve as a testbed for future evaluation of different period estimation methods. The semi-parametric model outperforms an existing algorithm on this simulated test data set as measured by period recovery rate and quality of the resulting period–luminosity relations.

  13. SNaX: A Database of Supernova X-Ray Light Curves

    International Nuclear Information System (INIS)

    Ross, Mathias; Dwarkadas, Vikram V.

    2017-01-01

    We present the Supernova X-ray Database (SNaX), a compilation of the X-ray data from young supernovae (SNe). The database includes the X-ray fluxes and luminosities of young SNe, from days to years after outburst. The original goal and intent of this study was to present a database of Type IIn SNe (SNe IIn), which we have accomplished. Our ongoing goal is to expand the database to include all SNe for which published data are available. The database interface allows one to search for SNe using various criteria, plot all or selected data points, and download both the data and the plot. The plotting facility allows for significant customization. There is also a facility for the user to submit data that can be directly incorporated into the database. We include an option to fit the decay of any given SN light curve with a power-law. The database includes a conversion of most data points to a common 0.3–8 keV band so that SN light curves may be directly compared with each other. A mailing list has been set up to disseminate information about the database. We outline the structure and function of the database, describe its various features, and outline the plans for future expansion.

  14. Cosmological Parameter Uncertainties from SALT-II Type Ia Supernova Light Curve Models

    Energy Technology Data Exchange (ETDEWEB)

    Mosher, J. [Pennsylvania U.; Guy, J. [LBL, Berkeley; Kessler, R. [Chicago U., KICP; Astier, P. [Paris U., VI-VII; Marriner, J. [Fermilab; Betoule, M. [Paris U., VI-VII; Sako, M. [Pennsylvania U.; El-Hage, P. [Paris U., VI-VII; Biswas, R. [Argonne; Pain, R. [Paris U., VI-VII; Kuhlmann, S. [Argonne; Regnault, N. [Paris U., VI-VII; Frieman, J. A. [Fermilab; Schneider, D. P. [Penn State U.

    2014-08-29

    We use simulated type Ia supernova (SN Ia) samples, including both photometry and spectra, to perform the first direct validation of cosmology analysis using the SALT-II light curve model. This validation includes residuals from the light curve training process, systematic biases in SN Ia distance measurements, and a bias on the dark energy equation of state parameter w. Using the SN-analysis package SNANA, we simulate and analyze realistic samples corresponding to the data samples used in the SNLS3 analysis: ~120 low-redshift (z < 0.1) SNe Ia, ~255 Sloan Digital Sky Survey SNe Ia (z < 0.4), and ~290 SNLS SNe Ia (z ≤ 1). To probe systematic uncertainties in detail, we vary the input spectral model, the model of intrinsic scatter, and the smoothing (i.e., regularization) parameters used during the SALT-II model training. Using realistic intrinsic scatter models results in a slight bias in the ultraviolet portion of the trained SALT-II model, and w biases (w (input) – w (recovered)) ranging from –0.005 ± 0.012 to –0.024 ± 0.010. These biases are indistinguishable from each other within the uncertainty, the average bias on w is –0.014 ± 0.007.

  15. Effect of stellar activity on the high precision transit light curve

    Directory of Open Access Journals (Sweden)

    Oshagh, M.

    2015-01-01

    Full Text Available Stellar activity features such as spots and plages can create difficulties in determining planetary parameters through spectroscopic and photometric observations. The overlap of a transiting planet and a stellar spot, for instance, can produce anomalies in the transit light curve that may lead to inaccurate estimation of the transit duration, depth, and timing. Such inaccuracies can affect the precise derivation of the planet’s radius. In this talk we will present the results of a quantitative study on the effects of stellar spots on high precision transit light curves. We show that spot anomalies can lead to the estimate of a planet radius that is 4% smaller than the real value. The effects on the transit duration can also be of the order of 4%, longer or shorter. Depending on the size and distribution of spots, anomalies can also produce transit timing variations with significant amplitudes. For instance, TTVs with signal amplitudes of 200 seconds can be produced by spots as large as the largest sunspot. Finally, we examine the impact of active regions on the transit depth measurements in different wavelengths, in order to probe the impact of this effect on transmission spectroscopy measurements. We show that significant (up to 10% underestimation/overestimation of the planet-to-star radius ratio can be measured, especially in the short wavelength regime.

  16. KIC 4552982: outbursts and pulsations in the longest-ever pseudo-continuous light curve of a ZZ Ceti

    Directory of Open Access Journals (Sweden)

    Bell K. J.

    2015-01-01

    Full Text Available KIC 4552982 was the first ZZ Ceti (hydrogen-atmosphere pulsating white dwarf identified to lie in the Kepler field, resulting in the longest pseudo-continuous light curve ever obtained for this type of variable star. In addition to the pulsations, this light curve exhibits stochastic episodes of brightness enhancement unlike any previously studied white dwarf phenomenon. We briefly highlight the basic outburst and pulsation properties in these proceedings.

  17. Infrared rotational light curves on Jupiter induced by wave activities and cloud patterns andimplications on brown dwarfs

    Science.gov (United States)

    Ge, Huazhi; Zhang, Xi; Fletcher, Leigh; Orton, Glenn S.; Sinclair, James Andrew; Fernandes,, Joshua; Momary, Thomas W.; Warren, Ari; Kasaba, Yasumasa; Sato, Takao M.; Fujiyoshi, Takuya

    2017-10-01

    Many brown dwarfs exhibit infrared rotational light curves with amplitude varying from a fewpercent to twenty percent (Artigau et al. 2009, ApJ, 701, 1534; Radigan et al. 2012, ApJ, 750,105). Recently, it was claimed that weather patterns, especially planetary-scale waves in thebelts and cloud spots, are responsible for the light curves and their evolutions on brown dwarfs(Apai et al. 2017, Science, 357, 683). Here we present a clear relationship between the direct IRemission maps and light curves of Jupiter at multiple wavelengths, which might be similar withthat on cold brown dwarfs. Based on infrared disk maps from Subaru/COMICS and VLT/VISIR,we constructed full maps of Jupiter and rotational light curves at different wavelengths in thethermal infrared. We discovered a strong relationship between the light curves and weatherpatterns on Jupiter. The light curves also exhibit strong multi-bands phase shifts and temporalvariations, similar to that detected on brown dwarfs. Together with the spectra fromTEXES/IRTF, our observations further provide detailed information of the spatial variations oftemperature, ammonia clouds and aerosols in the troposphere of Jupiter (Fletcher et al. 2016,Icarus, 2016 128) and their influences on the shapes of the light curves. We conclude that waveactivities in Jupiter’s belts (Fletcher et al. 2017, GRL, 44, 7140), cloud holes, and long-livedvortices such as the Great Red Spot and ovals control the shapes of IR light curves and multi-wavelength phase shifts on Jupiter. Our finding supports the hypothesis that observed lightcurves on brown dwarfs are induced by planetary-scale waves and cloud spots.

  18. LIMITS ON OPTICAL POLARIZATION DURING THE PROMPT PHASE OF GRB 140430A

    Energy Technology Data Exchange (ETDEWEB)

    Kopac, D.; Mundell, C. G.; Arnold, D. M.; Steele, I. A.; Kobayashi, S.; Lamb, G. P.; Smith, R. J.; Virgili, F. J. [Astrophysics Research Institute, Liverpool John Moores University, 146 Brownlow Hill, Liverpool, L3 5RF (United Kingdom); Japelj, J.; Gomboc, A. [Department of Physics, Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000 Ljubljana (Slovenia); Guidorzi, C.; Dichiara, S. [Department of Physics and Earth Sciences, University of Ferrara, via Saragat 1, I-44122, Ferrara (Italy); Harrison, R. M. [Department of Astrophysics, School of Physics and Astronomy, Tel Aviv University, 69978 Tel Aviv (Israel); Melandri, A. [INAF—Osservatorio Astronomico di Brera, via E. Bianchi 46, I-23807 Merate (Italy); Castro-Tirado, A. J.; Gorosabel, J.; Sánchez-Ramírez, R.; Oates, S. R. [Instituto de Astrofísica de Andalucía (IAA-CSIC), Glorieta de la Astronomia s/n, E-18008 Granada (Spain); Järvinen, A. [AIP—Leibniz-Institut für Astrophysik Potsdam, An der Sternwarte 16, D-14482 Potsdam (Germany); Jelínek, M., E-mail: drejc.kopac@fmf.uni-lj.si [ASU-CAS—Astronomical Institute of the Czech Academy of Sciences, Fričova 298, 251 65 Ondřejov (Czech Republic)

    2015-11-01

    Gamma-ray burst GRB 140430A was detected by the Swift satellite and observed promptly with the imaging polarimeter RINGO3 mounted on the Liverpool Telescope, with observations beginning while the prompt γ-ray emission was still ongoing. In this paper, we present densely sampled (10-s temporal resolution) early optical light curves (LCs) in 3 optical bands and limits to the degree of optical polarization. We compare optical, X-ray, and gamma-ray properties and present an analysis of the optical emission during a period of high-energy flaring. The complex optical LC cannot be explained merely with a combination of forward and reverse shock emission from a standard external shock, implying additional contribution of emission from internal shock dissipation. We estimate an upper limit for time averaged optical polarization during the prompt phase to be as low as P < 12% (1σ). This suggests that the optical flares and early afterglow emission in this GRB are not highly polarized. Alternatively, time averaging could mask the presence of otherwise polarized components of distinct origin at different polarization position angles.

  19. A Neutron Star Binary Merger Model for GW170817/GRB 170817A/SSS17a

    Energy Technology Data Exchange (ETDEWEB)

    Murguia-Berthier, A.; Ramirez-Ruiz, E.; Kilpatrick, C. D.; Foley, R. J.; Coulter, D. A.; Pan, Y.-C.; Prochaska, J. X.; Rojas-Bravo, C.; Siebert, M. R. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Kasen, D. [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Lee, W. H. [Instituto de Astronomía, Universidad Nacional Autónoma de México, Circuito Exterior, C.U., A. Postal 70-264, 04510 Cd. de México, México (Mexico); Piro, A. L.; Drout, M. R.; Madore, B. F.; Shappee, B. J.; Simon, J. D. [The Observatories of the Carnegie Institution for Science, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Rest, A. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)

    2017-10-20

    The merging neutron star gravitational-wave event GW170817 has been observed throughout the entire electromagnetic spectrum from radio waves to γ -rays. The resulting energetics, variability, and light curves are shown to be consistent with GW170817 originating from the merger of two neutron stars, in all likelihood followed by the prompt gravitational collapse of the massive remnant. The available γ -ray, X-ray, and radio data provide a clear probe for the nature of the relativistic ejecta and the non-thermal processes occurring within, while the ultraviolet, optical, and infrared emission are shown to probe material torn during the merger and subsequently heated by the decay of freshly synthesized r -process material. The simplest hypothesis, that the non-thermal emission is due to a low-luminosity short γ -ray burst (sGRB), seems to agree with the present data. While low-luminosity sGRBs might be common, we show here that the collective prompt and multi-wavelength observations are also consistent with a typical, powerful sGRB seen off-axis. Detailed follow-up observations are thus essential before we can place stringent constraints on the nature of the relativistic ejecta in GW170817.

  20. LIMITS ON OPTICAL POLARIZATION DURING THE PROMPT PHASE OF GRB 140430A

    International Nuclear Information System (INIS)

    Kopac, D.; Mundell, C. G.; Arnold, D. M.; Steele, I. A.; Kobayashi, S.; Lamb, G. P.; Smith, R. J.; Virgili, F. J.; Japelj, J.; Gomboc, A.; Guidorzi, C.; Dichiara, S.; Harrison, R. M.; Melandri, A.; Castro-Tirado, A. J.; Gorosabel, J.; Sánchez-Ramírez, R.; Oates, S. R.; Järvinen, A.; Jelínek, M.

    2015-01-01

    Gamma-ray burst GRB 140430A was detected by the Swift satellite and observed promptly with the imaging polarimeter RINGO3 mounted on the Liverpool Telescope, with observations beginning while the prompt γ-ray emission was still ongoing. In this paper, we present densely sampled (10-s temporal resolution) early optical light curves (LCs) in 3 optical bands and limits to the degree of optical polarization. We compare optical, X-ray, and gamma-ray properties and present an analysis of the optical emission during a period of high-energy flaring. The complex optical LC cannot be explained merely with a combination of forward and reverse shock emission from a standard external shock, implying additional contribution of emission from internal shock dissipation. We estimate an upper limit for time averaged optical polarization during the prompt phase to be as low as P < 12% (1σ). This suggests that the optical flares and early afterglow emission in this GRB are not highly polarized. Alternatively, time averaging could mask the presence of otherwise polarized components of distinct origin at different polarization position angles

  1. GRB 110530A: Peculiar Broad Bump and Delayed Plateau in Early Optical Afterglows

    Science.gov (United States)

    Zhong, Shu-Qing; Xin, Li-Ping; Liang, En-Wei; Wei, Jian-Yan; Urata, Yuji; Huang, Kui-Yun; Qiu, Yu-Lei; Deng, Can-Min; Wang, Yuan-Zhu; Deng, Jin-Song

    2016-11-01

    We report our very early optical observations of GRB 110530A and investigate its jet properties together with its X-ray afterglow data. A peculiar broad onset bump followed by a plateau is observed in its early R band afterglow light curve. The optical data in the other bands and the X-ray data are well consistent with the temporal feature of the R band light curve. Our joint spectral fits of the optical and X-ray data show that they are in the same regime, with a photon index of ∼1.70. The optical and X-ray afterglow light curves are well fitted with the standard external shock model by considering a delayed energy injection component. Based on our modeling results, we find that the radiative efficiency of the gamma-ray burst jet is ∼ 1 % and the magnetization parameter of the afterglow jet is \\lt 0.04 with a derived extremely low {ε }B (the ratio of shock energy to the magnetic field) of (1.64+/- 0.25)× {10}-6. These results indicate that the jet may be matter dominated. A discussion on delayed energy injection from the accretion of the late fall-back material of its pre-supernova star is also presented.

  2. GRB 081029: A Gamma-Ray Burst with a Multi-Component Afterglow

    Science.gov (United States)

    Holland, Stephen T.; DePasquale, Massimiliano; Mao, Jirong; Sakamoto, Taka; Shady, Patricia; Covino, Stefano; Yi-Zhong, Fan; Zhi-Ping, Jin; D'Avanzo, Paolo; Antonelli, Angelo; hide

    2011-01-01

    We present an analysis of the unusual optical light curve of the gamma-ray burst GRB 081029, a long-soft burst with a redshift of z = 3.8479. We combine X-ray and optical observations from the Swift X-Ray Telescope and the Swift UltraViolet Optical Telescope with ground-based optical and infrared data obtained using the REM and ROTSE telescopes to construct a detailed data set extending from 86 s to approx. 100000 s after the BAT trigger. Our data cover a wide energy range, from 10 keV to 0.77 eV (1.24 A to 16000 A). The X-ray afterglow shows a shallow initial decay followed by a rapid decay starting at about 18000 s. The optical and infrared afterglow, however, shows an uncharacteristic rise at about 5000 s that does not correspond to any feature in the X-ray light curve. Our data are not consistent with synchrotron radiation from a jet interacting with an external medium, a two-component jet, or continuous energy injection from the central engine. We find that the the optical light curves can be broadly explained by a collision between two ejecta shells within a two-component jet. A growing number of gamma-ray burst afterglows are consistent with complex jets, which suggests that some (or all) gamma-ray burst jets are complex and will require detailed modelling to fully understand them.

  3. A GRB and Broad-lined Type Ic Supernova from a Single Central Engine

    Science.gov (United States)

    Barnes, Jennifer; Duffell, Paul C.; Liu, Yuqian; Modjaz, Maryam; Bianco, Federica B.; Kasen, Daniel; MacFadyen, Andrew I.

    2018-06-01

    Unusually high velocities (≳0.1c) and correspondingly high kinetic energies have been observed in a subset of Type Ic supernovae (so-called “broad-lined Ic” supernovae; SNe Ic-BL), prompting a search for a central engine model capable of generating such energetic explosions. A clue to the explosion mechanism may lie in the fact that all supernovae that accompany long-duration gamma-ray bursts (GRBs) belong to the SN Ic-BL class. Using a combination of two-dimensional relativistic hydrodynamics and radiation transport calculations, we demonstrate that the central engine responsible for long GRBs can also trigger an SN Ic-BL. We find that a reasonable GRB engine injected into a stripped Wolf–Rayet progenitor produces a relativistic jet with energy ∼1051 erg, as well as an SN whose synthetic light curves and spectra are fully consistent with observed SNe Ic-BL during the photospheric phase. As a result of the jet’s asymmetric energy injection, the SN spectra and light curves depend on viewing angle. The impact of viewing angle on the spectrum is particularly pronounced at early times, while the viewing-angle dependence for the light curves (∼10% variation in bolometric luminosity) persists throughout the photospheric phase.

  4. GRB 081029: A GAMMA-RAY BURST WITH A MULTI-COMPONENT AFTERGLOW

    Energy Technology Data Exchange (ETDEWEB)

    Holland, Stephen T.; Sakamoto, Takanori [Astrophysics Science Division, Code 660.1, 8800 Greenbelt Road, Goddard Space Flight Centre, Greenbelt, MD 20771 (United States); De Pasquale, Massimiliano; Schady, Patricia [Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking RH5 6NT (United Kingdom); Mao, Jirong; Covino, Stefano; Jin, Zhi-Ping; D' Avanzo, Paolo; Chincarini, Guido [INAF-Osservatorio Astronomico di Brera, Via Emilio Bianchi 46, I-23807 Merate (Saint Lucia) (Italy); Fan, Yi-Zhong [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China); Antonelli, Angelo; D' Elia, Valerio; Fiore, Fabrizio [INAF-Osservatorio Astronomico di Roma, Via de Frascati 33, I-00040 Monteporzio Catone (Roma) (Italy); Pandey, Shashi Bhushan [Randall Laboratory of Physics, University of Michigan, 450 Church St, Ann Arbor, MI 48109-1040 (United States); Cobb, Bethany E., E-mail: Stephen.T.Holland@nasa.gov [Department of Physics, The George Washington University, 725 21st St NW, Washington, DC 20052 (United States)

    2012-01-20

    We present an analysis of the unusual optical light curve of the gamma-ray burst GRB 081029, a long-soft burst with a redshift of z = 3.8479. We combine X-ray and optical observations from the Swift X-Ray Telescope and the Swift UltraViolet/Optical Telescope with ground-based optical and infrared data obtained using the REM, ROTSE, and CTIO 1.3 m telescopes to construct a detailed data set extending from 86 s to {approx}100000 s after the BAT trigger. Our data cover a wide energy range from 10 keV to 0.77 eV (1.24 A-16000 A). The X-ray afterglow shows a shallow initial decay followed by a rapid decay starting at about 18000 s. The optical and infrared afterglow, however, shows an uncharacteristic rise at about 3000 s that does not correspond to any feature in the X-ray light curve. Our data are not consistent with synchrotron radiation from a jet interacting with an external medium, a two-component jet, or continuous energy injection from the central engine. We find that the optical light curves can be broadly explained by a collision between two ejecta shells within a two-component jet. A growing number of gamma-ray-burst afterglows are consistent with complex jets, which suggests that some (or all) gamma-ray-burst jets are complex and will require detailed modeling to fully understand them.

  5. Wavefronts, light rays and caustic of a circular wave reflected by an arbitrary smooth curve

    International Nuclear Information System (INIS)

    Marciano-Melchor, Magdalena; Silva-Ortigoza, Ramón; Montiel-Piña, Enrique; Román-Hernández, Edwin; Santiago-Santiago, José Guadalupe; Silva-Ortigoza, Gilberto; Rosado, Alfonso; Suárez-Xique, Román

    2011-01-01

    The aim of the present work is to obtain expressions for both the wavefront train and the caustic associated with the light rays reflected by an arbitrary smooth curve after being emitted by a point light source located at an arbitrary position in the two-dimensional free space. To this end, we obtain an expression for the k-function associated with the general integral of Stavroudis to the eikonal equation that describes the evolution of the reflected light rays. The caustic is computed by using the definitions of the critical and caustic sets of the two-dimensional map that describes the evolution of an arbitrary wavefront associated with the general integral. The general results are applied to circular and parabolic mirrors. The main motivation to carry out this research is to establish, in future work, the caustic touching theorem in a two-dimensional optical medium and to study the diffraction problem by using the k-function concept. Both problems are important in the computation of the image of an arbitrary object under reflection and refraction

  6. GLOBAL MAPPING OF EARTH-LIKE EXOPLANETS FROM SCATTERED LIGHT CURVES

    International Nuclear Information System (INIS)

    Kawahara, Hajime; Fujii, Yuka

    2010-01-01

    Scattered lights from terrestrial exoplanets provide valuable information about their planetary surface. Applying the surface reconstruction method proposed by Fujii et al. to both diurnal and annual variations of scattered light, we develop a reconstruction method of land distribution with both longitudinal and latitudinal resolutions. We find that one can recover a global map of an idealized Earth-like planet on the following assumptions: (1) cloudlessness, (2) a face-on circular orbit, (3) known surface types and their reflectance spectra, (4) lack of atmospheric absorption, (5) known rotation rate, (6) a static map, and (7) the absence of a moon. Using the dependence of light curves on planetary obliquity, we also show that the obliquity can be measured by adopting the χ 2 minimization or the extended information criterion. We demonstrate the feasibility of our methodology by applying it to a multi-band photometry of a cloudless model Earth with future space missions such as the occulting ozone observatory (O3). We conclude that future space missions can estimate both the surface distribution and the obliquity at least for cloudless Earth-like planets within 5 pc.

  7. GRB 030227: The first multiwavelength afterglow of an INTEGRAL GRB

    DEFF Research Database (Denmark)

    Castro-Tirado, A.J.; Gorosabel, J.; Guziy, S.

    2003-01-01

    We present multiwavelength observations of a gamma-ray burst detected by INTEGRAL (GRB 030227) between 5.3 hours and similar to1.7 days after the event. Here we report the discovery of a dim optical afterglow (OA) that would not have been detected by many previous searches due to its faintess (R ...

  8. Grb7 binds to Hax-1 and undergoes an intramolecular domain association that offers a model for Grb7 regulation

    OpenAIRE

    Siamakpour-Reihani, Sharareh; Peterson, Tabitha A.; Bradford, Andrew M.; Argiros, Haroula J.; Haas, Laura Lowell; Lor, Siamee N.; Haulsee, Zachary M.; Spuches, Anne M.; Johnson, Dennis L.; Rohrschneider, Larry R.; Shuster, Charles Brad; Lyons, Barbara A.

    2011-01-01

    Adaptor proteins mediate signal transduction from cell surface receptors to downstream signaling pathways. The Grb7 protein family of adaptor proteins is constituted by Grb7, Grb10, and Grb14. This protein family has been shown to be overexpressed in certain cancers and cancer cell lines. Grb7-mediated cell migration has been shown to proceed through a focal adhesion kinase (FAK)/Grb7 pathway, although the specific participants downstream of Grb7 in cell migration signaling have not been full...

  9. The EB factory project. I. A fast, neural-net-based, general purpose light curve classifier optimized for eclipsing binaries

    International Nuclear Information System (INIS)

    Paegert, Martin; Stassun, Keivan G.; Burger, Dan M.

    2014-01-01

    We describe a new neural-net-based light curve classifier and provide it with documentation as a ready-to-use tool for the community. While optimized for identification and classification of eclipsing binary stars, the classifier is general purpose, and has been developed for speed in the context of upcoming massive surveys such as the Large Synoptic Survey Telescope. A challenge for classifiers in the context of neural-net training and massive data sets is to minimize the number of parameters required to describe each light curve. We show that a simple and fast geometric representation that encodes the overall light curve shape, together with a chi-square parameter to capture higher-order morphology information results in efficient yet robust light curve classification, especially for eclipsing binaries. Testing the classifier on the ASAS light curve database, we achieve a retrieval rate of 98% and a false-positive rate of 2% for eclipsing binaries. We achieve similarly high retrieval rates for most other periodic variable-star classes, including RR Lyrae, Mira, and delta Scuti. However, the classifier currently has difficulty discriminating between different sub-classes of eclipsing binaries, and suffers a relatively low (∼60%) retrieval rate for multi-mode delta Cepheid stars. We find that it is imperative to train the classifier's neural network with exemplars that include the full range of light curve quality to which the classifier will be expected to perform; the classifier performs well on noisy light curves only when trained with noisy exemplars. The classifier source code, ancillary programs, a trained neural net, and a guide for use, are provided.

  10. Observations and light curve solutions of four ultrashort-period binaries

    Directory of Open Access Journals (Sweden)

    Kjurkchieva D.

    2016-01-01

    Full Text Available The paper presents light curve solutions of our observations of four new ultrashort-period eclipsing binaries with MS components. Two of them have periods almost at the upper limit (0.22 days of the ultrashort-period binaries, while the periods of around 0.18 days of CSS J171508.5+350658 and CSS J214633.8+120016 are amongst the shortest known orbital periods. CSS J171410.0+ 445850, CSS J214633.8+120016 and CSS J224326.0+154532 are over contact binaries with fill out factors around 0.25 while CSS J171508.5+350658 is a semidetached system. The two targets with shortest periods consist of M dwarfs.

  11. QUEST1 Variability Survey. II. Variability Determination Criteria and 200k Light Curve Catalog

    Science.gov (United States)

    Rengstorf, A. W.; Mufson, S. L.; Andrews, P.; Honeycutt, R. K.; Vivas, A. K.; Abad, C.; Adams, B.; Bailyn, C.; Baltay, C.; Bongiovanni, A.; Briceño, C.; Bruzual, G.; Coppi, P.; Della Prugna, F.; Emmet, W.; Ferrín, I.; Fuenmayor, F.; Gebhard, M.; Hernández, J.; Magris, G.; Musser, J.; Naranjo, O.; Oemler, A.; Rosenzweig, P.; Sabbey, C. N.; Sánchez, Ge.; Sánchez, Gu.; Schaefer, B.; Schenner, H.; Sinnott, J.; Snyder, J. A.; Sofia, S.; Stock, J.; van Altena, W.

    2004-12-01

    The QUEST (QUasar Equatorial Survey Team) Phase 1 camera has collected multibandpass photometry on a large strip of high Galactic latitude sky over a period of 26 months. This robust data set has been reduced and nightly catalogs compared to determine the photometric variability of the ensemble objects. Subsequent spectroscopic observations have confirmed a subset of the photometric variables as quasars, as previously reported. This paper reports on the details of the data reduction and analysis pipeline and presents multiple bandpass light curves for 198,213 QUEST1 objects, along with global variability information and matched Sloan photometry. Based on observations obtained at the Llano del Hato National Astronomical Observatory, operated by the Centro de Investigaciones de Astronomía for the Ministerio de Ciencia y Tecnologia of Venezuela.

  12. Light-Curve Modelling Constraints on the Obliquities and Aspect Angles of the Young Fermi Pulsars

    Science.gov (United States)

    Pierbattista, M.; Harding, A. K.; Grenier, I. A.; Johnson, T. J.; Caraveo, P. A.; Kerr, M.; Gonthier, P. L.

    2015-01-01

    In more than four years of observation the Large Area Telescope on board the Fermi satellite has identified pulsed gamma-ray emission from more than 80 young or middle-aged pulsars, in most cases providing light curves with high statistics. Fitting the observed profiles with geometrical models can provide estimates of the magnetic obliquity alpha and of the line of sight angle zeta, yielding estimates of the radiation beaming factor and radiated luminosity. Using different gamma-ray emission geometries (Polar Cap, Slot Gap, Outer Gap, One Pole Caustic) and core plus cone geometries for the radio emission, we fit gamma-ray light curves for 76 young or middle-aged pulsars and we jointly fit their gamma-ray plus radio light curves when possible. We find that a joint radio plus gamma-ray fit strategy is important to obtain (alpha, zeta) estimates that can explain simultaneously detectable radio and gamma-ray emission: when the radio emission is available, the inclusion of the radio light curve in the fit leads to important changes in the (alpha, gamma) solutions. The most pronounced changes are observed for Outer Gap and One Pole Caustic models for which the gamma-ray only fit leads to underestimated alpha or zeta when the solution is found to the left or to the right of the main alpha-zeta plane diagonal respectively. The intermediate-to-high altitude magnetosphere models, Slot Gap, Outer Gap, and One pole Caustic, are favored in explaining the observations. We find no apparent evolution of a on a time scale of 106 years. For all emission geometries our derived gamma-ray beaming factors are generally less than one and do not significantly evolve with the spin-down power. A more pronounced beaming factor vs. spin-down power correlation is observed for Slot Gap model and radio-quiet pulsars and for the Outer Gap model and radio-loud pulsars. The beaming factor distributions exhibit a large dispersion that is less pronounced for the Slot Gap case and that decreases from

  13. CHANDRA OBSERVATIONS OF SN 1987A: THE SOFT X-RAY LIGHT CURVE REVISITED

    Energy Technology Data Exchange (ETDEWEB)

    Helder, E. A.; Broos, P. S.; Burrows, D. N. [Department of Astronomy and Astrophysics, The Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802 (United States); Dewey, D. [MIT Kavli Institute, Cambridge, MA 02139 (United States); Dwek, E. [Observational Cosmology Laboratory, Code 665, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); McCray, R. [JILA, University of Colorado and NIST, 440 UCB, Boulder, CO 80309 (United States); Park, S. [Department of Physics, University of Texas at Arlington, Box 19059, Arlington, TX 76019 (United States); Racusin, J. L. [NASA, Goddard Space Flight Center, Code 661, Greenbelt, MD 20771 (United States); Zhekov, S. A. [Space Research and Technology Institute, Akad. G. Bonchev str., bl.1, Sofia 1113 (Bulgaria)

    2013-02-10

    We report on the present stage of SN 1987A as observed by the Chandra X-Ray Observatory. We reanalyze published Chandra observations and add three more epochs of Chandra data to get a consistent picture of the evolution of the X-ray fluxes in several energy bands. We discuss the implications of several calibration issues for Chandra data. Using the most recent Chandra calibration files, we find that the 0.5-2.0 keV band fluxes of SN 1987A have increased by {approx}6 Multiplication-Sign 10{sup -13} erg s{sup -1} cm{sup -2} per year since 2009. This is in contrast with our previous result that the 0.5-2.0 keV light curve showed a sudden flattening in 2009. Based on our new analysis, we conclude that the forward shock is still in full interaction with the equatorial ring.

  14. Finite source sizes and the information content of macho-type lens search light curves

    Science.gov (United States)

    Nemiroff, Robert J.; Wickramasinghe, W. A. D. T.

    1994-01-01

    If the dark halo matter is primarily composed of Massive Compact Halo Objects (MACHOs) toward the lower end of the possible detection range (less than 10(exp -3) solar mass) a fraction of the lens detection events should involve the lens crossing directly in front of the disk of the background star. Previously, Nemiroff has shown that each crossing would create an inflection point in the light curve of the MACHO event. Such inflection points would allow a measure of the time it took for the lens to cross the stellar disk. Given an independent estimate of the stellar radius by other methods, one could then obtain a more accurate estimate of the velocity of the lens. This velocity could then, in turn, be used to obtain a more accurate estimate of the mass range for the MACHO or disk star doing the lensing.

  15. Ultraviolet Light Curves of Gaia16apd in Superluminous Supernova Models

    Energy Technology Data Exchange (ETDEWEB)

    Tolstov, Alexey; Zhiglo, Andrey; Nomoto, Ken’ichi; Blinnikov, Sergei [Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo Institutes for Advanced Study, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583 (Japan); Sorokina, Elena [Sternberg Astronomical Institute, M.V.Lomonosov Moscow State University, 119234 Moscow (Russian Federation); Kozyreva, Alexandra, E-mail: alexey.tolstov@ipmu.jp [The Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978 (Israel)

    2017-08-10

    Observations of Gaia16apd revealed extremely luminous ultraviolet emission among superluminous supernovae (SLSNe). Using radiation hydrodynamics simulations, we perform a comparison of UV light curves, color temperatures, and photospheric velocities between the most popular SLSN models: pair-instability supernova, magnetar, and interaction with circumstellar medium. We find that the interaction model is the most promising to explain the extreme UV luminosity of Gaia16apd. The differences in late-time UV emission and in color evolution found between the models can be used to link an observed SLSN event to the most appropriate model. Observations at UV wavelengths can be used to clarify the nature of SLSNe and more attention should be paid to them in future follow-up observations.

  16. A posteriori noise estimation in variable data sets. With applications to spectra and light curves

    Science.gov (United States)

    Czesla, S.; Molle, T.; Schmitt, J. H. M. M.

    2018-01-01

    Most physical data sets contain a stochastic contribution produced by measurement noise or other random sources along with the signal. Usually, neither the signal nor the noise are accurately known prior to the measurement so that both have to be estimated a posteriori. We have studied a procedure to estimate the standard deviation of the stochastic contribution assuming normality and independence, requiring a sufficiently well-sampled data set to yield reliable results. This procedure is based on estimating the standard deviation in a sample of weighted sums of arbitrarily sampled data points and is identical to the so-called DER_SNR algorithm for specific parameter settings. To demonstrate the applicability of our procedure, we present applications to synthetic data, high-resolution spectra, and a large sample of space-based light curves and, finally, give guidelines to apply the procedure in situation not explicitly considered here to promote its adoption in data analysis.

  17. An information preserving method for producing full coverage CoRoT light curves

    Directory of Open Access Journals (Sweden)

    Pascual-Granado J.

    2015-01-01

    Full Text Available Invalid flux measurements, caused mainly by the South Atlantic Anomaly crossing of the CoRoT satellite, introduce aliases in the periodogram and wrong amplitudes. It has been demonstrated that replacing such invalid data with a linear interpolation is not harmless. On the other side, using power spectrum estimators for unevenly sampled time series is not only less computationally efficient but it leads to difficulties in the interpretation of the results. Therefore, even when the gaps are rather small and the duty cycle is high enough the use of gap-filling methods is a gain in frequency analysis. However, the method must preserve the information contained in the time series. In this work we give a short description of an information preserving method (MIARMA and show some results when applying it to CoRoT seismo light curves. The method is implemented as the second step of a pipeline for CoRoT data analysis.

  18. Spectral analysis of stellar light curves by means of neural networks

    Science.gov (United States)

    Tagliaferri, R.; Ciaramella, A.; Milano, L.; Barone, F.; Longo, G.

    1999-06-01

    Periodicity analysis of unevenly collected data is a relevant issue in several scientific fields. In astrophysics, for example, we have to find the fundamental period of light or radial velocity curves which are unevenly sampled observations of stars. Classical spectral analysis methods are unsatisfactory to solve the problem. In this paper we present a neural network based estimator system which performs well the frequency extraction in unevenly sampled signals. It uses an unsupervised Hebbian nonlinear neural algorithm to extract, from the interpolated signal, the principal components which, in turn, are used by the MUSIC frequency estimator algorithm to extract the frequencies. The neural network is tolerant to noise and works well also with few points in the sequence. We benchmark the system on synthetic and real signals with the Periodogram and with the Cramer-Rao lower bound. This work was been partially supported by IIASS, by MURST 40\\% and by the Italian Space Agency.

  19. A Study of Precataclysmic Binaries Through Theoretic Modeling of Light Curves and Spectra

    Science.gov (United States)

    Mitrofanova, A. A.; Shimansky, V. V.; Borisov, N. V.

    2017-06-01

    The article presents results of three pre-cataclysmic binaries (PN G068.1+11.0, TW Crv and RE J2013+4002) investigation. Spectroscopic and photometric observations were obtained on BTA and Zeiss-1000 of SAO RAS and on RTT-150. We used the modeling of light curves and spectra to determine the fundamental parameters for all three systems. The PN G068.1+11.0 parameters were obtained with the use of the evolutionary tracks for the nuclei of planetary nebulae of different masses. According to the results of the study, it was found that the secondary components of PN G068.1+11.0 and TW Crv have luminosity excess, but secondary component of RE J2013+4002 doesn't have one.

  20. Periods and light curves of 16 Cepheid variables in IC 1613 not completed by Baade

    International Nuclear Information System (INIS)

    Carlson, G.; Sandage, A.

    1990-01-01

    New periods and light curves are presented for 16 of the faintest Cepheids in IC 1613 which had not been finished by Baade. Magnitudes have been reduced to Freedman's new photometric scale. The P-L relation is extended to periods of 2 days using these new data. Comparison of the total Cepheid data now available in IC 1613 with the data in LMC shows no significant slope difference in the two P-L relations for periods of less than 10 days despite the lower metallicity of the young stars in IC 1613. Fifty new faint Cepheid candidates have been found in IC 1613 by blinking plates not used for this purpose by Baade. Most of these stars will have probable periods of less than 2 days, which will eventually permit an extension of the P-L relation in IC 1613 to fainter magnitudes when the photometry and period determinations are completed. 18 refs

  1. TYPE Ia SUPERNOVA LIGHT CURVE INFERENCE: HIERARCHICAL MODELS IN THE OPTICAL AND NEAR-INFRARED

    International Nuclear Information System (INIS)

    Mandel, Kaisey S.; Narayan, Gautham; Kirshner, Robert P.

    2011-01-01

    We have constructed a comprehensive statistical model for Type Ia supernova (SN Ia) light curves spanning optical through near-infrared (NIR) data. A hierarchical framework coherently models multiple random and uncertain effects, including intrinsic supernova (SN) light curve covariances, dust extinction and reddening, and distances. An improved BAYESN Markov Chain Monte Carlo code computes probabilistic inferences for the hierarchical model by sampling the global probability density of parameters describing individual SNe and the population. We have applied this hierarchical model to optical and NIR data of 127 SNe Ia from PAIRITEL, CfA3, Carnegie Supernova Project, and the literature. We find an apparent population correlation between the host galaxy extinction A V and the ratio of total-to-selective dust absorption R V . For SNe with low dust extinction, A V ∼ V ∼ 2.5-2.9, while at high extinctions, A V ∼> 1, low values of R V < 2 are favored. The NIR luminosities are excellent standard candles and are less sensitive to dust extinction. They exhibit low correlation with optical peak luminosities, and thus provide independent information on distances. The combination of NIR and optical data constrains the dust extinction and improves the predictive precision of individual SN Ia distances by about 60%. Using cross-validation, we estimate an rms distance modulus prediction error of 0.11 mag for SNe with optical and NIR data versus 0.15 mag for SNe with optical data alone. Continued study of SNe Ia in the NIR is important for improving their utility as precise and accurate cosmological distance indicators.

  2. Imprints of the quasar structure in time-delay light curves: Microlensing-aided reverberation mapping

    Science.gov (United States)

    Sluse, D.; Tewes, M.

    2014-11-01

    The advent of large area photometric surveys has raised a great deal of interest in the possibility of using broadband photometric data, instead of spectra, to measure the size of the broad line region of active galactic nuclei. We describe here a new method that uses time-delay lensed quasars where one or several images are affected by microlensing due to stars in the lensing galaxy. Because microlensing decreases (or increases) the flux of the continuum compared to the broad line region, it changes the contrast between these two emission components. We show that this effect can be used to effectively disentangle the intrinsic variability of those two regions, offering the opportunity to perform reverberation mapping based on single-band photometric data. Based on simulated light curves generated using a damped random walk model of quasar variability, we show that measurement of the size of the broad line region can be achieved using this method, provided one spectrum has been obtained independently during the monitoring. This method is complementary to photometric reverberation mapping and could also be extended to multi-band data. Because the effect described above produces a variability pattern in difference light curves between pairs of lensed images that is correlated with the time-lagged continuum variability, it can potentially produce systematic errors in measurement of time delays between pairs of lensed images. Simple simulations indicate that time-delay measurement techniques that use a sufficiently flexible model for the extrinsic variability are not affected by this effect and produce accurate time delays.

  3. Transit Timing Variation analysis with Kepler light curves of KOI 227 and Kepler 93b

    Science.gov (United States)

    Dulz, Shannon; Reed, Mike

    2017-01-01

    By searching for transit signals in approximately 150,000 stars, NASA’s Kepler Space telescope found thousands of exoplanets over its primary mission from 2009 to 2013 (Tenenbaum et al. 2014, ApJS, 211, 6). Yet, a detailed follow-up examination of Kepler light curves may contribute more evidence on system dynamics and planetary atmospheres of these objects. Kepler’s continuous observing of these systems over the mission duration produced light curves of sufficient duration to allow for the search for transit timing variations. Transit timing variations over the course of many orbits may indicate a precessing orbit or the existence of a non-transiting third body such as another exoplanet. Flux contributions of the planet just prior to secondary eclipse may provide a measurement of bond albedo from the day-side of the transiting planet. Any asymmetries of the transit shape may indicate thermal asymmetries which can measure upper atmosphere motion of the planet. These two factors can constrain atmospheric models of close orbiting exoplanets. We first establish our procedure with the well-documented TTV system, KOI 227 (Nesvorny et al. 2014, ApJ, 790, 31). Using the test case of KOI 227, we analyze Kepler-93b for TTVs and day-side flux contributions. Kepler-93b is likely a rocky planet with R = 1.50 ± 0.03 Earth Radii and M = 2.59 ± 2.0 Earth Masses (Marcy et al. 2014, ApJS, 210, 20). This research is funded by a NASA EPSCoR grant.

  4. REVISITING EVIDENCE OF CHAOS IN X-RAY LIGHT CURVES: THE CASE OF GRS 1915+105

    Energy Technology Data Exchange (ETDEWEB)

    Mannattil, Manu; Gupta, Himanshu; Chakraborty, Sagar, E-mail: mmanu@iitk.ac.in, E-mail: hiugupta@iitk.ac.in, E-mail: sagarc@iitk.ac.in [Department of Physics, Indian Institute of Technology Kanpur, Uttar Pradesh 208016 (India)

    2016-12-20

    Nonlinear time series analysis has been widely used to search for signatures of low-dimensional chaos in light curves emanating from astrophysical bodies. A particularly popular example is the microquasar GRS 1915+105, whose irregular but systematic X-ray variability has been well studied using data acquired by the Rossi X-ray Timing Explorer . With a view to building simpler models of X-ray variability, attempts have been made to classify the light curves of GRS 1915+105 as chaotic or stochastic. Contrary to some of the earlier suggestions, after careful analysis, we find no evidence for chaos or determinism in any of the GRS 1915+105 classes. The dearth of long and stationary data sets representing all the different variability classes of GRS 1915+105 makes it a poor candidate for analysis using nonlinear time series techniques. We conclude that either very exhaustive data analysis with sufficiently long and stationary light curves should be performed, keeping all the pitfalls of nonlinear time series analysis in mind, or alternative schemes of classifying the light curves should be adopted. The generic limitations of the techniques that we point out in the context of GRS 1915+105 affect all similar investigations of light curves from other astrophysical sources.

  5. Photometric light curves for seven rapidly-rotating K dwarfs in the Pleiades and Alpha Persei clusters

    Science.gov (United States)

    Stauffer, John R.; Schild, Rudolph A.; Baliunas, Sallie L.; Africano, John L.

    1987-01-01

    Light curves and period estimates were obtained for several Pleiades and Alpha Persei cluster K dwarfs which were identified as rapid rotators in earlier spectroscopic studies. A few of the stars have previously-published light curves, making it possible to study the long-term variability of the light-curve shapes. The general cause of the photometric variability observed for these stars is an asymmetric distribution of photospheric inhomogeneities (starspots). The presence of these inhomogeneities combined with the rotation of the star lead to the light curves observed. The photometric periods derived are thus identified with the rotation period of the star, making it possible to estimate equatorial rotational velocities for these K dwarfs. These data are of particular importance because the clusters are sufficiently young that stars of this mass should have just arrived on the main sequence. These data could be used to estimate the temperatures and sizes of the spot groups necessary to produce the observed light curves for these stars.

  6. Type Ia Supernova Light Curve Inference: Hierarchical Models for Nearby SN Ia in the Optical and Near Infrared

    Science.gov (United States)

    Mandel, Kaisey; Kirshner, R. P.; Narayan, G.; Wood-Vasey, W. M.; Friedman, A. S.; Hicken, M.

    2010-01-01

    I have constructed a comprehensive statistical model for Type Ia supernova light curves spanning optical through near infrared data simultaneously. The near infrared light curves are found to be excellent standard candles (sigma(MH) = 0.11 +/- 0.03 mag) that are less vulnerable to systematic error from dust extinction, a major confounding factor for cosmological studies. A hierarchical statistical framework incorporates coherently multiple sources of randomness and uncertainty, including photometric error, intrinsic supernova light curve variations and correlations, dust extinction and reddening, peculiar velocity dispersion and distances, for probabilistic inference with Type Ia SN light curves. Inferences are drawn from the full probability density over individual supernovae and the SN Ia and dust populations, conditioned on a dataset of SN Ia light curves and redshifts. To compute probabilistic inferences with hierarchical models, I have developed BayeSN, a Markov Chain Monte Carlo algorithm based on Gibbs sampling. This code explores and samples the global probability density of parameters describing individual supernovae and the population. I have applied this hierarchical model to optical and near infrared data of over 100 nearby Type Ia SN from PAIRITEL, the CfA3 sample, and the literature. Using this statistical model, I find that SN with optical and NIR data have a smaller residual scatter in the Hubble diagram than SN with only optical data. The continued study of Type Ia SN in the near infrared will be important for improving their utility as precise and accurate cosmological distance indicators.

  7. GRB 071112C: A CASE STUDY OF DIFFERENT MECHANISMS IN X-RAY AND OPTICAL TEMPORAL EVOLUTION

    Energy Technology Data Exchange (ETDEWEB)

    Huang, K. Y.; Tung, Y. H.; Lin, H. M.; Wang, S. Y.; Lehner, M. J.; Wang, J. H.; Wen, C. Y. [Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 106, Taiwan (China); Urata, Y.; Ip, W. H. [Institute of Astronomy, National Central University, Chung-Li 32054, Taiwan (China); Xin, L. P.; Qiu, Y.; Wei, J. [National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Yoshida, M. [Hiroshima Astrophysical Science Center, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Zheng, W.; Akerlof, C. [Department of Physics, University of Michigan, Ann Arbor, MI 48109 (United States); Bianco, F. B. [Department of Physics, University of California Santa Barbara, Mail Code 9530, Santa Barbara, CA 93106-9530 (United States); Kawai, N. [Department of Physics, Tokyo Institute of Technology, 2-21-1 Ookayama, Meguro-ku, Tokyo 152-8551 (Japan); Kuroda, D. [Okayama Astrophysical Observatory, National Astronomical Observatory of Japan, Kamogata, Asakuchi, Okayama 719-0232 (Japan); Marshall, S. L. [Kavli Institute for Particle Astrophysics and Cosmology, 2575 Sand Hill Road, MS 29, Menlo Park, CA 94025 (United States); Schwamb, M. E. [Department of Physics, Yale University, P.O. Box 208121, New Haven, CT 06520-8121 (United States); and others

    2012-03-20

    We present a study on GRB 071112C X-ray and optical light curves. In these two wavelength ranges, we have found different temporal properties. The R-band light curve showed an initial rise followed by a single power-law decay, while the X-ray light curve was described by a single power-law decay plus a flare-like feature. Our analysis shows that the observed temporal evolution cannot be described by the external shock model in which the X-ray and optical emission are produced by the same emission mechanism. No significant color changes in multi-band light curves and a reasonable value of the initial Lorentz factor ({Gamma}{sub 0} = 275 {+-} 20) in a uniform interstellar medium support the afterglow onset scenario as the correct interpretation for the early R band rise. The result suggests that the optical flux is dominated by afterglow. Our further investigations show that the X-ray flux could be created by an additional feature related to energy injection and X-ray afterglow. Different theoretical interpretations indicate the additional feature in X-ray can be explained by either late internal dissipation or local inverse-Compton scattering in the external shock.

  8. Periodicity Analysis of X-ray Light Curves of SS 433

    Science.gov (United States)

    Wang, Jun-yi; Lu, Xiang-long; Zhao, Qiu-wen; Dong, Dian-qiao; Lao, Bao-qiang; Lu, Yang; Wei, Yan-heng; Wu, Xiao-cong; An, Tao

    2017-01-01

    SS 433 is sofar the unique X-ray binary that has the simultaneously detected orbital period, super-orbital period, and nutation period, as well as a bidirectional spiral jet. The study on its X-ray light variability is helpful for understanding the dynamic process of the system, and the correlations between the different wavebands. In this paper, two time-series analysis techniques, i.e., the Lomb-Scargle periodogram and weighted wavelet Z-transform, are employed to search for the periods in the Swift/BAT (Burst Alert Telescope) (15-50 keV) and RXTE/ASM (Rose X-ray Timing Explorer/All Sky Monitor) (1.5-3, 3- 4, and 5-12 keV) light curves of SS 433, and the Monte Carlo simulation is performed for the obtained periodical components. For the 15-50 keV energy band, five significant periodical components are detected, which are P1(∼6.29 d), P2 (∼6.54 d), P3 (∼13.08 d), P4 (∼81.50 d), and P5 (∼162.30 d). For the 3-5 and 5-12 keV energy bands, the periodical components P3 (∼13 d) and P5 (∼162 d) are detected in both energy bands. However, for the 1.5-3 keV energy band, no significant periodic signal is detected. P5 is the strongest periodic signal in the power spectrum for all the energy bands of 3-5, 5-12, and 15-50 keV, and it is consistent with the previous result obtained from the study of optical light curves. Furthermore, in combination with the radio spiral jet of SS 433, it is suggested that the X-ray and optical variability of P5 (∼162 d) is probably related to the precession of its relativistic jet. The high correlation between the X-ray and optical light curves may also imply that the X-ray and optical radiations are of the same physical origin. P3 shows a good agreement with the orbital period (∼13.07 d) obtained by the previous study, and P2 and P4 are respectively the high-frequency harmonics of P3 and P5. P1 is detected only in the power spectrum of the 15-50 keV energy band, and it is consistent with the nutation period of the system. As

  9. f (T ) gravity after GW170817 and GRB170817A

    Science.gov (United States)

    Cai, Yi-Fu; Li, Chunlong; Saridakis, Emmanuel N.; Xue, Ling-Qin

    2018-05-01

    The combined observation of GW170817 and its electromagnetic counterpart GRB170817A reveals that gravitational waves propagate at the speed of light in high precision. We apply the standard analysis of cosmological perturbations, as well as the effective field theory approach, to investigate the experimental consequences for the theory of f (T ) gravity. Our analysis verifies for the first time that the speed of gravitational waves within f (T ) gravity is equal to the light speed, and hence, the constraints from GW170817 and GRB170817A are trivially satisfied. Nevertheless, by examining the dispersion relation and the frequency of cosmological gravitational waves, we observe a deviation from the results of general relativity, quantified by a new parameter. Although its value is relatively small in viable f (T ) models, its possible future measurement in advancing gravitational-wave astronomy would be the smoking gun of testing this type of modified gravity.

  10. THE INFRARED LIGHT CURVE OF SN 2011fe IN M101 AND THE DISTANCE TO M101

    International Nuclear Information System (INIS)

    Matheson, T.; Joyce, R. R.; Allen, L. E.; Saha, A.; Silva, D. R.; Binkert, W. S.; Butler, K.; Everett, M.; Wood-Vasey, W. M.; Adams, J. J.; Anderson, R. E.; Beck, T. L.; Bentz, M. C.; Bershady, M. A.; Eigenbrot, A.; Gallagher, J. S.; Camarata, M. A.; Garnavich, P. M.; Glikman, E.; Harbeck, D.

    2012-01-01

    We present near-infrared light curves of supernova (SN) 2011fe in M101, including 34 epochs in H band starting 14 days before maximum brightness in the B band. The light curve data were obtained with the WIYN High-Resolution Infrared Camera. When the data are calibrated using templates of other Type Ia SNe, we derive an apparent H-band magnitude at the epoch of B-band maximum of 10.85 ± 0.04. This implies a distance modulus for M101 that ranges from 28.86 to 29.17 mag, depending on which absolute calibration for Type Ia SNe is used.

  11. The Infrared Light Curve of SN 2011fe in M101 and the Distance to M101

    OpenAIRE

    Matheson, T.; Joyce, R. R.; Allen, L. E.; Saha, A.; Silva, D. R.; Wood-Vasey, W. M.; Adams, J. J.; Anderson, R. E.; Beck, T. L.; Bentz, M. C.; Bershady, M. A.; Binkert, W. S.; Butler, K.; Camarata, M. A.; Eigenbrot, A.

    2012-01-01

    We present near infra-red light curves of supernova (SN) 2011fe in M101, including 34 epochs in H band starting fourteen days before maximum brightness in the B-band. The light curve data were obtained with the WIYN High-Resolution Infrared Camera (WHIRC). When the data are calibrated using templates of other Type Ia SNe, we derive an apparent H-band magnitude at the epoch of B-band maximum of 10.85 \\pm 0.04. This implies a distance modulus for M101 that ranges from 28.86 to 29.17 mag, depend...

  12. THE INFRARED LIGHT CURVE OF SN 2011fe IN M101 AND THE DISTANCE TO M101

    Energy Technology Data Exchange (ETDEWEB)

    Matheson, T.; Joyce, R. R.; Allen, L. E.; Saha, A.; Silva, D. R.; Binkert, W. S.; Butler, K.; Everett, M. [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States); Wood-Vasey, W. M. [Pittsburgh Particle Physics, Astrophysics, and Cosmology Center (PITT-PACC), University of Pittsburgh, 3941 O' Hara Street, Pittsburgh, PA 15260 (United States); Adams, J. J. [Observatories of the Carnegie Institution of Washington, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Anderson, R. E.; Beck, T. L. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Bentz, M. C. [Department of Physics and Astronomy, Georgia State University, Astronomy Offices, One Park Place South SE, Suite 700, Atlanta, GA 30303 (United States); Bershady, M. A.; Eigenbrot, A.; Gallagher, J. S. [Department of Astronomy, University of Wisconsin-Madison, 475 North Charter Street, Madison, WI 53706 (United States); Camarata, M. A. [Department of Physics, Southern Connecticut State University, 501 Crescent Street, New Haven, CT 06515 (United States); Garnavich, P. M. [Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States); Glikman, E. [Department of Astronomy, Yale University, New Haven, CT 06511 (United States); Harbeck, D., E-mail: matheson@noao.edu [WIYN Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States); and others

    2012-07-20

    We present near-infrared light curves of supernova (SN) 2011fe in M101, including 34 epochs in H band starting 14 days before maximum brightness in the B band. The light curve data were obtained with the WIYN High-Resolution Infrared Camera. When the data are calibrated using templates of other Type Ia SNe, we derive an apparent H-band magnitude at the epoch of B-band maximum of 10.85 {+-} 0.04. This implies a distance modulus for M101 that ranges from 28.86 to 29.17 mag, depending on which absolute calibration for Type Ia SNe is used.

  13. THE XMM-NEWTON/EPIC X-RAY LIGHT CURVE ANALYSIS OF WR 6

    International Nuclear Information System (INIS)

    Ignace, R.; Gayley, K. G.; Hamann, W.-R.; Oskinova, L. M.; Huenemoerder, D. P.; Pollock, A. M. T.; McFall, M.

    2013-01-01

    We obtained four pointings of over 100 ks each of the well-studied Wolf-Rayet star WR 6 with the XMM-Newton satellite. With a first paper emphasizing the results of spectral analysis, this follow-up highlights the X-ray variability clearly detected in all four pointings. However, phased light curves fail to confirm obvious cyclic behavior on the well-established 3.766 day period widely found at longer wavelengths. The data are of such quality that we were able to conduct a search for event clustering in the arrival times of X-ray photons. However, we fail to detect any such clustering. One possibility is that X-rays are generated in a stationary shock structure. In this context we favor a corotating interaction region (CIR) and present a phenomenological model for X-rays from a CIR structure. We show that a CIR has the potential to account simultaneously for the X-ray variability and constraints provided by the spectral analysis. Ultimately, the viability of the CIR model will require both intermittent long-term X-ray monitoring of WR 6 and better physical models of CIR X-ray production at large radii in stellar winds

  14. THE XMM-NEWTON/EPIC X-RAY LIGHT CURVE ANALYSIS OF WR 6

    Energy Technology Data Exchange (ETDEWEB)

    Ignace, R. [Department of Physics and Astronomy, East Tennessee State University, Johnson City, TN 37663 (United States); Gayley, K. G. [Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52245 (United States); Hamann, W.-R.; Oskinova, L. M. [Institute for Physics and Astronomy, University Potsdam, D-14476 Potsdam (Germany); Huenemoerder, D. P. [Massachusetts Institute of Technology, Kavli Institute for Astrophysics and Space Research, 70 Vassar Street, Cambridge, MA 02139 (United States); Pollock, A. M. T. [European Space Agency XMM-Newton Science Operations Centre, European Space Astronomy Centre, Apartado 78, Villanueva de la Cañada, E-28691 Madrid (Spain); McFall, M., E-mail: ignace@etsu.edu [Department of Physics, 191 W. Woodruff Avenue, Ohio State University, Columbus, OH 43210 (United States)

    2013-09-20

    We obtained four pointings of over 100 ks each of the well-studied Wolf-Rayet star WR 6 with the XMM-Newton satellite. With a first paper emphasizing the results of spectral analysis, this follow-up highlights the X-ray variability clearly detected in all four pointings. However, phased light curves fail to confirm obvious cyclic behavior on the well-established 3.766 day period widely found at longer wavelengths. The data are of such quality that we were able to conduct a search for event clustering in the arrival times of X-ray photons. However, we fail to detect any such clustering. One possibility is that X-rays are generated in a stationary shock structure. In this context we favor a corotating interaction region (CIR) and present a phenomenological model for X-rays from a CIR structure. We show that a CIR has the potential to account simultaneously for the X-ray variability and constraints provided by the spectral analysis. Ultimately, the viability of the CIR model will require both intermittent long-term X-ray monitoring of WR 6 and better physical models of CIR X-ray production at large radii in stellar winds.

  15. A New Relationship Between Soft X-Rays and EUV Flare Light Curves

    Science.gov (United States)

    Thiemann, Edward

    2016-05-01

    Solar flares are the result of magnetic reconnection in the solar corona which converts magnetic energy into kinetic energy resulting in the rapid heating of solar plasma. As this plasma cools, it emits radiation at different EUV wavelengths when the dropping temperature passes a line’s temperature of formation. This results in a delay in the emissions from cooler EUV lines relative to hotter EUV lines. Therefore, characterizing how this hot plasma cools is important for understanding how the corresponding geo-effective extreme ultraviolet (EUV) irradiance evolves in time. I present a simple new framework in which to study flare cooling by using a Lumped Element Thermal Model (LETM). LETM is frequently used in science and engineering to simplify a complex multi-dimensional thermal system by reducing it to a 0-D thermal circuit. For example, a structure that conducts heat out of a system is simplified with a resistive element and a structure that allows a system to store heat is simplified with a capacitive element. A major advantage of LETM is that the specific geometry of a system can be ignored, allowing for an intuitive analysis of the major thermal processes. I show that LETM is able to accurately reproduce the temporal evolution of cooler flare emission lines based on hotter emission line evolution. In particular, it can be used to predict the evolution of EUV flare light curves using the NOAA X-Ray Sensor (XRS).

  16. Light curve and pulse profile of the x-ray pulsar Vela X-1

    International Nuclear Information System (INIS)

    Nagase, Fumiaki; Hayakawa, Satio; Makino, Fumiyoshi; Sato, Naohisa; Makishima, Kazuo.

    1983-01-01

    The following properties of the X-ray binary pulsar Vela X-1 are presented by reference to its observations in March 1980. The light curve shows a high state and a low state in the first and second halves of an orbital period, respectively, but they may rather be defined as a soft state and hard state, respectively, since the intensity above 9 keV does not appreciably change between these two states. The energy spectra in these states indicate the presence of circumstellar absorption. The pulse profiles at high (9-22 keV) and low (1-9 keV) energies are different, indicating the absorption by cold matter which is probably in the accretion column. The absorber which is responsible for the soft and hard states is attributed to the stellar wind whose flow pattern is consistent with that obtained from optical absorption spectra. The orbital period is obtained by a combined analysis of X-ray data since 1972. No appreciable change of the period gives a constraint on the dynamical behavior of the binary system. (author)

  17. IRTF/SPEX OBSERVATIONS OF THE UNUSUAL KEPLER LIGHT CURVE SYSTEM KIC 8462852

    Energy Technology Data Exchange (ETDEWEB)

    Lisse, C. M. [JHU-APL, 11100 Johns Hopkins Road, Laurel, MD 20723 (United States); Sitko, M. L. [Department of Physics, University of Cincinnati, Cincinnati, OH 45221-0011 (United States); Marengo, M., E-mail: carey.lisse@jhuapl.edu [Department of Physics and Astronomy, Iowa State University, 12 Physics Hall, Ames, IA 50010 (United States)

    2015-12-20

    We have utilized the NASA/IRTF 3 m SpeX instrument’s high-resolution spectral mode to observe and characterize the near-infrared flux emanating from the unusual Kepler light curve system KIC 8462852. By comparing the resulting 0.8–4.2 μm spectrum to a mesh of model photospheric spectra, the 6 emission line analyses of the Rayner et al. catalog, and the 25 system collections of debris disks we have observed to date using SpeX under the Near InfraRed Debris disk Survey, we have been able to additionally characterize the system. Within the errors of our measurements, this star looks like a normal solar abundance main-sequence F1V to F3V dwarf star without any obvious traces of significant circumstellar dust or gas. Using Connelley and Greene’s emission measures, we also see no evidence of significant ongoing accretion onto the star nor any stellar outflow away from it. Our results are inconsistent with large amounts of static close-in obscuring material or the unusual behavior of a YSO system, but are consistent with the favored episodic giant comet models of a Gyr old stellar system favored by Boyajian et al. We speculate that KIC 8462852, like the ∼1.4 Gyr old F2V system η Corvi, is undergoing a late heavy bombardment, but is only in its very early stages.

  18. M DWARFS IN SLOAN DIGITAL SKY SURVEY STRIPE 82: PHOTOMETRIC LIGHT CURVES AND FLARE RATE ANALYSIS

    International Nuclear Information System (INIS)

    Kowalski, Adam F.; Hawley, Suzanne L.; Hilton, Eric J.; Becker, Andrew C.; Sesar, Branimir; West, Andrew A.; Bochanski, John J.

    2009-01-01

    We present a flare rate analysis of 50,130 M dwarf light curves in Sloan Digital Sky Survey Stripe 82. We identified 271 flares using a customized variability index to search ∼2.5 million photometric observations for flux increases in the u and g bands. Every image of a flaring observation was examined by eye and with a point-spread function-matching and image subtraction tool to guard against false positives. Flaring is found to be strongly correlated with the appearance of Hα in emission in the quiet spectrum. Of the 99 flare stars that have spectra, we classify eight as relatively inactive. The flaring fraction is found to increase strongly in stars with redder colors during quiescence, which can be attributed to the increasing flare visibility and increasing active fraction for redder stars. The flaring fraction is strongly correlated with |Z| distance such that most stars that flare are within 300 pc of the Galactic plane. We derive flare u-band luminosities and find that the most luminous flares occur on the earlier-type m dwarfs. Our best estimate of the lower limit on the flaring rate (averaged over Stripe 82) for flares with Δu ≥ 0.7 mag on stars with u -1 deg -2 but can vary significantly with the line of sight.

  19. Pair-instability Supernova Simulations: Progenitor Evolution, Explosion, and Light Curves

    Energy Technology Data Exchange (ETDEWEB)

    Gilmer, Matthew S.; Fröhlich, Carla [Department of Physics, North Carolina State University, Raleigh, NC 27695 (United States); Kozyreva, Alexandra [The Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978 (Israel); Hirschi, Raphael [Astrophysics group, School of Chemical and Physical Sciences, Keele University, Keele, Staffordshire ST5 5BG (United Kingdom); Yusof, Norhasliza, E-mail: msgilmer@ncsu.edu [Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2017-09-10

    In recent years, the viability of the pair-instability supernova (PISN) scenario for explaining superluminous supernovae has all but disappeared except for a few slowly-evolving examples. However, PISNe are not predicted to be superluminous throughout the bulk of their mass range. In fact, it is more likely that the first PISN we see (if we have not seen one already) will not be superluminous. Here, we present hydrodynamic simulations of PISNe for four stellar models with unique envelope properties spanning the PISN mass range. In addition, we compute synthetic light curves (LCs) for comparison with current and future observations. We also investigate, in the context of our most massive model, the prospect of mixing in the supernova ejecta, alleviating discrepancies between current PISN models and the remaining superluminous candidate events. To this end, we present the first published 3D hydrodynamic simulations of PISNe. After achieving convergence between 1D, 2D, and 3D simulations, we examine mixing in the supernova ejecta and its affect on the bolometric LC. We observe slight deviations from spherical symmetry, which increase with the number of dimensions. We find no significant effects on the bolometric LC; however, we conclude that mixing between the silicon and oxygen rich layers caused by the Rayleigh–Taylor instability may affect spectra.

  20. THE IMPORTANCE OF {sup 56}Ni IN SHAPING THE LIGHT CURVES OF TYPE II SUPERNOVAE

    Energy Technology Data Exchange (ETDEWEB)

    Nakar, Ehud; Poznanski, Dovi [The Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978 (Israel); Katz, Boaz [Department of Particle Physics and Astrophysics, Weizmann Institute of Science, Rehovot 76100 (Israel)

    2016-06-01

    What intrinsic properties shape the light curves of SNe II? To address this question we derive observational measures that are robust (i.e., insensitive to detailed radiative transfer) and constrain the contribution from {sup 56}Ni as well as a combination of the envelope mass, progenitor radius, and explosion energy. By applying our methods to a sample of SNe II from the literature, we find that a {sup 56}Ni contribution is often significant. In our sample, its contribution to the time-weighted integrated luminosity during the photospheric phase ranges between 8% and 72% with a typical value of 30%. We find that the {sup 56}Ni relative contribution is anti-correlated with the luminosity decline rate. When added to other clues, this in turn suggests that the flat plateaus often observed in SNe II are not a generic feature of the cooling envelope emission, and that without {sup 56}Ni many of the SNe that are classified as II-P would have shown a decline rate that is steeper by up to 1 mag/100 days. Nevertheless, we find that the cooling envelope emission, and not {sup 56}Ni contribution, is the main driver behind the observed range of decline rates. Furthermore, contrary to previous suggestions, our findings indicate that fast decline rates are not driven by lower envelope masses. We therefore suggest that the difference in observed decline rates is mainly a result of different density profiles of the progenitors.

  1. AN X-RAY AND OPTICAL LIGHT CURVE MODEL OF THE ECLIPSING SYMBIOTIC BINARY SMC3

    International Nuclear Information System (INIS)

    Kato, Mariko; Hachisu, Izumi; Mikołajewska, Joanna

    2013-01-01

    Some binary evolution scenarios for Type Ia supernovae (SNe Ia) include long-period binaries that evolve to symbiotic supersoft X-ray sources in their late stage of evolution. However, symbiotic stars with steady hydrogen burning on the white dwarf's (WD) surface are very rare, and the X-ray characteristics are not well known. SMC3 is one such rare example and a key object for understanding the evolution of symbiotic stars to SNe Ia. SMC3 is an eclipsing symbiotic binary, consisting of a massive WD and red giant (RG), with an orbital period of 4.5 years in the Small Magellanic Cloud. The long-term V light curve variations are reproduced as orbital variations in the irradiated RG, whose atmosphere fills its Roche lobe, thus supporting the idea that the RG supplies matter to the WD at rates high enough to maintain steady hydrogen burning on the WD. We also present an eclipse model in which an X-ray-emitting region around the WD is almost totally occulted by the RG swelling over the Roche lobe on the trailing side, although it is always partly obscured by a long spiral tail of neutral hydrogen surrounding the binary in the orbital plane.

  2. Modelling gamma-ray light curves of phase-aligned millisecond pulsars

    Science.gov (United States)

    Chang, Shan; Zhang, Li; Li, Xiang; Jiang, Zejun

    2018-04-01

    Three gamma-ray millisecond pulsars (MSPs), PSR J1939+2134, PSR J1959+2048, and PSR J0034-0534, have been confirmed to have a common feature of phase-aligned in radio and gamma-ray bands. With a geometric (two-pole caustic) model and a physical outer gap model (revised 3D outer gap model) in a three dimensional (3D) retarded magnetic dipole with a perturbation magnetic field, the observed features of these MSPs are studied. In order to obtained the best-fitting model parameters, the Markov chain Monte Carlo technique is used and reasonable GeV band light curves for three MSPs are given. Our calculations indicate that MSPs emit high energy photons with smaller inclination angles (α ≈ 10°-50°), larger view angles (ζ ≈ 65°-100°), and smaller perturbation factor (ɛ ≈ -0.15-0.1). Note that the factor ɛ, describing the strength of the perturbed magnetic field, is all less than zero in these two models, so the magnetic field caused by current-induced play a leading role in the pulsed location of MSPs.

  3. AGAINST THE WIND: RADIO LIGHT CURVES OF TYPE IA SUPERNOVAE INTERACTING WITH LOW-DENSITY CIRCUMSTELLAR SHELLS

    Energy Technology Data Exchange (ETDEWEB)

    Harris, Chelsea E.; Nugent, Peter E.; Kasen, Daniel N., E-mail: chelseaharris@berkeley.edu [Astronomy Department, University of California Berkeley, Berkeley, CA (United States)

    2016-06-01

    For decades a wide variety of observations spanning the radio through optical and on to the X-ray have attempted to uncover signs of type Ia supernovae (SNe Ia) interacting with a circumstellar medium (CSM). The goal of these studies is to constrain the nature of the hypothesized SN Ia mass-donor companion. A continuous CSM is typically assumed when interpreting observations of interaction. However, while such models have been successfully applied to core-collapse SNe, the assumption of continuity may not be accurate for SNe Ia, because shells of CSM could be formed by pre-supernova eruptions (novae). In this work, we model the interaction of SNe with a spherical, low-density, finite-extent CSM and create a suite of synthetic radio synchrotron light curves. We find that CSM shells produce sharply peaked light curves. We also identify a fiducial set of models that obey a common evolution and can be used to generate radio light curves for an interaction with an arbitrary shell. The relations obeyed by the fiducial models can be used to deduce CSM properties from radio observations; we demonstrate this by applying them to the nondetections of SN 2011fe and SN 2014J. Finally, we explore a multiple shell CSM configuration and describe its more complicated dynamics and the resultant radio light curves.

  4. High-precision 2MASS JHK{sub s} light curves and other data for RR Lyrae star SDSS J015450 + 001501: Strong constraints for nonlinear pulsation models

    Energy Technology Data Exchange (ETDEWEB)

    Szabó, Róbert; Ivezić, Željko; Kiss, László L.; Kolláth, Zoltán [Konkoly Observatory, MTA CSFK, Konkoly Thege Miklós út 15-17, H-1121 Budapest (Hungary); Jones, Lynne; Becker, Andrew C.; Davenport, James R. A. [Astronomy Department, University of Washington, Box 351580, Seattle, WA 98195-1580 (United States); Sesar, Branimir [Division of Physics, Mathematics and Astronomy, Caltech, Pasadena, CA 91125 (United States); Cutri, Roc M., E-mail: rszabo@konkoly.hu [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States)

    2014-01-01

    We present and discuss an extensive data set for the non-Blazhko ab-type RR Lyrae star SDSS J015450+001501, including optical Sloan Digital Sky Survey ugriz light curves and spectroscopic data, LINEAR and Catalina Sky Survey unfiltered optical light curves, and infrared Two Micron All Sky Survey (2MASS) JHK{sub s} and Wide-field Infrared Survey Explorer W1 and W2 light curves. Most notable is that light curves obtained by 2MASS include close to 9000 photometric measures collected over 3.3 yr and provide an exceedingly precise view of near-infrared variability. These data demonstrate that static atmosphere models are insufficient to explain multiband photometric light-curve behavior and present strong constraints for nonlinear pulsation models for RR Lyrae stars. It is a challenge to modelers to produce theoretical light curves that can explain data presented here, which we make publicly available.

  5. On the mean profiles of radio pulsars - II. Reconstruction of complex pulsar light curves and other new propagation effects

    Science.gov (United States)

    Hakobyan, H. L.; Beskin, V. S.; Philippov, A. A.

    2017-08-01

    Our previous paper outlined the general aspects of the theory of radio light curve and polarization formation for pulsars. We predicted the one-to-one correspondence between the tilt of the linear polarization position angle of the the circular polarization. However, some of the radio pulsars indicate a clear deviation from that correlation. In this paper, we apply the theory of the radio wave propagation in the pulsar magnetosphere for the analysis of individual effects leading to these deviations. We show that within our theory the circular polarization of a given mode can switch its sign, without the need to introduce a new radiation mode or other effects. Moreover, we show that the generation of different emission modes on different altitudes can explain pulsars, that presumably have the X-O-X light-curve pattern, different from what we predict. General properties of radio emission within our propagation theory are also discussed. In particular, we calculate the intensity patterns for different radiation altitudes and present light curves for different observer viewing angles. In this context we also study the light curves and polarization profiles for pulsars with interpulses. Further, we explain the characteristic width of the position angle curves by introducing the concept of a wide emitting region. Another important feature of radio polarization profiles is the shift of the position angle from the centre, which in some cases demonstrates a weak dependence on the observation frequency. Here we demonstrate that propagation effects do not necessarily imply a significant frequency-dependent change of the position angle curve.

  6. Time evolution of the spectral break in the high-energy extra component of GRB 090926A

    Science.gov (United States)

    Yassine, M.; Piron, F.; Mochkovitch, R.; Daigne, F.

    2017-10-01

    Aims: The prompt light curve of the long GRB 090926A reveals a short pulse 10 s after the beginning of the burst emission, which has been observed by the Fermi observatory from the keV to the GeV energy domain. During this bright spike, the high-energy emission from GRB 090926A underwent a sudden hardening above 10 MeV in the form of an additional power-law component exhibiting a spectral attenuation at a few hundreds of MeV. This high-energy break has been previously interpreted in terms of gamma-ray opacity to pair creation and has been used to estimate the bulk Lorentz factor of the outflow. In this article, we report on a new time-resolved analysis of the GRB 090926A broadband spectrum during its prompt phase and on its interpretation in the framework of prompt emission models. Methods: We characterized the emission from GRB 090926A at the highest energies with Pass 8 data from the Fermi Large Area Telescope (LAT), which offer a greater sensitivity than any data set used in previous studies of this burst, particularly in the 30-100 MeV energy band. Then, we combined the LAT data with the Fermi Gamma-ray Burst Monitor (GBM) in joint spectral fits to characterize the time evolution of the broadband spectrum from keV to GeV energies. We paid careful attention to the systematic effects that arise from the uncertainties on the LAT response. Finally, we performed a temporal analysis of the light curves and we computed the variability timescales from keV to GeV energies during and after the bright spike. Results: Our analysis confirms and better constrains the spectral break, which has been previously reported during the bright spike. Furthermore, it reveals that the spectral attenuation persists at later times with an increase of the break characteristic energy up to the GeV domain until the end of the prompt phase. We discuss these results in terms of keV-MeV synchroton radiation of electrons accelerated during the dissipation of the jet energy and inverse Compton

  7. Modeling Phase-Aligned Gamma-Ray and Radio Millisecond Pulsar Light Curves

    Science.gov (United States)

    Venter, C.; Johnson, T.; Harding, A.

    2012-01-01

    Since the discovery of the first eight gamma-ray millisecond pulsars (MSPs) by the Fermi Large Area Telescope, this population has been steadily expanding. Four of the more recent detections, PSR J00340534, PSR J1939+2134 (B1937+21; the first MSP ever discovered), PSR J1959+2048 (B1957+20; the first discovery of a black widow system), and PSR J2214+3000, exhibit a phenomenon not present in the original discoveries: nearly phase-aligned radio and gamma-ray light curves (LCs). To account for the phase alignment, we explore models where both the radio and gamma-ray emission originate either in the outer magnetosphere near the light cylinder or near the polar caps. Using a Markov Chain Monte Carlo technique to search for best-fit model parameters, we obtain reasonable LC fits for the first three of these MSPs in the context of altitude-limited outer gap (alOG) and two-pole caustic (alTPC) geometries (for both gamma-ray and radio emission). These models differ from the standard outer gap (OG)/two-pole caustic (TPC) models in two respects: the radio emission originates in caustics at relatively high altitudes compared to the usual conal radio beams, and we allow both the minimum and maximum altitudes of the gamma-ray and radio emission regions to vary within a limited range (excluding the minimum gamma-ray altitude of the alTPC model, which is kept constant at the stellar radius, and that of the alOG model, which is set to the position-dependent null charge surface altitude). Alternatively, phase-aligned solutions also exist for emission originating near the stellar surface in a slot gap scenario (low-altitude slot gap (laSG) models). We find that the alTPC models provide slightly better LC fits than the alOG models, and both of these give better fits than the laSG models (for the limited range of parameters considered in the case of the laSG models). Thus, our fits imply that the phase-aligned LCs are likely of caustic origin, produced in the outer magnetosphere, and

  8. Light and Color Curve Properties of Type Ia Supernovae: Theory Versus Observations

    Energy Technology Data Exchange (ETDEWEB)

    Hoeflich, P.; Hsiao, E. Y. [Department of Physics, Florida State University, Tallahassee, FL 32306 (United States); Ashall, C. [Astrophysics Research Institute, Liverpool John Moore University, 146 Brownlow Hill, Liverpool L3 5RF (United Kingdom); Burns, C. R. [Observatories of the Carnegie Institution for Science, 813 Santa Barbara St., Pasadena, CA 91101 (United States); Diamond, T. R. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Phillips, M. M. [Carnegie Observatories, Las Campanas Observatory, Casilla 601 La Serena (Chile); Sand, D. [Physics and Astronomy Department, Texas Tech University, Box 41051, Lubbock, TX 79409-1051 (United States); Stritzinger, M. D. [Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000, Aarhus (Denmark); Suntzeff, N.; Krisciunas, K.; Wang, L. [The G.P. and C. Woods Mitchell Institute for Fundamental Physics and Astronomy, Texas A and M University, Department of Physics and Astronomy, 4242 TAMU, College Station, TX 77843 (United States); Contreras, C.; Morrell, N., E-mail: phoeflich77@gmail.com [Departamento de Física, Universidad Técnica Federico Santa Maria, Ava España 1680, Casilla 110-V, Valparaiso (Chile)

    2017-09-01

    We study the optical light curve (LC) relations of Type Ia supernovae (SNe Ia) for their use in cosmology using high-quality photometry published by the Carnegie Supernova Project (CSP-I). We revisit the classical luminosity decline rate (Δ m {sub 15}) relation and the Lira relation, as well as investigate the time evolution of the ( B − V ) color and B ( B − V ), which serves as the basis of the color–stretch relation and Color–MAgnitude Intercept Calibrations (CMAGIC). Our analysis is based on explosion and radiation transport simulations for spherically symmetric delayed-detonation models (DDT) producing normal-bright and subluminous SNe Ia. Empirical LC relations can be understood as having the same physical underpinnings, i.e., opacities, ionization balances in the photosphere, and radioactive energy deposition changing with time from below to above the photosphere. Some three to four weeks past maximum, the photosphere recedes to {sup 56}Ni-rich layers of similar density structure, leading to a similar color evolution. An important secondary parameter is the central density ρ {sub c} of the WD because at higher densities, more electron-capture elements are produced at the expense of {sup 56}Ni production. This results in a Δ m {sub 15} spread of 0.1 mag in normal-bright and 0.7 mag in subluminous SNe Ia and ≈0.2 mag in the Lira relation. We show why color–magnitude diagrams emphasize the transition between physical regimes and enable the construction of templates that depend mostly on Δ m {sub 15} with little dispersion in both the CSP-I sample and our DDT models. This allows intrinsic SN Ia variations to be separated from the interstellar reddening characterized by E ( B − V ) and R {sub B}. Invoking different scenarios causes a wide spread in empirical relations, which may suggest one dominant scenario.

  9. THE LICK AGN MONITORING PROJECT 2011: SPECTROSCOPIC CAMPAIGN AND EMISSION-LINE LIGHT CURVES

    Energy Technology Data Exchange (ETDEWEB)

    Barth, Aaron J. [Department of Physics and Astronomy, 4129 Frederick Reines Hall, University of California, Irvine, CA, 92697-4575 (United States); Bennert, Vardha N. [Physics Department, California Polytechnic State University, San Luis Obispo, CA 93407 (United States); Canalizo, Gabriela [Department of Physics and Astronomy, University of California, Riverside, CA 92521 (United States); Filippenko, Alexei V.; Li, Weidong [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Gates, Elinor L. [Lick Observatory, P.O. Box 85, Mount Hamilton, CA 95140 (United States); Greene, Jenny E. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Malkan, Matthew A.; Treu, Tommaso [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095-1547 (United States); Pancoast, Anna [Department of Physics, University of California, Santa Barbara, CA 93106 (United States); Sand, David J. [Texas Tech University, Physics Department, Box 41051, Lubbock, TX 79409-1051 (United States); Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Boulevard, Pasadena, CA 91109 (United States); Woo, Jong-Hak [Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of); Assef, Roberto J. [Núcleo de Astronomía de la Facultad de Ingeniería, Universidad Diego Portales, Av. Ejército Libertador 441, Santiago (Chile); Bae, Hyun-Jin [Department of Astronomy and Center for Galaxy Evolution Research, Yonsei University, Seoul 120-749 (Korea, Republic of); Brewer, Brendon J. [Department of Statistics, The University of Auckland, Private Bag 92019, Auckland 1142 (New Zealand); Cenko, S. Bradley [Astrophysics Science Division, NASA Goddard Space Flight Center, MC 661, Greenbelt, MD 20771 (United States); and others

    2015-04-15

    In the Spring of 2011 we carried out a 2.5 month reverberation mapping campaign using the 3 m Shane telescope at Lick Observatory, monitoring 15 low-redshift Seyfert 1 galaxies. This paper describes the observations, reductions and measurements, and data products from the spectroscopic campaign. The reduced spectra were fitted with a multicomponent model in order to isolate the contributions of various continuum and emission-line components. We present light curves of broad emission lines and the active galactic nucleus (AGN) continuum, and measurements of the broad Hβ line widths in mean and rms spectra. For the most highly variable AGNs we also measured broad Hβ line widths and velocity centroids from the nightly spectra. In four AGNs exhibiting the highest variability amplitudes, we detect anticorrelations between broad Hβ width and luminosity, demonstrating that the broad-line region “breathes” on short timescales of days to weeks in response to continuum variations. We also find that broad Hβ velocity centroids can undergo substantial changes in response to continuum variations; in NGC 4593, the broad Hβ velocity shifted by ∼250 km s{sup −1} over a 1 month period. This reverberation-induced velocity shift effect is likely to contribute a significant source of confusion noise to binary black hole searches that use multi-epoch quasar spectroscopy to detect binary orbital motion. We also present results from simulations that examine biases that can occur in measurement of broad-line widths from rms spectra due to the contributions of continuum variations and photon-counting noise.

  10. CAN LARGE TIME DELAYS OBSERVED IN LIGHT CURVES OF CORONAL LOOPS BE EXPLAINED IN IMPULSIVE HEATING?

    International Nuclear Information System (INIS)

    Lionello, Roberto; Linker, Jon A.; Mikić, Zoran; Alexander, Caroline E.; Winebarger, Amy R.

    2016-01-01

    The light curves of solar coronal loops often peak first in channels associated with higher temperatures and then in those associated with lower temperatures. The delay times between the different narrowband EUV channels have been measured for many individual loops and recently for every pixel of an active region observation. The time delays between channels for an active region exhibit a wide range of values. The maximum time delay in each channel pair can be quite large, i.e., >5000 s. These large time delays make-up 3%–26% (depending on the channel pair) of the pixels where a trustworthy, positive time delay is measured. It has been suggested that these time delays can be explained by simple impulsive heating, i.e., a short burst of energy that heats the plasma to a high temperature, after which the plasma is allowed to cool through radiation and conduction back to its original state. In this paper, we investigate whether the largest observed time delays can be explained by this hypothesis by simulating a series of coronal loops with different heating rates, loop lengths, abundances, and geometries to determine the range of expected time delays between a set of four EUV channels. We find that impulsive heating cannot address the largest time delays observed in two of the channel pairs and that the majority of the large time delays can only be explained by long, expanding loops with photospheric abundances. Additional observations may rule out these simulations as an explanation for the long time delays. We suggest that either the time delays found in this manner may not be representative of real loop evolution, or that the impulsive heating and cooling scenario may be too simple to explain the observations, and other potential heating scenarios must be explored

  11. Light and Color Curve Properties of Type Ia Supernovae: Theory Versus Observations

    International Nuclear Information System (INIS)

    Hoeflich, P.; Hsiao, E. Y.; Ashall, C.; Burns, C. R.; Diamond, T. R.; Phillips, M. M.; Sand, D.; Stritzinger, M. D.; Suntzeff, N.; Krisciunas, K.; Wang, L.; Contreras, C.; Morrell, N.

    2017-01-01

    We study the optical light curve (LC) relations of Type Ia supernovae (SNe Ia) for their use in cosmology using high-quality photometry published by the Carnegie Supernova Project (CSP-I). We revisit the classical luminosity decline rate (Δ m 15 ) relation and the Lira relation, as well as investigate the time evolution of the ( B − V ) color and B ( B − V ), which serves as the basis of the color–stretch relation and Color–MAgnitude Intercept Calibrations (CMAGIC). Our analysis is based on explosion and radiation transport simulations for spherically symmetric delayed-detonation models (DDT) producing normal-bright and subluminous SNe Ia. Empirical LC relations can be understood as having the same physical underpinnings, i.e., opacities, ionization balances in the photosphere, and radioactive energy deposition changing with time from below to above the photosphere. Some three to four weeks past maximum, the photosphere recedes to 56 Ni-rich layers of similar density structure, leading to a similar color evolution. An important secondary parameter is the central density ρ c of the WD because at higher densities, more electron-capture elements are produced at the expense of 56 Ni production. This results in a Δ m 15 spread of 0.1 mag in normal-bright and 0.7 mag in subluminous SNe Ia and ≈0.2 mag in the Lira relation. We show why color–magnitude diagrams emphasize the transition between physical regimes and enable the construction of templates that depend mostly on Δ m 15 with little dispersion in both the CSP-I sample and our DDT models. This allows intrinsic SN Ia variations to be separated from the interstellar reddening characterized by E ( B − V ) and R B . Invoking different scenarios causes a wide spread in empirical relations, which may suggest one dominant scenario.

  12. Statistical improvement in detection level of gravitational microlensing events from their light curves

    Science.gov (United States)

    Ibrahim, Ichsan; Malasan, Hakim L.; Kunjaya, Chatief; Timur Jaelani, Anton; Puannandra Putri, Gerhana; Djamal, Mitra

    2018-04-01

    In astronomy, the brightness of a source is typically expressed in terms of magnitude. Conventionally, the magnitude is defined by the logarithm of received flux. This relationship is known as the Pogson formula. For received flux with a small signal to noise ratio (S/N), however, the formula gives a large magnitude error. We investigate whether the use of Inverse Hyperbolic Sine function (hereafter referred to as the Asinh magnitude) in the modified formulae could allow for an alternative calculation of magnitudes for small S/N flux, and whether the new approach is better for representing the brightness of that region. We study the possibility of increasing the detection level of gravitational microlensing using 40 selected microlensing light curves from the 2013 and 2014 seasons and by using the Asinh magnitude. Photometric data of the selected events are obtained from the Optical Gravitational Lensing Experiment (OGLE). We found that utilization of the Asinh magnitude makes the events brighter compared to using the logarithmic magnitude, with an average of about 3.42 × 10‑2 magnitude and an average in the difference of error between the logarithmic and the Asinh magnitude of about 2.21 × 10‑2 magnitude. The microlensing events OB140847 and OB140885 are found to have the largest difference values among the selected events. Using a Gaussian fit to find the peak for OB140847 and OB140885, we conclude statistically that the Asinh magnitude gives better mean squared values of the regression and narrower residual histograms than the Pogson magnitude. Based on these results, we also attempt to propose a limit in magnitude value for which use of the Asinh magnitude is optimal with small S/N data.

  13. Real-time evaluation of two light delivery systems for photodynamic disinfection of Candida albicans biofilm in curved root canals.

    Science.gov (United States)

    Sabino, C P; Garcez, A S; Núñez, S C; Ribeiro, M S; Hamblin, M R

    2015-08-01

    Antimicrobial photodynamic therapy (APDT) combined with endodontic treatment has been recognized as an alternative approach to complement conventional root canal disinfection methods on bacterial biofilms. We developed an in  vitro model of bioluminescent Candida albicans biofilm inside curved dental root canals and investigated the microbial reduction produced when different light delivery methods are employed. Each light delivery method was evaluated in respect to the light distribution provided inside curved root canals. After conventional endodontic preparation, teeth were sterilized before canals were contaminated by a bioluminescent strain of C. albicans (CEC789). Methylene blue (90 μM) was introduced into the canals and then irradiated (λ = 660 nm, P = 100 mW, beam diameter = 2 mm) with laser tip either in contact with pulp chamber or within the canal using an optical diffuser fiber. Light distribution was evaluated by CCD camera, and microbial reduction was monitored through bioluminescence imaging. Our findings demonstrated that the bioluminescent C. albicans biofilm model had good reproducibility and uniformity. Light distribution in dental tissue was markedly dependent on the light delivery system, and this strategy was directly related to microbial destruction. Both light delivery systems performed significant fungal inactivation. However, when irradiation was performed with optical diffuser fiber, microbial burden reduction was nearly 100 times more effective. Bioluminescence is an interesting real-time analysis to endodontic C. albicans biofilm inactivation. APDT showed to be an effective way to inactivate C. albicans biofilms. Diffuser fibers provided optimized light distribution inside curved root canals and significantly increased APDT efficiency.

  14. Magnetars in Ultra-Long Gamma-Ray Bursts and GRB 111209A

    Energy Technology Data Exchange (ETDEWEB)

    Gompertz, B.; Fruchter, A., E-mail: bgompertz@stsci.edu [Space Telescope Science Institute, Baltimore, MD 21218 (United States)

    2017-04-10

    Supernova 2011kl, associated with the ultra-long gamma-ray burst (ULGRB) 111209A, exhibited a higher-than-normal peak luminosity, placing it in the parameter space between regular supernovae and super-luminous supernovae. Its light curve can only be matched by an abnormally high fraction of {sup 56}Ni that appears inconsistent with the observed spectrum, and as a result it has been suggested that the supernova, and by extension the gamma-ray burst, are powered by the spin-down of a highly magnetized millisecond pulsar, known as a magnetar. We investigate the broadband observations of ULGRB 111209A and find two independent measures that suggest a high density circumburst environment. However, the light curve of the GRB afterglow shows no evidence of a jet break (the steep decline that would be expected as the jet slows due to the resistance of the external medium) out to three weeks after trigger, implying a wide jet. Combined with the high isotropic energy of the burst, this implies that only a magnetar with a spin period of ∼1 ms or faster can provide enough energy to power both ULGRB 111209A and Supernova 2011kl.

  15. Study of WATCH GRB error boxes

    DEFF Research Database (Denmark)

    Gorosabel, J.; Castro-Tirado, A. J.; Lund, Niels

    1995-01-01

    We have studied the first WATCH GRB Catalogue ofγ-ray Bursts in order to find correlations between WATCH GRB error boxes and a great variety of celestial objects present in 33 different catalogues. No particular class of objects has been found to be significantly correlated with the WATCH GRBs....

  16. IS THE LATE NEAR-INFRARED BUMP IN SHORT-HARD GRB 130603B DUE TO THE LI-PACZYNSKI KILONOVA?

    International Nuclear Information System (INIS)

    Jin, Zhi-Ping; Fan, Yi-Zhong; Wei, Da-Ming; Xu, Dong; Wu, Xue-Feng

    2013-01-01

    Short-hard gamma-ray bursts (GRBs) are widely believed to be produced by the merger of two binary compact objects, specifically by two neutron stars or by a neutron star orbiting a black hole. According to the Li-Paczynski kilonova model, the merger would launch sub-relativistic ejecta and a near-infrared/optical transient would then occur, lasting up to days, which is powered by the radioactive decay of heavy elements synthesized in the ejecta. The detection of a late bump using the Hubble Space Telescope (HST) in the near-infrared afterglow light curve of the short-hard GRB 130603B is indeed consistent with such a model. However, as shown in this Letter, the limited HST near-infrared light curve behavior can also be interpreted as the synchrotron radiation of the external shock driven by a wide mildly relativistic outflow. In such a scenario, the radio emission is expected to peak with a flux of ∼100 μJy, which is detectable for current radio arrays. Hence, the radio afterglow data can provide complementary evidence on the nature of the bump in GRB 130603B. It is worth noting that good spectroscopy during the bump phase in short-hard bursts can test the validity of either model above, analogous to spectroscopy of broad-lined Type Ic supernova in long-soft GRBs

  17. An Empirical Fitting Method for Type Ia Supernova Light Curves: A Case Study of SN 2011fe

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, WeiKang; Filippenko, Alexei V., E-mail: zwk@astro.berkeley.edu [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States)

    2017-03-20

    We present a new empirical fitting method for the optical light curves of Type Ia supernovae (SNe Ia). We find that a variant broken-power-law function provides a good fit, with the simple assumption that the optical emission is approximately the blackbody emission of the expanding fireball. This function is mathematically analytic and is derived directly from the photospheric velocity evolution. When deriving the function, we assume that both the blackbody temperature and photospheric velocity are constant, but the final function is able to accommodate these changes during the fitting procedure. Applying it to the case study of SN 2011fe gives a surprisingly good fit that can describe the light curves from the first-light time to a few weeks after peak brightness, as well as over a large range of fluxes (∼5 mag, and even ∼7 mag in the g band). Since SNe Ia share similar light-curve shapes, this fitting method has the potential to fit most other SNe Ia and characterize their properties in large statistical samples such as those already gathered and in the near future as new facilities become available.

  18. ASTEROID LIGHT CURVES FROM THE PALOMAR TRANSIENT FACTORY SURVEY: ROTATION PERIODS AND PHASE FUNCTIONS FROM SPARSE PHOTOMETRY

    Energy Technology Data Exchange (ETDEWEB)

    Waszczak, Adam [Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125 (United States); Chang, Chan-Kao; Cheng, Yu-Chi; Ip, Wing-Huen; Kinoshita, Daisuke [Institute of Astronomy, National Central University, Jhongli, Taiwan (China); Ofek, Eran O. [Benoziyo Center for Astrophysics, Weizmann Institute of Science, Rehovot (Israel); Laher, Russ; Surace, Jason [Spitzer Science Center, California Institute of Technology, Pasadena, CA 91125 (United States); Masci, Frank; Helou, George [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States); Levitan, David; Prince, Thomas A.; Kulkarni, Shrinivas, E-mail: waszczak@caltech.edu [Division of Physics, Mathematics and Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States)

    2015-09-15

    We fit 54,296 sparsely sampled asteroid light curves in the Palomar Transient Factory survey to a combined rotation plus phase-function model. Each light curve consists of 20 or more observations acquired in a single opposition. Using 805 asteroids in our sample that have reference periods in the literature, we find that the reliability of our fitted periods is a complicated function of the period, amplitude, apparent magnitude, and other light-curve attributes. Using the 805-asteroid ground-truth sample, we train an automated classifier to estimate (along with manual inspection) the validity of the remaining ∼53,000 fitted periods. By this method we find that 9033 of our light curves (of ∼8300 unique asteroids) have “reliable” periods. Subsequent consideration of asteroids with multiple light-curve fits indicates a 4% contamination in these “reliable” periods. For 3902 light curves with sufficient phase-angle coverage and either a reliable fit period or low amplitude, we examine the distribution of several phase-function parameters, none of which are bimodal though all correlate with the bond albedo and with visible-band colors. Comparing the theoretical maximal spin rate of a fluid body with our amplitude versus spin-rate distribution suggests that, if held together only by self-gravity, most asteroids are in general less dense than ∼2 g cm{sup −3}, while C types have a lower limit of between 1 and 2 g cm{sup −3}. These results are in agreement with previous density estimates. For 5–20 km diameters, S types rotate faster and have lower amplitudes than C types. If both populations share the same angular momentum, this may indicate the two types’ differing ability to deform under rotational stress. Lastly, we compare our absolute magnitudes (and apparent-magnitude residuals) to those of the Minor Planet Center’s nominal (G = 0.15, rotation-neglecting) model; our phase-function plus Fourier-series fitting reduces asteroid photometric rms

  19. Supernovae with two peaks in the optical light curve and the signature of progenitors with low-mass extended envelopes

    Energy Technology Data Exchange (ETDEWEB)

    Nakar, Ehud [Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978 (Israel); Piro, Anthony L. [Theoretical Astrophysics, California Institute of Technology, 1200 East California Boulevard, M/C 350-17, Pasadena, CA 91125 (United States)

    2014-06-20

    Early observations of supernova light curves are powerful tools for shedding light on the pre-explosion structures of their progenitors and their mass-loss histories just prior to explosion. Some core-collapse supernovae that are detected during the first days after the explosion prominently show two peaks in the optical bands, including the R and I bands, where the first peak appears to be powered by the cooling of shocked surface material and the second peak is clearly powered by radioactive decay. Such light curves have been explored in detail theoretically for SN 1993J and 2011dh, where it was found that they may be explained by progenitors with extended, low-mass envelopes. Here, we generalize these results. We first explore whether any double-peaked light curve of this type can be generated by a progenitor with a 'standard' density profile, such as a red supergiant or a Wolf-Rayet star. We show that a standard progenitor (1) cannot produce a double-peaked light curve in the R and I bands and (2) cannot exhibit a fast drop in the bolometric luminosity as is seen after the first peak. We then explore the signature of a progenitor with a compact core surrounded by extended, low-mass material. This may be a hydrostatic low-mass envelope or material ejected just prior to the explosion. We show that it naturally produces both of these features. We use this result to provide simple formulae to estimate (1) the mass of the extended material from the time of the first peak, (2) the extended material radius from the luminosity of the first peak, and (3) an upper limit on the core radius from the luminosity minimum between the two peaks.

  20. The ultraluminous GRB 110918A

    International Nuclear Information System (INIS)

    Frederiks, D. D.; Svinkin, D. S.; Pal'shin, V. D.; Aptekar, R. L.; Golenetskii, S. V.; Mazets, E. P.; Oleynik, Ph. P.; Tsvetkova, A. E.; Ulanov, M. V.; Kokomov, A. A.; Hurley, K.; Mangano, V.; Burrows, D. N.; Sbarufatti, B.; Siegel, M. H.; Oates, S.; Cline, T. L.; Krimm, H. A.; Pagani, C.; Mitrofanov, I. G.

    2013-01-01

    GRB 110918A is the brightest long gamma-ray burst (GRB) detected by Konus-WIND during its almost 19 yr of continuous observations and the most luminous GRB ever observed since the beginning of the cosmological era in 1997. We report on the final Interplanetary Network localization of this event and its detailed multiwavelength study with a number of space-based instruments. The prompt emission is characterized by a typical duration, a moderate peak energy of the time-integrated spectrum, and strong hard-to-soft evolution. The high observed energy fluence yields, at z = 0.984, a huge isotropic-equivalent energy release E iso = (2.1 ± 0.1) × 10 54 erg. The record-breaking energy flux observed at the peak of the short, bright, hard initial pulse results in an unprecedented isotropic-equivalent luminosity L iso = (4.7 ± 0.2) × 10 54 erg s –1 . A tail of the soft γ-ray emission was detected with temporal and spectral behavior typical of that predicted by the synchrotron forward-shock model. The Swift/X-Ray Telescope and the Swift/Ultraviolet Optical Telescope observed the bright afterglow from 1.2 to 48 days after the burst and revealed no evidence of a jet break. The post-break scenario for the afterglow is preferred from our analysis, with a hard underlying electron spectrum and interstellar-medium-like circumburst environment implied. We conclude that, among the multiple reasons investigated, the tight collimation of the jet must have been a key ingredient to produce this unusually bright burst. The inferred jet opening angle of 1.°7-3.°4 results in reasonable values of the collimation-corrected radiated energy and the peak luminosity, which, however, are still at the top of their distributions for such tightly collimated events. We estimate a detection horizon for a similar ultraluminous GRB of z ∼ 7.5 for Konus-WIND and z ∼ 12 for the Swift/Burst Alert Telescope, which stresses the importance of GRBs as probes of the early Universe.

  1. Effects of forward and backward transitions in light intensities in tau-illuminance curves of the rat motor activity rhythm under constant dim light.

    Science.gov (United States)

    Cambras, Trinitat; Díez-Noguera, Antoni

    2012-07-01

    Circadian rhythms are strongly influenced by light intensity, the effects of which may persist beyond the duration of light exposure (aftereffects). Here, the authors constructed period-illuminance curves for the motor activity circadian rhythm of male and female rats by recording the effects of a series of small upward and downward steps in light intensity (illuminance ranging between .01 lux of dim red light and 1 lux of white light) on their activity. In all cases, stepwise changes were made in five logarithmic steps (irradiance: dim red light: .692 µW/cm(2) and white light: .006, .016, .044, .12, and .315 µW/cm(2), corresponding, respectively, to .02, .05, .14, .13, and 1 lux measured at cage level), with changes in intensity every 2 wks. One group of rats (DLD) started in dim red light, moved up to 1 lux white light, and then back down to the original light intensity. Another group (LDL) started at 1 lux, moved down to .01 lux, and then back up to the original intensity. Motor activity data were recorded throughout the experiment and tau values, the percentage of variance explained by the rhythm, and the mean motor activity for each stage and group were calculated. The results show differences in the dynamics of tau values between the DLD and LDL groups and between males and females. In the LDL group, the tau values of both males and females were dependent on light intensity, and were similar for the forward and backward transitions. In other words, no aftereffects were found, and no differences were detected between males and females. In the DLD group, however, differences were found between males and females. Males had a tau value of 24 h 20 min under dim red light, 25 h 40 min under 1 lux, and 24 h 50 min on return to dim red light. It is noticeable that the tau values of the backward branch of the illuminance curve contradicted classical predictions, since at .38 and .14 lux the tau values were shorter than those found under the same intensities after

  2. CHARACTERIZATION OF THE X-RAY LIGHT CURVE OF THE {gamma} Cas-LIKE B1e STAR HD 110432

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Myron A. [Catholic University of America, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Lopes de Oliveira, Raimundo [Departamento de Fisica, Universidade Federal de Sergipe, Av. Marechal Rondon s/n, 49100-000 Sao Cristovao, SE (Brazil); Motch, Christian, E-mail: msmith@stsci.edu [Observatoire Astronomique, Universite de Strasbourg, CNRS UMR 7550, 11 rue de l' Universite, F-67000 Strasbourg (France)

    2012-08-10

    HD 110432 (BZ Cru; B1Ve) is the brightest member of a small group of '{gamma} Cas analogs' that emit copious hard X-ray flux, punctuated by ubiquitous 'flares'. To characterize the X-ray time history of this star, we made a series of six RXTE multi-visit observations in 2010 and an extended observation with the XMM-Newton in 2007. We analyzed these new light curves along with three older XMM-Newton observations from 2002 to 2003. Distributed over five months, the RXTE observations were designed to search for long X-ray modulations over a few months. These observations indeed suggest the presence of a long cycle with P Almost-Equal-To 226 days and an amplitude of a factor of two. We also used X-ray light curves constructed from XMM-Newton observations to characterize the lifetimes, strengths, and interflare intervals of 1615 flare-like events in the light curves. After accounting for false positive events, we infer the presence of 955 (2002-2003) and 386 (2007) events we identified as flares. Similarly, as a control we measured the same attributes for an additional group of 541 events in XMM-Newton light curves of {gamma} Cas, which, after a similar correction, yielded 517 flares. We found that the flare properties of HD 110432 are mostly similar to our control group. In both cases the distribution of flare strengths are best fit with log-linear relations. Both the slopes of these distributions and the flaring frequencies themselves exhibit modest fluctuations. We discovered that some flares in the hard X-ray band of HD 110432 were weak or unobserved in the soft band and vice versa. The light curves also occasionally show rapid curve drop-offs that are sustained for hours. We discuss the existence of the long cycle and these flare properties in the backdrop of two rival scenarios to produce hard X-rays, a magnetic star-disk interaction, and the accretion of blobs onto a secondary white dwarf.

  3. Light curve of the CX Cep eclipsing binary system and characteristics of a Wolf-Rayet star

    International Nuclear Information System (INIS)

    Lipunova, N.A.; Cherepashchuk, A.M.

    1982-01-01

    The photoelectric B, V, R observations of the eclipsing Wolf-Rayet binary CX Cep (WN 5 + 08V, V approximately equal to 12sup(m),1, p approximately equal to 2sup(d),127) have been carried out. The physical characteristics of the WN 5 star, the core radius r 0 =(4.5+-2.5) Rsub(S) (Rsub(S) is the Sun radius) and the brightness temperature of the core Tsub(b)>50 000 K, are determined from the analysis of the light curve lambdasub(eff) approximately equal to 6 000 A. These characteristics are close to those of the WN 5 star in the eclipsing Wolf-Rayet binary V 444 Cyg. The results of the interpretation of the light curves of two eclipsing Wolf-Rayet binaries (V 444 Cyg and CX Cep) confirm the conclusions of the modern theory of evolution of massive close binary systems [ru

  4. An adaptive-binning method for generating constant-uncertainty/constant-significance light curves with Fermi-LAT data

    International Nuclear Information System (INIS)

    Lott, B.; Escande, L.; Larsson, S.; Ballet, J.

    2012-01-01

    Here, we present a method enabling the creation of constant-uncertainty/constant-significance light curves with the data of the Fermi-Large Area Telescope (LAT). The adaptive-binning method enables more information to be encapsulated within the light curve than with the fixed-binning method. Although primarily developed for blazar studies, it can be applied to any sources. Furthermore, this method allows the starting and ending times of each interval to be calculated in a simple and quick way during a first step. The reported mean flux and spectral index (assuming the spectrum is a power-law distribution) in the interval are calculated via the standard LAT analysis during a second step. In the absence of major caveats associated with this method Monte-Carlo simulations have been established. We present the performance of this method in determining duty cycles as well as power-density spectra relative to the traditional fixed-binning method.

  5. Non-regularized inversion method from light scattering applied to ferrofluid magnetization curves for magnetic size distribution analysis

    International Nuclear Information System (INIS)

    Rijssel, Jos van; Kuipers, Bonny W.M.; Erné, Ben H.

    2014-01-01

    A numerical inversion method known from the analysis of light scattering by colloidal dispersions is now applied to magnetization curves of ferrofluids. The distribution of magnetic particle sizes or dipole moments is determined without assuming that the distribution is unimodal or of a particular shape. The inversion method enforces positive number densities via a non-negative least squares procedure. It is tested successfully on experimental and simulated data for ferrofluid samples with known multimodal size distributions. The created computer program MINORIM is made available on the web. - Highlights: • A method from light scattering is applied to analyze ferrofluid magnetization curves. • A magnetic size distribution is obtained without prior assumption of its shape. • The method is tested successfully on ferrofluids with a known size distribution. • The practical limits of the method are explored with simulated data including noise. • This method is implemented in the program MINORIM, freely available online

  6. Gamma-ray pulsar physics: gap-model populations and light-curve analyses in the Fermi era

    International Nuclear Information System (INIS)

    Pierbattista, M.

    2010-01-01

    This thesis research focusses on the study of the young and energetic isolated ordinary pulsar population detected by the Fermi gamma-ray space telescope. We compared the model expectations of four emission models and the LAT data. We found that all the models fail to reproduce the LAT detections, in particular the large number of high E objects observed. This inconsistency is not model dependent. A discrepancy between the radio-loud/radio-quiet objects ratio was also found between the observed and predicted samples. The L γ α E 0.5 relation is robustly confirmed by all the assumed models with particular agreement in the slot gap (SG) case. On luminosity bases, the intermediate altitude emission of the two pole caustic SG model is favoured. The beaming factor f Ω shows an E dependency that is slightly visible in the SG case. Estimates of the pulsar orientations have been obtained to explain the simultaneous gamma and radio light-curves. By analysing the solutions we found a relation between the observed energy cutoff and the width of the emission slot gap. This relation has been theoretically predicted. A possible magnetic obliquity α alignment with time is rejected -for all the models- on timescale of the order of 10 6 years. The light-curve morphology study shows that the outer magnetosphere gap emission (OGs) are favoured to explain the observed radio-gamma lag. The light curve moment studies (symmetry and sharpness) on the contrary favour a two pole caustic SG emission. All the model predictions suggest a different magnetic field layout with an hybrid two pole caustic and intermediate altitude emission to explain both the pulsar luminosity and light curve morphology. The low magnetosphere emission mechanism of the polar cap model, is systematically rejected by all the tests done. (author) [fr

  7. VizieR Online Data Catalog: SNe II light curves & spectra from the CfA (Hicken+, 2017)

    Science.gov (United States)

    Hicken, M.; Friedman, A. S.; Blondin, S.; Challis, P.; Berlind, P.; Calkins, M.; Esquerdo, G.; Matheson, T.; Modjaz, M.; Rest, A.; Kirshner, R. P.

    2018-01-01

    Since all of the optical photometry reported here was produced as part of the CfA3 and CfA4 processing campaigns, see Hicken+ (2009, J/ApJ/700/331) and Hicken+ (2012, J/ApJS/200/12) for greater details on the instruments, observations, photometry pipeline, calibration, and host-galaxy subtraction used to create the CfA SN II light curves. (8 data files).

  8. The frequency content of Double-Mode Cepheids light curves and the importance of the cross-coupling terms

    OpenAIRE

    Poretti, Ennio

    1997-01-01

    The recent results (Pardo & Poretti 1997, A&A 324, 121; Poretti & Pardo 1997, A&A 324, 133) obtained on the frequency content of Double-Mode Cepheids light curves and the properties of their Fourier parameters are reviewed. Some points briefly discussed in previous papers (no third periodicity, methodological aspects on the true peaks detection, the action of the cross coupling terms and the impact on theoretical models) are described.

  9. Gamma-Ray Bursts: Lighting Up the High-Redshift Universe

    Science.gov (United States)

    Toy, Vicki Louise

    Gamma-ray bursts (GRBs) are the most luminous events in the Universe with Egamma,iso ˜ 1048-54 erg. Leading models hypothesize that GRBs are created from inter- nal collisions within collimated and ultrarelativistic jets. The jets then shock-heat the surrounding material (e.g. interstellar medium) to create GRB afterglows. These afterglows are extremely useful probes of the Universe because long GRBs are (1) bright events that can be used as backlights for absorption studies, (2) able to probe at all redshifts massive stars exist, and (3) transient events that allow us to follow- up on the host galaxies at late times. In this thesis we study the environments of GRBs. We first explore the relationship between GRB and supernova (SN) using a nearby GRB-SN (GRB 130702A/SN 2013dx) at z = 0.145. There are only nine other GRB-SNe that were close enough to have extensive spectroscopic and photometric follow-up of the SN at late times. We create a quasi-bolometic light curve of SN 2013dx and fit an analytical equation to the quasi-bolometric light curve combined with measurements of the photospheric velocity to determine SN parameters: mass of 56Ni, kinetic energy, and ejecta mass. We examine the relationship between SN parameters and E gamma,iso for the 10 well-studied GRB-SNe, but find no correlations despite numerical simulation predictions that the mass of 56Ni should correlate with the degree of asymmetry. We then move to larger distance scales and use GRB afterglows as bright back- lights to study distant galaxies. We examine the galactic environments of Damped Lyman-alpha systems (DLAs; NHI ≥ 1020.3 cm-2 ) identified with GRB afterglows at z ˜ 2 - 6. We use late-time photometry after the GRB afterglow has faded to determine star formation rates (SFRs) from rest-frame ultraviolet measurements or spectral energy distribution (SED) models from multiband photometry. We com- pare our sample's SFRs to a sample of quasars (QSOs) DLA host galaxies. Despite the

  10. Synchrotron self-inverse Compton radiation from reverse shock on GRB 120326A

    Energy Technology Data Exchange (ETDEWEB)

    Urata, Yuji [Institute of Astronomy, National Central University, Chung-Li 32054, Taiwan (China); Huang, Kuiyun; Takahashi, Satoko [Academia Sinica Institute of Astronomy and Astrophysics, Taipei 106, Taiwan (China); Im, Myungshin; Kim, Jae-Woo; Jang, Minsung [Center for the Exploration of the Origin of the Universe, Department of Physics and Astronomy, FPRD, Seoul National University, Shillim-dong, San 56-1, Kwanak-gu, Seoul (Korea, Republic of); Yamaoka, Kazutaka [Solar-Terrestrial Environment Laboratory, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8601 (Japan); Tashiro, Makoto [Department of Physics, Saitama University, Shimo-Okubo, Saitama 338-8570 (Japan); Pak, Soojong, E-mail: urata@astro.ncu.edu.tw [School of Space Research, Kyung Hee University, Yongin, Gyeonggi 446-701 (Korea, Republic of)

    2014-07-10

    We present multi-wavelength observations of a typical long duration GRB 120326A at z = 1.798, including rapid observations using a Submillimeter Array (SMA) and a comprehensive monitoring in the X-ray and optical. The SMA observation provided the fastest detection to date among seven submillimeter afterglows at 230 GHz. The prompt spectral analysis, using Swift and Suzaku, yielded a spectral peak energy of E{sub peak}{sup src}=107.8{sub −15.3}{sup +15.3} keV and an equivalent isotropic energy of E{sub iso} as 3.18{sub −0.32}{sup +0.40}×10{sup 52} erg. The temporal evolution and spectral properties in the optical were consistent with the standard forward shock synchrotron with jet collimation (6.°69 ± 0.°16). The forward shock modeling, using a two-dimensional relativistic hydrodynamic jet simulation, was also determined by the reasonable burst explosion and the synchrotron radiation parameters for the optical afterglow. The X-ray light curve showed no apparent jet break and the temporal decay index relation between the X-ray and optical (αo – α{sub X} = –1.45 ± 0.10) indicated different radiation processes in each of them. Introducing synchrotron self-inverse Compton radiation from reverse shock is a possible solution, and the detection and slow decay of the afterglow in submillimeter supports that this is a plausible idea. The observed temporal evolution and spectral properties, as well as forward shock modeling parameters, enabled us to determine reasonable functions to describe the afterglow properties. Because half of the events share similar properties in the X-ray and optical as the current event, GRB 120326A will be a benchmark with further rapid follow-ups, using submillimeter instruments such as an SMA and the Atacama Large Millimeter/submillimeter Array.

  11. Synchrotron self-inverse Compton radiation from reverse shock on GRB 120326A

    International Nuclear Information System (INIS)

    Urata, Yuji; Huang, Kuiyun; Takahashi, Satoko; Im, Myungshin; Kim, Jae-Woo; Jang, Minsung; Yamaoka, Kazutaka; Tashiro, Makoto; Pak, Soojong

    2014-01-01

    We present multi-wavelength observations of a typical long duration GRB 120326A at z = 1.798, including rapid observations using a Submillimeter Array (SMA) and a comprehensive monitoring in the X-ray and optical. The SMA observation provided the fastest detection to date among seven submillimeter afterglows at 230 GHz. The prompt spectral analysis, using Swift and Suzaku, yielded a spectral peak energy of E peak src =107.8 −15.3 +15.3 keV and an equivalent isotropic energy of E iso as 3.18 −0.32 +0.40 ×10 52 erg. The temporal evolution and spectral properties in the optical were consistent with the standard forward shock synchrotron with jet collimation (6.°69 ± 0.°16). The forward shock modeling, using a two-dimensional relativistic hydrodynamic jet simulation, was also determined by the reasonable burst explosion and the synchrotron radiation parameters for the optical afterglow. The X-ray light curve showed no apparent jet break and the temporal decay index relation between the X-ray and optical (αo – α X = –1.45 ± 0.10) indicated different radiation processes in each of them. Introducing synchrotron self-inverse Compton radiation from reverse shock is a possible solution, and the detection and slow decay of the afterglow in submillimeter supports that this is a plausible idea. The observed temporal evolution and spectral properties, as well as forward shock modeling parameters, enabled us to determine reasonable functions to describe the afterglow properties. Because half of the events share similar properties in the X-ray and optical as the current event, GRB 120326A will be a benchmark with further rapid follow-ups, using submillimeter instruments such as an SMA and the Atacama Large Millimeter/submillimeter Array.

  12. The All-Sky Automated Survey for Supernovae (ASAS-SN) Light Curve Server v1.0

    Science.gov (United States)

    Kochanek, C. S.; Shappee, B. J.; Stanek, K. Z.; Holoien, T. W.-S.; Thompson, Todd A.; Prieto, J. L.; Dong, Subo; Shields, J. V.; Will, D.; Britt, C.; Perzanowski, D.; Pojmański, G.

    2017-10-01

    The All-Sky Automated Survey for Supernovae (ASAS-SN) is working toward imaging the entire visible sky every night to a depth of V˜ 17 mag. The present data covers the sky and spans ˜2-5 years with ˜100-400 epochs of observation. The data should contain some ˜1 million variable sources, and the ultimate goal is to have a database of these observations publicly accessible. We describe here a first step, a simple but unprecedented web interface https://asas-sn.osu.edu/ that provides an up to date aperture photometry light curve for any user-selected sky coordinate. The V band photometry is obtained using a two-pixel (16.″0) radius aperture and is calibrated against the APASS catalog. Because the light curves are produced in real time, this web tool is relatively slow and can only be used for small samples of objects. However, it also imposes no selection bias on the part of the ASAS-SN team, allowing the user to obtain a light curve for any point on the celestial sphere. We present the tool, describe its capabilities, limitations, and known issues, and provide a few illustrative examples.

  13. Oscillatory patterns in the light curves of five long-term monitored type 1 active galactic nuclei

    Science.gov (United States)

    Kovačević, Andjelka B.; Pérez-Hernández, Ernesto; Popović, Luka Č.; Shapovalova, Alla I.; Kollatschny, Wolfram; Ilić, Dragana

    2018-04-01

    New combined data of five well-known type 1 active galactic nuclei (AGNs) are probed with a novel hybrid method in a search for oscillatory behaviour. Additional analysis of artificial light curves obtained from the coupled oscillatory models gives confirmation for detected periods that could have a physical background. We find periodic variations in the long-term light curves of 3C 390.3, NGC 4151 and NGC 5548, and E1821 + 643, with correlation coefficients larger than 0.6. We show that the oscillatory patterns of two binary black hole candidates, NGC 5548 and E1821 + 643, correspond to qualitatively different dynamical regimes of chaos and stability, respectively. We demonstrate that the absence of oscillatory patterns in Arp 102B could be the result of a weak coupling between oscillatory mechanisms. This is the first good evidence that 3C 390.3 and Arp 102B, categorized as double-peaked Balmer line objects, have qualitative different dynamics. Our analysis shows a novelty in the oscillatory dynamical patterns of the light curves of these type 1 AGNs.

  14. PyTranSpot: A tool for multiband light curve modeling of planetary transits and stellar spots

    Science.gov (United States)

    Juvan, Ines G.; Lendl, M.; Cubillos, P. E.; Fossati, L.; Tregloan-Reed, J.; Lammer, H.; Guenther, E. W.; Hanslmeier, A.

    2018-02-01

    Several studies have shown that stellar activity features, such as occulted and non-occulted starspots, can affect the measurement of transit parameters biasing studies of transit timing variations and transmission spectra. We present PyTranSpot, which we designed to model multiband transit light curves showing starspot anomalies, inferring both transit and spot parameters. The code follows a pixellation approach to model the star with its corresponding limb darkening, spots, and transiting planet on a two dimensional Cartesian coordinate grid. We combine PyTranSpot with a Markov chain Monte Carlo framework to study and derive exoplanet transmission spectra, which provides statistically robust values for the physical properties and uncertainties of a transiting star-planet system. We validate PyTranSpot's performance by analyzing eleven synthetic light curves of four different star-planet systems and 20 transit light curves of the well-studied WASP-41b system. We also investigate the impact of starspots on transit parameters and derive wavelength dependent transit depth values for WASP-41b covering a range of 6200-9200 Å, indicating a flat transmission spectrum.

  15. The X-Ray Light Curve of the Very Luminous Supernova SN 1978K in NGC 1313

    Science.gov (United States)

    Schlegel, Eric M.; Petre, R.; Colbert, E. J. M.

    1996-01-01

    We present the 0.5-2.0 keV light curve of the X-ray luminous supernova SN 1978K in NGC 1313, based on six ROSAT observations spanning 1990 July to t994 July. SN 1978K is one of a few supernovae or supernova remnants that are very luminous (˜1039-1040 ergs s-1) in the X-ray, optical, and radio bands, and the first, at a supernova age of 10-20 yr, for which sufficient data exist to create an X-ray light curve. The X-ray flux is approximately constant over the 4 yr sampled by our observations, which were obtained 12-16 yr after the initial explosion. Three models exist to explain the large X-ray luminosity: pulsar input, a reverse shock running back into the expanding debris of the supernova, and the outgoing shock crushing of cloudlets in the debris field. Based upon calculations of Chevalier & Fransson, a pulsar cannot provide sufficient energy to produce the soft X-ray luminosity. Based upon the models and the light curve to date, it is not possible to discern the evolutionary phase of the supernova.

  16. GRB 081029: A Gamma-Ray Burst with a Multi-Component Afterglow

    Science.gov (United States)

    Holland, Stephen T.; De Pasquale, Massimiliano; Mao, Jirong; Sakamoto, Takanori; Schady, Patricia; Covino, Stefano; Fan, Yi-Zhong; Jin, Zhi-Ping; D'Avanzo, Paolo; Antonelli, Angelo; hide

    2012-01-01

    We present an analysis of the unusual optical light curve of the gamma-ray burst GRB 081029, a long-soft burst with a redshift of z = 3.8479. We combine X-ray and optical observations from the Swift X-Ray Telescope and the Swift Ultra Violet/Optical Telescope with ground-based optical and infrared data obtained using the REM, ROTSE, and CTIO 1.3-m telescopes to construct a detailed data set extending from 86 s to approx.100,000 s after the BAT trigger. Our data covers a wide energy range, from 10 keV to 0.77 eV (1.24 A to 16000 A). The X-ray afterglow shows a shallow initial decay followed by a rapid decay starting at about 18,000 s. The optical and infrared afterglow, however, shows an uncharacteristic rise at about 3000 s that does not correspond to any feature in the X-ray light curve. Our data are not consistent with synchrotron radiation from a jet interacting with an external medium, a two-component jet, or continuous energy injection from the central engine. We find that the optical light curves can be broadly explained by a collision between two ejecta shells within a two-component jet. A growing number of gamma-ray burst afterglows are consistent with complex jets, which suggests that some (or all) gamma-ray burst jets are complex and will require detailed modelling to fully understand them.injection

  17. Broad band simulation of Gamma Ray Bursts (GRB) prompt emission in presence of an external magnetic field

    Science.gov (United States)

    Ziaeepour, Houri; Gardner, Brian

    2011-12-01

    The origin of prompt emission in GRBs is not yet well understood. The simplest and most popular model is Synchrotron Self-Compton (SSC) emission produced by internal shocks inside an ultra-relativistic jet. However, recent observations of a delayed high energy component by the Fermi-LAT instrument have encouraged alternative models. Here we use a recently developed formulation of relativistic shocks for GRBs to simulate light curves and spectra of synchrotron and self-Compton emissions in the framework of internal shock model. This model takes into account the evolution of quantities such as densities of colliding shells, and fraction of kinetic energy transferred to electrons and to induced magnetic field. We also extend this formulation by considering the presence of a precessing external magnetic field. These simulations are very realistic and present significant improvement with respect to previous phenomenological GRB simulations. They reproduce light curves of separate peaks of real GRBs and variety of spectral slopes at E > Epeak observed by the Fermi-LAT instrument. The high energy emission can be explained by synchrotron emission and a subdominant contribution from inverse Compton. We also suggest an explanation for extended tail emission and relate it to the screening of the magnetic field and/or trapping of accelerated electrons in the electromagnetic energy structure of the plasma in the shock front. Spectral slopes of simulated bursts at E external magnetic field, we show that due to the fast variation of other quantities, its signature in the Power Distribution Spectrum (PDS) is significantly suppressed and only when the duration of the burst is few times longer than the oscillation period it can be detected, otherwise either it is confused with the Poisson noise or with intrinsic variations of the emission. Therefore, low significant oscillations observed in the PDS of GRB 090709a are most probably due to a precessing magnetic field.

  18. Helical Tomography of an Accretion Disk by Superhump Light Curves of the 2001 Outburst of WZ Sagittae

    Science.gov (United States)

    Osaki, Yoji

    2003-06-01

    A new method for analyzing complex superhump light curves for the 2001 outburst of WZ Sagittae is proposed. The complexity arises because intrinsically time-varying and non-axisymmetric distributions of superhump light sources are coupled with the aspect effects around the binary orbital phase because of its high orbital inclination. The new method can disentangle these complexities by separating the non-axisymmetric spatial distribution in the disk from the time variation with the superhump period. It may be called a helical tomography of an accretion disk because it can reconstruct a series of disk images (i.e., disk's azimuthal structures) at different superhump phases. The power spectral data of superhump light curves of the 2001 outburst of WZ Sge by Patterson et al. (2002, PASP, 114, 721) are now interpreted under a new light based on the concept of helical tomography, and the azimuthal wave numbers of various frequency modes are identified. In particular, a frequen! cy component, nω0 - Ω, where ω0 and Ω are the orbital frequency and a low frequency of the apsidal precession of the eccentric disk, is understood as an (n - 1)-armed traveling wave in the disk. A vigorous excitation of a wave component of cos(2Θ - 3ω0t) in the first week of the superhump era of WZ Sge, where Θ is the azimuthal angle, supports Lubow's (1991, AAA 54.064.175) theory of non-linear wave coupling of the eccentric Lindblad resonance for the superhump phenomenon. This method can in principle be applied to other SU UMa stars with high orbital inclination if light curves are fully covered over the beat cycle.

  19. B and V photoelectric photometry and light curve solution of the interacting binary systems HI Puppis, BL Eridani and SY Horologii

    International Nuclear Information System (INIS)

    Kern, J.R.

    1985-01-01

    The first photoelectric observations of the eclipsing binary systems HI Puppis, BL Eridani, and SY Horologii were obtained and complete B and V light curves are presented. Improved light elements were derived for all three systems. The light curves of HI Puppis were analyzed by the three different computer models of Wilson and Devinney (1971), Binnendijk (1977), and Wood (1971) to get the geometrical and photometric elements of the system. HI Puppis, whose light curves show a total eclipse at secondary minimum, is shown to be a classic A-Type W Ursae Majoris system. The geometrical and photometric elements of BL Eridani were obtained from the analysis of the light curves using the method of Wilson and Devinney. The asymmetric nature of the light curve is treated as being due to the presence of an underluminous starspot on the primary component. The light curves of BL Eri show secondary eclipse to be total. The system is found to be a near contact system with the primary component filling its Roche lobe and the secondary nearly filling its lobe with a fill-out ratio of approximately 1.0. The light curves of SY Horologii were also subjected to the model of Wilson and Devinney. Both primary and secondary eclipses are partial

  20. The effect of scattered light sensor orientation on roughness measurement of curved polished surfaces

    DEFF Research Database (Denmark)

    Pilny, Lukas; Bissacco, Giuliano; De Chiffre, Leonardo

    directions, and its acquisition within ± 16º angular range with a linear detector array. From the distribution of the acquired scattered light intensity, a number of statistical parameters describing the surface texture are calculated, where the Aq parameter (variance of the scattered light distribution...

  1. The mass of the black hole in 1A 0620-00, revisiting the ellipsoidal light curve modelling

    Science.gov (United States)

    van Grunsven, Theo F. J.; Jonker, Peter G.; Verbunt, Frank W. M.; Robinson, Edward L.

    2017-12-01

    The mass distribution of stellar-mass black holes can provide important clues to supernova modelling, but observationally it is still ill constrained. Therefore, it is of importance to make black hole mass measurements as accurate as possible. The X-ray transient 1A 0620-00 is well studied, with a published black hole mass of 6.61 ± 0.25 M⊙, based on an orbital inclination i of 51.0° ± 0.9°. This was obtained by Cantrell et al. (2010) as an average of independent fits to V-, I- and H-band light curves. In this work, we perform an independent check on the value of i by re-analysing existing YALO/SMARTS V-, I- and H-band photometry, using different modelling software and fitting strategy. Performing a fit to the three light curves simultaneously, we obtain a value for i of 54.1° ± 1.1°, resulting in a black hole mass of 5.86 ± 0.24 M⊙. Applying the same model to the light curves individually, we obtain 58.2° ± 1.9°, 53.6° ± 1.6° and 50.5° ± 2.2° for V-, I- and H-band, respectively, where the differences in best-fitting i are caused by the contribution of the residual accretion disc light in the three different bands. We conclude that the mass determination of this black hole may still be subject to systematic effects exceeding the statistical uncertainty. Obtaining more accurate masses would be greatly helped by continuous phase-resolved spectroscopic observations simultaneous with photometry.

  2. Tyrosine phosphorylation of Grb14 by Tie2

    Directory of Open Access Journals (Sweden)

    Dumont Daniel J

    2010-10-01

    Full Text Available Abstract Background Growth factor receptor bound (Grb proteins 7, 10 and 14 are a family of structurally related multi-domain adaptor proteins involved in a variety of biological processes. Grb7, 10 and 14 are known to become serine and/or threonine phosphorylated in response to growth factor (GF stimulation. Grb7 and 10 have also been shown to become tyrosine phosphorylated under certain conditions. Under experimental conditions Grb7 is tyrosine phosphorylated by the Tie2/Tie-2/Tek angiogenic receptor tyrosine kinase (RTK. Furthermore, Grb14 has also been shown to interact with Tie2, however tyrosine phosphorylation of this Grb family member has yet to be reported. Results Here we report for the first time tyrosine phosphorylation of Grb14. This phosphorylation requires a kinase competent Tie2 as well as intact tyrosines 1100 and 1106 (Y1100 and Y1106 on the receptor. Furthermore, a complete SH2 domain on Grb14 is required for Grb14 tyrosine phosphorylation by Tie2. Grb14 was also able to become tyrosine phosphorylated in primary endothelial cells when treated with a soluble and potent variant of the Tie2 ligand, cartilage oligomeric matrix protein (COMP Ang1. Conclusion Our results show that Grb14, like its family members Grb7 and Grb10, is able to be tyrosine phosphorylated. Furthermore, our data indicate a role for Grb14 in endothelial signaling downstream of the Tie2 receptor.

  3. On the number of light rings in curved spacetimes of ultra-compact objects

    Science.gov (United States)

    Hod, Shahar

    2018-01-01

    In a very interesting paper, Cunha, Berti, and Herdeiro have recently claimed that ultra-compact objects, self-gravitating horizonless solutions of the Einstein field equations which have a light ring, must possess at least two (and, in general, an even number of) light rings, of which the inner one is stable. In the present compact paper we explicitly prove that, while this intriguing theorem is generally true, there is an important exception in the presence of degenerate light rings which, in the spherically symmetric static case, are characterized by the simple dimensionless relation 8 πrγ2 (ρ +pT) = 1 [here rγ is the radius of the light ring and { ρ ,pT } are respectively the energy density and tangential pressure of the matter fields]. Ultra-compact objects which belong to this unique family can have an odd number of light rings. As a concrete example, we show that spherically symmetric constant density stars with dimensionless compactness M / R = 1 / 3 possess only one light ring which, interestingly, is shown to be unstable.

  4. Circadian phase response curves to light in older and young women and men

    Directory of Open Access Journals (Sweden)

    Rex Katharine M

    2007-07-01

    Full Text Available Abstract Background The phase of a circadian rhythm reflects where the peak and the trough occur, for example, the peak and trough of performance within the 24 h. Light exposure can shift this phase. More extensive knowledge of the human circadian phase response to light is needed to guide light treatment for shiftworkers, air travelers, and people with circadian rhythm phase disorders. This study tested the hypotheses that older adults have absent or weaker phase-shift responses to light (3000 lux, and that women's responses might differ from those of men. Methods After preliminary health screening and home actigraphic recording baselines, 50 young adults (ages 18–31 years and 56 older adults (ages 59–75 years remained in light-controlled laboratory surroundings for 4.7 to 5.6 days, while experiencing a 90-min ultra-short sleep-wake cycle. Following at least 30 h in-lab baseline, over the next 51 h, participants were given 3 treatments with 3000 lux white light, each treatment for 3 h, centered at one of 8 clock times. The circadian rhythms of urinary aMT6s (a melatonin metabolite, free cortisol, oral temperature, and wrist activity were assessed at baseline and after treatment. Results Light (3000 lux for 3 h on 3 days induced maximal phase shifts of about 3 h. Phase shifts did not differ significantly in amplitude among older and young groups or among women and men. At home and at baseline, compared to the young, the older adults were significantly phase-advanced in sleep, cortisol, and aMT6s onset, but not advanced in aMT6s acrophase or the temperature rhythm. The inflection from delays to advances was approximately 1.8 h earlier among older compared to young participants in reference to their aMT6s rhythm peaks, and it was earlier in clock time. Conclusion In these experimental conditions, 3000 lux light could shift the phase of circadian rhythms to about the same extent among older and young adults, but the optimal light timing for

  5. One-phase and two-phase homologous curves for coolant pumps of the pressurized light water nuclear reactors

    International Nuclear Information System (INIS)

    Santos, G.A. dos.

    1990-01-01

    The two-phase coolant pump model of pressurized light water nuclear reactors is an important point for the loss of primary coolant accident analysis. The single-phase pump characteristics are an essential feature for operational transients studies, for example, the shut-down and start-up of pump. These parameters, in terms of the homologous curves, set up the complete performance of the pump and are input for transients and accidents analysis thermal-hydraulic codes. This work propose a mathematical model able to predict the single-phase and two-phase homologous curves where it was incorporated geometric and operational pump condition. The results were compared with the experimental tests data from literature and it has showed a good agreement. (author)

  6. CONSTRUCTION OF AN EARTH MODEL: ANALYSIS OF EXOPLANET LIGHT CURVES AND MAPPING THE NEXT EARTH WITH THE NEW WORLDS OBSERVER

    International Nuclear Information System (INIS)

    Oakley, P. H. H.; Cash, W.

    2009-01-01

    The orbital light curve of a terrestrial exoplanet will likely contain valuable information about the surface and atmospheric features of the planet, both in its overall shape and hourly variations. We have constructed an empirically based code capable of simulating observations of the Earth from any orientation, at any time of year with continuously updated cloud and snow coverage with a New Worlds Observatory. By simulating these observations over a full orbital revolution at a distance of 10 pc we determine that the detection of an obliquity or seasonal terrain change is possible at low inclinations. In agreement with other studies, a 4 m New Worlds Observer can accurately determine the rotation rate of the planet at a success rate from ∼30% to 80% with only 5 days of observations depending on the signal to noise of the observations. We also attempt simple inversions of these diurnal light curves to sketch a map of the reflecting planet's surface features. This mapping technique is only successful with highly favorable systems and in particular requires that the cloud coverage must be lower than the Earth's average. Our test case of a 2 M + planet at 7 pc distance with low exo-zodiacal light and 25% cloud coverage produced crude, but successful results. Additionally, with these highly favorable systems NWO may be able to discern the presence of liquid surface water (or other smooth surfaces) though it requires a complex detection available only at crescent phases in high inclination systems.

  7. GRB 111005A at z = 0.0133 and the Prospect of Establishing Long-Short GRB/GW Association

    Science.gov (United States)

    Wang, Yuan-Zhu; Huang, Yong-Jia; Liang, Yun-Feng; Li, Xiang; Jin, Zhi-Ping; Zhang, Fu-Wen; Zou, Yuan-Chuan; Fan, Yi-Zhong; Wei, Da-Ming

    2017-12-01

    GRB 111005A, a long-duration gamma-ray burst (GRB) that occurred within a metal-rich environment that lacks massive stars with {M}{ZAMS}≥slant 15 {M}⊙ , is not coincident with supernova emission down to a stringent limit and thus should be classified as a “long-short” GRB (lsGRB; also known as an SN-less long GRB or hybrid GRB), like GRB 060505 and GRB 060614. In this work, we show that in the neutron star merger model the non-detection of the optical/infrared emission of GRB 111005A requires sub-relativistic neutron-rich ejecta with a mass of ≤slant 0.01 {M}⊙ , which is (significantly) less massive than that of GRB 130603B, GRB 060614, GRB 050709, and GRB 170817A. The lsGRBs are found to have a high rate density and the neutron star merger origin model can be unambiguously tested by the joint observations of the second-generation gravitational-wave (GW) detectors and the full-sky gamma-ray monitors such as Fermi-GBM and the proposed GECAM. If no lsGRB/GW association is observed in the 2020s, alternative scenarios have to be systematically investigated. With the detailed environmental information achievable for the nearby events, a novel kind of merger or explosion origin may be identified.

  8. GRB 170817A as a jet counterpart to gravitational wave trigger GW 170817

    Science.gov (United States)

    Lamb, Gavin P.; Kobayashi, Shiho

    2018-05-01

    Fermi/GBM (Gamma-ray Burst Monitor) and INTEGRAL (the International Gamma-ray Astrophysics Laboratory) reported the detection of the γ-ray counterpart, GRB 170817A, to the LIGO (Light Interferometer Gravitational-wave Observatory)/Virgo gravitational wave detected binary neutron star merger, GW 170817. GRB 170817A is likely to have an internal jet or another origin such as cocoon emission, shock-breakout, or a flare from a viscous disc. In this paper we assume that the γ-ray emission is caused by energy dissipation within a relativistic jet and we model the afterglow synchrotron emission from a reverse- and forward-shock in the outflow. We show the afterglow for a low-luminosity γ-ray burst (GRB) jet with a high Lorentz-factor (Γ); a low-Γ and low-kinetic energy jet; a low-Γ, high kinetic energy jet; structured jets viewed at an inclination within the jet-half-opening angle; and an off-axis `typical' GRB jet. All jet models will produce observable afterglows on various timescales. The late-time afterglow from 10-110 days can be fit by a Gaussian structured jet viewed at a moderate inclination, however the GRB is not directly reproduced by this model. These jet afterglow models can be used for future GW detected NS merger counterparts with a jet afterglow origin.

  9. Effect of F- and Z2-light illumination on thermal glow curves of pretreated NaCl:Ca phosphors

    International Nuclear Information System (INIS)

    Joshi, R.V.; Dhake, K.P.; Joshi, T.R.

    1985-01-01

    It is known that colour centres are produced when doped or undoped alkali halides are exposed to ionizing radiation. Earlier work has also revealed an intimate relationship between the thermoluminescence (TL) centres associated with the glow peaks and different species of colour centres. The aim of the present investigation has been to find out the species of colour centres associated with the observed thermal glow peaks. The measurements were carried out on thermally treated Ca-doped NaCl phosphors. The thermal treatment involves annealing of the phosphors at 550 C. The specimens were irradiated by a 90 Sr 20 mCi source. A figure showing the glow curves recorded immediately after β-irradiation, after β-irradiation followed by F-light illumination and after β-irradiation followed by 20 min decay at room temperature. The F-light illumination leads to the quenching of the peak at 137 C and generates new peaks at 113 and 157 C. The bleaching effect becomes more significant with the increase in the duration of F-light illumination. The effect of F-light illumination followed by Z 2 -light illumination shows that of the two peaks appearing earlier, the 113 C peak is selectively suppressed. The isothermal bleaching at room temperature for 20 min does not affect the intensity of the 137 C peak. The results are discussed. (author)

  10. CSI 2264: CHARACTERIZING YOUNG STARS IN NGC 2264 WITH SHORT-DURATION PERIODIC FLUX DIPS IN THEIR LIGHT CURVES

    Energy Technology Data Exchange (ETDEWEB)

    Stauffer, John; Cody, Ann Marie; Rebull, Luisa; Plavchan, Peter; Carey, Sean [Spitzer Science Center, California Institute of Technology, Pasadena, CA 91125 (United States); McGinnis, Pauline; Alencar, Silvia H. P. [Departamento de Física—ICEx—UFMG, Av. Antônio Carlos, 6627, 30270-901, Belo Horizonte, MG (Brazil); Hillenbrand, Lynne A.; Carpenter, John [Astronomy Department, California Institute of Technology, Pasadena, CA 91125 (United States); Turner, Neal J. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Terebey, Susan [Department of Physics and Astronomy, 5151 State University Drive, California State University at Los Angeles, Los Angeles, CA 90032 (United States); Morales-Calderón, María [Centro de Astrobiología, Dpto. de Astrofísica, INTA-CSIC, PO BOX 78, E-28691, ESAC Campus, Villanueva de la Cañada, Madrid (Spain); Bouvier, Jerome; Venuti, Laura [Université de Grenoble, Institut de Planétologie et d’Astrophysique de Grenoble (IPAG), F-38000 Grenoble (France); CNRS, IPAG, F-38000 Grenoble (France); Hartmann, Lee; Calvet, Nuria [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48105 (United States); Micela, Giusi; Flaccomio, Ettore [INAF—Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, I-90134, Palermo (Italy); Song, Inseok [Department of Physics and Astronomy, The University of Georgia, Athens, GA 30602–2451 (United States); Gutermuth, Rob, E-mail: stauffer@ipac.caltech.edu [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States); and others

    2015-04-15

    We identify nine young stellar objects (YSOs) in the NGC 2264 star-forming region with optical CoRoT light curves exhibiting short-duration, shallow periodic flux dips. All of these stars have infrared excesses that are consistent with their having inner disk walls near the Keplerian co-rotation radius. The repeating photometric dips have FWHMs generally less than 1 day, depths almost always less than 15%, and periods (3 < P < 11 days) consistent with dust near the Keplerian co-rotation period. The flux dips vary considerably in their depth from epoch to epoch, but usually persist for several weeks and, in two cases, were present in data collected in successive years. For several of these stars, we also measure the photospheric rotation period and find that the rotation and dip periods are the same, as predicted by standard “disk-locking” models. We attribute these flux dips to clumps of material in or near the inner disk wall, passing through our line of sight to the stellar photosphere. In some cases, these dips are also present in simultaneous Spitzer IRAC light curves at 3.6 and 4.5 microns. We characterize the properties of these dips, and compare the stars with light curves exhibiting this behavior to other classes of YSOs in NGC 2264. A number of physical mechanisms could locally increase the dust scale height near the inner disk wall, and we discuss several of those mechanisms; the most plausible mechanisms are either a disk warp due to interaction with the stellar magnetic field or dust entrained in funnel-flow accretion columns arising near the inner disk wall.

  11. CSI 2264: CHARACTERIZING YOUNG STARS IN NGC 2264 WITH SHORT-DURATION PERIODIC FLUX DIPS IN THEIR LIGHT CURVES

    International Nuclear Information System (INIS)

    Stauffer, John; Cody, Ann Marie; Rebull, Luisa; Plavchan, Peter; Carey, Sean; McGinnis, Pauline; Alencar, Silvia H. P.; Hillenbrand, Lynne A.; Carpenter, John; Turner, Neal J.; Terebey, Susan; Morales-Calderón, María; Bouvier, Jerome; Venuti, Laura; Hartmann, Lee; Calvet, Nuria; Micela, Giusi; Flaccomio, Ettore; Song, Inseok; Gutermuth, Rob

    2015-01-01

    We identify nine young stellar objects (YSOs) in the NGC 2264 star-forming region with optical CoRoT light curves exhibiting short-duration, shallow periodic flux dips. All of these stars have infrared excesses that are consistent with their having inner disk walls near the Keplerian co-rotation radius. The repeating photometric dips have FWHMs generally less than 1 day, depths almost always less than 15%, and periods (3 < P < 11 days) consistent with dust near the Keplerian co-rotation period. The flux dips vary considerably in their depth from epoch to epoch, but usually persist for several weeks and, in two cases, were present in data collected in successive years. For several of these stars, we also measure the photospheric rotation period and find that the rotation and dip periods are the same, as predicted by standard “disk-locking” models. We attribute these flux dips to clumps of material in or near the inner disk wall, passing through our line of sight to the stellar photosphere. In some cases, these dips are also present in simultaneous Spitzer IRAC light curves at 3.6 and 4.5 microns. We characterize the properties of these dips, and compare the stars with light curves exhibiting this behavior to other classes of YSOs in NGC 2264. A number of physical mechanisms could locally increase the dust scale height near the inner disk wall, and we discuss several of those mechanisms; the most plausible mechanisms are either a disk warp due to interaction with the stellar magnetic field or dust entrained in funnel-flow accretion columns arising near the inner disk wall

  12. SDSS J14584479+3720215: A BENCHMARK JHK{sub S} BLAZAR LIGHT CURVE FROM THE 2MASS CALIBRATION SCANS

    Energy Technology Data Exchange (ETDEWEB)

    Davenport, James R. A.; Ruan, John J.; Becker, Andrew C. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Macleod, Chelsea L. [Physics Department, The United States Naval Academy, 572c Holloway Road, Annapolis, MD 21402 (United States); Cutri, Roc M., E-mail: jrad@astro.washington.edu [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States)

    2015-04-10

    Active galactic nuclei (AGNs) are well-known to exhibit flux variability across a wide range of wavelength regimes, but the precise origin of the variability at different wavelengths remains unclear. To investigate the relatively unexplored near-IR (NIR) variability of the most luminous AGNs, we conduct a search for variability using well sampled JHK{sub s}-band light curves from the Two Micron All Sky Survey (2MASS) calibration fields. Our sample includes 27 known quasars with an average of 924 epochs of observation over three years, as well as one spectroscopically confirmed blazar (SDSS J14584479+3720215) with 1972 epochs of data. This is the best-sampled NIR photometric blazar light curve to date, and it exhibits correlated, stochastic variability that we characterize with continuous auto-regressive moving average (CARMA) models. None of the other 26 known quasars had detectable variability in the 2MASS bands above the photometric uncertainty. A blind search of the 2MASS calibration field light curves for active galactic nucleus (AGN) candidates based on fitting CARMA(1,0) models (damped-random walk) uncovered only seven candidates. All seven were young stellar objects within the ρ Ophiuchus star forming region, five with previous X-ray detections. A significant γ-ray detection (5σ) for the known blazar using 4.5 yr of Fermi photon data is also found. We suggest that strong NIR variability of blazars, such as seen for SDSS J14584479+3720215, can be used as an efficient method of identifying previously unidentified γ-ray blazars, with low contamination from other AGNs.

  13. Modelling the KIC8462852 light curves: compatibility of the dips and secular dimming with an exocomet interpretation

    Science.gov (United States)

    Wyatt, M. C.; van Lieshout, R.; Kennedy, G. M.; Boyajian, T. S.

    2018-02-01

    This paper shows how the dips and secular dimming in the KIC8462852 light curve can originate in circumstellar material distributed around a single elliptical orbit (e.g. exocomets). The expected thermal emission and wavelength dependent dimming is derived for different orbital parameters and geometries, including dust that is optically thick to stellar radiation, and for a size distribution of dust with realistic optical properties. We first consider dust distributed evenly around the orbit, then show how to derive its uneven distribution from the optical light curve and to predict light curves at different wavelengths. The fractional luminosity of an even distribution is approximately the level of dimming times stellar radius divided by distance from the star at transit. Non-detection of dust thermal emission for KIC8462852 thus provides a lower limit on the transit distance to complement the 0.6 au upper limit imposed by 0.4 d dips. Unless the dust distribution is optically thick, the putative 16 per cent century-long secular dimming must have disappeared before the WISE 12 μm measurement in 2010, and subsequent 4.5 μm observations require transits at >0.05 au. However, self-absorption of thermal emission removes these constraints for opaque dust distributions. The passage of dust clumps through pericentre is predicted to cause infrared brightening lasting tens of days and dimming during transit, such that total flux received decreases at wavelengths dimming levels than seen for KIC8462852 are more common in the Galactic population and may be detected in future transit surveys.

  14. Current-voltage characteristics of bulk heterojunction organic solar cells: connection between light and dark curves

    Energy Technology Data Exchange (ETDEWEB)

    Boix, Pablo P.; Guerrero, Antonio; Garcia-Belmonte, Germa; Bisquert, Juan [Photovoltaic and Optoelectronic Devices Group, Departament de Fisica, Universitat Jaume I, ES-12071 Castello (Spain); Marchesi, Luis F. [Laboratorio Interdisciplinar de, Eletroquimica e Ceramica (LIEC), Universidade Federal de Sao Carlos (Brazil); Photovoltaic and Optoelectronic Devices Group, Departament de Fisica, Universitat Jaume I, ES-12071 Castello (Spain)

    2011-11-15

    A connection is established between recombination and series resistances extracted from impedance spectroscopy and current-voltage curves of polythiophene:fullerene organic solar cells. Recombination is shown to depend exclusively on the (Fermi level) voltage, which allows construction of the current-voltage characteristics in any required conditions based on a restricted set of measurements. The analysis highlights carrier recombination current as the determining mechanism of organic solar cell performance. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Hardness ratio evolutionary curves of gamma-ray bursts expected by the curvature effect

    International Nuclear Information System (INIS)

    Qin, Y.-P.; Su, C.-Y.; Fan, J. H.; Gupta, A. C.

    2006-01-01

    We have investigated the gamma-ray bursts (GRBs) pulses with a fast rise and an exponential decay phase, assumed to arise from relativistically expending fireballs, and found that the curvature effect influences the evolutionary curve of the corresponding hardness ratio (hereafter HRC). We find, due to the curvature effect, the evolutionary curve of the pure hardness ratio (when the background count is not included) would peak at the very beginning of the curve, and then would undergo a drop-to-rise-to-decay phase. In the case of the raw hardness ratio (when the background count is included), the curvature effect would give rise to several types of evolutionary curve, depending on the hardness of a burst. For a soft burst, an upside down pulse of its raw HRC would be observed; for a hard burst, its raw HRC shows a pulselike profile with a sinkage in its decaying phase; for a very hard burst, the raw HRC possesses a pulselike profile without a sinkage in its decaying phase. For a pulselike raw HRC as shown in the case of the hard and very hard bursts, its peak would appear in advance of that of the corresponding light curve, which was observed previously in some GRBs. For illustration, we have studied here the HRC of GRB 920216, GRB 920830, and GRB 990816 in detail. The features of the raw HRC expected in the hard burst are observed in these bursts. A fit to the three bursts shows that the curvature effect alone could indeed account for the predicted characteristics of HRCs. In addition, we find that the observed hardness ratio tends to be harder at the beginning of the pulses than what the curvature effect could predict and be softer at the late time of the pulses. We believe this is an evidence showing the existence of intrinsic hard-to-soft radiation which might be due to the acceleration-to-deceleration mode of shocks

  16. Light distributions in a port wine stain model containing multiple cylindrical and curved blood vessels

    NARCIS (Netherlands)

    Lucassen, G. W.; Verkruysse, W.; Keijzer, M.; van Gemert, M. J.

    1996-01-01

    Knowledge of the light distribution in skin tissue is important for the understanding, prediction, and improvement of the clinical results in laser treatment of port wine stains (PWS). The objective of this study is to improve modelling of PWS treated by laser using an improved and more realistic

  17. WASP-36b: A NEW TRANSITING PLANET AROUND A METAL-POOR G-DWARF, AND AN INVESTIGATION INTO ANALYSES BASED ON A SINGLE TRANSIT LIGHT CURVE

    Energy Technology Data Exchange (ETDEWEB)

    Smith, A. M. S.; Anderson, D. R.; Hellier, C.; Maxted, P. F. L.; Smalley, B.; Southworth, J. [Astrophysics Group, Keele University, Staffordshire, ST5 5BG (United Kingdom); Collier Cameron, A. [SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, Fife, KY16 9SS (United Kingdom); Gillon, M.; Jehin, E. [Institut d' Astrophysique et de Geophysique, Universite de Liege, Allee du 6 Aout, 17 Bat. B5C, Liege 1 (Belgium); Lendl, M.; Queloz, D.; Triaud, A. H. M. J.; Pepe, F.; Segransan, D.; Udry, S. [Observatoire de Geneve, Universite de Geneve, 51 Chemin des Maillettes, 1290 Sauverny (Switzerland); West, R. G. [Department of Physics and Astronomy, University of Leicester, Leicester, LE1 7RH (United Kingdom); Barros, S. C. C.; Pollacco, D. [Astrophysics Research Centre, School of Mathematics and Physics, Queen' s University, University Road, Belfast, BT7 1NN (United Kingdom); Street, R. A., E-mail: amss@astro.keele.ac.uk [Las Cumbres Observatory, 6740 Cortona Drive Suite 102, Goleta, CA 93117 (United States)

    2012-04-15

    We report the discovery, from WASP and CORALIE, of a transiting exoplanet in a 1.54 day orbit. The host star, WASP-36, is a magnitude V = 12.7, metal-poor G2 dwarf (T{sub eff} = 5959 {+-} 134 K), with [Fe/H] =-0.26 {+-} 0.10. We determine the planet to have mass and radius, respectively, 2.30 {+-} 0.07 and 1.28 {+-} 0.03 times that of Jupiter. We have eight partial or complete transit light curves, from four different observatories, which allow us to investigate the potential effects on the fitted system parameters of using only a single light curve. We find that the solutions obtained by analyzing each of these light curves independently are consistent with our global fit to all the data, despite the apparent presence of correlated noise in at least two of the light curves.

  18. Change of characteristic curves using light emission spectrum of the intensifying screens

    International Nuclear Information System (INIS)

    Yoon, Chul Ho; Kang, Hong Seok; Lee, In Ja; Huh, Joon

    1990-01-01

    This report is study about difference of H-D curve in regular film and ortho type film, and obtained results as follows: 1. In the blue-color emission intensifying screen, ortho type films and in the green-color emission intensifying screens, regular type are decreased in their gradient. 2. When joint use of regular type film and ortho type film, the gradient difference not seen in blue color screen. 3. The gradient difference seen clearly in G4, KM screens (green color emission intensifying). Especially, in part of high film density, the gradient difference are great. So we have to right use of screen and film because not matched used of there the sensitivity and gradient are decrease

  19. Theoretical light curve for the recurrent nova RS Ophiuchi - Determination of the white dwarf mass, composition, and distance

    International Nuclear Information System (INIS)

    Kato, M.

    1991-01-01

    Sequences of steady mass-loss solutions are constructed for the envelopes on a white dwarf with mass 1.33, 1.35, 1.36, 1.37, and 1.377 solar mass as models of the decay phase of novae. The envelopes are assumed to have a uniform chemical composition with X = 0.73, 0.6, 0.52, 0.44, 0.33, and 0.11 for hydrogen and Z = 0.02 for heavy elements by weight. An excellent agreement with the observed light curves of UV and optical is obtained in the models with a white dwarf mass of 1.36 solar mass with hydrogen content X = 0.52, and 1.37 solar mass with X = 0.6. The distance of RS Oph is obtained to be 1.6 kpc from the comparison between the theoretical and observed light curves. The success of this wind model is a strong indication from the theoretical point of view that RS Oph is a thermonuclear runaway event. 31 refs

  20. AGAPEROS Searches for microlensing in the LMC with the Pixel Method; 1, Data treatment and pixel light curves production

    CERN Document Server

    Melchior, A.-L.; Ansari, R.; Aubourg, E.; Baillon, P.; Bareyre, P.; Bauer, F.; Beaulieu, J.-Ph.; Bouquet, A.; Brehin, S.; Cavalier, F.; Char, S.; Couchot, F.; Coutures, C.; Ferlet, R.; Fernandez, J.; Gaucherel, C.; Giraud-Heraud, Y.; Glicenstein, J.-F.; Goldman, B.; Gondolo, P.; Gros, M.; Guibert, J.; Gry, C.; Hardin, D.; Kaplan, J.; de Kat, J.; Lachieze-Rey, M.; Laurent, B.; Lesquoy, E.; Magneville, Ch.; Mansoux, B.; Marquette, J.-B.; Maurice, E.; Milsztajn, A.; Moniez, M.; Moreau, O.; Moscoso, L.; Palanque-Delabrouille, N.; Perdereau, O.; Prevot, L.; Renault, C.; Queinnec, F.; Rich, J.; Spiro, M.; Vigroux, L.; Zylberajch, S.; Vidal-Madjar, A.; Magneville, Ch.

    1999-01-01

    The presence and abundance of MAssive Compact Halo Objects (MACHOs) towards the Large Magellanic Cloud (LMC) can be studied with microlensing searches. The 10 events detected by the EROS and MACHO groups suggest that objects with 0.5 Mo could fill 50% of the dark halo. This preferred mass is quite surprising, and increasing the presently small statistics is a crucial issue. Additional microlensing of stars too dim to be resolved in crowded fields should be detectable using the Pixel Method. We present here an application of this method to the EROS 91-92 data (one tenth of the whole existing data set). We emphasize the data treatment required for monitoring pixel fluxes. Geometric and photometric alignments are performed on each image. Seeing correction and error estimates are discussed. 3.6" x 3.6" super-pixel light curves, thus produced, are very stable over the 120 days time-span. Fluctuations at a level of 1.8% of the flux in blue and 1.3% in red are measured on the pixel light curves. This level of stabil...

  1. A Data-driven Study of RR Lyrae Near-IR Light Curves: Principal Component Analysis, Robust Fits, and Metallicity Estimates

    Science.gov (United States)

    Hajdu, Gergely; Dékány, István; Catelan, Márcio; Grebel, Eva K.; Jurcsik, Johanna

    2018-04-01

    RR Lyrae variables are widely used tracers of Galactic halo structure and kinematics, but they can also serve to constrain the distribution of the old stellar population in the Galactic bulge. With the aim of improving their near-infrared photometric characterization, we investigate their near-infrared light curves, as well as the empirical relationships between their light curve and metallicities using machine learning methods. We introduce a new, robust method for the estimation of the light-curve shapes, hence the average magnitudes of RR Lyrae variables in the K S band, by utilizing the first few principal components (PCs) as basis vectors, obtained from the PC analysis of a training set of light curves. Furthermore, we use the amplitudes of these PCs to predict the light-curve shape of each star in the J-band, allowing us to precisely determine their average magnitudes (hence colors), even in cases where only one J measurement is available. Finally, we demonstrate that the K S-band light-curve parameters of RR Lyrae variables, together with the period, allow the estimation of the metallicity of individual stars with an accuracy of ∼0.2–0.25 dex, providing valuable chemical information about old stellar populations bearing RR Lyrae variables. The methods presented here can be straightforwardly adopted for other classes of variable stars, bands, or for the estimation of other physical quantities.

  2. GRB 070610: A Curious Galactic Transient

    Science.gov (United States)

    Kasliwal, M. M.; Cenko, S. B.; Kulkarni, S. R.; Cameron, P. B.; Nakar, E.; Ofek, E. O.; Rau, A.; Soderberg, A. M.; Campana, S.; Bloom, J. S.; Perley, D. A.; Pollack, L. K.; Barthelmy, S.; Cummings, J.; Gehrels, N.; Krimm, H. A.; Markwardt, C. B.; Sato, G.; Chandra, P.; Frail, D.; Fox, D. B.; Price, P. A.; Berger, E.; Grebenev, S. A.; Krivonos, R. A.; Sunyaev, R. A.

    2008-05-01

    GRB 070610 is a typical high-energy event with a duration of 5 s. Yet within the burst localization we detect a highly unusual X-ray and optical transient, Swift J195509.6+261406. We see high-amplitude X-ray and optical variability on very short timescales even at late times. Using near-infrared imaging assisted by a laser guide star and adaptive optics, we identified the counterpart of Swift J195509.6+261406. Late-time optical and near-infrared imaging constrain the spectral type of the counterpart to be fainter than a K-dwarf, assuming it is of Galactic origin. It is possible that GRB 070610 and Swift J195509.6+261406 are unrelated sources. However, the absence of a typical X-ray afterglow from GRB 070610 in conjunction with the spatial and temporal coincidence of the two motivate us to suggest that the sources are related. The closest (imperfect) analog to Swift J195509.6+261406 is V4641 Sgr, an unusual black hole binary. We suggest that Swift J195509.6+261406 along with V4641 Sgr define a subclass of stellar black hole binaries—the fast X-ray novae. We further suggest that fast X-ray novae are associated with bursts of gamma rays. If so, GRB 070610 defines a new class of celestial gamma-ray bursts and these bursts dominate the long-duration GRB demographics.

  3. A Multi-year Search for Transits of Proxima Centauri. I. Light Curves Corresponding to Published Ephemerides

    Science.gov (United States)

    Blank, David L.; Feliz, Dax; Collins, Karen A.; White, Graeme L.; Stassun, Keivan G.; Curtis, Ivan A.; Hart, Rhodes; Kielkopf, John F.; Nelson, Peter; Relles, Howard; Stockdale, Christopher; Jayawardene, Bandupriya; Pennypacker, Carlton R.; Shankland, Paul; Reichart, Daniel E.; Haislip, Joshua B.; Kouprianov, Vladimir V.

    2018-06-01

    Proxima Centauri has become the subject of intense study since the radial-velocity (RV) discovery by Anglada-Escudé et al. of a planet orbiting this nearby M dwarf every ∼11.2 days. If Proxima Centauri b transits its host star, independent confirmation of its existence is possible, and its mass and radius can be measured in units of the stellar host mass and radius. To date, there have been three independent claims of possible transit-like event detections in light curve observations obtained by the MOST satellite (in 2014–15), the Bright Star Survey Telescope telescope in Antarctica (in 2016), and the Las Campanas Observatory (in 2016). The claimed possible detections are tentative, due in part to the variability intrinsic to the host star, and in the case of the ground-based observations, also due to the limited duration of the light curve observations. Here, we present preliminary results from an extensive photometric monitoring campaign of Proxima Centauri, using telescopes around the globe and spanning from 2006 to 2017, comprising a total of 329 observations. Considering our data that coincide directly and/or phased with the previously published tentative transit detections, we are unable to independently verify those claims. We do, however, verify the previously reported ubiquitous and complex variability of the host star. We discuss possible interpretations of the data in light of the previous claims, and we discuss future analyses of these data that could more definitively verify or refute the presence of transits associated with the RV-discovered planet.

  4. miR-411-5p inhibits proliferation and metastasis of breast cancer cell via targeting GRB2

    International Nuclear Information System (INIS)

    Zhang, Yunda; Xu, Guoxing; Liu, Gang; Ye, Yongzhi; Zhang, Chuankai; Fan, Chuannan; Wang, Haibin; Cai, Huali; Xiao, Rui; Huang, Zhengjie; Luo, Qi

    2016-01-01

    miR-411-5p (previously called miR-411) is severely involved in human diseases, however, the relationship between miR-411-5p and breast cancer has not been investigated thoroughly. Here, we found that the expression of miR-411-5p was downregulated in breast cancer tissues compared with their matched adjacent non-neoplastic tissues. In addition, the expression of miR-411-5p was also lower in breast cancer cell lines in contrast with MCF-10A. Moreover, we investigated the target and mechanism of miR-411-5p in breast cancer using mimic and inhibitor, and demonstrated the involvement of GRB2 and Ras activation. Ectopic expression of miR-411-5p suppressed the breast cancer cell proliferation, migration and invasion while low expression of miR-411-5p exhibited the opposite effect. Furthermore, GRB2 was demonstrated to be significantly overexpressed in breast cancer tissues compared with normal tissues, and low expression of GRB2 had a longer overall survival compared with high expression of GRB2 in breast cancer. In general, our study shed light on the miR-411-5p related mechanism in the progression of breast cancer and, miR-411-5p/GRB2/Ras axis is potential to be molecular target for breast cancer therapy. - Highlights: • miR-411-5p is downregulated in breast cancer tissues and cell lines. • miR-411-5p inhibits breast cancer cells growth, migration and invasion in vitro. • GRB2 is a direct target of miR-411-5p in breast cancer. • GRB2 is overexpressed in breast cancer and associates with disease outcome. • miR-411-5p suppresses breast cancer progression though GRB2-SOS-Ras pathway.

  5. miR-411-5p inhibits proliferation and metastasis of breast cancer cell via targeting GRB2

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yunda [Department of Gastrointestinal Surgery, First Affiliated Hospital of Xiamen University, Xiamen 361003 (China); State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen 361102 (China); Xu, Guoxing [Department of Gastrointestinal Surgery, First Affiliated Hospital of Xiamen University, Xiamen 361003 (China); Department of Gastrointestinal Surgery, First Clinical Medical College of Fujian Medical University, Fuzhou 350005 (China); Liu, Gang; Ye, Yongzhi [Department of Gastrointestinal Surgery, First Affiliated Hospital of Xiamen University, Xiamen 361003 (China); Zhang, Chuankai [Department of Gastrointestinal Surgery, First Affiliated Hospital of Xiamen University, Xiamen 361003 (China); State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen 361102 (China); Fan, Chuannan [State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen 361102 (China); Wang, Haibin; Cai, Huali; Xiao, Rui [Department of Gastrointestinal Surgery, First Affiliated Hospital of Xiamen University, Xiamen 361003 (China); Department of Gastrointestinal Surgery, First Clinical Medical College of Fujian Medical University, Fuzhou 350005 (China); Huang, Zhengjie, E-mail: huangzhengjie@xmu.edu.cn [Department of Gastrointestinal Surgery, First Affiliated Hospital of Xiamen University, Xiamen 361003 (China); Department of Gastrointestinal Surgery, First Clinical Medical College of Fujian Medical University, Fuzhou 350005 (China); Luo, Qi, E-mail: luoqixmzsh@126.com [Department of Gastrointestinal Surgery, First Affiliated Hospital of Xiamen University, Xiamen 361003 (China); Department of Gastrointestinal Surgery, First Clinical Medical College of Fujian Medical University, Fuzhou 350005 (China)

    2016-08-05

    miR-411-5p (previously called miR-411) is severely involved in human diseases, however, the relationship between miR-411-5p and breast cancer has not been investigated thoroughly. Here, we found that the expression of miR-411-5p was downregulated in breast cancer tissues compared with their matched adjacent non-neoplastic tissues. In addition, the expression of miR-411-5p was also lower in breast cancer cell lines in contrast with MCF-10A. Moreover, we investigated the target and mechanism of miR-411-5p in breast cancer using mimic and inhibitor, and demonstrated the involvement of GRB2 and Ras activation. Ectopic expression of miR-411-5p suppressed the breast cancer cell proliferation, migration and invasion while low expression of miR-411-5p exhibited the opposite effect. Furthermore, GRB2 was demonstrated to be significantly overexpressed in breast cancer tissues compared with normal tissues, and low expression of GRB2 had a longer overall survival compared with high expression of GRB2 in breast cancer. In general, our study shed light on the miR-411-5p related mechanism in the progression of breast cancer and, miR-411-5p/GRB2/Ras axis is potential to be molecular target for breast cancer therapy. - Highlights: • miR-411-5p is downregulated in breast cancer tissues and cell lines. • miR-411-5p inhibits breast cancer cells growth, migration and invasion in vitro. • GRB2 is a direct target of miR-411-5p in breast cancer. • GRB2 is overexpressed in breast cancer and associates with disease outcome. • miR-411-5p suppresses breast cancer progression though GRB2-SOS-Ras pathway.

  6. Hubble Space Telescope Ultraviolet Light Curves Reveal Interesting Properties of CC Sculptoris and RZ Leonis

    Energy Technology Data Exchange (ETDEWEB)

    Szkody, Paula; Mukadam, Anjum S. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Toloza, Odette; Gänsicke, Boris T.; Pala, Anna F. [Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom); Dai, Zhibin [Yunnan Observatories, Chinese Academy of Sciences, 396 Yangfangwang, Guandu District, Kunming, 650216 (China); Waagen, Elizabeth O. [AAVSO, 48 Bay State Rd, Cambridge, MA 02138 (United States); Godon, Patrick; Sion, Edward M., E-mail: szkody@astro.washington.edu [Department of Astrophysics and Planetary Science, Villanova University, Villanova, PA 19085 (United States)

    2017-03-01

    Time-tag ultraviolet data obtained on the Hubble Space Telescope in 2013 reveal interesting variability related to the white dwarf spin in the two cataclysmic variables RZ Leo and CC Scl. RZ Leo shows a period at 220 s and its harmonic at 110 s, thus identifying it as a likely Intermediate Polar (IP). The spin signal is not visible in a short single night of ground-based data in 2016, but the shorter exposures in that data set indicate a possible partial eclipse. The much larger UV amplitude of the spin signal in the known IP CC Scl allows the spin of 389 s, previously only seen at outburst, to be visible at quiescence. Spectra created from the peaks and troughs of the spin times indicate a hotter temperature of several thousand degrees during the peak phases, with multiple components contributing to the UV light.

  7. GRB 080913 at redshift 6.7

    DEFF Research Database (Denmark)

    Greiner, J.; Krühler, T.; Fynbo, J. P. U.

    2009-01-01

    We report on the detection by Swift of GRB 080913, and subsequent optical/near-infrared follow-up observations by GROND, which led to the discovery of its optical/NIR afterglow and the recognition of its high-z nature via the detection of a spectral break between the i' and z' bands. Spectroscopy...... obtained at the ESO-VLT revealed a continuum extending down to ¿ = 9400 Å, and zero flux for 7500 Åinterpret as the onset of a Gunn-Peterson trough at z = 6.695± 0.025 (95.5% confidence level), making GRB 080913 the highest-redshift gamma-ray burst (GRB) to date, and more distant than...

  8. A New Era of Submillimeter GRB Afterglow Follow-Ups with the Greenland Telescope

    Directory of Open Access Journals (Sweden)

    Yuji Urata

    2015-01-01

    Full Text Available Planned rapid submillimeter (submm gamma-ray-bursts (GRBs follow-up observations conducted using the Greenland Telescope (GLT are presented. The GLT is a 12-m submm telescope to be located at the top of the Greenland ice sheet, where the high altitude and dry weather porvide excellent conditions for observations at submm wavelengths. With its combination of wavelength window and rapid responding system, the GLT will explore new insights on GRBs. Summarizing the current achievements of submm GRB follow-ups, we identify the following three scientific goals regarding GRBs: (1 systematic detection of bright submm emissions originating from reverse shock (RS in the early afterglow phase, (2 characterization of forward shock and RS emissions by capturing their peak flux and frequencies and performing continuous monitoring, and (3 detections of GRBs at a high redshift as a result of the explosion of first generation stars through systematic rapid follow-ups. The light curves and spectra calculated by available theoretical models clearly show that the GLT could play a crucial role in these studies.

  9. A New Era of Submillimeter GRB Afterglow Follow-Ups with the Greenland Telescope

    Science.gov (United States)

    Urata, Yuji; Huang, Kuiyun; Asada, Keiichi; Hirashita, Hiroyuki; Inoue, Makoto; Ho, Paul T. P.

    A planned rapid submillimeter (submm) Gamma Ray Burst (GRBs) follow-up observations conducted using the Greenland Telescope (GLT) is presented. The GLT is a 12-m submm telescope to be located at the top of the Greenland ice sheet, where the high-altitude and dry weather porvides excellent conditions for observations at submm wavelengths. With its combination of wavelength window and rapid responding system, the GLT will explore new insights on GRBs. Summarizing the current achievements of submm GRB follow-ups, we identify the following three scientific goals regarding GRBs: (1) systematic detection of bright submm emissions originating from reverse shock (RS) in the early afterglow phase, (2) characterization of forward shock and RS emissions by capturing their peak flux and frequencies and performing continuous monitoring, and (3) detections of GRBs as a result of the explosion of first-generation stars result of GRBs at a high redshift through systematic rapid follow ups. The light curves and spectra calculated by available theoretical models clearly show that the GLT could play a crucial role in these studies.

  10. Dimerization in the Grb7 Protein

    OpenAIRE

    Peterson, Tabitha A.; Benallie, Renee L.; Bradford, Andrew M.; Pias, Sally C.; Yazzie, Jaron.; Lor, Siamee N.; Haulsee, Zachary M.; Park, Chad K.; Johnson, Dennis L.; Rohrschneider, Larry R.; Spuches, Anne.; Lyons, Barbara A.

    2012-01-01

    In previous studies, we showed that the tyrosine phosphorylation state of growth factor receptor–bound protein 7 (Grb7) affects its ability to bind to the transcription regulator FHL2 and the cortactin-interacting protein, human HS-1-associated protein-1. Here, we present results describing the importance of dimerization in the Grb7–Src homology 2 (SH2) domain in terms of its structural integrity and the ability to bind phosphorylated tyrosine peptide ligands. A tyrosine phosphorylation-mimic...

  11. Light curve solutions and out-of-eclipse variability of KIC 10031409, KIC 11228612, KIC 11403216 and KIC 11913071

    Directory of Open Access Journals (Sweden)

    Kjurkchieva D.

    2017-01-01

    Full Text Available We carried out light curve solutions of four detached binaries observed by Kepler. As a result, their orbital inclinations, temperatures and relative stellar radii were determined. KIC 10031409 and KIC 11228612 reveal partial eclipses while the components of KIC 11403216 and KIC 11913071 undergo total eclipses. The secondary component of KIC 11403216 is probably a very late M dwarf or brown dwarf. The out-of-eclipse brightness of KIC 10031409, KIC 11228612 and KIC 11913071 vary with the orbital period and might be explained by spots on synchronously-rotating star(s. The out-of-eclipse variability of KIC 11403216 is with a period that is a third of its orbital period and may be due to spot on asynchronous rotating component. The resonance 1:3 needs future study of KIC 11403216.

  12. SN 2015as: a low-luminosity Type IIb supernova without an early light-curve peak

    Science.gov (United States)

    Gangopadhyay, Anjasha; Misra, Kuntal; Pastorello, A.; Sahu, D. K.; Tomasella, L.; Tartaglia, L.; Singh, Mridweeka; Dastidar, Raya; Srivastav, S.; Ochner, P.; Brown, Peter J.; Anupama, G. C.; Benetti, S.; Cappellaro, E.; Kumar, Brajesh; Kumar, Brijesh; Pandey, S. B.

    2018-05-01

    We present results of the photometric (from 3 to 509 d post-explosion) and spectroscopic (up to 230 d post-explosion) monitoring campaign of the He-rich Type IIb supernova (SN) 2015as. The (B - V) colour evolution of SN 2015as closely resemble those of SN 2008ax, suggesting that SN 2015as belongs to the SN IIb subgroup that does not show the early, short-duration photometric peak. The light curve of SN 2015as reaches the B-band maximum about 22 d after the explosion, at an absolute magnitude of -16.82 ± 0.18 mag. At ˜75 d after the explosion, its spectrum transitions from that of a SN II to a SN Ib. P Cygni features due to He I lines appear at around 30 d after explosion, indicating that the progenitor of SN 2015as was partially stripped. For SN 2015as, we estimate a 56Ni mass of ˜0.08 M⊙ and ejecta mass of 1.1-2.2 M⊙, which are similar to the values inferred for SN 2008ax. The quasi-bolometric analytical light-curve modelling suggests that the progenitor of SN 2015as has a modest mass (˜0.1 M⊙), a nearly compact (˜0.05 × 1013 cm) H envelope on top of a dense, compact (˜2 × 1011 cm) and a more massive (˜1.2 M⊙) He core. The analysis of the nebular phase spectra indicates that ˜0.44 M⊙ of O is ejected in the explosion. The intensity ratio of the [Ca II]/[O I] nebular lines favours either a main-sequence progenitor mass of ˜15 M⊙ or a Wolf-Rayet star of 20 M⊙.

  13. SEVEN NEW BINARIES DISCOVERED IN THE KEPLER LIGHT CURVES THROUGH THE BEER METHOD CONFIRMED BY RADIAL-VELOCITY OBSERVATIONS

    International Nuclear Information System (INIS)

    Faigler, S.; Mazeh, T.; Tal-Or, L.; Quinn, S. N.; Latham, D. W.

    2012-01-01

    We present seven newly discovered non-eclipsing short-period binary systems with low-mass companions, identified by the recently introduced BEER algorithm, applied to the publicly available 138-day photometric light curves obtained by the Kepler mission. The detection is based on the beaming effect (sometimes called Doppler boosting), which increases (decreases) the brightness of any light source approaching (receding from) the observer, enabling a prediction of the stellar Doppler radial-velocity (RV) modulation from its precise photometry. The BEER algorithm identifies the BEaming periodic modulation, with a combination of the well-known Ellipsoidal and Reflection/heating periodic effects, induced by short-period companions. The seven detections were confirmed by spectroscopic RV follow-up observations, indicating minimum secondary masses in the range 0.07-0.4 M ☉ . The binaries discovered establish for the first time the feasibility of the BEER algorithm as a new detection method for short-period non-eclipsing binaries, with the potential to detect in the near future non-transiting brown-dwarf secondaries, or even massive planets.

  14. Short GRB afterglows observed with GROND

    DEFF Research Database (Denmark)

    Nicuesa Guelbenzu, A.; Klose, S.; Rossi, A.

    2013-01-01

    We report on follow-up observations of 20 short-duration gamma-ray bursts (T90 < 2s) performed in g′r′i′z′JHK s with the Gamma-Ray Burst Optical Near-Infrared Detector (GROND) between mid-2007 and the end of 2010. This is the most homogeneous and comprehensive data set on GRB afterglow observatio...

  15. SOAP-T: a tool to study the light curve and radial velocity of a system with a transiting planet and a rotating spotted star

    Science.gov (United States)

    Oshagh, M.; Boisse, I.; Boué, G.; Montalto, M.; Santos, N. C.; Bonfils, X.; Haghighipour, N.

    2013-01-01

    We present an improved version of SOAP named "SOAP-T", which can generate the radial velocity variations and light curves for systems consisting of a rotating spotted star with a transiting planet. This tool can be used to study the anomalies inside transit light curves and the Rossiter-McLaughlin effect, to better constrain the orbital configuration and properties of planetary systems and the active zones of their host stars. Tests of the code are presented to illustrate its performance and to validate its capability when compared with analytical models and real data. Finally, we apply SOAP-T to the active star, HAT-P-11, observed by the NASA Kepler space telescope and use this system to discuss the capability of this tool in analyzing light curves for the cases where the transiting planet overlaps with the star's spots. The tool's public interface is available at http://www.astro.up.pt/resources/soap-t/

  16. TOWARD CHARACTERIZATION OF THE TYPE IIP SUPERNOVA PROGENITOR POPULATION: A STATISTICAL SAMPLE OF LIGHT CURVES FROM Pan-STARRS1

    Energy Technology Data Exchange (ETDEWEB)

    Sanders, N. E.; Soderberg, A. M.; Chornock, R.; Berger, E.; Challis, P.; Drout, M.; Kirshner, R. P.; Lunnan, R.; Marion, G. H.; Margutti, R.; McKinnon, R.; Milisavljevic, D. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Gezari, S. [Department of Astronomy, University of Maryland, College Park, MD 20742-2421 (United States); Betancourt, M. [Department of Statistics, University of Warwick, Coventry (United Kingdom); Foley, R. J. [Astronomy Department, University of Illinois at Urbana-Champaign, 1002 West Green Street, Urbana, IL 61801 (United States); Narayan, G. [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States); Rest, A. [Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); Kankare, E.; Mattila, S. [Finnish Centre for Astronomy with ESO (FINCA), University of Turku, Väisäläntie 20, 21500 Piikkiö (Finland); Smartt, S. J., E-mail: nsanders@cfa.harvard.edu [Astrophysics Research Centre, School of Mathematics and Physics, Queens University, BT7 1NN, Belfast (United Kingdom); and others

    2015-02-01

    In recent years, wide-field sky surveys providing deep multiband imaging have presented a new path for indirectly characterizing the progenitor populations of core-collapse supernovae (SNe): systematic light-curve studies. We assemble a set of 76 grizy-band Type IIP SN light curves from Pan-STARRS1, obtained over a constant survey program of 4 yr and classified using both spectroscopy and machine-learning-based photometric techniques. We develop and apply a new Bayesian model for the full multiband evolution of each light curve in the sample. We find no evidence of a subpopulation of fast-declining explosions (historically referred to as ''Type IIL'' SNe). However, we identify a highly significant relation between the plateau phase decay rate and peak luminosity among our SNe IIP. These results argue in favor of a single parameter, likely determined by initial stellar mass, predominantly controlling the explosions of red supergiants. This relation could also be applied for SN cosmology, offering a standardizable candle good to an intrinsic scatter of ≲ 0.2 mag. We compare each light curve to physical models from hydrodynamic simulations to estimate progenitor initial masses and other properties of the Pan-STARRS1 Type IIP SN sample. We show that correction of systematic discrepancies between modeled and observed SN IIP light-curve properties and an expanded grid of progenitor properties are needed to enable robust progenitor inferences from multiband light-curve samples of this kind. This work will serve as a pathfinder for photometric studies of core-collapse SNe to be conducted through future wide-field transient searches.

  17. Efficient dye-sensitized solar cells from curved silicate microsheet caged TiO2 photoanodes. An avenue of enhancing light harvesting

    International Nuclear Information System (INIS)

    Wang, Zubin; Tang, Qunwei; He, Benlin; Chen, Haiyan; Yu, Liangmin

    2015-01-01

    Graphical abstract: - Highlights: • Curved silicate microsheets are incorporated with TiO 2 for light harvesting in DSSC • The optical matching between silicate and TiO 2 is superior to light reflection. • The curved silicate can hinder the recombination reaction of electrons with I 3 − . • The DSSC with TiO 2 /curved silicate photoanode shows an efficiency of 9.22% - Abstract: Enhancement of light harvesting has been a persistent objective for elevating dye excitation and therefore power conversion efficiency of dye-sensitized solar cells (DSSCs). Here we launch a strategy of markedly enhancing light harvesting by caging TiO 2 nanoparticles with curved silica microsheets. The results show that the strategy is versatile in suppressing the recombination reaction of electrons with I 3 − species in liquid electrolyte. Due to the superior reflective behaviors of curved silica microsheets, an optimal efficiency of 9.22% is recorded under simulated air mass 1.5 global sunlight on the DSSC in comparison with 6.51% and 7.51% from pristine TiO 2 and planar silicate microsheet incorporated TiO 2 photoanode based solar cells, respectively. This strategy is also believed to be applicable to other solar cells such as perovskite solar cells and quantum dot-sensitized solar cells.

  18. Light-curve analysis of KOI 2700b: the second extrasolar planet with a comet-like tail

    Science.gov (United States)

    Garai, Z.

    2018-03-01

    Context. The Kepler object KOI 2700b (KIC 8639908b) was discovered recently as the second exoplanet with a comet-like tail. It exhibits a distinctly asymmetric transit profile, likely indicative of the emission of dusty effluents and reminiscent of KIC 12557548b, the first exoplanet with a comet-like tail. Aim. The scientific goal of this work is to verify the disintegrating-planet scenario of KOI 2700b by modeling its light curve and to put constraints on various tail and planet properties, as was done in the case of KIC 12557548b. Methods: We obtained the phase-folded and binned transit light curve of KOI 2700b, which we subsequently iteratively modeled using the radiative-transfer code SHELLSPEC. We modeled the comet-like tail as part of a ring around the parent star and we also included the solid body of the planet in the model. During the modeling we applied selected species and dust particle sizes. Results: We confirmed the disintegrating-planet scenario of KOI 2700b. Furthermore, via modeling, we derived some interesting features of KOI 2700b and its comet-like tail. It turns out that the orbital plane of the planet and its tail are not edge-on, but the orbital inclination angle is from the interval [85.1, 88.6] deg. In comparison with KIC 12557548b, KOI 2700b exhibits a relatively low dust density decreasing in its tail. We also derived the dust density at the beginning of the ring and the highest optical depth through the tail in front of the star, based on a tail-model with a cross-section of 0.05 × 0.05 R⊙ at the beginning and 0.09 × 0.09 R⊙ at its end. Our results show that the dimension of the planet is Rp/Rs ≤ 0.014 (Rp ≤ 0.871 R⊕, or ≤5551 km). We also estimated the mass-loss rate from KOI 2700b, and we obtained Ṁ values from the interval [5.05 × 107, 4.41 × 1015] g s-1. On the other hand, we could not draw any satisfactory conclusions about the typical grain size in the dust tail.

  19. "TNOs are Cool": A survey of the trans-Neptunian region. XII. Thermal light curves of Haumea, 2003 VS2 and 2003 AZ84 with Herschel/PACS

    Science.gov (United States)

    Santos-Sanz, P.; Lellouch, E.; Groussin, O.; Lacerda, P.; Müller, T. G.; Ortiz, J. L.; Kiss, C.; Vilenius, E.; Stansberry, J.; Duffard, R.; Fornasier, S.; Jorda, L.; Thirouin, A.

    2017-08-01

    Context. Time series observations of the dwarf planet Haumea and the Plutinos 2003 VS2 and 2003 AZ84 with Herschel/PACS are presented in this work. Thermal emission of these trans-Neptunian objects (TNOs) were acquired as part of the "TNOs are Cool" Herschel Space Observatory key programme. Aims: We search for the thermal light curves at 100 and 160 μm of Haumea and 2003 AZ84, and at 70 and 160 μm for 2003 VS2 by means of photometric analysis of the PACS data. The goal of this work is to use these thermal light curves to obtain physical and thermophysical properties of these icy Solar System bodies. Methods: When a thermal light curve is detected, it is possible to derive or constrain the object thermal inertia, phase integral and/or surface roughness with thermophysical modeling. Results: Haumea's thermal light curve is clearly detected at 100 and 160 μm. The effect of the reported dark spot is apparent at 100 μm. Different thermophysical models were applied to these light curves, varying the thermophysical properties of the surface within and outside the spot. Although no model gives a perfect fit to the thermal observations, results imply an extremely low thermal inertia (0.73) for Haumea's surface. We note that the dark spot region appears to be only weakly different from the rest of the object, with modest changes in thermal inertia and/or phase integral. The thermal light curve of 2003 VS2 is not firmly detected at 70 μm and at 160 μm but a thermal inertia of (2 ± 0.5) MKS can be derived from these data. The thermal light curve of 2003 AZ84 is not firmly detected at 100 μm. We apply a thermophysical model to the mean thermal fluxes and to all the Herschel/PACS and Spitzer/MIPS thermal data of 2003 AZ84, obtaining a close to pole-on orientation as the most likely for this TNO. Conclusions: For the three TNOs, the thermal inertias derived from light curve analyses or from the thermophysical analysis of the mean thermal fluxes confirm the generally small

  20. MULTI-COLOR OPTICAL AND NEAR-INFRARED LIGHT CURVES OF 64 STRIPPED-ENVELOPE CORE-COLLAPSE SUPERNOVAE

    Energy Technology Data Exchange (ETDEWEB)

    Bianco, F. B.; Modjaz, M. [Center for Cosmology and Particle Physics, New York University, 4 Washington Place, New York, NY 10003 (United States); Hicken, M.; Friedman, A.; Kirshner, R. P.; Challis, P.; Marion, G. H. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Bloom, J. S. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Wood-Vasey, W. M. [PITT PACC, Department of Physics and Astronomy, 3941 O' Hara Street, University of Pittsburgh, Pittsburgh, PA 15260 (United States); Rest, A., E-mail: fb55@nyu.edu [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)

    2014-08-01

    We present a densely sampled, homogeneous set of light curves of 64 low-redshift (z ≲ 0.05) stripped-envelope supernovae (SNe of Type IIb, Ib, Ic, and Ic-BL). These data were obtained between 2001 and 2009 at the Fred L. Whipple Observatory (FLWO) on Mount Hopkins in Arizona, with the optical FLWO 1.2 m and the near-infrared (NIR) Peters Automated Infrared 1.3 m telescopes. Our data set consists of 4543 optical photometric measurements on 61 SNe, including a combination of U BV RI, U BV r{sup ′}i{sup ′}, and u{sup ′} BV r{sup ′}i{sup ′}, and 1919 JHK{sub s} NIR measurements on 25 SNe. This sample constitutes the most extensive multi-color data set of stripped-envelope SNe to date. Our photometry is based on template-subtracted images to eliminate any potential host-galaxy light contamination. This work presents these photometric data, compares them with data in the literature, and estimates basic statistical quantities: date of maximum, color, and photometric properties. We identify promising color trends that may permit the identification of stripped-envelope SN subtypes from their photometry alone. Many of these SNe were observed spectroscopically by the Harvard-Smithsonian Center for Astrophysics (CfA) SN group, and the spectra are presented in a companion paper. A thorough exploration that combines the CfA photometry and spectroscopy of stripped-envelope core-collapse SNe will be presented in a follow-up paper.

  1. Noise reduction methods in the analysis of near infrared lunar occultation light curves for high angular resolution measurements

    International Nuclear Information System (INIS)

    Baug Tapas; Chandrasekhar Thyagarajan

    2013-01-01

    A lunar occultation (LO) technique in the near-infrared (NIR) provides angular resolution down to milliarcseconds for an occulted source, even with ground-based 1 m class telescopes. LO observations are limited to brighter objects because they require a high signal-to-noise ratio (S/N ∼40) for proper extraction of angular diameter values. Hence, methods to improve the S/N ratio by reducing noise using Fourier and wavelet transforms have been explored in this study. A sample of 54 NIR LO light curves observed with the IR camera at Mt Abu Observatory has been used. It is seen that both Fourier and wavelet methods have shown an improvement in S/N compared to the original data. However, the application of wavelet transforms causes a slight smoothing of the fringes and results in a higher value for angular diameter. Fourier transforms which reduce discrete noise frequencies do not distort the fringe. The Fourier transform method seems to be effective in improving the S/N, as well as improving the model fit, particularly in the fainter regime of our sample. These methods also provide a better model fit for brighter sources in some cases, though there may not be a significant improvement in S/N

  2. A Hybrid Algorithm for Period Analysis from Multiband Data with Sparse and Irregular Sampling for Arbitrary Light-curve Shapes

    Science.gov (United States)

    Saha, Abhijit; Vivas, A. Katherina

    2017-12-01

    Ongoing and future surveys with repeat imaging in multiple bands are producing (or will produce) time-spaced measurements of brightness, resulting in the identification of large numbers of variable sources in the sky. A large fraction of these are periodic variables: compilations of these are of scientific interest for a variety of purposes. Unavoidably, the data sets from many such surveys not only have sparse sampling, but also have embedded frequencies in the observing cadence that beat against the natural periodicities of any object under investigation. Such limitations can make period determination ambiguous and uncertain. For multiband data sets with asynchronous measurements in multiple passbands, we wish to maximally use the information on periodicity in a manner that is agnostic of differences in the light-curve shapes across the different channels. Given large volumes of data, computational efficiency is also at a premium. This paper develops and presents a computationally economic method for determining periodicity that combines the results from two different classes of period-determination algorithms. The underlying principles are illustrated through examples. The effectiveness of this approach for combining asynchronously sampled measurements in multiple observables that share an underlying fundamental frequency is also demonstrated.

  3. An Optical Low-frequency Quasi-Periodic Oscillation in the Kepler Light Curve of an Active Galaxy

    Science.gov (United States)

    Mushotzky, Richard; Smith, Krista Lynne; Boyd, Patricia; Wagoner, Robert

    2018-01-01

    We report the discovery of a candidate quasi-periodic oscillation (QPO) in the optical light curve of KIC 9650712, a Seyfert 1 galaxy in the original Kepler field. After the development and application of a pipeline for Kepler data specific to active galactic nuclei (AGN), one of our sample of 21 AGN selected by infrared photometry and X-ray flux demonstrates a peak in the power spectrum at 10-6.58 Hz, corresponding to a temporal period of 44 days. >From optical spectroscopy, we measure the black hole mass of this AGN as log M = 8.17 M_sun. Despite this high mass, the optical spectrum of KIC 9650712 bears many similarities to Narrow Line Seyfert 1 (NLS1) galaxies, including strong Fe II emission and a low [O III]/Hβ ratio. So far, X-ray QPOs have primarily been seen in NLS1 galaxies. Finally, we find that this frequency lies along a correlation between low-frequency QPOs and black hole mass from stellar and intermediate mass black holes to AGN, similar to the known correlation in high-frequency QPOs.

  4. Light curve solutions and study of roles of magnetic fields in period variations of the UV Leo system

    Directory of Open Access Journals (Sweden)

    D Manzoori

    2009-12-01

    Full Text Available The solutions of photometric BV light curves for the Algol like system UV Leo were obtained using Wilson-Devinney code. The physical and orbital parameters along with absolute dimensions of the system were determined. It has been found that to best fit the V light curve of the system, assumptions of three dark spots were necessary two on the secondary and one on the primary. The absolute visual magnitudes (Mv of the individual components i.e., primary and secondary were estimated to 4.41 and 4.43, respectively, through the color curve analysis. The period analysis of the system presented elsewhere, indicated a cyclic period change of 12 yr duration, which was attributed to magnetic activity cycle, as a main cause of period variation in the system, through the Applegate mechanism. To verify the Applegate model I preformed calculations of some related parameters barrowed from Apllegate and Kalimeris. Values of all the calculated parameters were in accordance to those obtained for similar systems by Applegate. The differential magnitudes Δ B and Δ V, along with corresponding values of Δ(B-V color index. The cyclic variations in brightness are quite clear. There are three predictions of Applegate's theory concerning effects of cyclic magnetic changes on the period variations, which can be checked through the observations, these are as follows: I The long term variations in mean brightness (at outside of eclipses and cyclic changes of orbital period, vary with the same period. II The active star gets bluer as it gets brightened and/or the brightness and color variations are to be in phase. III Changes in luminosity due to changes in quadrupole moment should be of the order 0.1 mag. All the above mentioned predictions of Applegate’s theory are verified. These results combined with cyclic character of P(E presented elsewhere and also consistency of parameters which are obtained in this paper, led me to conclude that one the main causes of period

  5. Observation of X-ray lines from a gamma-ray burst (GRB991216): evidence of moving ejecta from the progenitor.

    Science.gov (United States)

    Piro, L; Garmire, G; Garcia, M; Stratta, G; Costa, E; Feroci, M; Mészáros, P; Vietri, M; Bradt, H; Frail, D; Frontera, F; Halpern, J; Heise, J; Hurley, K; Kawai, N; Kippen, R M; Marshall, F; Murakami, T; Sokolov, V V; Takeshima, T; Yoshida, A

    2000-11-03

    We report on the discovery of two emission features observed in the x-ray spectrum of the afterglow of the gamma-ray burst (GRB) of 16 December 1999 by the Chandra X-ray Observatory. These features are identified with the Ly(alpha) line and the narrow recombination continuum by hydrogenic ions of iron at a redshift z = 1.00 +/- 0.02, providing an unambiguous measurement of the distance of a GRB. Line width and intensity imply that the progenitor of the GRB was a massive star system that ejected, before the GRB event, a quantity of iron approximately 0.01 of the mass of the sun at a velocity approximately 0.1 of the speed of light, probably by a supernova explosion.

  6. Gas Kinematics in GRB Host Galaxies

    DEFF Research Database (Denmark)

    Arabsalmani, Maryam

    towards a relation between gas kinematics and mass. This also provides information on how the metallicities measured from absorption and emission methods differ from each other. Finally, in a direct study I show that gas velocity widths in both phases can be used as a proxy of stellar mass...... that their interstellar media imprint on the GRBs’ spectra. Hence they are invaluable tools to probe the star formation history of the Universe back to the earliest cosmic epochs. To this end, it is essential to achieve a comprehensive picture of the interplay between star formation and its fuel, neutral gas, in GRB...... simultaneously with a high velocity resolution. For the large GRB sample, I find the spatially averaged velocity to correlate with metallicity in both gas phases. This is an indicator of a mass-metallicity relation. Moreover, the velocity widths in the two gas phases correlate with each other which too points...

  7. Possible GRB Observation with the MAGIC Telescope

    Science.gov (United States)

    Bastieri, D.; Bigongiari, C.; Mariotti, M.; Peruzzo, L.; Saggion, A.

    2001-08-01

    The MAGIC Telescope, with its reflecting parabolic dish of 17 m of diameter and its careful design of a robust, lightweight, alto-azimuthal mount, is an ideal detector for GRB phenomena. The telescope is an air Cherenkov telescope that, even in the first phase, equipped with standard PMTs, can reach an energy threshold below 30 GeV. The threshold is going to drop well below 10 GeV in the envisaged second phase, when chamber PMTs will be substituted by high quantum efficiency APDs. The telescope can promptly respond to GRB alerts coming, for instance, from GCN, and can reposition itself in less than 30 seconds, 20 seconds being the time to turn half a round for the azimuth bearing. In this report, the effective area of the detector as a function of energy and zenith angle is taken into account, in order to evaluate the expected yearly occurrence and the response to different kinds of GRBs.

  8. An analysis of the small amplitude variations in the light curves of the R Coronae Borealis variables, S Apodis and UW Centauri

    International Nuclear Information System (INIS)

    Kilkenny, D.; Flanagan, C.

    1983-01-01

    The small amplitude variations in the light curves of the R CrB stars, S Aps and UW Cen, are examined. The periodicity of these variations appears to be changing rapidly in S Aps and slowly, if at all, in UW Cen. The evolutionary consequences of these effects are discussed. (author)

  9. Light Curve and SED Modeling of the Gamma-Ray Binary 1FGL J1018.6–5856: Constraints on the Orbital Geometry and Relativistic Flow

    Energy Technology Data Exchange (ETDEWEB)

    An, Hongjun; Romani, Roger W., E-mail: hjan@chungbuk.ac.kr [Department of Physics/KIPAC, Stanford University, Stanford, CA 94305-4060 (United States)

    2017-04-01

    We present broadband spectral energy distributions and light curves of the gamma-ray binary 1FGL J1018.6−5856 measured in the X-ray and the gamma-ray bands. We find that the orbital modulation in the low-energy gamma-ray band is similar to that in the X-ray band, suggesting a common spectral component. However, above a GeV the orbital light curve changes significantly. We suggest that the GeV band contains significant flux from a pulsar magnetosphere, while the X-ray to TeV light curves are dominated by synchrotron and Compton emission from an intrabinary shock (IBS). We find that a simple one-zone model is inadequate to explain the IBS emission, but that beamed Synchrotron-self Compton radiation from adiabatically accelerated plasma in the shocked pulsar wind can reproduce the complex multiband light curves, including the variable X-ray spike coincident with the gamma-ray maximum. The model requires an inclination of ∼50° and an orbital eccentricity of ∼0.35, consistent with the limited constraints from existing optical observations. This picture motivates searches for pulsations from the energetic young pulsar powering the wind shock.

  10. LIGHT CURVES OF CORE-COLLAPSE SUPERNOVAE WITH SUBSTANTIAL MASS LOSS USING THE NEW OPEN-SOURCE SUPERNOVA EXPLOSION CODE (SNEC)

    International Nuclear Information System (INIS)

    Morozova, Viktoriya; Renzo, Mathieu; Ott, Christian D.; Clausen, Drew; Couch, Sean M.; Ellis, Justin; Roberts, Luke F.; Piro, Anthony L.

    2015-01-01

    We present the SuperNova Explosion Code (SNEC), an open-source Lagrangian code for the hydrodynamics and equilibrium-diffusion radiation transport in the expanding envelopes of supernovae. Given a model of a progenitor star, an explosion energy, and an amount and distribution of radioactive nickel, SNEC generates the bolometric light curve, as well as the light curves in different broad bands assuming blackbody emission. As a first application of SNEC, we consider the explosions of a grid of 15 M ⊙ (at zero-age main sequence, ZAMS) stars whose hydrogen envelopes are stripped to different extents and at different points in their evolution. The resulting light curves exhibit plateaus with durations of ∼20–100 days if ≳1.5–2 M ⊙ of hydrogen-rich material is left and no plateau if less hydrogen-rich material is left. If these shorter plateau lengths are not seen for SNe IIP in nature, it suggests that, at least for ZAMS masses ≲20 M ⊙ , hydrogen mass loss occurs as an all or nothing process. This perhaps points to the important role binary interactions play in generating the observed mass-stripped supernovae (i.e., Type Ib/c events). These light curves are also unlike what is typically seen for SNe IIL, arguing that simply varying the amount of mass loss cannot explain these events. The most stripped models begin to show double-peaked light curves similar to what is often seen for SNe IIb, confirming previous work that these supernovae can come from progenitors that have a small amount of hydrogen and a radius of ∼500 R ⊙

  11. LIGHT CURVES OF CORE-COLLAPSE SUPERNOVAE WITH SUBSTANTIAL MASS LOSS USING THE NEW OPEN-SOURCE SUPERNOVA EXPLOSION CODE (SNEC)

    Energy Technology Data Exchange (ETDEWEB)

    Morozova, Viktoriya; Renzo, Mathieu; Ott, Christian D.; Clausen, Drew; Couch, Sean M.; Ellis, Justin; Roberts, Luke F. [TAPIR, Walter Burke Institute for Theoretical Physics, MC 350-17, California Institute of Technology, Pasadena, CA 91125 (United States); Piro, Anthony L., E-mail: morozvs@tapir.caltech.edu [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States)

    2015-11-20

    We present the SuperNova Explosion Code (SNEC), an open-source Lagrangian code for the hydrodynamics and equilibrium-diffusion radiation transport in the expanding envelopes of supernovae. Given a model of a progenitor star, an explosion energy, and an amount and distribution of radioactive nickel, SNEC generates the bolometric light curve, as well as the light curves in different broad bands assuming blackbody emission. As a first application of SNEC, we consider the explosions of a grid of 15 M{sub ⊙} (at zero-age main sequence, ZAMS) stars whose hydrogen envelopes are stripped to different extents and at different points in their evolution. The resulting light curves exhibit plateaus with durations of ∼20–100 days if ≳1.5–2 M{sub ⊙} of hydrogen-rich material is left and no plateau if less hydrogen-rich material is left. If these shorter plateau lengths are not seen for SNe IIP in nature, it suggests that, at least for ZAMS masses ≲20 M{sub ⊙}, hydrogen mass loss occurs as an all or nothing process. This perhaps points to the important role binary interactions play in generating the observed mass-stripped supernovae (i.e., Type Ib/c events). These light curves are also unlike what is typically seen for SNe IIL, arguing that simply varying the amount of mass loss cannot explain these events. The most stripped models begin to show double-peaked light curves similar to what is often seen for SNe IIb, confirming previous work that these supernovae can come from progenitors that have a small amount of hydrogen and a radius of ∼500 R{sub ⊙}.

  12. Rotation of cometary nuclei: new light curves and an update of the ensemble properties of Jupiter-family comets

    Science.gov (United States)

    Kokotanekova, R.; Snodgrass, C.; Lacerda, P.; Green, S. F.; Lowry, S. C.; Fernández, Y. R.; Tubiana, C.; Fitzsimmons, A.; Hsieh, H. H.

    2017-11-01

    We report new light curves and phase functions for nine Jupiter-family comets (JFCs). They were observed in the period 2004-2015 with various ground telescopes as part of the Survey of Ensemble Physical Properties of Cometary Nuclei as well as during devoted observing campaigns. We add to this a review of the properties of 35 JFCs with previously published rotation properties. The photometric time series were obtained in Bessel R, Harris R and SDSS r΄ filters and were absolutely calibrated using stars from the Pan-STARRS survey. This specially developed method allowed us to combine data sets taken at different epochs and instruments with absolute-calibration uncertainty down to 0.02 mag. We used the resulting time series to improve the rotation periods for comets 14P/Wolf, 47P/Ashbrook-Jackson, 94P/Russell and 110P/Hartley 3 and to determine the rotation rates of comets 93P/Lovas and 162P/Siding Spring for the first time. In addition to this, we determined the phase functions for seven of the examined comets and derived geometric albedos for eight of them. We confirm the known cut-off in bulk densities at ˜0.6 g cm-3 if JFCs are strengthless. Using a model for prolate ellipsoids with typical density and elongations, we conclude that none of the known JFCs requires tensile strength larger than 10-25 Pa to remain stable against rotational instabilities. We find evidence for an increasing linear phase function coefficient with increasing geometric albedo. The median linear phase function coefficient for JFCs is 0.046 mag deg-1 and the median geometric albedo is 4.2 per cent.

  13. Light mirror reflection combined with heating/cooling curves as a method of studying phase transitions in transparent and opaque petroleum products: Apparatus and theory

    International Nuclear Information System (INIS)

    Shishkin, Yu.L.

    2007-01-01

    A portable low weight low cost apparatus 'Phasafot' and method for determining pour and cloud points of petroleum products, as well as precipitation and melting temperatures of paraffins in both transparent (diesel fuels), semi-transparent (lube oils) and opaque (crude oils) samples are described. The method consists in illuminating the surface of a sample with an oblique light beam and registering the intensity of specularly reflected light while heating/cooling the sample in the temperature range of its structural transitions. The mirror reflection of a light beam from an ideally smooth liquid surface falls in intensity when the surface becomes rough (dim) due to crystal formation. Simultaneous recording of the temperature ramp curve and the mirror reflection curve enables the determination of the beginning and end of crystallization of paraffins in both transparent and opaque petroleum products. Besides, their rheological properties can be accurately determined by rocking or tilting the instrument while monitoring the sample movement via its mirror reflection

  14. AEOLUS: A MARKOV CHAIN MONTE CARLO CODE FOR MAPPING ULTRACOOL ATMOSPHERES. AN APPLICATION ON JUPITER AND BROWN DWARF HST LIGHT CURVES

    Energy Technology Data Exchange (ETDEWEB)

    Karalidi, Theodora; Apai, Dániel; Schneider, Glenn; Hanson, Jake R. [Steward Observatory, Department of Astronomy, University of Arizona, 933 N. Cherry Avenue, Tucson, AZ 85721 (United States); Pasachoff, Jay M., E-mail: tkaralidi@email.arizona.edu [Hopkins Observatory, Williams College, 33 Lab Campus Drive, Williamstown, MA 01267 (United States)

    2015-11-20

    Deducing the cloud cover and its temporal evolution from the observed planetary spectra and phase curves can give us major insight into the atmospheric dynamics. In this paper, we present Aeolus, a Markov chain Monte Carlo code that maps the structure of brown dwarf and other ultracool atmospheres. We validated Aeolus on a set of unique Jupiter Hubble Space Telescope (HST) light curves. Aeolus accurately retrieves the properties of the major features of the Jovian atmosphere, such as the Great Red Spot and a major 5 μm hot spot. Aeolus is the first mapping code validated on actual observations of a giant planet over a full rotational period. For this study, we applied Aeolus to J- and H-band HST light curves of 2MASS J21392676+0220226 and 2MASS J0136565+093347. Aeolus retrieves three spots at the top of the atmosphere (per observational wavelength) of these two brown dwarfs, with a surface coverage of 21% ± 3% and 20.3% ± 1.5%, respectively. The Jupiter HST light curves will be publicly available via ADS/VIZIR.

  15. The bright optical flash and afterglow from the gamma-ray burst GRB 130427A.

    Science.gov (United States)

    Vestrand, W T; Wren, J A; Panaitescu, A; Wozniak, P R; Davis, H; Palmer, D M; Vianello, G; Omodei, N; Xiong, S; Briggs, M S; Elphick, M; Paciesas, W; Rosing, W

    2014-01-03

    The optical light generated simultaneously with x-rays and gamma rays during a gamma-ray burst (GRB) provides clues about the nature of the explosions that occur as massive stars collapse. We report on the bright optical flash and fading afterglow from powerful burst GRB 130427A. The optical and >100-megaelectron volt (MeV) gamma-ray flux show a close correlation during the first 7000 seconds, which is best explained by reverse shock emission cogenerated in the relativistic burst ejecta as it collides with surrounding material. At later times, optical observations show the emergence of emission generated by a forward shock traversing the circumburst environment. The link between optical afterglow and >100-MeV emission suggests that nearby early peaked afterglows will be the best candidates for studying gamma-ray emission at energies ranging from gigaelectron volts to teraelectron volts.

  16. A CENSUS OF ROTATION AND VARIABILITY IN L1495: A UNIFORM ANALYSIS OF TRANS-ATLANTIC EXOPLANET SURVEY LIGHT CURVES FOR PRE-MAIN-SEQUENCE STARS IN TAURUS

    International Nuclear Information System (INIS)

    Xiao Hongyu; Covey, Kevin R.; Lloyd, James P.; Rebull, Luisa; Charbonneau, David; Mandushev, Georgi; O'Donovan, Francis; Slesnick, Catherine

    2012-01-01

    We analyze light curves obtained by the Trans-atlantic Exoplanet Survey (TrES) for a field centered on the L1495 dark cloud in Taurus. The Spitzer Taurus Legacy Survey catalog identifies 179 bona fide Taurus members within the TrES field; 48 of the known Taurus members are detected by TrES, as well as 26 candidate members identified by the Spitzer Legacy team. We quantify the variability of each star in our sample using the ratio of the standard deviation of the original light curve (σ orig. ) to the standard deviation of a light curve that has been smoothed by 9 or 1001 epochs (σ 9 and σ 1001 , respectively). Known Taurus members typically demonstrate (σ orig. /σ 9 ) orig. /σ 1001 ) orig. /σ 9 ) ∼ 3.0 and (σ orig. /σ 1001 ) ∼ 10, as expected for light curves dominated by unstructured white noise. Of the 74 Taurus members/candidates with TrES light curves, we detect significant variability in 49 sources. Adapting a quantitative metric originally developed to assess the reliability of transit detections, we measure the amount of red and white noise in each light curve and identify 18 known or candidate Taurus members with highly significant period measurements. These appear to be the first periods measured for four of these sources (HD 282276, CX Tau, FP Tau, TrES J042423+265008), and in two other cases, the first non-aliased periods (LkCa 21 and DK Tau AB). For the remainder, the TrES measurements typically agree very well (δP < 1%) with previously reported values. Including periods measured at lower confidence for 15 additional sources, we report periods for 11 objects where no previous periods were found, including 8 confirmed Taurus members. We also identify 10 of the 26 candidate Taurus members that demonstrate variability levels consistent with being bona fide T Tauri stars. A Kolomgorov-Smirnov (K-S) test confirms that these new periods confirm the distinction between the rotation period distributions of stars with and without circumstellar

  17. GRB 030329: 3 years of radio afterglow monitoring

    NARCIS (Netherlands)

    van der Horst, A.J.; Kamble, A.; Wijers, R.A.M.J.; Resmi, L.; Bhattacharya, D.; Rol, E.; Strom, R.; Kouveliotou, C.; Oosterloo, T.; Ishwara-Chandra, C.H.

    2007-01-01

    Radio observations of gamma-ray burst (GRB) afterglows are essential for our understanding of the physics of relativistic blast waves, as they enable us to follow the evolution of GRB explosions much longer than the afterglows in any other wave band. We have performed a three-year monitoring

  18. A MATURE DUSTY STAR-FORMING GALAXY HOSTING GRB 080607 AT z = 3.036

    International Nuclear Information System (INIS)

    Chen, Hsiao-Wen; Perley, Daniel A.; Cenko, S. Bradley; Bloom, Joshua S.; Wilson, Christine D.; Levan, Andrew J.; Prochaska, Jason X.; Tanvir, Nial R.; Dessauges-Zavadsky, Miroslava; Pettini, Max

    2010-01-01

    We report the discovery of the host galaxy of Swift dark burst GRB 080607 at z GRB = 3.036. GRB 080607 is a unique case of a highly extinguished (A V ∼ 3 mag) afterglow that was yet sufficiently bright for high-quality absorption-line spectroscopy. The host galaxy is clearly resolved in deep Hubble Space Telescope (HST) WF3/IR F160W images and well detected in the Spitzer IRAC 3.5 μm and 4.5 μm channels, while displaying little/no fluxes in deep optical images from Keck and Magellan. The extremely red optical-infrared colors are consistent with the large extinction seen in the afterglow light, suggesting that the large amount of dust and gas surface mass density seen along the afterglow sight line is not merely local but likely reflects the global dust content across the entire host galaxy. Adopting the dust properties and metallicity of the host interstellar medium derived from studies of early-time afterglow light and absorption-line spectroscopy, we perform a stellar population synthesis analysis of the observed spectral energy distribution to constrain the intrinsic luminosity and stellar population of this dark burst host. The host galaxy is best described by an exponentially declining star formation rate of e-folding time τ = 2 Gyr and an age of ∼2 Gyr. We also derive an extinction-corrected star formation rate of SFR ∼ 125 h -2 M sun yr -1 and a total stellar mass of M * ∼ 4 x 10 11 h -2 M sun . Our study provides an example of massive, dusty star-forming galaxies contributing to the γ-ray burst (GRB) host galaxy population, supporting the notion that long-duration GRBs trace the bulk of cosmic star formation.

  19. Observations and light curve solutions of the eclipsing binaries USNO-B1.0 1395-0370184 and USNO-B1.0 1395-0370731

    Directory of Open Access Journals (Sweden)

    Kjurkchieva D.

    2016-01-01

    Full Text Available We present follow-up photometric observations in Sloan filters g', i' of the newly discovered eclipsing stars USNO-B1.0 1395-0370184 and USNO-B1.0 1395-0370731. Our data revealed that their orbital periods are considerably bigger than the previous values. This result changed the classification of USNO-B1.0 1395-0370184 from ultrashort-period binary (P=0.197 d to short-period system (P=0.251 d. The light curve solutions of our observations revealed that USNOB1.0 1395-0370184 and USNO-B1.0 1395-0370731 are overcontact binaries in which components are K dwarfs, close in masses and radii. The light curve distortions were reproduced by cool spots with angular radius of around 20°.

  20. The Structure and Dynamics of GRB Jets

    Energy Technology Data Exchange (ETDEWEB)

    Granot, Jonathan; /KIPAC, Menlo Park

    2006-10-25

    There are several lines of evidence which suggest that the relativistic outflows in gamma-ray bursts (GRBs) are collimated into narrow jets. The jet structure has important implications for the true energy release and the event rate of GRBs, and can constrain the mechanism responsible for the acceleration and collimation of the jet. Nevertheless, the jet structure and its dynamics as it sweeps up the external medium and decelerates, are not well understood. In this review I discuss our current understanding of GRB jets, stressing their structure and dynamics.

  1. GRB 070610: a curious galactic transient

    OpenAIRE

    Kasliwal, M. M.; Cenko, S. B.; Kulkarni, S. R.; Cameron, P. B.; Nakar, E.; Ofek, E. O.; Rau, A.; Soderberg, A. M.; Campana, S.; Bloom, J. S.; Perley, D. A.; Pollack, L. K.; Barthelmy, S.; Cummings, J.; Gehrels, N.

    2008-01-01

    GRB 070610 is a typical high-energy event with a duration of 5 s. Yet within the burst localization we detect a highly unusual X-ray and optical transient, Swift J195509.6+261406. We see high-amplitude X-ray and optical variability on very short timescales even at late times. Using near-infrared imaging assisted by a laser guide star and adaptive optics, we identified the counterpart of Swift J195509.6+261406. Late-time optical and near-infrared imaging constrain the spectral type of the coun...

  2. Determinations of its Absolute Dimensions and Distance by the Analyses of Light and Radial-Velocity Curves of the Contact Binary -I. V417 Aquilae

    Directory of Open Access Journals (Sweden)

    Jae Woo Lee

    2004-06-01

    Full Text Available New photometric and spectroscopic solutions of W-type overcontact binary V417 Aql were obtained by solving the UBV light curves of Samec et al. (1997 and radial-velocity ones of Lu & Rucinski (1999 with the 2003 version of the Wilson-Devinney binary code. In the light curve synthesis the light of a third-body, which Qian (2003 proposed, was considered and obtained about 2.7%, 2.2%, and 0.4% for U, B, and V bandpasses, respectively. The model with third-light is better fitted to eclipse parts than that with no third-light. Absolute dimensions of V417 Aql are determined from our solution as M1=0.53 M⊙, M2=1.45 M⊙, R1=0.84 R⊙ and R2=1.31 M⊙, and the distance to it is deduced as about 216pc. Our distance is well consistent with that (204pc derived from Rucinski & Duerbeck's (1997 relation, MV=MV(log P, B-V, but is more distant than that (131±40pc determined by the Hipparcos trigonometric parallax. The difference may result from the relatively large error of Hipparcos parallax for V417 Aql.

  3. Design, fabrication, and calibration of curved integral coils for measuring transfer function, uniformity, and effective length of LBL ALS [Lawrence Berkeley Laboratory Advanced Light Source] Booster Dipole Magnets

    International Nuclear Information System (INIS)

    Green, M.I.; Nelson, D.; Marks, S.; Gee, B.; Wong, W.; Meneghetti, J.

    1989-03-01

    A matched pair of curved integral coils has been designed, fabricated and calibrated at Lawrence Berkeley Laboratory for measuring Advanced Light Source (ALS) Booster Dipole Magnets. Distinctive fabrication and calibration techniques are described. The use of multifilar magnet wire in fabrication integral search coils is described. Procedures used and results of AC and DC measurements of transfer function, effective length and uniformity of the prototype booster dipole magnet are presented in companion papers. 8 refs

  4. Testing the nature of the supermassive black hole candidate in SgrA* with light curves and images of hot spots

    International Nuclear Information System (INIS)

    Li, Zilong; Kong, Lingyao; Bambi, Cosimo

    2014-01-01

    General relativity makes clear predictions about the spacetime geometry around black holes. In the near future, new facilities will have the capability to explore the metric around SgrA*, the supermassive black hole candidate at the center of our Galaxy, and to open a new window to test the Kerr black hole hypothesis. In this paper, we compute light curves and images associated with compact emission regions (hot spots) orbiting around Kerr and non-Kerr black holes. We study how the analysis of the properties of the radiation emitted by a hot spot can be used to test the Kerr nature of SgrA*. We find that the sole observation of the hot spot light curve can at most constrain a combination of the black hole spin and of possible deviations from the Kerr solution. This happens because the same orbital frequency around a Kerr black hole can be found for a non-Kerr object with a different spin parameter. Second order corrections in the light curve due to the background geometry are typically too small to be identified. While the observation of the hot spot centroid track can potentially bound possible deviations from the Kerr solution, that is out of reach for the near future for the Very Large Telescope Interferometer instrument GRAVITY. The Kerr black hole hypothesis could really be tested in the case of the discovery of a radio pulsar in a compact orbit around SgrA*. Radio observations of such a pulsar would provide precise estimates of the mass and the spin of SgrA*, and the combination of these measurements (probing the weak field) with the hot spot light curve information (probing the strong field) may constrain/find possible deviations from the Kerr solution with quite good precision.

  5. The Effect of an Offset Polar Cap Dipolar Magnetic Field on the Modeling of the Vela Pulsar's Gamma-Ray Light Curves

    Science.gov (United States)

    Barnard, M.; Venter, C.; Harding, A. K.

    2016-01-01

    We performed geometric pulsar light curve modeling using static, retarded vacuum, and offset polar cap (PC) dipole B-fields (the latter is characterized by a parameter epsilon), in conjunction with standard two-pole caustic (TPC) and outer gap (OG) emission geometries. The offset-PC dipole B-field mimics deviations from the static dipole (which corresponds to epsilon equals 0). In addition to constant-emissivity geometric models, we also considered a slot gap (SG) E-field associated with the offset-PC dipole B-field and found that its inclusion leads to qualitatively different light curves. Solving the particle transport equation shows that the particle energy only becomes large enough to yield significant curvature radiation at large altitudes above the stellar surface, given this relatively low E-field. Therefore, particles do not always attain the radiation-reaction limit. Our overall optimal light curve fit is for the retarded vacuum dipole field and OG model, at an inclination angle alpha equals 78 plus or minus 1 degree and observer angle zeta equals 69 plus 2 degrees or minus 1 degree. For this B-field, the TPC model is statistically disfavored compared to the OG model. For the static dipole field, neither model is significantly preferred. We found that smaller values of epsilon are favored for the offset-PC dipole field when assuming constant emissivity, and larger epsilon values favored for variable emissivity, but not significantly so. When multiplying the SG E-field by a factor of 100, we found improved light curve fits, with alpha and zeta being closer to best fits from independent studies, as well as curvature radiation reaction at lower altitudes.

  6. Testing the nature of the supermassive black hole candidate in SgrA* with light curves and images of hot spots

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zilong; Kong, Lingyao; Bambi, Cosimo [Center for Field Theory and Particle Physics and Department of Physics, Fudan University, 200433 Shanghai (China)

    2014-06-01

    General relativity makes clear predictions about the spacetime geometry around black holes. In the near future, new facilities will have the capability to explore the metric around SgrA*, the supermassive black hole candidate at the center of our Galaxy, and to open a new window to test the Kerr black hole hypothesis. In this paper, we compute light curves and images associated with compact emission regions (hot spots) orbiting around Kerr and non-Kerr black holes. We study how the analysis of the properties of the radiation emitted by a hot spot can be used to test the Kerr nature of SgrA*. We find that the sole observation of the hot spot light curve can at most constrain a combination of the black hole spin and of possible deviations from the Kerr solution. This happens because the same orbital frequency around a Kerr black hole can be found for a non-Kerr object with a different spin parameter. Second order corrections in the light curve due to the background geometry are typically too small to be identified. While the observation of the hot spot centroid track can potentially bound possible deviations from the Kerr solution, that is out of reach for the near future for the Very Large Telescope Interferometer instrument GRAVITY. The Kerr black hole hypothesis could really be tested in the case of the discovery of a radio pulsar in a compact orbit around SgrA*. Radio observations of such a pulsar would provide precise estimates of the mass and the spin of SgrA*, and the combination of these measurements (probing the weak field) with the hot spot light curve information (probing the strong field) may constrain/find possible deviations from the Kerr solution with quite good precision.

  7. NEAR-INFRARED LIGHT CURVES OF THE BROWN DWARF ECLIPSING BINARY 2MASS J05352184-0546085: CAN SPOTS EXPLAIN THE TEMPERATURE REVERSAL?

    International Nuclear Information System (INIS)

    Gomez Maqueo Chew, Yilen; Stassun, Keivan G.; Prsa, Andrej; Mathieu, Robert D.

    2009-01-01

    We present near-infrared JHK S light curves for the double-lined eclipsing binary system Two Micron All Sky Survey J05352184 - 0546085, in which both components have been shown to be brown dwarfs with an age of ∼1 Myr. We analyze these light curves together with the previously published I C -band light curve and radial velocities to provide refined measurements of the system's physical parameters. The component masses and radii are here determined with an accuracy of ∼6.5% and ∼1.5%, respectively. In addition, we confirm the previous surprising finding that the primary brown dwarf has a cooler effective temperature than its lower mass companion. Next, we perform a detailed study of the residual variations in the out-of-eclipse phases of the light curves to ascertain the properties of any inhomogeneities (e.g., spots) on the surfaces of the brown dwarfs. Our analysis reveals two low-amplitude (∼0.02 mag) periodic signals, one attributable to the rotation of the primary with a period of 3.293 ± 0.001 d and the other to the rotation of the secondary with a period of 14.05 ± 0.05 d. Both periods are consistent with the measured vsin i and radii. Finally, we explore the effects on the derived physical parameters of the system when spots are included in the modeling of the light curves. The observed low-amplitude rotational modulations are well fitted by cool spots covering a small fraction (∼<10%) of the brown dwarfs' surfaces. Such small spots negligibly affect the physical properties of the brown dwarfs, and thus by themselves cannot explain the primary's unexpectedly low surface temperature. To mimic the observed ∼200 K suppression of the primary's temperature, our model requires that the primary possesses a very large spot coverage fraction of ∼65%. These spots must in addition be symmetrically distributed on the primary's surface so as not to produce photometric variations larger than observed. Altogether, a spot configuration in which the primary

  8. Light-curve Modulation of Low-mass Stars in K2. I. Identification of 481 Fast Rotators in the Solar Neighborhood

    Science.gov (United States)

    Saylor, Dicy; Lepine, Sebastien; Crossfield, Ian; Petigura, Erik A.

    2018-01-01

    The K2 mission is targeting large numbers of nearby (d 40 mas yr‑1, V < 20). Additionally, the mission is targeting low-mass, high proper motion stars associated with the local (d < 500 pc) Galactic halo population also selected from SUPERBLINK. K2 campaigns 0 through 8 monitored a total of 26,518 of these cool main-sequence stars. We used the auto-correlation function to search for fast rotators by identifying short-period photometric modulations in the K2 light curves. We identified 481 candidate fast rotators with rotation periods <4 days that show light-curve modulations consistent with starspots. Their kinematics show low average transverse velocities, suggesting that they are part of the young disk population. A subset (13) of the fast rotators is found among those targets with colors and kinematics consistent with the local Galactic halo population and may represent stars spun up by tidal interactions in close binary systems. We further demonstrate that the M dwarf fast rotators selected from the K2 light curves are significantly more likely to have UV excess and discuss the potential of the K2 mission to identify new nearby young GKM dwarfs on the basis of their fast rotation rates. Finally, we discuss the possible use of local halo stars as fiducial, non-variable sources in the Kepler fields.

  9. Detection of a repeated transit signature in the light curve of the enigma star KIC 8462852: A possible 928-day period

    Science.gov (United States)

    Kiefer, F.; Lecavelier des Étangs, A.; Vidal-Madjar, A.; Hébrard, G.; Bourrier, V.; Wilson, P. A.

    2017-12-01

    As revealed by its peculiar Kepler light curve, the enigmatic star KIC 8462852 undergoes short and deep flux dimmings at a priori unrelated epochs. This star presents nonetheless all other characteristics of a quiet 1 Gyr old F3V star. These dimmings resemble the absorption features expected for the transit of dust cometary tails. The exocomet scenario is therefore most commonly advocated. We reanalysed the Kepler data and extracted a new high-quality light curve to allow for the search of shallow signatures of single or a few exocomets. We discovered that among the 22 flux dimming events that we identified, two events present a striking similarity. These events occurred 928.25 days apart and lasted for 4.4 days with a drop in the star brightness by 1000 ppm. We show that the light curve of these events is well explained by the occultation of the star by a giant ring system or by the transit of a string of half a dozen exocomets with a typical dust production rate of 105-106 kg s-1. Assuming that these two similar events are related to the transit of the same object, we derive a period of 928.25 days. The following transit was expected in March 2017 but bad weather prohibited us from detecting it from ground-based spectroscopy. We predict that the next event will occur between 3-8 October 2019.

  10. The hamster clock phase-response curve from summerlike light:dark cycles and its role in daily and seasonal timekeeping.

    Science.gov (United States)

    Alleva, John J; Alleva, Frederic R

    2002-11-01

    We address the subject of entrainment of the hamster clock by the day:night cycle in summer when the sun sets after 6 PM and rises before 6 AM (nights cycles were simulated by 6 light:dark (LD) cycles with D estrus and wheel running in hamsters. The onset of estrus was observed every 4 d in the same hamsters as a phase marker of their 24 h clock. On the day before an experimental estrus, preceded and followed by control onsets, a dark period was imposed to cover a putative 6 PM-6 AM light-sensitive period (LSP). This was scanned with a light pulse (and periodic 5 sec bell alarms) lasting 5-240 min. Shifts in onset of estrus on the next day were plotted vs. the end of the light pulse for PM times ("dusk") and its onset for AM times ("dawn"). The resulting phase shifts from the six SLDs were similar, permitting their combination into a single phase-response curve (PRC) of 1605 shifts. This SLD composite PRC rose at 10:15 PM, peaked at 2 AM (81 min advanced shift), fell linearly to 5:55 AM, and then abruptly to normal at 6 AM (no shift). Peak shift was unaffected by light pulse duration or intensity, or hamster age. The SLD composite PRC lacked the 6 PM-9 PM curve of delayed shifts present in reported PRCs from LD 12 h:12 h and DD. However, a two-pulse experiment showed that all light from 6 PM to L-off was needed to block (balance) the advancing action of a 5 min morning light pulse, thereby maintaining entrainment. A working hypothesis to explain daily entrainment and seasonal fertility in the golden hamster is illustrated. A nomenclature for labeling the phases of the hamster clock (circadian time) is proposed.

  11. A binary neutron star GRB model

    International Nuclear Information System (INIS)

    Wilson, J.R.; Salmonson, J.D.; Wilson, J.R.; Mathews, G.J.

    1998-01-01

    In this paper we present the preliminary results of a model for the production of gamma-ray bursts (GRBs) through the compressional heating of binary neutron stars near their last stable orbit prior to merger. Recent numerical studies of the general relativistic (GR) hydrodynamics in three spatial dimensions of close neutron star binaries (NSBs) have uncovered evidence for the compression and heating of the individual neutron stars (NSs) prior to merger 12. This effect will have significant effect on the production of gravitational waves, neutrinos and, ultimately, energetic photons. The study of the production of these photons in close NSBs and, in particular, its correspondence to observed GRBs is the subject of this paper. The gamma-rays arise as follows. Compressional heating causes the neutron stars to emit neutrino pairs which, in turn, annihilate to produce a hot electron-positron pair plasma. This pair-photon plasma expands rapidly until it becomes optically thin, at which point the photons are released. We show that this process can indeed satisfy three basic requirements of a model for cosmological gamma-ray bursts: (1) sufficient gamma-ray energy release (>10 51 ergs) to produce observed fluxes, (2) a time-scale of the primary burst duration consistent with that of a 'classical' GRB (∼10 seconds), and (3) the peak of the photon number spectrum matches that of 'classical' GRB (∼300 keV). copyright 1998 American Institute of Physics

  12. The host galaxy of GRB 990712

    DEFF Research Database (Denmark)

    Christensen, L.; Hjorth, J.; Gorosabel, J.

    2004-01-01

    We present a comprehensive study of the z = 0.43 host galaxy of GRB 990712, involving ground-based photometry, spectroscopy, and HST imaging. The broad-band UBVRIJHKs photometry is used to determine the global spectral energy distribution (SED) of the host galaxy. Comparison with that of known...... galaxy types shows that the host is similar to a moderately kreddened starburst galaxy with a young stellar population. The estimated internal extinction in the host is A(V) = 0.15 +/- 0.1 and the star-formation rate (SFR) from the UV continuum is 1.3 +/- 0.3 M-circle dot yr(-1) (not corrected...... for the effects of extinction). Other galaxy template spectra than starbursts failed to reproduce the observed SED. We also present VLT spectra leading to the detection of Halpha from the GRB host galaxy. A SFR of 2.8 +/- 0.7 M-circle dot yr(-1) is inferred from the Halpha line flux, and the presence of a young...

  13. A Strong Limit on the Very-high-energy Emission from GRB 150323A

    Science.gov (United States)

    Abeysekara, A. U.; Archer, A.; Benbow, W.; Bird, R.; Brose, R.; Buchovecky, M.; Bugaev, V.; Connolly, M. P.; Cui, W.; Errando, M.; Falcone, A.; Feng, Q.; Finley, J. P.; Flinders, A.; Fortson, L.; Furniss, A.; Gillanders, G. H.; Hütten, M.; Hanna, D.; Hervet, O.; Holder, J.; Hughes, G.; Humensky, T. B.; Johnson, C. A.; Kaaret, P.; Kar, P.; Kelley-Hoskins, N.; Kertzman, M.; Kieda, D.; Krause, M.; Krennrich, F.; Lang, M. J.; Lin, T. T. Y.; Maier, G.; McArthur, S.; Moriarty, P.; Mukherjee, R.; O’Brien, S.; Ong, R. A.; Park, N.; Perkins, J. S.; Petrashyk, A.; Pohl, M.; Popkow, A.; Pueschel, E.; Quinn, J.; Ragan, K.; Reynolds, P. T.; Richards, G. T.; Roache, E.; Rulten, C.; Sadeh, I.; Santander, M.; Sembroski, G. H.; Shahinyan, K.; Tyler, J.; Wakely, S. P.; Weiner, O. M.; Weinstein, A.; Wells, R. M.; Wilcox, P.; Wilhelm, A.; Williams, D. A.; Zitzer, B.; VERITAS Collaboration; Vurm, Indrek; Beloborodov, Andrei

    2018-04-01

    On 2015 March 23, the Very Energetic Radiation Imaging Telescope Array System (VERITAS) responded to a Swift-Burst Alert Telescope (BAT) detection of a gamma-ray burst, with observations beginning 270 s after the onset of BAT emission, and only 135 s after the main BAT emission peak. No statistically significant signal is detected above 140 GeV. The VERITAS upper limit on the fluence in a 40-minute integration corresponds to about 1% of the prompt fluence. Our limit is particularly significant because the very-high-energy (VHE) observation started only ∼2 minutes after the prompt emission peaked, and Fermi-Large Area Telescope observations of numerous other bursts have revealed that the high-energy emission is typically delayed relative to the prompt radiation and lasts significantly longer. Also, the proximity of GRB 150323A (z = 0.593) limits the attenuation by the extragalactic background light to ∼50% at 100–200 GeV. We conclude that GRB 150323A had an intrinsically very weak high-energy afterglow, or that the GeV spectrum had a turnover below ∼100 GeV. If the GRB exploded into the stellar wind of a massive progenitor, the VHE non-detection constrains the wind density parameter to be A ≳ 3 × 1011 g cm‑1, consistent with a standard Wolf–Rayet progenitor. Alternatively, the VHE emission from the blast wave would be weak in a very tenuous medium such as the interstellar medium, which therefore cannot be ruled out as the environment of GRB 150323A.

  14. Limb darkening laws for two exoplanet host stars derived from 3D stellar model atmospheres. Comparison with 1D models and HST light curve observations

    Science.gov (United States)

    Hayek, W.; Sing, D.; Pont, F.; Asplund, M.

    2012-03-01

    We compare limb darkening laws derived from 3D hydrodynamical model atmospheres and 1D hydrostatic MARCS models for the host stars of two well-studied transiting exoplanet systems, the late-type dwarfs HD 209458 and HD 189733. The surface brightness distribution of the stellar disks is calculated for a wide spectral range using 3D LTE spectrum formation and opacity sampling⋆. We test our theoretical predictions using least-squares fits of model light curves to wavelength-integrated primary eclipses that were observed with the Hubble Space Telescope (HST). The limb darkening law derived from the 3D model of HD 209458 in the spectral region between 2900 Å and 5700 Å produces significantly better fits to the HST data, removing systematic residuals that were previously observed for model light curves based on 1D limb darkening predictions. This difference arises mainly from the shallower mean temperature structure of the 3D model, which is a consequence of the explicit simulation of stellar surface granulation where 1D models need to rely on simplified recipes. In the case of HD 189733, the model atmospheres produce practically equivalent limb darkening curves between 2900 Å and 5700 Å, partly due to obstruction by spectral lines, and the data are not sufficient to distinguish between the light curves. We also analyze HST observations between 5350 Å and 10 500 Å for this star; the 3D model leads to a better fit compared to 1D limb darkening predictions. The significant improvement of fit quality for the HD 209458 system demonstrates the higher degree of realism of 3D hydrodynamical models and the importance of surface granulation for the formation of the atmospheric radiation field of late-type stars. This result agrees well with recent investigations of limb darkening in the solar continuum and other observational tests of the 3D models. The case of HD 189733 is no contradiction as the model light curves are less sensitive to the temperature stratification of

  15. The Macronova in GRB 050709 and the GRB-macronova connection

    Science.gov (United States)

    Jin, Zhi-Ping; Hotokezaka, Kenta; Li, Xiang; Tanaka, Masaomi; D'Avanzo, Paolo; Fan, Yi-Zhong; Covino, Stefano; Wei, Da-Ming; Piran, Tsvi

    2016-01-01

    GRB 050709 was the first short Gamma-ray Burst (sGRB) with an identified optical counterpart. Here we report a reanalysis of the publicly available data of this event and the discovery of a Li-Paczynski macronova/kilonova that dominates the optical/infrared signal at t>2.5 days. Such a signal would arise from 0.05 r-process material launched by a compact binary merger. The implied mass ejection supports the suggestion that compact binary mergers are significant and possibly main sites of heavy r-process nucleosynthesis. Furthermore, we have reanalysed all afterglow data from nearby short and hybrid GRBs (shGRBs). A statistical study of shGRB/macronova connection reveals that macronova may have taken place in all these GRBs, although the fraction as low as 0.18 cannot be ruled out. The identification of two of the three macronova candidates in the I-band implies a more promising detection prospect for ground-based surveys. PMID:27659791

  16. Fermi Observation of GRB 080916C

    International Nuclear Information System (INIS)

    Piron, F.

    2009-01-01

    We present the observations of the long-duration Gamma-Ray Burst GRB 080916C by the Fermi Gamma-ray Burst Monitor (GBM) and Large Area Telescope (LAT). This event was observed from 8 keV to a photon with an energy of 13.2 GeV. It develops over a 1400 s interval during which the highest number of photons with energy above 100 MeV are detected from a burst. The onset of the high-energy (>100 MeV) emission is delayed by ∼4.5 s with respect to the low-energy (<1 MeV) emission, which is not detected past 200 s. The broad-band spectrum of the burst is consistent with a single spectral form.

  17. The Accuracy of GBM GRB Localizations

    Science.gov (United States)

    Briggs, Michael Stephen; Connaughton, V.; Meegan, C.; Hurley, K.

    2010-03-01

    We report an study of the accuracy of GBM GRB localizations, analyzing three types of localizations: those produced automatically by the GBM Flight Software on board GBM, those produced automatically with ground software in near real time, and localizations produced with human guidance. The two types of automatic locations are distributed in near real-time via GCN Notices; the human-guided locations are distributed on timescale of many minutes or hours using GCN Circulars. This work uses a Bayesian analysis that models the distribution of the GBM total location error by comparing GBM locations to more accurate locations obtained with other instruments. Reference locations are obtained from Swift, Super-AGILE, the LAT, and with the IPN. We model the GBM total location errors as having systematic errors in addition to the statistical errors and use the Bayesian analysis to constrain the systematic errors.

  18. Column Store for GWAC: A High-cadence, High-density, Large-scale Astronomical Light Curve Pipeline and Distributed Shared-nothing Database

    Science.gov (United States)

    Wan, Meng; Wu, Chao; Wang, Jing; Qiu, Yulei; Xin, Liping; Mullender, Sjoerd; Mühleisen, Hannes; Scheers, Bart; Zhang, Ying; Nes, Niels; Kersten, Martin; Huang, Yongpan; Deng, Jinsong; Wei, Jianyan

    2016-11-01

    The ground-based wide-angle camera array (GWAC), a part of the SVOM space mission, will search for various types of optical transients by continuously imaging a field of view (FOV) of 5000 degrees2 every 15 s. Each exposure consists of 36 × 4k × 4k pixels, typically resulting in 36 × ˜175,600 extracted sources. For a modern time-domain astronomy project like GWAC, which produces massive amounts of data with a high cadence, it is challenging to search for short timescale transients in both real-time and archived data, and to build long-term light curves for variable sources. Here, we develop a high-cadence, high-density light curve pipeline (HCHDLP) to process the GWAC data in real-time, and design a distributed shared-nothing database to manage the massive amount of archived data which will be used to generate a source catalog with more than 100 billion records during 10 years of operation. First, we develop HCHDLP based on the column-store DBMS of MonetDB, taking advantage of MonetDB’s high performance when applied to massive data processing. To realize the real-time functionality of HCHDLP, we optimize the pipeline in its source association function, including both time and space complexity from outside the database (SQL semantic) and inside (RANGE-JOIN implementation), as well as in its strategy of building complex light curves. The optimized source association function is accelerated by three orders of magnitude. Second, we build a distributed database using a two-level time partitioning strategy via the MERGE TABLE and REMOTE TABLE technology of MonetDB. Intensive tests validate that our database architecture is able to achieve both linear scalability in response time and concurrent access by multiple users. In summary, our studies provide guidance for a solution to GWAC in real-time data processing and management of massive data.

  19. Multi-color light curves of type Ia supernovae on the color-magnitude diagram: A novel step toward more precise distance and extinction estimates

    International Nuclear Information System (INIS)

    Wang, Lifan; Goldhaber, Gerson; Aldering, Greg; Perlmutter, Saul

    2003-01-01

    We show empirically that fits to the color-magnitude relation of Type Ia supernovae after optical maximum can provide accurate relative extragalactic distances. We report the discovery of an empirical color relation for Type Ia light curves: During much of the first month past maximum, the magnitudes of Type Ia supernovae defined at a given value of color index have a very small magnitude dispersion; moreover, during this period the relation between B magnitude and B-V color (or B-Ror B-I color) is strikingly linear, to the accuracy of existing well-measured data. These linear relations can provide robust distance estimates, in particular, by using the magnitudes when the supernova reaches a given color. After correction for light curve stretch factor or decline rate, the dispersion of the magnitudes taken at the intercept of the linear color-magnitude relation are found to be around 0 m .08 for the sub-sample of supernovae with (B max - V max ) (le) 0 m 0.5, and around 0 m .11 for the sub-sample with (B max - V max ) (le) 0 m .2. This small dispersion is consistent with being mostly due to observational errors. The method presented here and the conventional light curve fitting methods can be combined to further improve statistical dispersions of distance estimates. It can be combined with the magnitude at maximum to deduce dust extinction. The slopes of the color-magnitude relation may also be used to identify intrinsically different SN Ia systems. The method provides a tool that is fundamental to using SN Ia to estimate cosmological parameters such as the Hubble constant and the mass and dark energy content of the universe

  20. Determination of the orientation of the white dwarf's magnetic axis from X-ray orbital light curves

    International Nuclear Information System (INIS)

    Andronov, I.L.

    1986-01-01

    The directional pattern of soft X-ray radiation produced in a ''polar cap'' on the white dwarf's surface is calculated taking into account the absorption in the axially symmetrical accretion column, homogeneous along its height. An algorithm for the determination of orientation of the magnetic axis of a compact star from orbital curves of soft X-ray flux, is suggested. The values of the orbital inclination i (51 deg <=i<64 deg) and the angle between the rotational and magnetic axes σ (30 deg <=σ<=34 deg) were calculated for the polar AM Herculis for different values of model parameters

  1. CONSTRAINTS ON VERY HIGH ENERGY EMISSION FROM GRB 130427A

    International Nuclear Information System (INIS)

    Aliu, E.; Errando, M.; Aune, T.; Barnacka, A.; Beilicke, M.; Buckley, J. H.; Bugaev, V.; Benbow, W.; Cerruti, M.; Berger, K.; Biteau, J.; Byrum, K.; Cardenzana, J. V; Dickinson, H. J.; Eisch, J. D.; Chen, X.; Ciupik, L.; Connaughton, V.; Cui, W.; Falcone, A.

    2014-01-01

    Prompt emission from the very fluent and nearby (z = 0.34) gamma-ray burst GRB 130427A was detected by several orbiting telescopes and by ground-based, wide-field-of-view optical transient monitors. Apart from the intensity and proximity of this GRB, it is exceptional due to the extremely long-lived high-energy (100 MeV to 100 GeV) gamma-ray emission, which was detected by the Large Area Telescope on the Fermi Gamma-Ray Space Telescope for ∼70 ks after the initial burst. The persistent, hard-spectrum, high-energy emission suggests that the highest-energy gamma rays may have been produced via synchrotron self-Compton processes though there is also evidence that the high-energy emission may instead be an extension of the synchrotron spectrum. VERITAS, a ground-based imaging atmospheric Cherenkov telescope array, began follow-up observations of GRB 130427A ∼71 ks (∼20 hr) after the onset of the burst. The GRB was not detected with VERITAS; however, the high elevation of the observations, coupled with the low redshift of the GRB, make VERITAS a very sensitive probe of the emission from GRB 130427A for E > 100 GeV. The non-detection and consequent upper limit derived place constraints on the synchrotron self-Compton model of high-energy gamma-ray emission from this burst

  2. The GW170817/GRB 170817A/AT 2017gfo Association: Some Implications for Physics and Astrophysics

    Science.gov (United States)

    Wang, Hao; Zhang, Fu-Wen; Wang, Yuan-Zhu; Shen, Zhao-Qiang; Liang, Yun-Feng; Li, Xiang; Liao, Neng-Hui; Jin, Zhi-Ping; Yuan, Qiang; Zou, Yuan-Chuan; Fan, Yi-Zhong; Wei, Da-Ming

    2017-12-01

    On 2017 August 17, a gravitational-wave event (GW170817) and an associated short gamma-ray burst (GRB 170817A) from a binary neutron star merger had been detected. The follow-up optical/infrared observations also identified the macronova/kilonova emission (AT 2017gfo). In this work, we discuss some implications of the remarkable GW170817/GRB 170817A/AT 2017gfo association. We show that the ∼1.7 s time delay between the gravitational-wave (GW) and GRB signals imposes very tight constraints on the superluminal movement of gravitational waves (i.e., the relative departure of GW velocity from the speed of light is ≤slant 4.3× {10}-16) or the possible violation of the weak equivalence principle (i.e., the difference of the gamma-ray and GW trajectories in the gravitational field of the galaxy and the local universe should be within a factor of ∼ 3.4× {10}-9). The so-called Dark Matter Emulators and a class of contender models for cosmic acceleration (“Covariant Galileon”) are ruled out as well. The successful identification of lanthanide elements in the macronova/kilonova spectrum also excludes the possibility that the progenitors of GRB 170817A are a binary strange star system. The high neutron star merger rate (inferred from both the local sGRB data and the gravitational-wave data) together with the significant ejected mass strongly suggest that such mergers are the prime sites of heavy r-process nucleosynthesis.

  3. Hubble space telescope observations of the afterglow, supernova, and host galaxy associated with the extremely bright GRB 130427A

    Energy Technology Data Exchange (ETDEWEB)

    Levan, A. J. [Department of Physics, University of Warwick, Coventry, CV4 7AL (United Kingdom); Tanvir, N. R.; Wiersema, K. [Department of Physics and Astronomy, University of Leicester, University Road, Leicester, LE1 7RH (United Kingdom); Fruchter, A. S.; Hounsell, R. A.; Graham, J. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Hjorth, J.; Fynbo, J. P. U. [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen (Denmark); Pian, E. [INAF, Trieste Astronomical Observatory, via G.B. Tiepolo 11, I-34143 Trieste (Italy); Mazzali, P. [Astrophysics Research Institute, Liverpool John Moores University, IC2 Liverpool Science Park 146 Brownlow Hill, Liverpool L3 5RF (United Kingdom); Perley, D. A. [Department of Astronomy, California Institute of Technology, MC 249-17, 1200 East California Blvd., Pasadena, CA 91125 (United States); Cano, Z. [Centre for Astrophysics and Cosmology, Science Institute, University of Iceland, Dunhagi 5, 107 Reykjavik (Iceland); Cenko, S. B. [Astrophysics Science Division, NASA Goddard Space Flight Center, Mail Code 661, Greenbelt, MD 20771 (United States); Kouveliotou, C. [Science and Technology Office, ZP12, NASA/Marshall Space Flight Center, Huntsville, AL 35812 (United States); Pe' er, A. [Department of Physics, University College Cork, Cork (Ireland); Misra, K., E-mail: a.j.levan@warwick.ac.uk [Aryabhatta Research Institute of Observational Sciences, Manora Peak, Nainital-263 002 (India)

    2014-09-10

    We present Hubble Space Telescope (HST) observations of the exceptionally bright and luminous Swift gamma-ray burst (GRB), GRB 130427A. At z = 0.34, this burst affords an excellent opportunity to study the supernova (SN) and host galaxy associated with an intrinsically extremely luminous burst (E {sub iso} > 10{sup 54} erg): more luminous than any previous GRB with a spectroscopically associated SN. We use the combination of the image quality, UV capability, and invariant point-spread function of HST to provide the best possible separation of the afterglow, host, and SN contributions to the observed light ∼17 rest-frame days after the burst, utilizing a host subtraction spectrum obtained one year later. Advanced Camera for Surveys grism observations show that the associated SN, SN 2013cq, has an overall spectral shape and luminosity similar to SN 1998bw (with a photospheric velocity, v {sub ph} ∼ 15, 000 km s{sup –1}). The positions of the bluer features are better matched by the higher velocity SN 2010bh (v {sub ph} ∼ 30, 000 km s{sup –1}), but this SN is significantly fainter and fails to reproduce the overall spectral shape, perhaps indicative of velocity structure in the ejecta. We find that the burst originated ∼4 kpc from the nucleus of a moderately star forming (1 M {sub ☉} yr{sup –1}), possibly interacting disk galaxy. The absolute magnitude, physical size, and morphology of this galaxy, as well as the location of the GRB within it, are also strikingly similar to those of GRB 980425/SN 1998bw. The similarity of the SNe and environment from both the most luminous and least luminous GRBs suggests that broadly similar progenitor stars can create GRBs across six orders of magnitude in isotropic energy.

  4. UVES/VLT high resolution spectroscopy of GRB 050730 afterglow: probing the features of the GRB environment

    International Nuclear Information System (INIS)

    D'Elia, V.; Fiore, F.; Piranomonte, S.; Sbordone, L.; Stella, L.; Antonelli, L.A.; Fontana, A.; Giannini, T.; Guetta, D.; Israel, G.; Testa, V.; Meurs, E.J.A.; Vergani, S.D.; Ward, P.; Chincarini, G.; Tagliaferri, G.; Campana, S.; Fugazza, D.; Molinari, E.; Moretti, A.; Chincarini, G.; Melandri, A.; Norci, L.; Vergani, S.D.; Pellizza, L.; Filliatre, P.; Perna, R.; Lazzati, D.

    2007-01-01

    Aims. The aim of this paper is to study the Gamma Ray Burst (GRB) environment through the analysis of the optical absorption features due to the gas surrounding the GRB. Methods. To this purpose we analyze high resolution spectroscopic observations (R = 20000-45000, corresponding to 14 kms -1 at 4200 Angstroms and 6.6 kms -1 at 9000 Angstroms of the optical afterglow of GRB050730, obtained with UVES-VLT ∼ 4 h after the GRB trigger. Results. The spectrum shows that the ISM of the GRB host galaxy at z = 3.967 is complex, with at least five components contributing to the main absorption system. We detect strong CII*, SiII*, OI* and FeII* fine structure absorption lines associated to the second and third component. Conclusions. For the first three components we derive information on the relative distance from the site of the GRB explosion. Component 1, which has the longest wavelength, highest positive velocity shift, does not present any fine structure nor low ionization lines; it only shows very high ionization features, such as C IV and O VI, suggesting that this component is very close to the GRB site. From the analysis of low and high ionization lines and fine structure lines, we find evidences that the distance of component 2 from the site of the GRB explosion is 10-100 times smaller than that of component 3. We evaluated the mean metallicity of the z = 3.967 system obtaining values approximate to 10 -2 of the solar metallicity or less. However, this should not be taken as representative of the circum-burst medium, since the main contribution to the hydrogen column density comes from the outer regions of the galaxy while that of the other elements presumably comes from the ISM closer to the GRB site. Furthermore, difficulties in evaluating dust depletion correction can modify significantly these values. The mean [C/Fe] ratio agrees well with that expected by single star-formation event models. Interestingly the [C/Fe] of component 2 is smaller than that of

  5. VLT/X-shooter GRBs: Individual extinction curves of star-forming regions★

    Science.gov (United States)

    Zafar, T.; Watson, D.; Møller, P.; Selsing, J.; Fynbo, J. PU; Schady, P.; Wiersema, K.; Levan, A. J.; Heintz, K. E.; Postigo, A. de Ugarte; D'Elia, V.; Jakobsson, P.; Bolmer, J.; Japelj, J.; Covino, S.; Gomboc, A.; Cano, Z.

    2018-05-01

    The extinction profiles in Gamma-Ray Burst (GRB) afterglow spectral energy distributions (SEDs) are usually described by the Small Magellanic Cloud (SMC)-type extinction curve. In different empirical extinction laws, the total-to-selective extinction, RV, is an important quantity because of its relation to dust grain sizes and compositions. We here analyse a sample of 17 GRBs (0.34a single or broken power-law together with a parametric extinction law is used to model the individual SEDs. We find 10 cases with significant dust, where the derived extinction, AV, ranges from 0.1-1.0 mag. In four of those, the inferred extinction curves are consistent with the SMC curve. The GRB individual extinction curves have a flat RV distribution with an optimal weighted combined value of RV = 2.61 ± 0.08 (for seven broad coverage cases). The `average GRB extinction curve' is similar to, but slightly steeper than the typical SMC, and consistent with the SMC Bar extinction curve at ˜95% confidence level. The resultant steeper extinction curves imply populations of small grains, where large dust grains may be destroyed due to GRB activity. Another possibility could be that young age and/or lower metallicities of GRBs environments are responsible for the steeper curves.

  6. Molecular cloning of the mouse grb2 gene: differential interaction of the Grb2 adaptor protein with epidermal growth factor and nerve growth factor receptors.

    OpenAIRE

    Suen, K L; Bustelo, X R; Pawson, T; Barbacid, M

    1993-01-01

    We report the isolation and molecular characterization of the mouse grb2 gene. The product of this gene, the Grb2 protein, is highly related to the Caenorhabditis elegans sem-5 gene product and the human GRB2 protein and displays the same SH3-SH2-SH3 structural motifs. In situ hybridization studies revealed that the mouse grb2 gene is widely expressed throughout embryonic development (E9.5 to P0). However, grb2 transcripts are not uniformly distributed, and in certain tissues (e.g., thymus) t...

  7. BEER ANALYSIS OF KEPLER AND CoRoT LIGHT CURVES. IV. DISCOVERY OF FOUR NEW LOW-MASS WHITE DWARF COMPANIONS IN THE KEPLER DATA

    Energy Technology Data Exchange (ETDEWEB)

    Faigler, S.; Kull, I.; Mazeh, T.; Kiefer, F. [School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978 (Israel); Latham, D. W. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Bloemen, S. [Department of Astrophysics, IMAPP, Radboud University Nijmegen, P.O. BOX 9010, NL-6500 GL Nijmegen (Netherlands)

    2015-12-10

    We report the discovery of four short-period eclipsing systems in the Kepler light curves, consisting of an A-star primary and a low-mass white dwarf (WD) secondary (dA+WD)—KIC 4169521, KOI-3818, KIC 2851474, and KIC 9285587. The systems show BEaming, Ellipsoidal and Reflection (BEER) phase modulations together with primary and secondary eclipses. These add to the 6 Kepler and 18 WASP short-period eclipsing dA+WD binaries that were previously known. The light curves, together with follow-up spectroscopic observations, allow us to derive the masses, radii, and effective temperatures of the two components of the four systems. The orbital periods, of 1.17–3.82 days, and WD masses, of 0.19–0.22 M{sub ⊙}, are similar to those of the previously known systems. The WD radii of KOI-3818, KIC 2851474, and KIC 9285587 are 0.026, 0.035, and 0.026 R{sub ⊙}, respectively, the smallest WD radii derived so far for short-period eclipsing dA+WD binaries. These three binaries extend the previously known population to older systems with cooler and smaller WD secondaries. KOI-3818 displays evidence for a fast-rotating primary and a minute but significant eccentricity, ∼1.5 × 10{sup −3}. These features are probably the outcome of the mass-transfer process.

  8. A Correlation Between the Intrinsic Brightness and Average Decay Rate of Gamma-Ray Burst X-Ray Afterglow Light Curves

    Science.gov (United States)

    Racusin, J. L.; Oates, S. R.; De Pasquale, M.; Kocevski, D.

    2016-01-01

    We present a correlation between the average temporal decay (alpha X,avg, greater than 200 s) and early-time luminosity (LX,200 s) of X-ray afterglows of gamma-ray bursts as observed by the Swift X-ray Telescope. Both quantities are measured relative to a rest-frame time of 200 s after the gamma-ray trigger. The luminosity â€" average decay correlation does not depend on specific temporal behavior and contains one scale-independent quantity minimizing the role of selection effects. This is a complementary correlation to that discovered by Oates et al. in the optical light curves observed by the Swift Ultraviolet Optical Telescope. The correlation indicates that, on average, more luminous X-ray afterglows decay faster than less luminous ones, indicating some relative mechanism for energy dissipation. The X-ray and optical correlations are entirely consistent once corrections are applied and contamination is removed. We explore the possible biases introduced by different light-curve morphologies and observational selection effects, and how either geometrical effects or intrinsic properties of the central engine and jet could explain the observed correlation.

  9. Multi-color light curves of type Ia supernovae on thecolor-magnitude diagram: A novel step toward more precise distance andextinction estimates

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lifan; Goldhaber, Gerson; Aldering, Greg; Perlmutter, Saul

    2003-01-31

    We show empirically that fits to the color-magnituderelation of Type Ia supernovae after optical maximum can provide accuraterelative extragalactic distances. We report the discovery of an empiricalcolor relation for Type Ia light curves: During much of the first monthpast maximum, the magnitudes of Type Ia supernovae defined at a givenvalue of color index have a very small magnitude dispersion; moreover,during this period the relation between B magnitude and B-V color (or B-Ror B-I color) is strikingly linear, to the accuracy of existingwell-measured data. These linear relations can provide robust distanceestimates, in particular, by using the magnitudes when the supernovareaches a given color. After correction for light curve stretch factor ordecline rate, the dispersion of the magnitudes taken at the intercept ofthe linear color-magnitude relation are found to be around 0^m .08 forthe sub-sample of supernovae with (B_max - V_max) ?= 0^m 0.5, andaround 0^m.11 for the sub-sample with (B_max - V_max) ?= 0^m .2.This small dispersion is consistent with being mostly due toobservational errors. The method presented here and the conventionallight curve fitting methods can be combined to further improvestatistical dispersions of distance estimates. It can be combined withthe magnitude at maximum to deduce dust extinction. Theslopes of thecolor-magnitude relation may also be used to identify intrinsicallydifferent SN Ia systems. The method provides a tool that is fundamentalto using SN Ia to estimate cosmological parameters such as the Hubbleconstant and the mass and dark energy content of theuniverse.

  10. Correlation between SiO v = 3 J = 1 → 0 maser excitation and the light curve of a long-period variable star

    Science.gov (United States)

    Oyadomari, Miyako; Imai, Hiroshi; Nagayama, Takumi; Oyama, Tomoaki; Matsumoto, Naoko; Nakashima, Jun-ichi; Cho, Se-Hyung

    2018-03-01

    In order to understand the excitation mechanisms of silicon monoxide (SiO) masers around long-period variables (LPVs), we have investigated distributions of the SiO v = 2 and v = 3 J = 1 → 0 masers around 12 LPVs by very long baseline interferometry (VLBI) observations with the VLBI Exploration of Radio Astrometry (VERA) and the Nobeyama 45 m telescopes. VLBI fringes of the v = 3 maser emission were detected for five LPVs. The composite maps of the v = 2 and v = 3 masers were made for T Cep, W Hya, WX Psc, and R Leo using the spectral line phase-referencing technique. The v = 2 maser spots were distributed in a ring-like form around the central stars, while it is difficult to recognize any specific morphology in the v = 3 maser distributions due to the small number of v = 3 spots detected. However in T Cep, we find that the distribution of the v = 3 maser spots correlates well with the v = 2 masers within a few milliarcseconds (0.2-0.3 au) in position and 1 km s-1 in line-of-sight velocity at the light curve phase of ϕ = 0.28 (ϕ = 0.0 and 1.0 correspond to the visible light maxima). This correlation implies that the mechanism of line-overlapping between the mid-infrared lines of H2O and SiO molecules works in T Cep at ϕ = 0.28. We discuss the possibility that the line-overlapping may work at the limited duration from the maximum to the minimum of the stellar light curve.

  11. A Fe K Line in GRB 970508

    Science.gov (United States)

    Protassov, R.; van Dyk, D.; Connors, A.; Kashyap, V.; Siemiginowska, A.

    2000-12-01

    We examine the x-ray spectrum of the afterglow of GRB 970508, analyzed for Fe line emission by Piro et al (1999, ApJL, 514, L73). This is a difficult and extremely important measurement: the detection of x-ray afterglows from γ -ray bursts is at best a tricky business, relying on near-real satellite time response to unpredictable events; and a great deal of luck in catching a burst bright enough for a useful spectral analysis. Detecting a clear atomic (or cyclotron) line in the generally smooth and featureless afterglow (or burst) emission not only gives one of the few very specific keys to the physics local to the emission region, but also provides clues or confirmation of its distance (via redshift). Unfortunately, neither the likelihood ratio test or the related F-statistic commonly used to detect spectral lines adhere to their nominal Chi square and F-distributions. Thus we begin by calibrating the F-statistic used in Piro et al (1999, ApJL, 514, L73) via a simulation study. The simulation study relies on a completely specified source model, i.e. we do Monte Carlo simulations with all model parameters fixed (so--called ``parametric bootstrapping''). Second, we employ the method of posterior predictive p-values to calibrate a LRT statistic while accounting for the uncertainty in the parameters of the source model. Our analysis reveals evidence for the Fe K line.

  12. Hyper-Eddington accretion in GRB

    International Nuclear Information System (INIS)

    Janiuk, A.; Czerny, B.; Perna, R.; Di Matteo, T.

    2005-01-01

    Popular models of the GRB origin associate this event with a cosmic explosion, birth of a stellar mass black ho le and jet ejection. Due to the shock collisions that happen in the jet, the gamma rays are produced and we detect a burst of duration up to several tens of seconds. This burst duration is determined by the lifetime of the central engine, which may be different in various scenarios. Characteristically, the observed bursts have a bimodal distribution and constitute the two classes: short (t < 2 s) and long bursts. Theoretical models invoke the mergers of two neutron stars or a neutron star with a black hole, or, on the other hand, a massive star explosion (collapsar). In any of these models we have a phase of disc accretion onto a newly born black hole: the di se is formed from the disrupted neutron star or fed by the material fallback from the ejected collapsar envelope. The disc is extremely hot and dense, and the accretion rate is orders of magnitude higher than the Eddington rate. In such physical conditions the main cooling mechanism is neutrino emission, and one of possible ways of energy extraction from the accretion disc is the neutrino-antineutrino annihilation

  13. A Spatially Resolved Study of the GRB 020903 Host Galaxy

    Science.gov (United States)

    Thorp, Mallory D.; Levesque, Emily M.

    2018-03-01

    GRB 020903 is a long-duration gamma-ray burst with a host galaxy close enough and extended enough for spatially resolved observations, making it one of less than a dozen GRBs where such host studies are possible. GRB 020903 lies in a galaxy host complex that appears to consist of four interacting components. Here we present the results of spatially resolved spectroscopic observations of the GRB 020903 host. By taking observations at two different position angles, we were able to obtain optical spectra (3600–9000 Å) of multiple regions in the galaxy. We confirm redshifts for three regions of the host galaxy that match that of GRB 020903. We measure the metallicity of these regions, and find that the explosion site and the nearby star-forming regions both have comparable subsolar metallicities. We conclude that, in agreement with past spatially resolved studies of GRBs, the GRB explosion site is representative of the host galaxy as a whole rather than localized in a metal-poor region of the galaxy.

  14. The adapter protein, Grb10, is a positive regulator of vascular endothelial growth factor signaling.

    Science.gov (United States)

    Giorgetti-Peraldi, S; Murdaca, J; Mas, J C; Van Obberghen, E

    2001-07-05

    Vascular endothelial growth factor (VEGF) is an important regulator of vasculogenesis and angiogenesis. Activation of VEGF receptors leads to the recruitment of SH2 containing proteins which link the receptors to the activation of signaling pathways. Here we report that Grb10, an adapter protein of which the biological role remains unknown, is tyrosine phosphorylated in response to VEGF in endothelial cells (HUVEC) and in 293 cells expressing the VEGF receptor KDR. An intact SH2 domain is required for Grb10 tyrosine phosphorylation in response to VEGF, and this phosphorylation is mediated in part through the activation of Src. In HUVEC, VEGF increases Grb10 mRNA level. Expression of Grb10 in HUVEC or in KDR expressing 293 cells results in an increase in the amount and in the tyrosine phosphorylation of KDR. In 293 cells, this is correlated with the activation of signaling molecules, such as MAP kinase. By expressing mutants of Grb10, we found that the positive action of Grb10 is independent of its SH2 domain. Moreover, these Grb10 effects on KDR seem to be specific since Grb10 has no effect on the insulin receptor, and Grb2, another adapter protein, does not mimic the effect of Grb10 on KDR. In conclusion, we propose that VEGF up-regulates Grb10 level, which in turn increases KDR molecules, suggesting that Grb10 could be involved in a positive feedback loop in VEGF signaling.

  15. Calibration and Simulation of the GRB trigger detector of the Ultra Fast Flash Observatory

    DEFF Research Database (Denmark)

    Huang, M.-H.A.; Ahmad, S.; Barrillon, P.

    2013-01-01

    The UFFO (Ultra-Fast Flash Observatory) is a GRB detector on board the Lomonosov satellite, to be launched in 2013. The GRB trigger is provided by an X-ray detector, called UBAT (UFFO Burst Alarm & Trigger Telescope), which detects X-rays from the GRB and then triggers to determine the direction ...

  16. Constraining convection parameters from the light curve shapes of pulsating white dwarf stars: the cases of EC 14012-1446 and WD 1524-0030

    Energy Technology Data Exchange (ETDEWEB)

    Handler, G; Lendl, M; Beck, P [Institut fuer Astronomie, Universitaet Wien, Tuerkenschanzstrasse 17, A-1180 Wien (Austria); Provencal, J L; Montgomery, M H [Mt. Cuba Observatory and Department of Physics and Astronomy, University of Delaware, 223 Sharp Laboratory, Newark, DE 19716 (Cuba); Romero-Colmenero, E [South AfricAN Astronomical Observatory, PO Box 9, Observatory 7935 (South Africa); Sanchawala, K; Chen, W-P [Graduate Institute of Astronomy, National Central University, Chung-Li 32054, Taiwan (China); Wood, M A; Silver, I [Department of Physics and Space Sciences and SARA Observatory, Florida Institute of Technology, Melbourne, FL 32901 (United States)], E-mail: handler@astro.univie.ac.at

    2008-10-15

    Montgomery [1] developed a method to probe convection in pulsating white dwarf stars which allows the recovery of the thermal response time of the convection zone by fitting observed nonsinusoidal light curves. He applied this method to two objects; the Whole Earth Telescope (WET) observed the pulsating DB white dwarf GD 358 for just this purpose. Given this WET run's success, it is time to extend Montgomery's method to pulsating DA white dwarf (ZZ Ceti) stars. We present observations of two ZZ Ceti stars, WD 1524-0030 and EC 14012-1446, both observed from multiple sites. EC 14012-1446 seems better suited thAN WD1524-0030 for a future WET run because it has more pulsation modes excited and because it pulsation spectrum appears to be more stable in time. We call for participation in this effort to take place in April 2008.

  17. The Complete Light-curve Sample of Spectroscopically Confirmed SNe Ia from Pan-STARRS1 and Cosmological Constraints from the Combined Pantheon Sample

    Science.gov (United States)

    Scolnic, D. M.; Jones, D. O.; Rest, A.; Pan, Y. C.; Chornock, R.; Foley, R. J.; Huber, M. E.; Kessler, R.; Narayan, G.; Riess, A. G.; Rodney, S.; Berger, E.; Brout, D. J.; Challis, P. J.; Drout, M.; Finkbeiner, D.; Lunnan, R.; Kirshner, R. P.; Sanders, N. E.; Schlafly, E.; Smartt, S.; Stubbs, C. W.; Tonry, J.; Wood-Vasey, W. M.; Foley, M.; Hand, J.; Johnson, E.; Burgett, W. S.; Chambers, K. C.; Draper, P. W.; Hodapp, K. W.; Kaiser, N.; Kudritzki, R. P.; Magnier, E. A.; Metcalfe, N.; Bresolin, F.; Gall, E.; Kotak, R.; McCrum, M.; Smith, K. W.

    2018-06-01

    We present optical light curves, redshifts, and classifications for 365 spectroscopically confirmed Type Ia supernovae (SNe Ia) discovered by the Pan-STARRS1 (PS1) Medium Deep Survey. We detail improvements to the PS1 SN photometry, astrometry, and calibration that reduce the systematic uncertainties in the PS1 SN Ia distances. We combine the subset of 279 PS1 SNe Ia (0.03 Ia from the Sloan Digital Sky Survey (SDSS), SNLS, and various low-z and Hubble Space Telescope samples to form the largest combined sample of SNe Ia, consisting of a total of 1048 SNe Ia in the range of 0.01 Ia to measure dark energy.

  18. BEER ANALYSIS OF KEPLER AND CoRoT LIGHT CURVES. I. DISCOVERY OF KEPLER-76b: A HOT JUPITER WITH EVIDENCE FOR SUPERROTATION

    International Nuclear Information System (INIS)

    Faigler, S.; Tal-Or, L.; Mazeh, T.; Latham, D. W.; Buchhave, L. A.

    2013-01-01

    We present the first case in which the BEER algorithm identified a hot Jupiter in the Kepler light curve, and its reality was confirmed by orbital solutions based on follow-up spectroscopy. The companion Kepler-76b was identified by the BEER algorithm, which detected the BEaming (sometimes called Doppler boosting) effect together with the Ellipsoidal and Reflection/emission modulations (BEER), at an orbital period of 1.54 days, suggesting a planetary companion orbiting the 13.3 mag F star. Further investigation revealed that this star appeared in the Kepler eclipsing binary catalog with estimated primary and secondary eclipse depths of 5 × 10 –3 and 1 × 10 –4 , respectively. Spectroscopic radial velocity follow-up observations with Tillinghast Reflector Echelle Spectrograph and SOPHIE confirmed Kepler-76b as a transiting 2.0 ± 0.26 M Jup hot Jupiter. The mass of a transiting planet can be estimated from either the beaming or the ellipsoidal amplitude. The ellipsoidal-based mass estimate of Kepler-76b is consistent with the spectroscopically measured mass while the beaming-based estimate is significantly inflated. We explain this apparent discrepancy as evidence for the superrotation phenomenon, which involves eastward displacement of the hottest atmospheric spot of a tidally locked planet by an equatorial superrotating jet stream. This phenomenon was previously observed only for HD 189733b in the infrared. We show that a phase shift of 10.°3 ± 2.°0 of the planet reflection/emission modulation, due to superrotation, explains the apparently inflated beaming modulation, resolving the ellipsoidal/beaming amplitude discrepancy. Kepler-76b is one of very few confirmed planets in the Kepler light curves that show BEER modulations and the first to show superrotation evidence in the Kepler band. Its discovery illustrates for the first time the ability of the BEER algorithm to detect short-period planets and brown dwarfs.

  19. Power spectra decomposition of 36 RS CVn UBV photometric light curves from the first two years of the automatic photoelectric telescope

    International Nuclear Information System (INIS)

    Nelson, E.R.

    1988-01-01

    The first search for multiple periodic structure of a major subset of the RS CVn class of interacting binary stars systems, using a rigorous numerical approach appropriate to unevenly-spaced gapped data, is presented. The main intent of this dissertation is to characterize properly the power spectral content of RS CVn binary light curves and describe how this information can constrain the current models for the systems. If the light curve can be considered as a tracer of stellar surface activity, then the photometric distortions can be used to characterize magnetic activity cycles and add to the understanding of stellar dynamics. Most of the systems exhibit multiple periodic structure, 40% of which show changes in the photometric period on a time scale of a few hundred days. A preference is observed for photometric periods with time scales near the orbital and half orbital periods. The effect is particularly strong for the shorter period systems and is interpreted as evidence for synchronous, or near synchronous, rotation. A strong linear correlation in the periods for the multiply periodic systems is observed which indicates a preferential pairing of spot groups on the stellar surface. No correlation is found for the relative phases of the multiple periodic signals. Changes in the photometric period are associated with variations in the amplitude of the distortion wave, which would indicate the growth and decay of spot groups. The growth and decay of pairs of spot groups, arbitrarily separated in phase, on a differentially rotating star is the model most consistent with the results of my analysis

  20. THE RADIO LIGHT CURVE OF THE GAMMA-RAY NOVA IN V407 CYG: THERMAL EMISSION FROM THE IONIZED SYMBIOTIC ENVELOPE, DEVOURED FROM WITHIN BY THE NOVA BLAST

    Energy Technology Data Exchange (ETDEWEB)

    Chomiuk, Laura; Krauss, Miriam I.; Rupen, Michael P.; Roy, Nirupam; Mioduszewski, Amy [National Radio Astronomy Observatory, P.O. Box O, Socorro, NM 87801 (United States); Nelson, Thomas [School of Physics and Astronomy, University of Minnesota, 116 Church Street SE, Minneapolis, MN 55455 (United States); Sokoloski, Jennifer L.; Weston, Jennifer [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Mukai, Koji [CRESST and X-ray Astrophysics Laboratory, NASA/GSFC, Greenbelt, MD 20771 (United States); Munari, Ulisse [INAF Astronomical Observatory of Padova, I-36012 Asiago (VI) (Italy); O' Brien, Tim J. [Jodrell Bank Centre for Astrophysics, University of Manchester, Manchester M13 9PL (United Kingdom); Eyres, Stewart P. S. [Jeremiah Horrocks Institute, University of Central Lancashire, Preston PR1 2HE (United Kingdom); Bode, Michael F., E-mail: chomiuk@pa.msu.edu [Astrophysics Research Institute, Liverpool John Moores University, Twelve Quays House, Egerton Wharf, Birkenhead CH41 1LD (United Kingdom)

    2012-12-20

    We present multi-frequency radio observations of the 2010 nova event in the symbiotic binary V407 Cygni, obtained with the Karl G. Jansky Very Large Array (VLA) and spanning 1-45 GHz and 17-770 days following discovery. This nova-the first ever detected in gamma rays-shows a radio light curve dominated by the wind of the Mira giant companion, rather than the nova ejecta themselves. The radio luminosity grew as the wind became increasingly ionized by the nova outburst, and faded as the wind was violently heated from within by the nova shock. This study marks the first time that this physical mechanism has been shown to dominate the radio light curve of an astrophysical transient. We do not observe a thermal signature from the nova ejecta or synchrotron emission from the shock, due to the fact that these components were hidden behind the absorbing screen of the Mira wind. We estimate a mass-loss rate for the Mira wind of M-dot{sub w} approx. 10{sup -6} M{sub Sun} yr{sup -1}. We also present the only radio detection of V407 Cyg before the 2010 nova, gleaned from unpublished 1993 archival VLA data, which shows that the radio luminosity of the Mira wind varies by a factor of {approx}>20 even in quiescence. Although V407 Cyg likely hosts a massive accreting white dwarf, making it a candidate progenitor system for a Type Ia supernova, the dense and radially continuous circumbinary material surrounding V407 Cyg is inconsistent with observational constraints on the environments of most Type Ia supernovae.

  1. The X-ray Power Density Spectrum of the Seyfert 2 Galaxy NGC 4945: Analysis and Application of the Method of Light Curve Simulations

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, Martin; /SLAC

    2010-12-16

    The study of the power density spectrum (PDS) of fluctuations in the X-ray flux from active galactic nuclei (AGN) complements spectral studies in giving us a view into the processes operating in accreting compact objects. An important line of investigation is the comparison of the PDS from AGN with those from galactic black hole binaries; a related area of focus is the scaling relation between time scales for the variability and the black hole mass. The PDS of AGN is traditionally modeled using segments of power laws joined together at so-called break frequencies; associations of the break time scales, i.e., the inverses of the break frequencies, with time scales of physical processes thought to operate in these sources are then sought. I analyze the Method of Light Curve Simulations that is commonly used to characterize the PDS in AGN with a view to making the method as sensitive as possible to the shape of the PDS. I identify several weaknesses in the current implementation of the method and propose alternatives that can substitute for some of the key steps in the method. I focus on the complications introduced by uneven sampling in the light curve, the development of a fit statistic that is better matched to the distributions of power in the PDS, and the statistical evaluation of the fit between the observed data and the model for the PDS. Using archival data on one AGN, NGC 3516, I validate my changes against previously reported results. I also report new results on the PDS in NGC 4945, a Seyfert 2 galaxy with a well-determined black hole mass. This source provides an opportunity to investigate whether the PDS of Seyfert 1 and Seyfert 2 galaxies differ. It is also an attractive object for placement on the black hole mass-break time scale relation. Unfortunately, with the available data on NGC 4945, significant uncertainties on the break frequency in its PDS remain.

  2. The Radio Light Curve of the Gamma-Ray Nova in V407 CYG: Thermal Emission from the Ionized Symbiotic Envelope, Devoured from Within by the Nova Blast

    Science.gov (United States)

    Chomiuk, Laura; Krauss, Miriam I.; Rupen, Michael P.; Nelson, Thomas; Roy, Nirupam; Sokoloski, Jennifer L.; Mukai, Koji; Munari, Ulisse; Mioduszewski, Amy; Weston, Jeninfer; hide

    2012-01-01

    We present multi-frequency radio observations of the 2010 nova event in the symbiotic binary V407 Cygni, obtained with the Karl G. Jansky Very Large Array (VLA) and spanning 1.45 GHz and 17.770 days following discovery. This nova.the first ever detected in gamma rays.shows a radio light curve dominated by the wind of the Mira giant companion, rather than the nova ejecta themselves. The radio luminosity grewas the wind became increasingly ionized by the nova outburst, and faded as the wind was violently heated from within by the nova shock. This study marks the first time that this physical mechanism has been shown to dominate the radio light curve of an astrophysical transient. We do not observe a thermal signature from the nova ejecta or synchrotron emission from the shock, due to the fact that these components were hidden behind the absorbing screen of the Mira wind. We estimate a mass-loss rate for the Mira wind of .Mw approximately equals 10(exp -6) Solar mass yr(exp -1). We also present the only radio detection of V407 Cyg before the 2010 nova, gleaned from unpublished 1993 archival VLA data, which shows that the radio luminosity of the Mira wind varies by a factor of 20 even in quiescence. Although V407 Cyg likely hosts a massive accreting white dwarf, making it a candidate progenitor system for a Type Ia supernova, the dense and radially continuous circumbinary material surrounding V407 Cyg is inconsistent with observational constraints on the environments of most Type Ia supernovae.

  3. Lighting.

    Energy Technology Data Exchange (ETDEWEB)

    United States. Bonneville Power Administration.

    1992-09-01

    Since lighting accounts for about one-third of the energy used in commercial buildings, there is opportunity to conserve. There are two ways to reduce lighting energy use: modify lighting systems so that they used less electricity and/or reduce the number of hours the lights are used. This booklet presents a number of ways to do both. Topics covered include: reassessing lighting levels, reducing lighting levels, increasing bulb & fixture efficiency, using controls to regulate lighting, and taking advantage of daylight.

  4. Firework Model: Time Dependent Spectral Evolution of GRB

    Science.gov (United States)

    Barbiellini, Guido; Longo, Francesco; Ghirlanda, G.; Celotti, A.; Bosnjak, Z.

    2004-09-01

    The energetics of the long duration GRB phenomenon is compared with models of a rotating BH in a strong magnetic field generated by an accreting torus. The GRB energy emission is attributed to magnetic field vacuum breakdown that gives origin to a e +/- fireball. Its subsequent evolution is hypothesized in analogy with the in-flight decay of an elementary particle. An anisotropy in the fireball propagation is thus naturally produced. The recent discovery in some GRB of an initial phase characterized by a thermal spectrum could be interpreted as the photon emission of the fireball photosphere when it becomes transparent. In particular, the temporal evolution of the emission can be explained as the effect of a radiative deceleration of the out-moving ejecta.

  5. Validation of Kepler's multiple planet candidates. III. Light curve analysis and announcement of hundreds of new multi-planet systems

    International Nuclear Information System (INIS)

    Rowe, Jason F.; Bryson, Stephen T.; Lissauer, Jack J.; Jontof-Hutter, Daniel; Mullally, Fergal; Howell, Steve B.; Borucki, William J.; Haas, Michael; Huber, Daniel; Thompson, Susan E.; Quintana, Elisa; Barclay, Thomas; Still, Martin; Marcy, Geoffrey W.; Issacson, Howard; Gilliland, Ronald L.; Ford, Eric; Steffen, Jason H.; Fortney, Jonathan; Gautier, T. N. III

    2014-01-01

    The Kepler mission has discovered more than 2500 exoplanet candidates in the first two years of spacecraft data, with approximately 40% of those in candidate multi-planet systems. The high rate of multiplicity combined with the low rate of identified false positives indicates that the multiplanet systems contain very few false positive signals due to other systems not gravitationally bound to the target star. False positives in the multi-planet systems are identified and removed, leaving behind a residual population of candidate multi-planet transiting systems expected to have a false positive rate less than 1%. We present a sample of 340 planetary systems that contain 851 planets that are validated to substantially better than the 99% confidence level; the vast majority of these have not been previously verified as planets. We expect ∼two unidentified false positives making our sample of planet very reliable. We present fundamental planetary properties of our sample based on a comprehensive analysis of Kepler light curves, ground-based spectroscopy, and high-resolution imaging. Since we do not require spectroscopy or high-resolution imaging for validation, some of our derived parameters for a planetary system may be systematically incorrect due to dilution from light due to additional stars in the photometric aperture. Nonetheless, our result nearly doubles the number verified exoplanets.

  6. A Reverse Shock in GRB 160509A

    Science.gov (United States)

    Laskar, Tanmoy; Alexander, Kate D.; Berger, Edo; Fong, Wen-fai; Margutti, Raffaella; Shivvers, Isaac; Williams, Peter K. G.; Kopač, Drejc; Kobayashi, Shiho; Mundell, Carole; Gomboc, Andreja; Zheng, WeiKang; Menten, Karl M.; Graham, Melissa L.; Filippenko, Alexei V.

    2016-12-01

    We present the second multi-frequency radio detection of a reverse shock in a γ-ray burst. By combining our extensive radio observations of the Fermi-Large Area Telescope γ-ray burst 160509A at z = 1.17 up to 20 days after the burst with Swift X-ray observations and ground-based optical and near-infrared data, we show that the afterglow emission comprises distinct reverse shock and forward shock contributions: the reverse shock emission dominates in the radio band at ≲10 days, while the forward shock emission dominates in the X-ray, optical, and near-infrared bands. Through multi-wavelength modeling, we determine a circumburst density of {n}0≈ {10}-3 {{cm}}-3, supporting our previous suggestion that a low-density circumburst environment is conducive to the production of long-lasting reverse shock radiation in the radio band. We infer the presence of a large excess X-ray absorption column, N H ≈ 1.5 × 1022 {{cm}}-2, and a high rest-frame optical extinction, A V ≈ 3.4 mag. We identify a jet break in the X-ray light curve at {t}{jet}≈ 6 {days}, and thus derive a jet opening angle of {θ }{jet}≈ 4^\\circ , yielding a beaming-corrected kinetic energy and radiated γ-ray energy of {E}{{K}}≈ 4× {10}50 erg and {E}γ ≈ 1.3× {10}51 erg (1-104 keV, rest frame), respectively. Consistency arguments connecting the forward shocks and reverse shocks suggest a deceleration time of {t}{dec} ≈ 460 s ≈ T 90, a Lorentz factor of {{Γ }}({t}{dec})≈ 330, and a reverse-shock-to-forward-shock fractional magnetic energy density ratio of {R}{{B}}\\equiv {ɛ }{{B},{RS}}/{ɛ }{{B},{FS}}≈ 8. Our study highlights the power of rapid-response radio observations in the study of the properties and dynamics of γ-ray burst ejecta.

  7. Lighting

    Data.gov (United States)

    Federal Laboratory Consortium — Lighting Systems Test Facilities aid research that improves the energy efficiency of lighting systems. • Gonio-Photometer: Measures illuminance from each portion of...

  8. Constraining Anisotropic Lorentz Violation via the Spectral-lag Transition of GRB 160625B

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Jun-Jie; Wu, Xue-Feng; Shao, Lang [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China); Zhang, Bin-Bin [Instituto de Astrofísica de Andalucá (IAA-CSIC), P.O. Box 03004, E-18080 Granada (Spain); Mészáros, Peter [Department of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802 (United States); Kostelecký, V. Alan, E-mail: xfwu@pmo.ac.cn, E-mail: kostelec@indiana.edu [Physics Department, Indiana University, Bloomington, IN 47405 (United States)

    2017-06-20

    Violations of Lorentz invariance can lead to an energy-dependent vacuum dispersion of light, which results in arrival-time differences of photons with different energies arising from a given transient source. In this work, direction-dependent dispersion constraints are obtained on nonbirefringent Lorentz-violating effects using the observed spectral lags of the gamma-ray burst GRB 160625B. This burst has unusually large high-energy photon statistics, so we can obtain constraints from the true spectral time lags of bunches of high-energy photons rather than from the rough time lag of a single highest-energy photon. Also, GRB 160625B is the only burst to date having a well-defined transition from positive lags to negative lags, providing a unique opportunity to distinguish Lorentz-violating effects from any source-intrinsic time lag in the emission of photons of different energy bands. Our results place comparatively robust two-sided constraints on a variety of isotropic and anisotropic coefficients for Lorentz violation, including the first bounds on Lorentz-violating effects from operators of mass dimension 10 in the photon sector.

  9. Light

    DEFF Research Database (Denmark)

    Prescott, N.B.; Kristensen, Helle Halkjær; Wathes, C.M.

    2004-01-01

    This chapter presents the effect of artificial light environments (light levels, colour, photoperiod and flicker) on the welfare of broilers in terms of vision, behaviour, lameness and mortality......This chapter presents the effect of artificial light environments (light levels, colour, photoperiod and flicker) on the welfare of broilers in terms of vision, behaviour, lameness and mortality...

  10. Hubble Space Telescope Observations of the Afterglow, Supernova and Host Galaxy Associated with the Extremely Bright GRB 130427A

    Science.gov (United States)

    Levan, A.J.; Tanvir, N. R.; Fruchter, A. S.; Hjorth, J.; Pian, E.; Mazzali, P.; Hounsell, R. A.; Perley, D. A.; Cano, Z.; Graham, J.; hide

    2014-01-01

    We present Hubble Space Telescope (HST) observations of the exceptionally bright and luminous Swift gamma-ray burst, GRB 130427A. At z=0.34 this burst affords an excellent opportunity to study the supernova and host galaxy associated with an intrinsically extremely luminous burst (E(sub iso) greater than 10(exp 54) erg): more luminous than any previous GRB with a spectroscopically associated supernova. We use the combination of the image quality, UV capability and and invariant PSF of HST to provide the best possible separation of the afterglow, host and supernova contributions to the observed light approximately 17 rest-frame days after the burst utilising a host subtraction spectrum obtained 1 year later. Advanced Camera for Surveys (ACS) grism observations show that the associated supernova, SN 2013cq, has an overall spectral shape and luminosity similar to SN 1998bw (with a photospheric velocity, vph approximately 15,000 kilometers per second). The positions of the bluer features are better matched by the higher velocity SN 2010bh (vph approximately 30,000 kilometers per second), but SN 2010bh (vph approximately 30,000 kilometers per second but this SN is significantly fainter, and fails to reproduce the overall spectral shape, perhaps indicative of velocity structure in the ejecta. We find that the burst originated approximately 4 kpc from the nucleus of a moderately star forming (1 Solar Mass yr(exp-1)), possibly interacting disc galaxy. The absolute magnitude, physical size and morphology of this galaxy, as well as the location of the GRB within it are also strikingly similar to those of GRB980425SN 1998bw. The similarity of supernovae and environment from both the most luminous and least luminous GRBs suggests broadly similar progenitor stars can create GRBs across six orders of magnitude in isotropic energy.

  11. Kepler-91b: a planet at the end of its life. Planet and giant host star properties via light-curve variations

    Science.gov (United States)

    Lillo-Box, J.; Barrado, D.; Moya, A.; Montesinos, B.; Montalbán, J.; Bayo, A.; Barbieri, M.; Régulo, C.; Mancini, L.; Bouy, H.; Henning, T.

    2014-02-01

    Context. The evolution of planetary systems is intimately linked to the evolution of their host stars. Our understanding of the whole planetary evolution process is based on the wide planet diversity observed so far. Only a few tens of planets have been discovered orbiting stars ascending the red giant branch. Although several theories have been proposed, the question of how planets die remains open owing to the small number statistics, making it clear that the sample of planets around post-main sequence stars needs to be enlarged. Aims: In this work we study the giant star Kepler-91 (KOI-2133) in order to determine the nature of a transiting companion. This system was detected by the Kepler Space Telescope, which identified small dims in its light curve with a period of 6.246580 ± 0.000082 days. However, its planetary confirmation is needed due to the large pixel size of the Kepler camera, which can hide other stellar configurations able to mimic planet-like transit events. Methods: We analysed Kepler photometry to 1) re-calculate transit parameters; 2) study the light-curve modulations; and 3) to perform an asteroseismic analysis (accurate stellar parameter determination) by identifying solar-like oscillations on the periodogram. We also used a high-resolution and high signal-to-noise ratio spectrum obtained with the Calar Alto Fiber-fed Échelle spectrograph (CAFE) to measure stellar properties. Additionally, false-positive scenarios were rejected by obtaining high-resolution images with the AstraLux lucky imaging camera on the 2.2 m telescope at the Calar Alto Observatory. Results: We confirm the planetary nature of the object transiting the star Kepler-91 by deriving a mass of Mp=0.88+0.17-0.33 MJup and a planetary radius of Rp=1.384+0.011-0.054 RJup. Asteroseismic analysis produces a stellar radius of R⋆ = 6.30 ± 0.16 R⊙ and a mass of M⋆ = 1.31 ± 0.10 M⊙. We find that its eccentric orbit (e=0.066+0.013-0.017) is just 1.32+0.07-0.22 R⋆ away from

  12. The Extraordinary X-ray Light Curve of the Classical Nova V1494 Aql in Outburst: The Discovery of Pulsations and a ``Burst''

    Science.gov (United States)

    Starrfield, Sumner; Drake, Jeremy

    2001-09-01

    V1494 Aql (Nova Aql 1999 No. 2) was discovered on 2 December 1999. It reached Vmax ~4 making it the brightest northern hemisphere nova since V1500 Cyg erupted in 1975. Our early optical spectra showed that it was an ``Fe II'' class nova (Williams, R.E. AJ, 104, 725, 1992). We activated our CHANDRA Target of Opportunity proposal for bright novae in outburst and obtained ACIS-I spectra on 15 April and 7 June 2000 which showed only emission lines. Our third observation, on 6 August, showed that its spectrum had evolved into that characteristic of a Super Soft X-ray Source (at low resolution it resembled an ``emission'' line with a peak ~ 0.5 keV). We obtained HRC-S+LETG spectra on 28 September (8 ksec) and 1 October 2000 (17 ksec). These spectra qualitatively resembled those of CAL 83 obtained with XMM (Paerels, F., et al. 2001, A&A, 365, L308) and demonstrated that we were observing the atmosphere of a hot white dwarf which was probably still undergoing nuclear burning near the surface. An abundance analysis of the X-ray spectrum is in progress using new Non-LTE stellar atmospheres. We then analyzed the X-ray light curve of our grating observations and, to our surprise, found that we had discovered both a short time scale ``burst'' and that the nova was oscillating. Neither of these phenomena have ever been seen in the light curve of a nova in outburst. The ``burst'' was a factor of 6 rise in X-ray counts near the middle of the second observation which lasted about 1000 sec and exhibited at least two peaks plus other structure. Currently, we have no explanation for the cause of this burst. Our time series analysis of the combined 25 ksec observation showed a peak at 2500 sec which was present in independent analyses of both the zeroth order image and the dispersed spectrum. We also analyzed the light curves of the HRC-S+LETG observations of HZ 43, Sirius B, and V382 Vel (Nova Vel 1999) and found no sign of any periodic behavior in the data which implied that the

  13. Time resolved spectroscopy of GRB 030501 using INTEGRAL

    DEFF Research Database (Denmark)

    Beckmann, V.; Borkowski, J.; Courvoisier, T.J.L.

    2003-01-01

    The gamma-ray instruments on-board INTEGRAL offer an unique opportunity to perform time resolved analysis on GRBs. The imager IBIS allows accurate positioning of GRBs and broad band spectral analysis, while SPI provides high resolution spectroscopy. GRB 030501 was discovered by the INTEGRAL Burst...... the Ulysses and RHESSI experiments....

  14. Early danish GRB experiments - And some for the future?

    DEFF Research Database (Denmark)

    Lund, Niels

    2013-01-01

    by a japanese report of a balloon instrument for GRB studies based on a Rotation Modulation Collimator we at the Danish Space Research Institute started the development of an RMC detector for GRBs, the WATCH wide field monitor. Four WATCH units were flown on the Soviet Granat satellites, and one on ESA's EURECA...

  15. Featureless classification of light curves

    Science.gov (United States)

    Kügler, S. D.; Gianniotis, N.; Polsterer, K. L.

    2015-08-01

    In the era of rapidly increasing amounts of time series data, classification of variable objects has become the main objective of time-domain astronomy. Classification of irregularly sampled time series is particularly difficult because the data cannot be represented naturally as a vector which can be directly fed into a classifier. In the literature, various statistical features serve as vector representations. In this work, we represent time series by a density model. The density model captures all the information available, including measurement errors. Hence, we view this model as a generalization to the static features which directly can be derived, e.g. as moments from the density. Similarity between each pair of time series is quantified by the distance between their respective models. Classification is performed on the obtained distance matrix. In the numerical experiments, we use data from the OGLE (Optical Gravitational Lensing Experiment) and ASAS (All Sky Automated Survey) surveys and demonstrate that the proposed representation performs up to par with the best currently used feature-based approaches. The density representation preserves all static information present in the observational data, in contrast to a less-complete description by features. The density representation is an upper boundary in terms of information made available to the classifier. Consequently, the predictive power of the proposed classification depends on the choice of similarity measure and classifier, only. Due to its principled nature, we advocate that this new approach of representing time series has potential in tasks beyond classification, e.g. unsupervised learning.

  16. Investigating light curve modulation via kernel smoothing. I. Application to 53 fundamental mode and first-overtone Cepheids in the LMC

    Science.gov (United States)

    Süveges, Maria; Anderson, Richard I.

    2018-03-01

    Context. Recent studies have revealed a hitherto unknown complexity of Cepheid pulsations by discovering irregular modulated variability using photometry, radial velocities, and interferometry. Aim. We aim to perform a statistically rigorous search and characterization of such phenomena in continuous time, applying it to 53 classical Cepheids from the OGLE-III catalog. Methods: We have used local kernel regression to search for both period and amplitude modulations simultaneously in continuous time and to investigate their detectability. We determined confidence intervals using parametric and non-parametric bootstrap sampling to estimate significance, and investigated multi-periodicity using a modified pre-whitening approach that relies on time-dependent light curve parameters. Results: We find a wide variety of period and amplitude modulations and confirm that first overtone pulsators are less stable than fundamental mode Cepheids. Significant temporal variations in period are more frequently detected than those in amplitude. We find a range of modulation intensities, suggesting that both amplitude and period modulations are ubiquitous among Cepheids. Over the 12-year baseline offered by OGLE-III, we find that period changes are often nonlinear, sometimes cyclic, suggesting physical origins beyond secular evolution. Our method detects modulations (period and amplitude) more efficiently than conventional methods that are reliant on certain features in the Fourier spectrum, and pre-whitens time series more accurately than using constant light curve parameters, removing spurious secondary peaks effectively. Conclusions: Period and amplitude modulations appear to be ubiquitous among Cepheids. Current detectability is limited by observational cadence and photometric precision: detection of amplitude modulation below 3 mmag requires space-based facilities. Recent and ongoing space missions (K2, BRITE, MOST, CoRoT) as well as upcoming ones (TESS, PLATO) will

  17. Radio and γ -Ray Variability in the BL Lac PKS 0219−164: Detection of Quasi-periodic Oscillations in the Radio Light Curve

    Energy Technology Data Exchange (ETDEWEB)

    Bhatta, Gopal, E-mail: gopalbhatta716@gmail.com [Astronomical Observatory of the Jagiellonian University, ul. Orla 171, 30-244 Kraków (Poland); Mt. Suhora Observatory, Pedagogical University, ul. Podchorazych 2, 30-084 Kraków (Poland)

    2017-09-20

    In this work, we explore the long-term variability properties of the blazar PKS 0219−164 in the radio and the γ -ray regime, utilizing the OVRO 15 GHz and the Fermi /LAT observations from the period 2008–2017. We found that γ -ray emission is more variable than the radio emission implying that γ -ray emission possibly originated in more compact regions while the radio emission represented continuum emission from the large-scale jets. Also, in the γ -ray, the source exhibited spectral variability, characterized by the softer-when-brighter trend, a less frequently observed feature in the high-energy emission by BL Lacs. In radio, using Lomb–Scargle periodogram and weighted wavelet z -transform, we detected a strong signal of quasi-periodic oscillation (QPO) with a periodicity of 270 ± 26 days with possible harmonics of 550 ± 42 and 1150 ± 157 day periods. At a time when detections of QPOs in blazars are still under debate, the observed QPO with high statistical significance (∼97%–99% global significance over underlying red-noise processes) and persistent over nearly 10 oscillations could make one of the strongest cases for the detection of QPOs in blazar light curves. We discuss various blazar models that might lead to the γ -ray and radio variability, QPO, and the achromatic behavior seen in the high-energy emission from the source.

  18. AN EXTENDED AND MORE SENSITIVE SEARCH FOR PERIODICITIES IN ROSSI X-RAY TIMING EXPLORER/ALL-SKY MONITOR X-RAY LIGHT CURVES

    International Nuclear Information System (INIS)

    Levine, Alan M.; Bradt, Hale V.; Chakrabarty, Deepto; Corbet, Robin H. D.; Harris, Robert J.

    2011-01-01

    We present the results of a systematic search in ∼14 years of Rossi X-ray Timing Explorer All-Sky Monitor (ASM) data for evidence of periodicities. Two variations of the commonly used Fourier analysis search method have been employed to significantly improve upon the sensitivity achieved by Wen et al. in 2006, who also searched for periodicities in ASM data. In addition, the present search is comprehensive in terms of sources studied and frequency range covered, and has yielded the detection of the signatures of the orbital periods of eight low-mass X-ray binary systems and of ten high-mass X-ray binaries not listed in the tables of Wen et al. Orbital periods, epochs, signal amplitudes, modulation fractions, and folded light curves are given for each of these systems. Seven of the orbital periods are the most precise reported to date. In the course of this work, the 18.545 day orbital period of IGR J18483-0311 was co-discovered, and the first detections in X-rays were made of the ∼3.9 day orbital period of LMC X-1 and the ∼3.79 hr orbital period of 4U 1636-536. The results inform future searches for orbital and other periodicities in X-ray binaries.

  19. SEARCHING FOR SUB-KILOMETER TRANS-NEPTUNIAN OBJECTS USING PAN-STARRS VIDEO MODE LIGHT CURVES: PRELIMINARY STUDY AND EVALUATION USING ENGINEERING DATA

    International Nuclear Information System (INIS)

    Wang, J.-H.; Protopapas, P.; Alcock, C. R.; Chen, W.-P.; Burgett, W. S.; Morgan, J. S.; Price, P. A.; Tonry, J. L.; Dombeck, T.; Grav, T.

    2010-01-01

    We present a pre-survey study of using the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) high sampling rate video mode guide star images to search for trans-Neptunian objects (TNOs). Guide stars are primarily used by Pan-STARRS to compensate for image motion and hence improve the point-spread function. With suitable selection of the guide stars within the Pan-STARRS 7 deg 2 field of view, the light curves of these guide stars can also be used to search for occultations by TNOs. The best target stars for this purpose are stars with high signal-to-noise ratio (S/N) and small angular size. In order to do this, we compiled a catalog using the S/N calculated from stars with m V 0 ), we are able to set an upper limit of N(>0.5 km) ∼ 2.47 x 10 10 deg -2 at 95% confidence limit.

  20. Deletion of the Imprinted Gene Grb10 Promotes Hematopoietic Stem Cell Self-Renewal and Regeneration.

    Science.go