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Sample records for hole candidate sdss

  1. Constraining RRc candidates using SDSS colours

    CERN Document Server

    Bányai, E; Molnár, L; Dobos, L; Szabó, R

    2016-01-01

    The light variations of first-overtone RR Lyrae stars and contact eclipsing binaries can be difficult to distinguish. The Catalina Periodic Variable Star catalog contains several misclassified objects, despite the classification efforts by Drake et al. (2014). They used metallicity and surface gravity derived from spectroscopic data (from the SDSS database) to rule out binaries. Our aim is to further constrain the catalog using SDSS colours to estimate physical parameters for stars that did not have spectroscopic data.

  2. Extremely metal-poor star candidates in the SDSS

    Institute of Scientific and Technical Information of China (English)

    Si-Yao Xu; Hua-Wei Zhang; Xiao-Wei Liu

    2013-01-01

    For a sample of metal-poor stars (-3.3 ≤ [Fe/H] ≤-2.2) that have highresolution spectroscopic abundance determinations,we have measured equivalent widths of the Ca Ⅱ K,Mg Ⅰ b and near-infrared Ca Ⅱ triplet lines using low-resolution spectra from the Sloan Digital Sky Survey (SDSS),calculated effective temperatures from (g-z)o color,deduced stellar surface gravities by fitting stellar isochrones,and determined metallicities based on the aforementioned quantities.Metallicities thus derived from the Ca Ⅱ K line are in much better agreement with the results determined from high-resolution spectra than the values given in the SDSS Data Release 7.The metallicities derived from the Mg Ⅰ b lines have a large dispersion owing to the large measurement errors,whereas those deduced from the Ca Ⅱ triplet lines are too high due to both non-local thermodynamical equilibrium (NLTE) effects and measurement errors.Abundances after correction for the NLTE effect for the Mg Ⅰ b lines and Ca Ⅱ triplet lines are also presented.Following this method,we have identified six candidates of ultra-metal-poor stars with [Fe/H] ~-4.0 from a sample of 166 metal-poor star candidates.One of them,SDSS J102915+172927,was recently confirmed to be an ultra-metal-poor ([Fe/H] <-4.0) star with the lowest metallicity ever measured.Follow-up high-resolution spectroscopy for the other five ultra-metal-poor stars in our sample will therefore be of great interest.

  3. An Unobscured type II quasar candidate: SDSS J012032.19-005501.9

    CERN Document Server

    Li, Y; Zhou, H Y; Komossa, S; Ai, Y L; Liu, W J; Boisvert, J H

    2014-01-01

    We report the finding of an unobscured type II Active Galactic Nuclei (AGN) candidate, SDSS J012032.19-005501.9 at a relatively high redshift of 0.601,which shows a number of unusual properties. It varies significantly on timescales of years as typical type I AGNs and marginally on timescales of weeks. The color-magnitude relation and the structure function are also consistent with that of type I AGNs, which imply that its variability likely originates from the black hole accretion system .However, no broad emission line is detected in the SDSS spectrum, and the upper limit of the equivalent width of the H$\\rm \\beta$ broad emission line is much less than that of type I AGNs. These properties suggest that SDSS J012032.19-005501.9 may be an unobscured quasar without broad emission lines intrinsically, namely an unobscured type II AGN or "true" type II AGN. Furthermore, its continuum luminosity is at least one order of magnitude fainter than the average value of thepast century expected from the [OIII] emission ...

  4. An unobscured type II quasar candidate: SDSS J012032.19-005501.9

    Energy Technology Data Exchange (ETDEWEB)

    Li, Y.; Yuan, W.; Komossa, S. [National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Beijing 100012 (China); Zhou, H. Y.; Liu, W. J. [Key Laboratory for Research in Galaxies and Cosmology, University of Sciences and Technology of China, Chinese Academy of Sciences, Hefei, Anhui 230026 (China); Ai, Y. L. [Department of Astronomy, Peking University, Beijing 100871 (China); Boisvert, J. H., E-mail: liye@nao.cas.cn [Department of Physics and Astronomy, University of Nevada, Las Vegas, NV 89154 (United States)

    2015-02-01

    We report the finding of an unobscured type II active galactic nucleus (AGN) candidate, SDSS J012032.19-005501.9, at a relatively high redshift of 0.601, which shows a number of unusual properties. It varies significantly on timescales of years, typical of type I AGNs, and marginally on timescales of weeks. The color–magnitude relation and the structure function are also consistent with that of type I AGNs, which implies that its variability likely originates from the black hole accretion system. However, no broad emission line (BEL) is detected in the Sloan Digital Sky Survey spectrum, and the upper limit of the equivalent width of the Hβ BEL is much less than that of type I AGNs. These properties suggest that SDSS J012032.19-005501.9 may be an unobscured quasar without intrinsically broad emission lines, namely, an unobscured type II AGN or “true” type II AGN. Furthermore, its continuum luminosity is at least one order of magnitude fainter than the average value over the past century from the [O iii] emission line. This indicates that SDSS J012032.19-005501.9 may be switching off. Additional possible scenarios to explain this intriguing source are also discussed. Future deep observations at multiwavelengths are needed to reveal the nature of this peculiar and intriguing AGN.

  5. Biases in Virial Black Hole Masses: An SDSS Perspective

    CERN Document Server

    Shen, Yue; Strauss, Michael; Richards, Gordon T; Schneider, Donald P

    2007-01-01

    We compile black hole (BH) masses for $\\sim 60,000$ quasars in the redshift range $0.1 \\lesssim z \\lesssim 4.5$ included in the Fifth Data Release of the Sloan Digital Sky Survey (SDSS), using virial BH mass estimators based on the \\hbeta, \\MgII, and \\CIV emission lines. We find that: (1) within our sample, the widths of the three lines follow log-normal distributions, with means and dispersions that do not depend strongly on luminosity or redshift;(2) the \\MgII- and \\hbeta-estimated BH masses are consistent with one another; and (3) the \\CIV BH mass estimator may be more severely affected by a disk wind component than the \\MgII and \\hbeta estimators, giving a positive bias in mass correlated with the \\CIV-\\MgII blueshift. Most SDSS quasars have virial BH masses in the range $10^8-10^9 M_\\odot$. There is a clear upper mass limit of $\\sim 3\\times 10^9-10^{10} M_\\odot$ for active BHs at $z \\gtrsim 2$, decreasing at lower redshifts. Making the reasonable assumptions that the underlying BH mass distribution decre...

  6. Followup Observations of SDSS and CRTS Candidate Cataclysmic Variables

    OpenAIRE

    Szkody, Paula; Everett, Mark E.; Howell, Steve B.; Landolt, Arlo U.; Bond, Howard E.; Silva, David R.; Vasquez-Soltero, Stephanie

    2014-01-01

    We present photometry of 11 and spectroscopy of 35 potential cataclysmic variables from the Sloan Digital Sky Survey, the Catalina Real-Time Transient Survey and vsnet-alerts. The photometry results include quasi-periodic oscillations during the decline of V1363 Cyg, nightly accretion changes in the likely Polar (AM Herculis binary) SDSS J1344+20, eclipses in SDSS J2141+05 with an orbital period of 76+/-2 min, and possible eclipses in SDSS J2158+09 at an orbital period near 100 min. Time-reso...

  7. The Quasar SDSS J105041.35+345631.3: Black Hole Recoil or Extreme Double-Peaked Emitter?

    CERN Document Server

    Shields, G A; Smith, K L; Bonning, E W; Salviander, S; Singh-Kalirai, J; Strickler, R; Ramirez-Ruiz, E; Dutton, A A; Treu, T; Marshall, P J

    2009-01-01

    The quasar SDSS J105041.35+345631.3 (z = 0.272) has broad emission lines blueshifted by 3500 km/s relative to the narrow lines and the host galaxy. Such an object may be a candidate for a recoiling supermassive black hole, a binary black hole, a superposition of two objects, or an unusual geometry for the broad emission-line region (BLR). The absence of narrow lines at the broad line redshift argues against superposition. New Keck spectra of J1050+3456 place tight constraints on the binary model. The combination of large velocity shift and symmetrical H-beta profile, as well as aspects of the narrow line spectrum, make J1050+3456 an interesting candidate for black hole recoil. Other aspects of the spectrum suggest an extreme case of a double-peaked emitter. We discuss possible observational tests to determine the true nature of this exceptional object.

  8. [Data mining for cataclysmic variables candidates in SDSS-DR8].

    Science.gov (United States)

    Jiang, Bin; Pan, Jing-Chang; Wang, Wei

    2013-02-01

    An automatic and efficient method for cataclysmic variables candidates is presented in this paper. The nonlinear locally linear embedding-LLE method is applied in the newly released SDSS-DR8 spectra. Spectra are dimension-reduced by LLE and classified by artificial neural network. The greatly reduced final candidates can be identified manually. 6 new CVs candidates were found in the experiment, and the compare between LLE with PCA shows the feasibility of nonlinear method in data mining in astronomical data.

  9. Extremely Metal-Poor Star Candidates in the SDSS

    CERN Document Server

    Xu, Siyao; Liu, Xiaowei

    2012-01-01

    For a sample of metal-poor stars (-3.3< [Fe/H] <-2.2) that have high-resolution spectroscopic abundance determinations, we have measured equivalent widths (EW) of the Ca II K, Mg I b and near-infrared (NIR) Ca II triplet lines using low-resolution spectra of the Sloan Digital Sky Survey (SDSS), calculated effective temperatures from (g-z)0 color, deduced stellar surface gravities by fitting stellar isochrones, and determined metallicities based on the aforementioned quantities. Metallicities thus derived from the Ca II K line are in much better agreement with the results determined from high-resolution spectra than the values given in the SDSS Data Release 7 (DR7). The metallicities derived from the Mg I b lines have a large dispersion owing to the large measurement errors, whereas those deduced from the Ca II triplet lines are too high due to both non-local thermodynamical equilibrium (NLTE) effects and measurement errors. Abundances after corrected for the NLTE effect for the Mg I b lines and Ca II tr...

  10. Testing the Completeness of the SDSS Colour Selection for Ultramassive, Slowly Spinning Black Holes

    CERN Document Server

    Bertemes, Caroline; Schawinski, Kevin; Done, Chris; Elvis, Martin

    2016-01-01

    We investigate the sensitivity of the colour-based quasar selection algorithm of the Sloan Digital Sky Survey to several key physical parameters of supermassive black holes (SMBHs), focusing on BH spin ($a_{\\star}$) at the high BH-mass regime ($M_{BH} \\geqslant10^9\\, M_{\\odot}$). We use a large grid of model spectral energy distribution, assuming geometrically-thin, optically-thick accretion discs, and spanning a wide range of five physical parameters: BH mass $M_{BH}$, BH spin $a_{\\star}$, Eddington ratio $L / L_{Edd}$ , redshift $z$, and inclination angle $inc$. Based on the expected fluxes in the SDSS imaging ugriz bands, we find that $\\sim 99.8\\%$ of our models with $M_{BH} \\leqslant 10^{9.5}\\, M_{\\odot}$ are selected as quasar candidates and thus would have been targeted for spectroscopic follow-up. However, in the extremely high-mass regime, $\\geqslant 10^{10} M_{\\odot}$, we identify a bias against slowly/retrograde spinning SMBHs. The fraction of SEDs that would have been selected as quasar candidates ...

  11. New supernova candidates from the SDSS-DR7 spectral survey

    Institute of Scientific and Technical Information of China (English)

    Liang-Ping Tu; A-Li Luo; Fu-Chao Wu; Chao Wu; Yong-Heng Zhao

    2009-01-01

    This letter presents 25 supernova candidates discovered from SDSS-DR7 by using our dedicated method, called Sample Decrease. Ten of them have been confirmed by other research groups, while the remaining 15, including 14 Type Ia and one Type Ⅱ, are first discovered based on Supernova Identification analysis. The results demonstrate that our method is reliable. The description of the method and some detailed spectral analysis procedures are also presented.

  12. SDSS-III MARVELS Planet Candidate RV Follow-up

    Science.gov (United States)

    Ge, Jian; Thomas, Neil; Ma, Bo; Li, Rui; SIthajan, Sirinrat

    2014-02-01

    Planetary systems, discovered by the radial velocity (RV) surveys, reveal strong correlations between the planet frequency and stellar properties, such as metallicity and mass, and a greater diversity in planets than found in the solar system. However, due to the sample sizes of extant surveys (~100 to a few hundreds of stars) and their heterogeneity, many key questions remained to be addressed: Do metal poor stars obey the same trends for planet occurrence as metal rich stars? What is the distribution of giant planets around intermediate- mass stars and binaries? Is the ``planet desert'' within 0.6 AU in the planet orbital distribution of intermediate-mass stars real? The MARVELS survey has produced the largest homogeneous RV measurements of 3300 V=7.6-12 FGK stars. The latest data pipeline effort at UF has been able to remove long term systematic errors suffered in the earlier data pipeline. 18 high confident giant planet candidates have been identified among newly processed data. We propose to follow up these giant planet candidates with the KPNO EXPERT instrument to confirm the detection and also characterize their orbits. The confirmed planets will be used to measure occurrence rates, distributions and multiplicity of giants planets around F,G,K stars with a broad range of mass (~0.6-2.5 M_⊙) and metallicity ([Fe/H]~-1.5-0.5). The well defined MARVELS survey cadence allows robust determinations of completeness limits for rigorously testing giant planet formation theories and constraining models.

  13. 5.0 GHz Continuum eEVN Observations of the Recoiling Supermassive Black Hole Candidate SDSSS J113323.97+550415.8

    Science.gov (United States)

    Perez-Torres, M.; Piconcelli, N. Ramirez-Olivencia E.; Alberdi, A.; Komossa, S.; Herrero-Illana, R.

    2015-04-01

    We report electronic European VLBI Network (eEVN) radio observations of the recoiling supermassive black hole (SMBH) candidate SDSSS J113323.97+550415.8 (=SDSS1133), in the outskirts of the nearby (D=28.9 Mpc) galaxy Mrk 177 (Koss et al.

  14. [Searching for WDMS Candidates In SDSS-DR10 With Automatic Method].

    Science.gov (United States)

    Jiang, Bin; Wang, Cheng-you; Wang, Wen-yu; Wang, Wei

    2015-05-01

    The Sloan Digital Sky Survey (SDSS) has released the latest data (DR10) which covers the first APOGEE spectra. The massive spectra can be used for large sample research inscluding the structure and evolution of the Galaxy and multi-wave-band identi cation. In addition, the spectra are also ideal for searching for rare and special objects like white dwarf main-sequence star (WDMS). WDMS consist of a white dwarf primary and a low-mass main-sequence (MS) companion which has positive significance to the study of evolution and parameter of close binaries. WDMS is generally discovered by repeated imaging of the same area of sky, measuring light curves for objects or through photometric selection with follow-up observations. These methods require significant manual processing time with low accuracy and the real-time processing requirements can not be satisfied. In this paper, an automatic and efficient method for searching for WDMS candidates is presented. The method Genetic Algorithm (GA) is applied in the newly released SDSS-DR10 spectra. A total number of 4 140 WDMS candidates are selected by the method and 24 of them are new discoveries which prove that our approach of finding special celestial bodies in massive spectra data is feasible. In addition, this method is also applicable to mining other special celestial objects in sky survey telescope data. We report the identfication of 24 new WDMS with spectra. A compendium of positions, mjd, plate and fiberid of these new discoveries is presented which enrich the spectral library and will be useful to the research of binary evolution models.

  15. Early Giant Planet Candidates from the SDSS-III MARVELS Planet Survey

    Science.gov (United States)

    Thomas, Neil; Ge, J.; Li, R.; Sithajan, S.; Chen, Y.; Shi, J.; Ma, B.; Liu, J.

    2014-01-01

    We report the first discoveries of giant planet candidates from the SDSS-III MARVELS survey. These candidates are found using the new MARVELS data pipeline developed at UF from scratch over the past two years. Unlike the old data pipeline, this pipeline carefully corrects most of the instrument effects (such as trace, slant, distortion, drifts and dispersion) and observation condition effects (such as illumination profile). The result is long-term RV precisions that approach the photon limits in many cases and has yielded four giant planet candidates of ~1-6 Jupiter mass from only the initial fraction of data processed with the new techniques. More survey data is being processed which will likely lead to discoveries of additional giant planet candidates that will be verified and characterized with follow-up observations by the MARVELS team. The MARVELS survey has produced the largest homogeneous RV measurements of 3300 V=7.6-12 FGK stars with well defined cadence 27 RV measurements over 2 years). The MARVELS RV data and other follow-up data (photometry, high contrast imaging, high resolution spectroscopy and RV measurements) will explore the diversity of giant planet companion formation and evolution around stars with a broad range in metallicity ([Fe/H -1.5-0.5), mass ( 0.6-2.5M(sun)), and environment (thin disk and thick disk), and will help to address the key scientific questions identified for the MARVELS survey including, but not limited to: Do metal poor stars obey the same trends for planet occurrence as metal rich stars? What is the distribution of giant planets around intermediate-mass stars and binaries? Is the “planet desert” within 0.6 AU in the planet orbital distribution of intermediate-mass stars real?

  16. The catalog of nearby black hole candidates

    CERN Document Server

    Caramete, Laurentiu I

    2011-01-01

    Context. In order to study the association of the origin of ultra high energy cosmic rays (UHECR) with active galactic nuclei (AGN) at all levels of their activity we require an unbiased sample of black holes. Aims. Here we describe such a sample, of about 6 000 black holes, within the local Universe, inside the GZK (Greisen Zatsepin Kuzmin) limit, around 100 Mpc. Methods. The starting point is the 2 micron all sky survey, with the next steps as: test its com- pleteness down to low flux densities, confine it to redshifts z < 0.025, limit it to early Hubble type galaxies, test with B-V colors and with the FIR/Radio ratio the possible separation in classes of sources for the ultra high energy cosmic rays, use the spheroidal stellar component - black hole mass relationship to derive black hole masses, and test them with known black hole masses. Results. The statistics are consistent with the mass function of black hole masses, with a rel- atively flat distribution to about 10^8 Msol, and thereafter a very ste...

  17. Giant Planet Candidates, Brown Dwarfs, and Binaries from the SDSS-III MARVELS Planet Survey.

    Science.gov (United States)

    Thomas, Neil; Ge, Jian; Li, Rui; de Lee, Nathan M.; Heslar, Michael; Ma, Bo; SDSS-Iii Marvels Team

    2015-01-01

    We report the discoveries of giant planet candidates, brown dwarfs, and binaries from the SDSS-III MARVELS survey. The finalized 1D pipeline has provided 18 giant planet candidates, 16 brown dwarfs, and over 500 binaries. An additional 96 targets having RV variability indicative of a giant planet companion are also reported for future investigation. These candidates are found using the advanced MARVELS 1D data pipeline developed at UF from scratch over the past three years. This pipeline carefully corrects most of the instrument effects (such as trace, slant, distortion, drifts and dispersion) and observation condition effects (such as illumination profile, fiber degradation, and tracking variations). The result is long-term RV precisions that approach the photon limits in many cases for the ~89,000 individual stellar observations. A 2D version of the pipeline that uses interferometric information is nearing completion and is demonstrating a reduction of errors to half the current levels. The 2D processing will be used to increase the robustness of the detections presented here and to find new candidates in RV regions not confidently detectable with the 1D pipeline. The MARVELS survey has produced the largest homogeneous RV measurements of 3300 V=7.6-12 FGK stars with a well defined cadence of 27 RV measurements over 2 years. The MARVELS RV data and other follow-up data (photometry, high contrast imaging, high resolution spectroscopy and RV measurements) will explore the diversity of giant planet companion formation and evolution around stars with a broad range in metallicity (Fe/H -1.5-0.5), mass ( 0.6-2.5M(sun)), and environment (thin disk and thick disk), and will help to address the key scientific questions identified for the MARVELS survey including, but not limited to: Do metal poor stars obey the same trends for planet occurrence as metal rich stars? What is the distribution of giant planets around intermediate-mass stars and binaries? Is the 'planet desert

  18. Synchrotron peak luminosity,black hole mass and Eddington ratio for SDSS flat-spectrum radio quasars

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    For a sample of 185 flat-spectrum radio quasars(FSRQs) constructed from the SDSS DR3 quasar catalog,we found a significant correlation between the synchrotron peak luminosity and both the black hole mass and Eddington ratio.This implies that the physics of its jet formation is not only tightly related with the black hole mass,but also with the accretion rate.We verify that the synchrotron peak luminosity can be a better indicator of jet emission than 5 GHz luminosity,through comparing the relationships between each of these two parameters and both black hole mass and Eddington ratio.The fundamental plane of black hole activity for our FSRQs is established as Lr ∝ L0x.80 ± 0.06 Mbh -0.04 ± 0.09 with a weak dependence on black hole mass,however,the scatter is significant.

  19. A search of new samples of active galactic nuclei with low-mass black holes from SDSS

    Science.gov (United States)

    Liu, H.; Yuan, W.; Zhou, H.; Dong, X.-B.

    2016-02-01

    We report on the progress of our on-going work to search for low-mass black holes (LMBHs) in active galactic nuclei. The masses of black holes are estimated using the broad line width and luminosity obtained from one-epoch optical spectra. As the first step, we fitted the spectra of 1263 objects in the quasar catalog of the SDSS DR10 and obtained accurate measurement of the emission lines. Two AGNs are found to have M BH ~ 106 M⊙. The next step is to analyze the spectra of the DR10 galaxy sample, from which a much larger sample of low-mass AGNs is expected to be obtained.

  20. The mass function of nearby black hole candidates

    CERN Document Server

    Caramete, Laurentiu I

    2009-01-01

    The mass function of super-massive black holes in our cosmic neighborhood is required to understand the statistics of activity, specifically the production of ultra high energy particles. We determine a mass function of black hole candidates from the entire sky outside the Galactic plane. Using the 2MASS catalogue as a starting point, and the well established correlation between black hole mass and the old bulge population of stars, we derive a list of nearby black hole candidates within the redshift range z 10^7 M_sol has 5,634 entries. Here we use this catalogue to derive the mass function. We correct for volume, so that this mass function is a volume limited distribution to redshift 0.025. The mass function of nearby black hole candidates is a straight simple power-law, extending down into the mass range, where nuclear star clusters may replace the super-massive black holes. The slope of this mass function can be explained in a simple merger picture. Integrating this mass function over the redshift range,...

  1. On Intrinsic Magnetic Moments In Black Hole Candidates

    CERN Document Server

    Robertson, S L; Robertson, Stanley L.; Leiter, Darryl J.

    2003-01-01

    In previous work we found that many of the spectral properties of low mass x-ray binaries, including galactic black hole candidates could be explained by a magnetic propeller model that requires an intrinsically magnetized central object. Here we describe how the Einstein field equations of General Relativity and equipartition magnetic fields permit the existence of highly red shifted, extremely long lived, collapsing, radiating objects. We examine the properties of these collapsed objects and discuss characteristics that might lead to their confirmation as the source of black hole candidate phenomena.

  2. The 3XMM/SDSS Stripe 82 Galaxy Cluster Survey: Cluster catalogue and discovery of two merging cluster candidates

    CERN Document Server

    Takey, Ali; Mahmoud, Eman A; Ali, Gamal B

    2016-01-01

    We present a galaxy cluster survey based on XMM-Newton observations that are located in the Stripe 82 of the Sloan Digital Sky Survey (SDSS). The survey covers an area of 11.25 deg$^2$. The X-ray cluster candidates were selected as serendipitously extended detected sources from the third XMM-Newton serendipitous source catalogue (3XMM-DR5). A cross-correlation of the candidate list that comprises 94 objects with recently published X-ray and optically selected cluster catalogues provided optical confirmations and redshift estimates for about half of the candidate sample. We present a catalogue of X-ray cluster candidates previously known in X-ray and/or optical bands from the matched catalogues or NED. The catalogue consists of 54 systems with redshift measurements in the range of 0.05-1.19 with a median of 0.36. Of these, 45 clusters have spectroscopic confirmations as stated in the matched catalogues. We spectroscopically confirmed another 6 clusters from the available spectroscopic redshifts in the SDSS-DR1...

  3. How Black Are Black Hole Candidates?

    CERN Document Server

    Robertson, S L; Robertson, Stanley L.; Leiter, Darryl J.

    2002-01-01

    In previous work we found that many of the spectral properties of x-ray binaries, including both galactic black hole candiates (GBHC) and neutron stars, were consistent with the existence of intrinsically magnetized central objects. Here we review and extend the observational evidence for the existence of intrinsically magnetized GBHC and show that their existence is consistent with a new class of solutions of the Einstein field equations of General Relativity. These solutions are based on a strict adherence to the Principle of Equivalence, which prevents the time-like geodesics of physical matter from becoming null on trapped surfaces of infinite red shift. The new solutions emerge from the fact that the structure and radiation transfer properties of the energy-momentum tensor on the right hand side of the Einstein field equations must have a form that is consistent with this Principle of Equivalence requirement. In this context, we show that the Einstein field equations allow the existence of highly red shi...

  4. MARVELS-1b: A Short-Period, Brown Dwarf Desert Candidate from the SDSS-III MARVELS Planet Search

    CERN Document Server

    Lee, Brian L; Fleming, Scott W; Stassun, Keivan G; Gaudi, B Scott; Barnes, Rory; Mahadevan, Suvrath; Eastman, Jason D; Wright, Jason; Siverd, Robert J; Gary, Bruce; Ghezzi, Luan; Laws, Chris; Wisniewski, John P; de Mello, G F Porto; Ogando, Ricardo L C; Maia, Marcio A G; da Costa, Luiz Nicolaci; Sivarani, Thirupathi; Pepper, Joshua; Nguyen, Duy Cuong; Hebb, Leslie; De Lee, Nathan; Wang, Ji; Wan, Xiaoke; Zhao, Bo; Chang, Liang; Groot, John; Varosi, Frank; Hearty, Fred; Hanna, Kevin; van Eyken, J C; Kane, Stephen R; Agol, Eric; Bizyaev, Dmitry; Bochanski, John J; Brewington, Howard; Chen, Zhiping; Costello, Erin; Dou, Liming; Eisenstein, Daniel J; Fletcher, Adam; Ford, Eric B; Guo, Pengcheng; Holtzman, Jon A; Jiang, Peng; Leger, R French; Liu, Jian; Long, Daniel C; Malanushenko, Elena; Malanushenko, Viktor; Malik, Mohit; Oravetz, Daniel; Pan, Kaike; Rohan, Pais; Schneider, Donald P; Shelden, Alaina; Snedden, Stephanie A; Simmons, Audrey; Weaver, B A; Weinberg, David H; Xie, Ji-Wei

    2010-01-01

    We present a new short-period brown dwarf candidate around the star TYC 1240-00945-1. This candidate was discovered in the first year of the Multi-object APO Radial Velocity Exoplanets Large-area Survey (MARVELS), which is part of the third phase of the Sloan Digital Sky Survey (SDSS-III), and we designate the brown dwarf as MARVELS-1b. MARVELS uses the technique of dispersed fixed-delay interferometery to simultaneously obtain radial velocity measurements for 60 objects per field using a single, custom-built instrument that is fiber fed from the SDSS 2.5-m telescope. From our 20 radial velocity measurements spread over a ~370 d time baseline, we derive a Keplerian orbital fit with semi-amplitude K=2.533+/-0.025 km/s, period P=5.8953+/-0.0004 d, and eccentricity consistent with circular. Independent follow-up radial velocity data confirm the orbit. Adopting a mass of 1.37+/-0.11 M_Sun for the slightly evolved F9 host star, we infer that the companion has a minimum mass of 28.0+/-1.5 M_Jup, a semimajor axis 0....

  5. The cosmic growth of the active black hole population at 1SDSS

    CERN Document Server

    Schulze, A; Gavignaud, I; Schramm, M; Silverman, J; Merloni, A; Zamorani, G; Hirschmann, M; Mainieri, V; Wisotzki, L; Shankar, F; Fiore, F; Koekemoer, A M; Temporin, G

    2014-01-01

    We present a census of the active black hole population at 1hole mass and Eddington ratio, employing a maximum likelihood fitting technique. The study of the active black hole mass function (BHMF) and the Eddington ratio distribution function (ERDF) allows to clearly disentangle the AGN downsizing phenomenon, present in the AGN luminosity function (AGN LF), into its physical processes of black hole mass downsizing and accretion rate evolution. We are utilizing type 1 AGN samples from 3 optical surveys (VVDS, zCOSMOS and SDSS), that cover a wide range of 3 dex in luminosity over our redshift interval of interest. We investigate the cosmic evolution of the AGN population as a function of AGN luminosity, black hole mass and accretion rate. Compared to z = 0 we find a distinct change in the shape of the BHMF and the ERDF, consistent with downsizing in black hole mass. The active fraction or duty cycle of type 1 AGN at z~1.5 is almost flat as...

  6. The 3XMM/SDSS Stripe 82 Galaxy Cluster Survey. I. Cluster catalogue and discovery of two merging cluster candidates

    Science.gov (United States)

    Takey, A.; Durret, F.; Mahmoud, E.; Ali, G. B.

    2016-10-01

    We present a galaxy cluster survey based on XMM-Newton observations that are located in Stripe 82 of the Sloan Digital Sky Survey (SDSS). The survey covers an area of 11.25 deg2. The X-ray cluster candidates were selected as serendipitously extended detected sources from the third XMM-Newton serendipitous source catalogue (3XMM-DR5). A cross-correlation of the candidate list that comprises 94 objects with recently published X-ray and optically selected cluster catalogues provided optical confirmations and redshift estimates for about half of the candidate sample. We present a catalogue of X-ray cluster candidates previously known in X-ray and/or optical bands from the matched catalogues or NED. The catalogue consists of 54 systems with redshift measurements in the range of 0.05-1.19 with a median of 0.36. Of these, 45 clusters have spectroscopic confirmations as stated in the matched catalogues. We spectroscopically confirmed another 6 clusters from the available spectroscopic redshifts in the SDSS-DR12. The cluster catalogue includes 17 newly X-ray discovered clusters, while the remainder were detected in previous XMM-Newton and/or ROSAT cluster surveys. Based on the available redshifts and fluxes given in the 3XMM-DR5 catalogue, we estimated the X-ray luminosities and masses for the cluster sample. We also present the list of the remaining X-ray cluster candidates (40 objects) that have no redshift information yet in the literature. Of these candidates, 25 sources are considered as distant cluster candidates beyond a redshift of 0.6. We also searched for galaxy cluster mergers in our cluster sample and found two strong candidates for newly discovered cluster mergers at redshifts of 0.11 and 0.26. The X-ray and optical properties of these systems are presented. Tables A.1, C.1, and C.2 are also 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/594/A32

  7. A CANDIDATE MASSIVE BLACK HOLE IN THE LOW-METALLICITY DWARF GALAXY PAIR MRK 709

    Energy Technology Data Exchange (ETDEWEB)

    Reines, Amy E.; Condon, James J. [National Radio Astronomy Observatory, Charlottesville, VA 22903 (United States); Plotkin, Richard M. [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States); Russell, Thomas D. [International Centre for Radio Astronomy Research, Curtin University, GPO Box U1987, Perth, WA 6845 (Australia); Mezcua, Mar [Instituto de Astrofísica de Canarias (IAC), E-38200 La Laguna, Tenerife (Spain); Sivakoff, Gregory R. [Department of Physics, University of Alberta, CCIS 4-181, Edmonton, AB T6G 2E1 (Canada); Johnson, Kelsey E., E-mail: areines@nrao.edu [Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904-4325 (United States)

    2014-06-01

    The incidence and properties of present-day dwarf galaxies hosting massive black holes (BHs) can provide important constraints on the origin of high-redshift BH seeds. Here we present high-resolution X-ray and radio observations of the low-metallicity, star-forming, dwarf-galaxy system Mrk 709 with the Chandra X-ray Observatory and the Karl G. Jansky Very Large Array. These data reveal spatially coincident hard X-ray and radio point sources with luminosities suggesting the presence of an accreting massive BH (M {sub BH} ∼ 10{sup 5-7} M {sub ☉}). Based on imaging from the Sloan Digital Sky Survey (SDSS), we find that Mrk 709 consists of a pair of compact dwarf galaxies that appear to be interacting with one another. The position of the candidate massive BH is consistent with the optical center of the southern galaxy (Mrk 709 S), while no evidence for an active BH is seen in the northern galaxy (Mrk 709 N). We derive stellar masses of M {sub *} ∼ 2.5 × 10{sup 9} M {sub ☉} and M {sub *} ∼ 1.1 × 10{sup 9} M {sub ☉} for Mrk 709 S and Mrk 709 N, respectively, and present an analysis of the SDSS spectrum of the BH host Mrk 709 S. At a metallicity of just ∼10% solar, Mrk 709 is among the most metal-poor galaxies with evidence for an active galactic nucleus. Moreover, this discovery adds to the growing body of evidence that massive BHs can form in dwarf galaxies and that deep, high-resolution X-ray and radio observations are ideally suited to reveal accreting massive BHs hidden at optical wavelengths.

  8. SDSS J080449.49+161624.8: A peculiar AM CVn star from a colour-selected sample of candidates

    CERN Document Server

    Roelofs, G H A; Steeghs, D; Rau, A; de Groot, E; Marsh, T R; Nelemans, G; Liebert, J; Woudt, P

    2008-01-01

    We describe a spectroscopic survey designed to uncover an estimated ~40 AM CVn stars hiding in the photometric database of the Sloan Digital Sky Survey (SDSS). We have constructed a relatively small sample of about 1500 candidates based on a colour selection, which should contain the majority of all AM CVn binaries while remaining small enough that spectroscopic identification of the full sample is feasible. We present the first new AM CVn star discovered using this strategy, SDSS J080449.49+161624.8, the ultracompact binary nature of which is demonstrated using high-time-resolution spectroscopy obtained at the Magellan telescopes at Las Campanas Observatory, Chile. A kinematic 'S-wave' feature is observed on a period 44.5+/-0.1min, which we propose is the orbital period, although the present data cannot yet exclude its nearest daily aliases. The new AM CVn star shows a peculiar spectrum of broad, single-peaked helium emission lines with unusually strong series of ionised helium, reminiscent of the (intermedi...

  9. Recoiling Black Holes: Electromagnetic Signatures, Candidates, and Astrophysical Implications

    Directory of Open Access Journals (Sweden)

    S. Komossa

    2012-01-01

    Full Text Available Supermassive black holes (SMBHs may not always reside right at the centers of their host galaxies. This is a prediction of numerical relativity simulations, which imply that the newly formed single SMBH, after binary coalescence in a galaxy merger, can receive kick velocities up to several 1000 km/s due to anisotropic emission of gravitational waves. Long-lived oscillations of the SMBHs in galaxy cores, and in rare cases even SMBH ejections from their host galaxies, are the consequence. Observationally, accreting recoiling SMBHs would appear as quasars spatially and/or kinematically offset from their host galaxies. The presence of the “kicks” has a wide range of astrophysical implications which only now are beginning to be explored, including consequences for black hole and galaxy assembly at the epoch of structure formation, black hole feeding, and unified models of active galactic nuclei (AGN. Here, we review the observational signatures of recoiling SMBHs and the properties of the first candidates which have emerged, including follow-up studies of the candidate recoiling SMBH of SDSSJ092712.65+294344.0.

  10. MARVELS-1b: A Short-period, Brown Dwarf Desert Candidate from the SDSS-III Marvels Planet Search

    Science.gov (United States)

    Lee, Brian L.; Ge, Jian; Fleming, Scott W.; Stassun, Keivan G.; Gaudi, B. Scott; Barnes, Rory; Mahadevan, Suvrath; Eastman, Jason D.; Wright, Jason; Siverd, Robert J.; Gary, Bruce; Ghezzi, Luan; Laws, Chris; Wisniewski, John P.; Porto de Mello, G. F.; Ogando, Ricardo L. C.; Maia, Marcio A. G.; Nicolaci da Costa, Luiz; Sivarani, Thirupathi; Pepper, Joshua; Nguyen, Duy Cuong; Hebb, Leslie; De Lee, Nathan; Wang, Ji; Wan, Xiaoke; Zhao, Bo; Chang, Liang; Groot, John; Varosi, Frank; Hearty, Fred; Hanna, Kevin; van Eyken, J. C.; Kane, Stephen R.; Agol, Eric; Bizyaev, Dmitry; Bochanski, John J.; Brewington, Howard; Chen, Zhiping; Costello, Erin; Dou, Liming; Eisenstein, Daniel J.; Fletcher, Adam; Ford, Eric B.; Guo, Pengcheng; Holtzman, Jon A.; Jiang, Peng; French Leger, R.; Liu, Jian; Long, Daniel C.; Malanushenko, Elena; Malanushenko, Viktor; Malik, Mohit; Oravetz, Daniel; Pan, Kaike; Rohan, Pais; Schneider, Donald P.; Shelden, Alaina; Snedden, Stephanie A.; Simmons, Audrey; Weaver, B. A.; Weinberg, David H.; Xie, Ji-Wei

    2011-02-01

    We present a new short-period brown dwarf (BD) candidate around the star TYC 1240-00945-1. This candidate was discovered in the first year of the Multi-object APO Radial Velocity Exoplanets Large-area Survey (MARVELS), which is part of the Sloan Digital Sky Survey (SDSS) III, and we designate the BD as MARVELS-1b. MARVELS uses the technique of dispersed fixed-delay interferometery to simultaneously obtain radial velocity (RV) measurements for 60 objects per field using a single, custom-built instrument that is fiber fed from the SDSS 2.5 m telescope. From our 20 RV measurements spread over a ~370 day time baseline, we derive a Keplerian orbital fit with semi-amplitude K = 2.533 ± 0.025 km s-1, period P = 5.8953 ± 0.0004 days, and eccentricity consistent with circular. Independent follow-up RV data confirm the orbit. Adopting a mass of 1.37 ± 0.11 M sun for the slightly evolved F9 host star, we infer that the companion has a minimum mass of 28.0 ± 1.5 M Jup, a semimajor axis 0.071 ± 0.002 AU assuming an edge-on orbit, and is probably tidally synchronized. We find no evidence for coherent intrinsic variability of the host star at the period of the companion at levels greater than a few millimagnitudes. The companion has an a priori transit probability of ~14%. Although we find no evidence for transits, we cannot definitively rule them out for companion radii lsim1 R Jup.

  11. Automated physical classification in the SDSS DR10. A catalogue of candidate Quasars

    CERN Document Server

    Brescia, Massimo; Longo, Giuseppe

    2015-01-01

    We discuss whether modern machine learning methods can be used to characterize the physical nature of the large number of objects sampled by the modern multi-band digital surveys. In particular, we applied the MLPQNA (Multi Layer Perceptron with Quasi Newton Algorithm) method to the optical data of the Sloan Digital Sky Survey - Data Release 10, investigating whether photometric data alone suffice to disentangle different classes of objects as they are defined in the SDSS spectroscopic classification. We discuss three groups of classification problems: (i) the simultaneous classification of galaxies, quasars and stars; (ii) the separation of stars from quasars; (iii) the separation of galaxies with normal spectral energy distribution from those with peculiar spectra, such as starburst or starforming galaxies and AGN. While confirming the difficulty of disentangling AGN from normal galaxies on a photometric basis only, MLPQNA proved to be quite effective in the three-class separation. In disentangling quasars ...

  12. Searching for metal-deficient emission-line galaxy candidates: the final sample of the SDSS DR12 galaxies

    CERN Document Server

    Guseva, N G; Fricke, K J; Henkel, C

    2016-01-01

    We present a spectroscopic study of metal-deficient dwarf galaxy candidates, selected from the SDSS DR12. The oxygen abundances were derived using the direct method in galaxies with the electron temperature-sensitive emission line [OIII]4363A measured with an accuracy better than 30%. The oxygen abundances for the remaining galaxies with larger uncertainties of the [OIII]4363A line fluxes were calculated using a strong-line semi-empirical method by Izotov and Thuan. The resulting sample consists of 287 low-metallicity candidates with oxygen abundances below 12+logO/H=7.65 including 23 extremely metal-deficient (XMD) candidates with 12+log O/H<7.35. Ten out of sixteen XMDs known so far (or ~60%) have been discovered by our team using the direct method. Three XMDs were found in the present study. We study relations between global parameters of low-metallicity galaxies, including absolute optical magnitudes, Hbeta luminosities (or equivalently star formation rates), stellar masses, mid-infrared colours, and o...

  13. Virial Black Hole Mass Estimates for 280,000 AGNs from the SDSS Broadband Photometry and Single-epoch Spectra

    Science.gov (United States)

    Kozłowski, Szymon

    2017-01-01

    We use the Sloan Digital Sky Survey (SDSS) Quasar Data Release 12 (DR12Q), containing nearly 300,000 active galactic nuclei (AGNs), to calculate the monochromatic luminosities at 5100, 3000, and 1350 Å, derived from the broadband extinction-corrected SDSS magnitudes. After matching these sources to their counterparts from the SDSS Quasar Data Release 7 (DR7Q), we find very high correlations between our luminosities and DR7Q spectra-based luminosities with minute mean offsets (∼0.01 dex) and dispersions of differences of 0.11, 0.10, and 0.12 dex, respectively, across a luminosity range of 2.5 dex. We then estimate the black hole (BH) masses of the AGNs using the broad line region radius–disk luminosity relations and the FWHM of the Mg ii and C iv emission lines, to provide a catalog of 283,033 virial BH mass estimates (132,451 for Mg ii, 213,071 for C iv, and 62,489 for both) along with the estimates of the bolometric luminosity and Eddington ratio for 0.1 < z < 5.5 and for roughly a quarter of the sky covered by SDSS. The BH mass estimates from Mg ii turned out to be closely matched to the ones from DR7Q with a dispersion of differences of 0.34 dex across a BH mass range of ∼2 dex. We uncovered a bias in the derived C iv FWHMs from DR12Q as compared to DR7Q, which we correct empirically. The C iv BH mass estimates should be used with caution because the C iv line is known to cause problems in the estimation of BH mass from single-epoch spectra. Finally, after the FWHM correction, the AGN BH mass estimates from C iv closely match the DR7Q ones (with a dispersion of 0.28 dex), and more importantly the Mg ii and C iv BH masses agree internally with a mean offset of 0.07 dex and a dispersion of 0.39 dex.

  14. Virial Black Hole Mass Estimates for 280,000 AGNs from the SDSS Broad-Band Photometry and Single Epoch Spectra

    CERN Document Server

    Kozłowski, Szymon

    2016-01-01

    We use the Sloan Digital Sky Survey (SDSS) Quasar Data Release 12 (DR12Q), containing nearly 300,000 AGNs, to calculate the monochromatic luminosities at 5100\\AA, 3000\\AA, and 1350\\AA, derived from the broad-band extinction-corrected SDSS magnitudes. After matching them to their counterparts based on spectra and published in the SDSS Quasar Data Release 7 (DR7Q), we find perfect correlations with minute mean offsets ($\\sim$0.01 dex) and dispersions of differences of 0.11, 0.10, 0.12 dex, respectively, across a 2.5 dex luminosity range. We then estimate the active galactic nuclei (AGNs) black hole masses using the broad line region radius--luminosity relations and the FWHM of the MgII and CIV emission lines, to provide a catalog of 283,032 virial black hole mass estimates (132,451 for MgII, 213,068 for CIV, and 62,487 for both) along with the bolometric luminosity and the Eddington ratio estimates for $0.1SDSS. The black hole mass estimates from MgI...

  15. WISE/2MASS-SDSS Brown Dwarfs candidates using Virtual Observatory tools

    CERN Document Server

    Aberasturi, M; Martin, E L

    2011-01-01

    Massive imaging surveys in different passbands are the main contributors to the discovery of brown dwarfs (BDs). The Virtual Observatory (VO) represents an adequate framework to efficiently handle these vast datasets and filter them out according to specific requirements. Having an statistically significant number of BDs is mandatory to better understand their general properties as well as to identify peculiar objects. WISE, an all-sky survey in the infrared, provides an excellent opportunity to significantly increase the number of BDs, in particular those at the lower end of the temperature scale. The main aim of this work is to demonstrate that VO tools are efficient to identify BDs by cross correlating public catalogues released by large imaging surveys. Using VO tools we have performed a cross-match of the WISE Preliminary Release, the 2MASS Point Source and SDSS Data Release 7 catalogues over the whole area of sky that they have in common. Photometric and proper motion criteria were used to obtain a list...

  16. Searching for metal-deficient emission-line galaxy candidates: the final sample of the SDSS DR12 galaxies

    Science.gov (United States)

    Guseva, N. G.; Izotov, Y. I.; Fricke, K. J.; Henkel, C.

    2017-03-01

    We present a spectroscopic study of metal-deficient dwarf galaxy candidates, selected from the SDSS DR12. The oxygen abundances were derived using the direct method in galaxies with the electron temperature-sensitive emission line [O iii]λ4363 Å measured with an accuracy better than 30%. The oxygen abundances for the remaining galaxies with larger uncertainties of the [O iii]λ4363 Å line fluxes were calculated using a strong-line semi-empirical method by Izotov and Thuan. The resulting sample consists of 287 low-metallicity candidates with oxygen abundances below 12 + log O/H = 7.65 including 23 extremely metal-deficient (XMD) candidates with 12 + log O/H ≤ 7.35. Ten out of sixteen XMDs known so far (or 60%) have been discovered by our team using the direct method. Three XMDs were found in the present study. We study relations between global parameters of low-metallicity galaxies, including absolute optical magnitudes, Hβ luminosities (or equivalently star formation rates), stellar masses, mid-infrared colours, and oxygen abundances. Low-metallicity and XMD galaxies strongly deviate to lower metallicities in L-Z, L(Hβ)-Z and M∗-Z diagrams than in relations obtained for large samples of low-redshift, star-forming galaxies with non-restricted metallicities. These less chemically evolved galaxies with stellar masses ≈106-108M⊙, Hβ luminosities ≈1038-1041 erg s-1, SFR ≈ 0.01-1.0 M⊙ yr-1, and sSFR 50 Gyr-1 have physical conditions which may be characteristic of high-redshift low-mass star-forming galaxies which are still awaiting discovery.

  17. High-Resolution Observations of a Binary Black Hole Candidate

    Science.gov (United States)

    Tsai, Chao-Wei; Phillips, Chris; Norris, Ray; Jarrett, Thomas; Emonts, Bjorn; Cluver, Michelle; Eisenhardt, Peter; Stern, Daniel; Assef, Roberto

    2012-10-01

    We propose a 12-hour 2.3 GHz continuum Long Baseline Array (LBA) observation of WISE J2332-5056, a newly discovered supermassive black hole (SMBH) merger candidate that is located in the nearby universe (z = 0.3447). Our recently acquired 9 GHz ATCA map shows unusual radio morphology: a one-sided, smaller (and likely younger) FR-I jet perpendicular to a larger, Doppler-boosted FR-II jet. Follow-up Gemini-S/GMOS spectroscopy of this WISE-selected radio galaxy reveals broad emission lines blue-shifted by > 3,500 km/s with respect to the narrow lines and host galaxy, hallmarks of a dual AGN system. Combined, the optical spectroscopy and radio morphology of this object are strongly suggestive of a black hole merger system. Even in the local universe these systems are extremely difficult to identify; yet the process of supermassive blackhole growth is vital toward understanding galaxy evolution from the early to the current universe. Moreover, nearby merging SMBHs may serve as outstanding targets for gravitational wave studies. The proposed high resolution LBA map, reaching 50 pc resolution at the source redshift will allow us to investigate the SMBH merger scenario hypothesis.

  18. Evidence For Intrinsic Magnetic Moments in Black Hole Candidates

    CERN Document Server

    Robertson, S L; Robertson, Stanley L.; Leiter, Darryl J.

    2002-01-01

    We show that the power law part of the quiescent x-ray emissions of neutron stars in low mass x-ray binaries is magnetospheric in origin. It can be very accurately calculated from rates of spin and the $\\sim 10^{3 - 4}$ times brighter luminosity at the transition to the hard spectral state. We establish that the spectral state transition for neutron stars is a magnetospheric propeller effect. We test the hypothesis that the similar spectral state switches and quiescent power law emissions of the black hole candidates might be magnetospheric effects. In the process we derive proposed magnetic moments and rates of spin for them and accurately predict their quiescent luminosities. We discuss other tests of the hypothesis and consider some attractive aspects of a unified magnetospheric model for low mass x-ray binaries. We also consider some of the changes that would be needed for strong-field gravity theories to accomodate intrinsic magnetic moments in collapsed objects.

  19. Gamma-Ray Spectral States of Galactic Black Hole Candidates

    CERN Document Server

    Grove, J E; Kroeger, R A; McNaron-Brown, K; Skibo, J G; Phlips, B F

    1998-01-01

    OSSE has observed seven transient black hole candidates: GRO J0422+32, GX339-4, GRS 1716-249, GRS 1009-45, 4U 1543-47, GRO J1655-40, and GRS 1915+105. Two gamma-ray spectral states are evident and, based on a limited number of contemporaneous X-ray and gamma-ray observations, these states appear to be correlated with X-ray states. The former three objects show hard spectra below 100 keV (photon number indices Gamma < 2) that are exponentially cut off with folding energy ~100 keV, a spectral form that is consistent with thermal Comptonization. This "breaking gamma-ray state" is the high-energy extension of the X-ray low, hard state. In this state, the majority of the luminosity is above the X-ray band, carried by photons of energy ~100 keV. The latter four objects exhibit a "power-law gamma-ray state" with a relatively soft spectral index (Gamma ~ 2.5-3) and no evidence for a spectral break. For GRO J1655-40, the lower limit on the break energy is 690 keV. GRS 1716-249 exhibits both spectral states, with th...

  20. SDSS quasars in the WISE preliminary data release and quasar candidate selection with the optical/infrared colors

    CERN Document Server

    Wu, Xue-Bing; Jia, Zhendong; Zhang, Yanxia; Peng, Nanbo

    2012-01-01

    We present a catalog of 37842 quasars in the Sloan Digital Sky Survey (SDSS) Data Release 7, which have counterparts within 6$"$ in the Wide-field Infrared Survey Explorer (WISE) Preliminary Data Release. The overall WISE detection rate of the SDSS quasars is 86.7%, and it decreases to less than 50.0% when the quasar magnitude is fainter than $i=20.5$. We derive the median color-redshift relations based on this SDSS-WISE quasar sample and apply them to estimate the photometric redshifts of the SDSS-WISE quasars. We find that by adding the WISE W1 and W2-band data to the SDSS photometry we can increase the photometric redshift reliability, defined as the percentage of sources with the photometric and spectroscopic redshift difference less than 0.2, from 70.3% to 77.2%. We also obtain the samples of WISE detected normal and late-type stars with SDSS spectroscopy, and present a criterion in the $z-W1$ vs. $g-z$ color-color diagram, $z-W1>0.66(g-z)+2.01$, to separate quasars from stars. With this criterion we can...

  1. Mass Functions of the Active Black Holes in Distant Quasars from the Large Bright Quasar Survey, the Bright Quasar Survey, and the Color-Selected Sample of the SDSS Fall Equatorial Stripe

    DEFF Research Database (Denmark)

    Vestergaard, Marianne; Osmer, Patrick S.

    2009-01-01

    We present mass functions of distant actively accreting supermassive black holes residing in luminous quasars discovered in the Large Bright Quasar Survey, the Bright Quasar Survey, and the Fall Equatorial Stripe of the Sloan Digital Sky Survey (SDSS). The quasars cover a wide range of redshifts (0...... functions at similar redshifts based on the SDSS Data Release 3 quasar catalog presented by Vestergaard et al. We see clear evidence of cosmic downsizing in the comoving space density distribution of active black holes in the LBQS sample alone. In forthcoming papers, further analysis, comparison......, and discussion of these mass functions will be made with other existing black hole mass functions, notably that based on the SDSS DR3 quasar catalog. We present the relationships used to estimate the black hole mass based on the MgII emission line; the relations are calibrated to the Hbeta and CIV relations...

  2. Search for Binary Black Hole Candidates from the VLBI Images of AGNs

    Indian Academy of Sciences (India)

    Xiang Liu

    2014-09-01

    We have searched the core-jet pairs in the VLBI scales (< 1 kpc), from several VLBI catalogues, and found out 5 possible Binary Black Hole (BBH) candidates. We present here the search results and analyse the candidates preliminarily. We plan to study with multi-band VLBI observation. We also plan to carry out optical line investigation in future.

  3. Spectral clustering for optical confirmation and redshift estimation of X-ray selected galaxy cluster candidates in the SDSS Stripe 82

    Science.gov (United States)

    Mahmoud, E.; Takey, A.; Shoukry, A.

    2016-07-01

    We develop a galaxy cluster finding algorithm based on spectral clustering technique to identify optical counterparts and estimate optical redshifts for X-ray selected cluster candidates. As an application, we run our algorithm on a sample of X-ray cluster candidates selected from the third XMM-Newton serendipitous source catalog (3XMM-DR5) that are located in the Stripe 82 of the Sloan Digital Sky Survey (SDSS). Our method works on galaxies described in the color-magnitude feature space. We begin by examining 45 galaxy clusters with published spectroscopic redshifts in the range of 0.1-0.8 with a median of 0.36. As a result, we are able to identify their optical counterparts and estimate their photometric redshifts, which have a typical accuracy of 0.025 and agree with the published ones. Then, we investigate another 40 X-ray cluster candidates (from the same cluster survey) with no redshift information in the literature and found that 12 candidates are considered as galaxy clusters in the redshift range from 0.29 to 0.76 with a median of 0.57. These systems are newly discovered clusters in X-rays and optical data. Among them 7 clusters have spectroscopic redshifts for at least one member galaxy.

  4. Spectral Clustering for Optical Confirmation and Redshift Estimation of X-ray Selected Galaxy Cluster Candidates in the SDSS Stripe 82

    CERN Document Server

    Mahmoud, Eman; Shoukry, Amin

    2016-01-01

    We develop a galaxy cluster finding algorithm based on spectral clustering technique to identify optical counterparts and estimate optical redshifts for X-ray selected cluster candidates. As an application, we run our algorithm on a sample of X-ray cluster candidates selected from the third XMM-Newton serendipitous source catalog (3XMM-DR5) that are located in the Stripe 82 of the Sloan Digital Sky Survey (SDSS). Our method works on galaxies described in the color-magnitude feature space. We begin by examining 45 galaxy clusters with published spectroscopic redshifts in the range of 0.1 to 0.8 with a median of 0.36. As a result, we are able to identify their optical counterparts and estimate their photometric redshifts, which have a typical accuracy of 0.025 and agree with the published ones. Then, we investigate another 40 X-ray cluster candidates (from the same cluster survey) with no redshift information in the literature and found that 12 candidates are considered as galaxy clusters in the redshift range ...

  5. Mass Functions of the Active Black Holes in Distant Quasars from the Large Bright Quasar Survey, the Bright Quasar Survey, and the Color-Selected Sample of the SDSS Fall Equatorial Stripe

    DEFF Research Database (Denmark)

    Vestergaard, Marianne; Osmer, Patrick S.

    2009-01-01

    We present mass functions of distant actively accreting supermassive black holes residing in luminous quasars discovered in the Large Bright Quasar Survey, the Bright Quasar Survey, and the Fall Equatorial Stripe of the Sloan Digital Sky Survey (SDSS). The quasars cover a wide range of redshifts (0...

  6. The X-ray spectrum of the black hole candidate Swift J1753.5-0127

    NARCIS (Netherlands)

    Mostafa, Reham; Mendez, Mariano; Hiemstra, Beike; Soleri, Paolo; Belloni, Tomaso; Ibrahim, Alaa I.; Yasein, Mohammed N.

    2013-01-01

    We present a spectral analysis of the black hole candidate and X-ray transient source Swift J1753.5-0127 making use of simultaneous observations of XMM-Newton and Rossi X-ray Timing Explorer in 2006, when the source was in outburst. The aim of this paper is to test whether a thermal component due to

  7. A 3x10^9 solar mass black hole in the quasar SDSS J1148+5251 at z=6.41

    CERN Document Server

    Willott, C J; Jarvis, M J; Willott, Chris J.; Lure, Ross J. Mc; Jarvis, Matt J.

    2003-01-01

    We present near-infrared H and K-band spectra of the z=6.41 quasar SDSS J114816.64+525150.3. The spectrum reveals a broad MgII 2799 emission line with a full-width half-maximium of 6000 km/s. From the peak wavelength of this emission line we obtain a more accurate redshift than is possible from the published optical spectrum and determine a redshift of z=6.41+/-0.01. If the true peak of the Lyman alpha emission is at the same redshift, then a large fraction of the flux blueward of the peak is absorbed. The equivalent width of the MgII emission line is similar to that of lower redshift quasars, suggesting that the UV continuum is not dominated by a beamed component. Making basic assumptions about the line-emitting gas we derive an estimate for the central black hole in this quasar of 3x10^9 solar masses. The very high luminosity of the quasar shows that it is accreting at the maximal allowable rate for a black hole of this mass adopting the Eddington limit criterion.

  8. The faint "heartbeats" of IGR J17091-3624: an exceptional black-hole candidate

    CERN Document Server

    Altamirano, D; Linares, M; van der Klis, M; Wijnands, R; Curran, P A; Kalamkar, M; Stiele, H; Motta, S; Munoz-Darias, T; Casella, P; Krimm, H

    2011-01-01

    We report on the first 180 days of RXTE observations of the outburst of the black hole candidate IGR J17091-3624. This source exhibits a broad variety of complex light curve patterns including periods of strong flares alternating with quiet intervals. Similar patterns in the X-ray light curves have been seen in the (up to now) unique black hole system GRS 1915+105. In the context of the variability classes defined by Belloni et al. (2000) for GRS 1915+105, we find that IGR J17091-3624 shows the \

  9. SDSS-D R10中WD MS光谱的自动搜索研究%Searching for WDMS Candidates In SDSS-DR10 With Automatic Method

    Institute of Scientific and Technical Information of China (English)

    姜斌; 王成优; 王文玉; 王为

    2015-01-01

    The Sloan Digital Sky Survey (SDSS) has released the latest data (DR10) which covers the first APOGEE spectra . The massive spectra can be used for large sample research including the structure and evolution of the Galaxy and multi-wave-band identi cation .In addition ,the spectra are also ideal for searching for rare and special objects like white dwarf main-sequence star (WDMS) .WDMS consist of a white dwarf primary and a low-mass main-sequence (MS) companion which has positive sig-nificance to the study of evolution and parameter of close binaries .WDMS is generally discovered by repeated imaging of the same area of sky ,measuring light curves for objects or through photometric selection with follow-up observations .These meth-ods require significant manual processing time with low accuracy and the real-time processing requirements can not be satisfied . In this paper ,an automatic and efficient method for searching for WDMS candidates is presented .The method Genetic Algorithm (GA) is applied in the newly released SDSS-DR10 spectra .A total number of 4 140 WDMS candidates are selected by the meth-od and 24 of them are new discoveries w hich prove that our approach of finding special celestial bodies in massive spectra data is feasible .In addition ,this method is also applicable to mining other special celestial objects in sky survey telescope data .We re-port the identfication of 24 new WDMS with spectra .A compendium of positions ,mjd ,plate and fiberid of these new discoveries is presented which enrich the spectral library and will be useful to the research of binary evolution models .%SDSS-DR10是美国SLOAN巡天望远镜发布的最新数据,包含了首批APOGEE光谱。这些海量的天文光谱除了可以用来探寻银河系的结构和进行多波段证认外,还蕴藏着包括白矮主序双星在内的特殊天体。白矮主序双星是一类特殊的双星系统,它由两颗主序星演化而来,包含了中低质量恒星演化的终

  10. The formation of bulges and black holes: lessons from a census of active galaxies in the SDSS.

    Science.gov (United States)

    Kauffmann, Guinevere; Heckman, Timothy M

    2005-03-15

    We examine the relationship between galaxies, supermassive black holes and AGN using a sample of 23,000 narrow-emission-line ('type 2') active galactic nuclei (AGN) drawn from a sample of 123,000 galaxies from the Sloan Digital Sky Survey. We have studied how AGN host properties compare with those of normal galaxies and how they depend on the luminosity of the active nucleus. We find that AGN reside in massive galaxies and have distributions of sizes and concentrations that are similar to those of the early-type galaxies in our sample. The host galaxies of low-luminosity AGN have stellar populations similar to normal early types. The hosts of high- luminosity AGN have much younger mean stellar ages, and a significant fraction have experienced recent starbursts. High-luminosity AGN are also found in lower-density environments. We then use the stellar velocity dispersions of the AGN hosts to estimate black hole masses and their [OIII]lambda5007 emission-line luminosities to estimate black hole accretion rates. We find that the volume averaged ratio of star formation to black hole accretion is approximately 1000 for the bulge-dominated galaxies in our sample. This is remarkably similar to the observed ratio of stellar mass to black hole mass in nearby bulges. Most of the present-day black hole growth is occurring in black holes with masses less than 3 x 10(7)M(3). Our estimated accretion rates imply that low-mass black holes are growing on a time-scale that is comparable with the age of the Universe. Around 50% this growth takes place in AGN that are radiating within a factor of five of the Eddington luminosity. Such systems are rare, making up only 0.2% of the low-mass black hole population at the present day. The remaining growth occurs in lower luminosity AGN. The growth time-scale increases by more than an order of magnitude for the most massive black holes in our sample. We conclude that the evolution of the AGN luminosity function documented in recent optical

  11. Two spectral states of the black-hole candidate GX 339-4

    Science.gov (United States)

    Lavrov, S. V.; Borozdin, K. N.; Aleksandrovich, N. L.; Aref'ev, V. A.; Sunyaev, R. A.; Skinner, G. K.

    1997-07-01

    We performed two series of observations of the X-ray source GX 339-4, a black-hole candidate, between 1989 and 1994 using the TTM instrument of the Roentgen Observatory. In March 1989, the source was in a soft state with a spectrum described by a multicolor accretion disk model (Shakura and Sunyaev 1973). In March 1994, a hard state with a power-law spectrum and a transition from the hard to the soft state was observed. The spectral states of the source show similarities to the spectra of other black-hole candidates. The presence of two states is considered as evidence that GX 339-4 belongs to this class of objects.

  12. Black Holes, Neutron Stars and White Dwarf Candidates from Microlensing with OGLE-III

    CERN Document Server

    Wyrzykowski, L; Skowron, J; Rybicki, K A; Mroz, P; Kozlowski, S; Udalski, A; Szymanski, M K; Pietrzynski, G; Soszynski, I; Ulaczyk, K; Pietrukowicz, P; Poleski, R; Pawlak, M; Ilkiewicz, K; Rattenbury, N J

    2015-01-01

    Most stellar remnants so far have been found in binary systems, where they interact with matter from their companions. Isolated neutron stars and black holes are difficult to find as they are dark, yet they are predicted to exist in our Galaxy in vast numbers. We explored the OGLE-III database of 150 million objects observed in years 2001-2009 and found 59 microlensing events exhibiting a parallax effect due to the Earth's motion around the Sun. Combining parallax and brightness measurements from microlensing light curves with expected proper motions in the Milky Way, we identified 15 microlensing events which are consistent with having a white dwarf, neutron star or a black hole lens and we estimated their masses and distances. The most massive of our black hole candidates has 8.3 M_Sun and is at a distance of 2.4 kpc. The distribution of masses of our candidates indicates a continuum in mass distribution with no mass gap between neutron stars and black holes. We also present predictions on how such events w...

  13. A complex state transition from the black hole candidate Swift J1753.5-0127

    CERN Document Server

    Soleri, P; Motta, S; Belloni, T; Casella, P; Méndez, M; Altamirano, D; Linares, M; Wijnands, R; Fender, R; van der Klis, M

    2012-01-01

    We present our monitoring campaign of the outburst of the black-hole candidate Swift J1753.5-0127, observed with the Rossi X-ray Timing Explorer and the Swift satellites. After ~4.5 years since its discovery, the source had a transition to the hard intermediate state. We performed spectral and timing studies of the transition showing that, unlike the majority of the transient black holes, the system did not go to the soft states but it returned to the hard state after a few months. During this transition Swift J1753.5-0127 features properties which are similar to those displayed by the black hole Cygnus X-1. We compared Swift J1753.5-0127 to one dynamically confirmed black hole and two neutron stars showing that its power spectra are in agreement with the binary hosting a black hole. We also suggest that the prolonged period at low flux that followed the initial flare is reminiscent of that observed in other X-ray binaries, as well as in cataclysmic variables.

  14. Candidate optical counterparts of MAXI J1543-564

    NARCIS (Netherlands)

    Russell, D.M.; Lewis, F.; Roche, P.; Altamirano, D.

    2011-01-01

    We report on optical observations of the field of the black hole candidate X-ray binary MAXI J1543-564 (ATel #3330, #3331, #3334, #3336, #3341, #3355) with the 2-m Faulkes Telescope South (located at Siding Spring, Australia). Three images were acquired in SDSS i'-band on 2011 May 11th, 14th and 15t

  15. IDENTIFICATION OF OUTFLOWS AND CANDIDATE DUAL ACTIVE GALACTIC NUCLEI IN SDSS QUASARS AT z = 0.8-1.6

    Energy Technology Data Exchange (ETDEWEB)

    Barrows, R. Scott; Lacy, Claud H. Sandberg; Kennefick, Julia; Kennefick, Daniel; Berrier, Joel C. [Arkansas Center for Space and Planetary Sciences, University of Arkansas, Fayetteville, AR 72701 (United States); Comerford, Julia M., E-mail: rbarrows@uark.edu [Astronomy Department, University of Texas at Austin, Austin, TX 78712 (United States)

    2013-06-01

    We present a sample of 131 quasars from the Sloan Digital Sky Survey at redshifts 0.8 < z < 1.6 with double peaks in either of the high-ionization narrow emission lines [Ne V] {lambda}3426 or [Ne III] {lambda}3869. These sources were selected with the intention of identifying high-redshift analogs of the z < 0.8 active galactic nuclei (AGNs) with double-peaked [O III] {lambda}5007 lines, which might represent AGN outflows or dual AGNs. Lines of high ionization potential are believed to originate in the inner, highly photoionized portion of the narrow line region, and we exploit this assumption to investigate the possible kinematic origins of the double-peaked lines. For comparison, we measure the [Ne V] {lambda}3426 and [Ne III] {lambda}3869 double peaks in low-redshift (z < 0.8) [O III]-selected sources. We find that [Ne V] {lambda}3426 and [Ne III] {lambda}3869 show a correlation between line splitting and line width similar to that of [O III] {lambda}5007 in other studies, and the velocity splittings are correlated with the quasar Eddington ratio. These results suggest an outflow origin for at least a subset of the double peaks, allowing us to study the high-ionization gas kinematics around quasars. However, we find that a non-negligible fraction of our sample show no evidence for an ionization stratification. For these sources, the outflow scenario is less compelling, leaving the dual AGN scenario as a viable possibility. Finally, we find that our sample shows an anti-correlation between the velocity-offset ratio and luminosity ratio of the components, which is a potential dynamical argument for the presence of dual AGNs. Therefore, this study serves as a first attempt at extending the selection of candidate dual AGNs to higher redshifts.

  16. Testing the Kerr Nature of Black Hole Candidates using Iron Line Spectra in the CPR Framework

    CERN Document Server

    Jiang, Jiachen; Steiner, James F

    2015-01-01

    The iron K$\\alpha$ line commonly observed in the X-ray spectrum of both stellar-mass and supermassive black hole candidates originates from X-ray fluorescence of the inner accretion disk. Accordingly, it can be used to map the spacetime geometry around these objects. In this paper, we extend previous work using the iron K$\\alpha$ line to test the Kerr black hole hypothesis. We adopt the Cardoso-Pani-Rico parametrization and we test the possibility of constraining possible deviations from the Kerr solution that can be obtained from observations across the range of black hole spins and inclination angles. We confirm previous claims that the iron K$\\alpha$ line is potentially a quite powerful probe for testing the Kerr metric given sufficiently high quality data and with systematics under control, especially in the case of fast-rotating black holes and high inclination angles since both conditions serve to maximize relativistic effects. We find that some geometric perturbations from Kerr geometry manifest more s...

  17. The nature of massive black hole binary candidates: I. Spectral properties and evolution

    CERN Document Server

    Decarli, Roberto; Fumagalli, Michele; Tsalmantza, Paraskevi; Montuori, Carmen; Lusso, Elisabeta; Hogg, David W; Prochaska, Jason X

    2013-01-01

    Theoretically, bound binaries of massive black holes are expected as the natural outcome of mergers of massive galaxies. From the observational side, however, massive black hole binaries remain elusive. Velocity shifts between narrow and broad emission lines in quasar spectra are considered a promising observational tool to search for spatially unresolved, dynamically bound binaries. In this series of papers we investigate the nature of such candidates through analyses of their spectra, images and multi-wavelength spectral energy distributions. Here we investigate the properties of the optical spectra, including the evolution of the broad line profiles, of all the sources identified in our previous study. We find a diverse phenomenology of broad and narrow line luminosities, widths, shapes, ionization conditions and time variability, which we can broadly ascribe to 4 classes based on the shape of the broad line profiles: 1) Objects with bell-shaped broad lines with big velocity shifts (>1000 km/s) compared to...

  18. Mapping the Broad-band Spectrum of a New Candidate Intermediate Mass Black Hole

    Science.gov (United States)

    Farrell, Sean

    2014-10-01

    We request joint XMM-Newton & HST observations of a new intermediate mass black hole candidate in the galaxy LEDA 87326 to map the broad-band spectral energy distribution from X-ray to near-IR. Previous observations with the XMM-Newton EPIC and OM cameras detected an X-ray source with an observed 0.2-10 keV luminosity of 6E41 erg/s, with the X-ray spectrum dominated by a hard power law and the UV/optical data consistent with thermal emission from a cool (~0.08 keV) accretion disc. The high X-ray luminosity and low disc temperature imply a black hole mass > 4000 Msun. By observing this source simultaneously with XMM-Newton and the HST we will confirm that the observed optical emission is from an accretion disc and determine whether any reprocessing in the outer disc is present.

  19. Outbursts and State Transitions in Black Hole Candidates observed by MAXI

    Science.gov (United States)

    Negoro, H.; Maxi Team

    2010-12-01

    MAXI continuously observes several black hole candidates in our Galaxy and LMC. MAXI already detected various state transitions in Cyg X-1, GX 339-4, Swift J1752.5-127, and black hole transients, H 1743-332, 4U 1630, XTE J1752-223, and MAXI J1659-125. From these observations, we try to clarify what happens during the transitions, and what triggers the transitions. In any case, fast alerts just before the transitions and soon after the outbursts are crucial to detect, for instance, radio and high energy gamma-ray jets or emission. We also present some successful examples of alerts from our MAXI transient alert system.

  20. The black hole candidate IGR J17091-3624 is still active

    Science.gov (United States)

    Altamirano, D.; Wijnands, R.; Rodriguez, J.; Corbel, S.; Belloni, T.

    2013-01-01

    In February 2011 the black hole candidate IGR J17091-3624 went into outburst (detected by Swift/BAT, see ATEL #3144). During this outburst IGR J17091-3624 exhibited strong and highly-structured X-ray variability (e.g. Altamirano et al. 2011, ApJL, 742, 17, and references therein) which so far had only been observed from the very-bright black hole X-ray transient GRS 1915+105. This 2011 outburst of IGR J17091-3624 has been studied using many multi-wavelength observations (ATEL #3148, #3150, #3159, #3167, #3168, #3179, #3203, #3225, #3229, #3230, #3232, #3266, #3299, #3913, #3916, #4173, #4282, #4283, #4360) except during the December-January periods, when sun constraints do not allow further observations to be performed.

  1. Characterization of few transient black hole candidates during their X-ray outbursts with TCAF Solution

    CERN Document Server

    Debnath, Dipak; Chakrabarti, S K; Jana, A; Molla, A A; Chatterjee, D

    2016-01-01

    The theoretical concept of Chakrabarti-Titarchuk two Component Advective Flow (TCAF) model was introduced around two decade ago in mid-90s. Recently after the inclusion of TCAF model into XSPEC as an additive table model, we find that it is quite capable to fit spectra from different phases of few transient black hole candidates (TBHCs) during their outbursts. This quite agrees with our theoretical understanding. Here, a brief summary of our recent studies of spectral and temporal properties of few TBHCs during their X-ray outbursts with TCAF will be discussed.

  2. The black hole candidate IGR J17091-3624 going to quiescence

    Science.gov (United States)

    Altamirano, D.; Wijnands, R.; Belloni, T.

    2013-06-01

    We report preliminary results on our Swift/XRT monitoring observations of the current outburst of the black hole candidate IGR J17091-3624 (e.g. Altamirano et al. 2011, ApJL, 742, 17, and references therein). Since our last report on 31 Jan 2013 (ATEL #4773), the X-ray flux as measured from Swift/XRT pointed observations has only varied by a factor not larger than 5. However, in the the last Swift/XRT pointed observation IGR J17091-3624 is barely detected, if detected at all.

  3. Re-scrutiny of a best intermediate mass black hole candidate M82 X-1

    Science.gov (United States)

    Liu, Jifeng; Xu, Xiaojie; Qiu, Yanli; Wang, Song

    2015-08-01

    While several recent works on ultraluminous X-ray sources show some of them to be stellar mass black holes or even neutron stars with special radiation mechanisms, M82 X-1 remains one of the best intermediate mass black hole candidates in the local universe. It exhibits amazing properties including quasi-periodic oscillations and extremely high X-ray luminosities suggesting an intermediate mass black hole, a 62-day orbital period from RXTE observations suggestive of a supergiant secondary, and possible radio flare emission that could result from relativistic beaming. Recently we have re-scrutinized this source with a wealth of data from Chandra, Swift/XRT and Hubble, and found three surprises about M82 X-1. Firstly, there is an X-ray transient that is only 1" away from M82 X-1, which has a peak luminosity only 1% of M82 X-1 and is usually hidden in the shadow of M82 X-1. This X-ray transient is associated with the previously reported radio flare. Secondly, two years' Swift/XRT observations, with much much better spatial resolution than RXTE observations, have shown that the 62-day period comes from another nearby less brighter ultra-luminous X-ray source, but definitely not from M82 X-1. Thirdly, we find an optical counterpart for M82 X-1 within the newly obtained 0.4" error circle on Hubble images, and its spectral energy distribution from Hubble photometry shows that it has excessive Halpha emission but no excessive SII emission. This lack of excessive SII emission suggests that the Halpha emission is not from the surrounding nebula but from an accretion disk. The monitoring of this Halpha emission line will allow us to determine the mass of the black hole via dynamical means.

  4. A Radio-Selected Black Hole X-ray Binary Candidate in the Milky Way Globular Cluster M62

    CERN Document Server

    Chomiuk, Laura; Maccarone, Thomas J; Miller-Jones, James C A; Heinke, Craig; Noyola, Eva; Seth, Anil C; Ransom, Scott

    2013-01-01

    We report the discovery of a candidate stellar-mass black hole in the Milky Way globular cluster M62. We detected the black hole candidate, which we term M62-VLA1, in the core of the cluster using deep radio continuum imaging from the Karl G. Jansky Very Large Array. M62-VLA1 is a faint source, with a flux density of 18.7 +/- 1.9 microJy at 6.2 GHz and a flat radio spectrum (alpha=-0.24 +/- 0.42, for S_nu = nu^alpha). M62 is the second Milky Way cluster with a candidate stellar-mass black hole; unlike the two candidate black holes previously found in the cluster M22, M62-VLA1 is associated with a Chandra X-ray source, supporting its identification as a black hole X-ray binary. Measurements of its radio and X-ray luminosity, while not simultaneous, place M62-VLA1 squarely on the well-established radio--X-ray correlation for stellar-mass black holes. In archival Hubble Space Telescope imaging, M62-VLA1 is coincident with a star near the lower red giant branch. This possible optical counterpart shows a blue exce...

  5. Correlations of Power-law Spectral and QPO Features In Black Hole Candidate Sources

    Science.gov (United States)

    Fiorito, Ralph; Titarchuk, Lev

    2004-01-01

    Recent studies have shown that strong correlations are observed between low frequency QPO s and the spectral power law index for a number of black hole candidate sources (BHCs), when these sources exhibit quasi-steady hard x-ray emission states. The dominant long standing interpretation of QPO's is that they are produced in and are the signature of the thermal accretion disk. Paradoxically, strong QPO's are present even in the cases where the thermal component is negligible. We present a model which identifies the origin of the QPO's and relates them directly to the properties of a compact coronal region which is bounded by the adjustment from Kepleriaa to sub-Kelperian inflow into the BH, and is primarily responsible for the observed power law spectrum. The model also predicts the relationship between high and low frequency QPO's and shows how BH's can be unique identified from observations of the soft states of NS's and BHC's.

  6. Multiwavelength Observations of the Black Hole Candidate XTE J1550-564 during the 2000 Outburst

    CERN Document Server

    Jain, R K; Orosz, J A; McClintock, J E; Remillard, R A

    2001-01-01

    We report optical, infrared, and X-ray light curves for the outburst, in 2000, of the black hole candidate XTE J1550-564. We find that the start of the outburst in the H and V bands precedes that seen in the RXTE All Sky Monitor by 11.5 +/- 0.9 and 8.8 +/- 0.6 days, respectively; a similar delay has been observed in two other systems. About 50 days after the primary maxima in the VIH light curves, we find secondary maxima, most prominently in H. This secondary peak is absent in the X-ray light curve, but coincides with a transition to the low/hard state. We suggest that this secondary peak may be due to non-thermal emission associated with the formation of a jet.

  7. Multiwavelength Observations of the Black Hole Candidate XTE J1550-564 during the 2000 Outburst

    Science.gov (United States)

    Jain, Raj K.; Bailyn, Charles D.; Orosz, Jerome A.; McClintock, Jeffrey E.; Remillard, Ronald A.

    2001-06-01

    We report optical, infrared, and X-ray light curves for the outburst, in 2000, of the black hole candidate XTE J1550-564. We find that the start of the outburst in the H and V bands precedes that seen in the Rossi X-Ray Timing Explorer All-Sky Monitor by 11.5+/-0.9 and 8.8+/-0.6 days, respectively; a similar delay has been observed in two other systems. About 50 days after the primary maxima in the VIH light curves, we find secondary maxima, most prominently in H. This secondary peak is absent in the X-ray light curve but coincides with a transition to the low/hard state. We suggest that this secondary peak may be due to nonthermal emission associated with the formation of a jet.

  8. The Magnetospheric Eternally Collapsing Object (MECO) Model of Galactic Black Hole Candidates and Active Galactic Nuclei

    CERN Document Server

    Robertson, S L; Robertson, Stanley L.; Leiter, Darryl J.

    2006-01-01

    The spectral, timing, and jet formation properties of neutron stars in low mass x-ray binary systems are influenced by the presence of central magnetic moments. Similar features shown by the galactic black hole candidates (GBHC) strongly suggest that their compact cores might be intrinsically magnetic as well. We show that the existence of intrinsically magnetic GBHC is consistent with a new class of solutions of the Einstein field equations of General Relativity. These solutions are based on a strict adherence to the Strong Principle of Equivalence (SPOE) requirement that the world lines of physical matter must remain timelike in all regions of spacetime. The new solutions emerge when the structure and radiation transfer properties of the energy momentum tensor on the right hand side of the Einstein field equations are appropriately chosen to dynamically enforce this SPOE requirement of timelike world line completeness. In this context, we find that the Einstein field equations allow the existence of highly ...

  9. The Faint "Heartbeats" of IGR J17091-3624: An Exceptional Black Hole Candidate

    Science.gov (United States)

    Altamirano, D.; Belloni, T.; Linares, M.; VanDerKlis, M.; Wunands, R.; Curran, P. A.; Kalamkar, M.; Stiele, H.; Motta, S.; Munoz-Darias, T.; Casella, P.; Krimm, H.

    2011-01-01

    We report on the first 180 days of Rossi X-Ray Timing Explorer observations of the outburst of the black hole candidate IGR Jl7091-3624. This source exhibits a broad variety of complex light curve patterns including periods of strong flares alternating with quiet intervals. Similar patterns in the X-ray light curves have been seen in the (up to now) unique black hole system GRS 1915+105. In the context of the variability classes defined by Belloni et al. for GRS 1915+105, we find that JGR J17091-3624 shows the nu, rho, alpha, lambda, Beta, and mu classes as well as quiet periods which resemble the chi class, all occurring at 2-60 keY count rate levels which can be 10-50 times lower than observed in GRS 1915+\\05. The so-called rho class "heartbeats" occur as fast as every few seconds and as slow as approx 100 s, tracing a loop in the hardness-intensity diagram which resembles that previously seen in GRS 1915+\\05. However, while GRS 1915+105 traverses this loop clockwise, IGR Jl7091-3624 does so in the opposite sense. We briefly discuss our findings in the context of the models proposed for GRS 1915+105 and find that either all models requiring near Eddington luminosities for GRS 1915+105-like variability fail, or IGR Il7091-3624 lies at a distance well in excess of 20 kpc, or it harbors one of the least massive black holes known( <3 solar M).

  10. Resolved, expanding jets in the Galactic black hole candidate XTE J1908+094

    Science.gov (United States)

    Rushton, A. P.; Miller-Jones, J. C. A.; Curran, P. A.; Sivakoff, G. R.; Rupen, M. P.; Paragi, Z.; Spencer, R. E.; Yang, J.; Altamirano, D.; Belloni, T.; Fender, R. P.; Krimm, H. A.; Maitra, D.; Migliari, S.; Russell, D. M.; Russell, T. D.; Soria, R.; Tudose, V.

    2017-07-01

    Black hole X-ray binaries undergo occasional outbursts caused by changing inner accretion flows. Here we report high angular resolution radio observations of the 2013 outburst of the black hole candidate X-ray binary system XTE J1908+094, using data from the Very Long Baseline Array and European VLBI Network. We show that following a hard-to-soft state transition, we detect moving jet knots that appear asymmetric in morphology and brightness, and expand to become laterally resolved as they move away from the core, along an axis aligned approximately -11° east of north. We initially see only the southern component, whose evolution gives rise to a 15-mJy radio flare and generates the observed radio polarization. This fades and becomes resolved out after 4 days, after which a second component appears to the north, moving in the opposite direction. From the timing of the appearance of the knots relative to the X-ray state transition, a 90° swing of the inferred magnetic field orientation, the asymmetric appearance of the knots, their complex and evolving morphology, and their low speeds, we interpret the knots as working surfaces where the jets impact the surrounding medium. This would imply a substantially denser environment surrounding XTE J1908+094 than has been inferred to exist around the microquasar sources GRS 1915+105 and GRO J1655-40.

  11. An X-ray Selected Sample of Candidate Black Holes in Dwarf Galaxies

    CERN Document Server

    Lemons, Sean; Plotkin, Richard; Gallo, Elena; Greene, Jenny

    2015-01-01

    We present a sample of hard X-ray selected candidate black holes (BHs) in 19 dwarf galaxies. BH candidates are identified by cross-matching a parent sample of ~44,000 local dwarf galaxies (M_stellar < 3 x 10^9 Msun, z<0.055) with the Chandra Source Catalog, and subsequently analyzing the original X-ray data products for matched sources. Of the 19 dwarf galaxies in our sample, 8 have X-ray detections reported here for the first time. We find a total of 43 point-like hard X-ray sources with individual luminosities L(2-10 keV) ~ 10^37 - 10^40 erg/s. Hard X-ray luminosities in this range can be attained by stellar-mass X-ray binaries (XRBs), and by massive BHs accreting at low Eddington ratio. We place an upper limit of 53% (10/19) on the fraction of galaxies in our sample hosting a detectable hard X-ray source consistent with the optical nucleus, although the galaxy center is poorly defined in many of our objects. We also find that 42% (8/19) of the galaxies in our sample exhibit statistically significant ...

  12. A Catalog Sample of Low-mass Galaxies Observed in X-Rays with Central Candidate Black Holes

    Science.gov (United States)

    Nucita, A. A.; Manni, L.; De Paolis, F.; Giordano, M.; Ingrosso, G.

    2017-03-01

    We present a sample of X-ray-selected candidate black holes in 51 low-mass galaxies with z ≤ 0.055 and masses up to 1010 M ⊙ obtained by cross-correlating the NASA-SLOAN Atlas with the 3XMM catalog. We have also searched in the available catalogs for radio counterparts of the black hole candidates and find that 19 of the previously selected sources also have a radio counterpart. Our results show that about 37% of the galaxies of our sample host an X-ray source (associated with a radio counterpart) spatially coincident with the galaxy center, in agreement with other recent works. For these nuclear sources, the X-ray/radio fundamental plane relation allows one to estimate the mass of the (central) candidate black holes, which are in the range of 104–2 × 108 M ⊙ (with a median value of ≃3 × 107 M ⊙ and eight candidates having masses below 107 M ⊙). This result, while suggesting that X-ray emitting black holes in low-mass galaxies may have had a key role in the evolution of such systems, makes it even more urgent to explain how such massive objects formed in galaxies. Of course, dedicated follow-up observations both in the X-ray and radio bands, as well as in the optical, are necessary in order to confirm our results.

  13. A late jet rebrightening revealed from multiwavelength monitoring of the black hole candidate XTE J1752-223

    NARCIS (Netherlands)

    Russell, D.M.; Curran, P.A.; Muñoz-Darias, T.; Lewis, F.; Motta, S.; Stiele, H.; Belloni, T.; Miller-Jones, J.C.A.; Jonker, P.G.; O'Brien, K.; Homan, J.; Casella, P.; Gandhi, P.; Soleri, P.; Markoff, S.; Maitra, D.; Gallo, E.; Cadolle Bel, M.

    2012-01-01

    We present optical monitoring of the black hole candidate XTE J1752−223 during its 2009-10 outburst and decay to quiescence. The optical light curve can be described by an exponential decay followed by a plateau, then a more rapid fade towards quiescence. The plateau appears to be due to an extra co

  14. The high-energy X-ray spectrum of black hole candidate GX 339-4 during a transition

    Science.gov (United States)

    Dolan, J. F.; Crannell, C. J.; Dennis, B. R.; Orwig, L. E.

    1987-01-01

    The X-ray emitting system GX 339-4 contains one of the prime candidates for a stellar mass-sized black hole. Determining the observational similarities and differences between the members of this group is of value in specifying which characteristics can be used to identify systems containing a black hole, especially those for which no mass determination can be made. The first observations of the E greater than 20 keV spectrum of GX 339-4 during a transition between luminosity states are reported here. The hard spectral state is the lower luminosity state of the system. GX 339-4 has a power-low spectrum above 20 keV which pivots during transitions between distinct luminosity states. The only other X-ray sources known to exhibit this behavior, Cyg XR-1 and (probably) A0620-00, are leading candidates for systems containing a black hole component based on their measured spectrocopic mass function.

  15. Regular black hole remnants and graviatoms with de Sitter interior as heavy dark matter candidates probing inhomogeneity of early universe

    CERN Document Server

    Dymnikova, Irina

    2015-01-01

    We address the question of regular primordial black holes with de Sitter interior, their remnants and gravitational vacuum solitons G-lumps as heavy dark matter candidates providing signatures for inhomogeneity of early universe, which is severely constrained by the condition that the contribution of these objects in the modern density does not exceed the total density of dark matter. Primordial black holes and their remnants seem to be most elusive among dark matter candidates. However, we reveal a nontrivial property of compact objects with de Sitter interior to induce proton decay or decay of neutrons in neutron stars. The point is that they can form graviatoms, binding electrically charged particles. Their observational signatures as dark matter candidates provide also signatures for inhomogeneity of the early universe. In graviatoms, the cross-section of the induced proton decay is strongly enhanced, what provides the possibility of their experimental searches. We predict proton decay paths induced by gr...

  16. The evolution of the X-ray phase lags during the outbursts of the black hole candidate GX 339-4

    NARCIS (Netherlands)

    Altamirano, Diego; Méndez, Mariano

    2015-01-01

    Owing to the frequency and reproducibility of its outbursts, the black hole candidate GX 339-4 has become the standard against which the outbursts of other black hole candidate are matched up. Here we present the first systematic study of the evolution of the X-ray lags of the broad-band variability

  17. Phase lags and coherence of X-ray variability in black hole candidates

    CERN Document Server

    Nowak, M A; Nowak, Michael A; Vaughan, Brian A

    1995-01-01

    The ``low'' (hard or ``non-thermal'') state of black hole candidates is sometimes modelled via an optically thick, hot Compton cloud that obscures a softer input source such as an accretion disk. In these models the observed output spectra consist entirely of photons reprocessed by the cloud, making it difficult to extract information about the input spectra. Recently Miller (1995) has argued that the Fourier phase (or time) lag between hard and soft X-ray photons in actuality represents the phase lags intrinsic to the input source, modulo a multiplicative factor. The phase lags thus would be a probe of the input photon source. In this paper we examine this claim and find that, although true for the limited parameter space considered by Miller, the intrinsic phase lag disappears whenever the output photon energy is much greater than the input photon energy. The remaining time lags represent a ``shelf'' due to differences between mean diffusion times across the cloud. As pointed out by Miller, the amplitude of...

  18. On the Origin of the Radio/X-Ray Luminosity Correlation in Black Hole Candidates

    CERN Document Server

    Robertson, S L; Robertson, Stanley L.; Leiter, Darryl J.

    2004-01-01

    In previous work we found that the spectral state switch and other spectral properties of both neutron star (NS) and galactic black hole candidates (GBHC), in low mass x-ray binary systems could be explained by a magnetic propeller effect that requires an intrinsically magnetic central compact object. In later work we showed that intrinsically magnetic GBHC could be easily accommodated by general relativity in terms of magnetospheric eternally collapsing objects (MECO), with lifetimes greater than a Hubble time, and examined some of their spectral properties. In this work we show how a standard thin accretion disk and corona can interact with the central magnetic field in atoll class NS, and GBHC and active galactic nuclei (AGN) modeled as MECO, to produce jets that emit radio through infrared luminosity $L_R$ that is correlated with mass and x-ray luminosity as $L_R \\propto M^{0.75 - 0.92}L_x^{2/3}$ up to a mass scale invariant cutoff at the low/high spectral state switch. Comparing the MECO-GBHC/AGN model t...

  19. VLBI detection of the Galactic black hole binary candidate MAXI J1836-194

    CERN Document Server

    Yang, Jun; Li, Zhixuan; Paragi, Zsolt; Campbell, Robert M; Gurvits, Leonid; Shen, Zhiqiang; Hong, Xiaoyu; Xia, Bo

    2012-01-01

    The X-ray transient MAXI J1836-194 is a newly-identified Galactic black hole binary candidate. As most X-ray transients, it was discovered at the beginning of an X-ray outburst. After the initial canonical X-ray hard state, the outburst evolved into a hard intermediate state and then went back to the hard state. The existing RATAN-600 radio monitoring observations revealed that it was variable on a timescale of days and had a flat or inverted spectrum, consistent with optically thick synchrotron emission, possibly from a self-absorbed jet in the vicinity of the central compact object. We observed the transient in the hard state near the end of the X-ray outburst with the European VLBI Network (EVN) at 5 GHz and the Chinese VLBI Network (CVN) at 2.3 and 8.3 GHz. The 8.3 GHz observations were carried out at a recording rate of 2048 Mbps using the newly-developed Chinese VLBI data acquisition system (CDAS), twice higher than the recording rate used in the other observations. We successfully detected the low-decl...

  20. A Transient Black-Hole Low-Mass X-Ray Binary Candidate in Centaurus A

    CERN Document Server

    Sivakoff, Gregory R; Jordán, Andrés; Juett, Adrienne M; Evans, Daniel A; Forman, William R; Hardcastle, Martin J; Sarazin, Craig L; Birkinshaw, Mark; Brassington, Nicola J; Croston, Judith H; Harris, William E; Jones, Christine; Murray, Stephen S; Raychaudhury, Somak; Woodley, Kristin A; Worrall, Diana M

    2008-01-01

    We report the discovery of a bright transient X-ray source, CXOU J132518.2-430304, towards Centaurus A (Cen A) using six new Chandra X-Ray Observatory observations in 2007 March--May. Between 2003 and 2007, its flux has increased by a factor of >770. The source is likely a low-mass X-ray binary in Cen A with unabsorbed 0.3-10 keV band luminosities of (2-3) x 10^{39} erg s^-1 and a transition from the steep-power law state to the thermal state during our observations. CXOU J132518.2-430304 is the most luminous X-ray source in an early-type galaxy with extensive timing information that reveals transience and a spectral state transition. Combined with its luminosity, these properties make this source one of the strongest candidates to date for containing a stellar-mass black hole in an early-type galaxy. Unless this outburst lasts many years, the rate of luminous transients in Cen A is anomalously high compared to other early-type galaxies.

  1. The identification of MAXI J1659-152 as a black hole candidate

    CERN Document Server

    Kalamkar, M; Altamirano, D; van der Klis, M; Casella, P; Linares, M

    2010-01-01

    We report on the analysis of all 65 pointed Rossi X-ray Timing Explorer observations of the recently discovered soft X-ray transient MAXI J1659-152 (initially referred to as GRB 100925A). The source was studied in terms of its evolution through the hardness-intensity diagram (HID) as well as its X-ray variability properties. MAXI J1659-152 traced out an anti-clockwise loop in the HID, which is commonly seen in transient low-mass X-ray binaries. The variability properties of the source, in particular the detection of type-B and type-C low-frequency quasi-periodic oscillations, and the way they evolve along the HID track, indicate that MAXI J1659-152 is a black hole candidate. The spectral and variability properties of MAXI J1659-152 imply that the source was observed in the hard and soft intermediate states during the RXTE observations, with several transitions between these two states.

  2. On the Nature of QPO Phase Lags in Black Hole Candidates

    Science.gov (United States)

    Shaposhnikov, Nikolai

    2012-01-01

    Observations of quasi-periodic oscillations (QPOs) in X-ray binaries hold a key to understanding many aspects of these enigmatic systems. Complex appearance of the Fourier phase lags related to QPOs is one of the most puzzling observational effects in accreting black holes. In this Letter we show that QPO properties, including phase lags, can be explained in a framework of a simple scenario, where the oscillating media provides a feedback on the emerging spectrum. We demonstrate that the QPO waveform is presented by the product of a perturbation and a time delayed response factors, where the response is energy dependent. The essential property of this effect is its non-linear and multiplicative nature. Our multiplicative reverberation model successfully describes the QPO components in energy dependent power spectra as well as the appearance of the phase lags between signal in different energy bands. We apply our model to QPOs observed by Rossi X-ray Timing Explorer in BH candidate XTE J1550-564. We briefly discuss the implications of the observed energy dependence of the QPO reverberation times and amplitudes to the nature of the power law spectral component and its variability.

  3. Long-Term Monitoring of the Black Hole Candidate Swift J1753.5-0127 with INTEGRAL/SPI

    CERN Document Server

    Rodi, James; Roques, Jean-Pierre

    2015-01-01

    The black hole candidate Swift J1753.5-0127 went into outburst in 2005 June. Rather than fade into quiescence as most black-hole-candidate transients do, it has remained in a low hard spectral state for most of the $\\sim$ 9 years after outburst. The persistent emission while in a hard state is reminiscent of the black hole Cyg X-1 and the black hole candidates 1E 1740.7-2942 and GRS 1758-258. Thus far hard X-ray/soft gamma-ray results have focused mainly on the 2005 flare, with a few additional observations during 2007. Here, we present results from INTEGRAL/SPI observations from 2005 - 2010 spanning the 22 - 650 keV energy range. Spectral analysis shows a weak high-energy excess ( $\\sim$ 2.9 $\\sigma$) above a cutoff powerlaw model that is well fit by a powerlaw suggesting an additional spectral component. Observations of Cyg X-1, 1E 1740.7-2942, and GRS 1758-258 have shown similar spectra requiring an additional high-energy component The SPI results are compared to previously reported results for Swift J1753...

  4. A Note on the Observational Evidence for the Existence of Event Horizons in Astrophysical Black Hole Candidates

    Directory of Open Access Journals (Sweden)

    Cosimo Bambi

    2013-01-01

    Full Text Available Black holes have the peculiar and intriguing property of having an event horizon, a one-way membrane causally separating their internal region from the rest of the Universe. Today, astrophysical observations provide some evidence for the existence of event horizons in astrophysical black hole candidates. In this short paper, I compare the constraint we can infer from the nonobservation of electromagnetic radiation from the putative surface of these objects with the bound coming from the ergoregion instability, pointing out the respective assumptions and limitations.

  5. CHANDRA HIGH-RESOLUTION OBSERVATIONS OF CID-42, A CANDIDATE RECOILING SUPERMASSIVE BLACK HOLE

    Energy Technology Data Exchange (ETDEWEB)

    Civano, F.; Elvis, M.; Lanzuisi, G.; Aldcroft, T.; Trichas, M.; Fruscione, A. [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States); Bongiorno, A.; Brusa, M. [Max-Planck-Institut fuer extraterrestrische Physik, Giessenbachstrasse 1, 85748 Garching (Germany); Blecha, L.; Loeb, A. [Department of Astronomy, Harvard University, 60 Garden Street, Cambridge, MA 02138 (United States); Comastri, A.; Gilli, R. [INAF-Osservatorio Astronomico di Bologna, Via Ranzani 1, Bologna 40127 (Italy); Salvato, M.; Komossa, S. [Max-Planck-Institute for Plasma Physics, Excellence Cluster, Boltzmannstrass 2, 85748 Garching (Germany); Koekemoer, A. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Mainieri, V. [ESO, Karl-Schwarzschild-Strasse 2, 85748 Garching (Germany); Piconcelli, E. [INAF-Osservatorio Astronomico di Roma, Via Frascati 33, Monteporzio-Catone 00040 (Italy); Vignali, C. [Dipartimento di Astronomia, Universita di Bologna, Via Ranzani 1, Bologna 40127 (Italy)

    2012-06-10

    We present Chandra High Resolution Camera observations of CID-42, a candidate recoiling supermassive black hole (SMBH) at z = 0.359 in the COSMOS survey. CID-42 shows two optical compact sources resolved in the HST/ACS image embedded in the same galaxy structure and a velocity offset of {approx}1300 km s{sup -1} between the H{beta} broad and narrow emission line, as presented by Civano et al. Two scenarios have been proposed to explain the properties of CID-42: a gravitational wave (GW) recoiling SMBH and a double Type 1/Type 2 active galactic nucleus (AGN) system, where one of the two is recoiling because of slingshot effect. In both scenarios, one of the optical nuclei hosts an unobscured AGN, while the other one, either an obscured AGN or a star-forming compact region. The X-ray Chandra data allow us to unambiguously resolve the X-ray emission and unveil the nature of the two optical sources in CID-42. We find that only one of the optical nuclei is responsible for the whole X-ray unobscured emission observed and a 3{sigma} upper limit on the flux of the second optical nucleus is measured. The upper limit on the X-ray luminosity plus the analysis of the multiwavelength spectral energy distribution indicate the presence of a star-forming region in the second source rather than an obscured SMBH, thus favoring the GW recoil scenario. However, the presence of a very obscured SMBH cannot be fully ruled out. A new X-ray feature, in a SW direction with respect to the main source, is discovered and discussed.

  6. QSOs in the combined SDSS/GALEX database

    CERN Document Server

    Hutchings, J B

    2008-01-01

    We discuss selection of QSO candidates from the combined SDSS and GALEX catalogues. We discuss properties of QSOs within the combined sample, and note uncertainties in number counts and completeness, compared with other SDSS-based samples. We discuss colour and other properties with redshift within the sample and the SEDs for subsets. We estimate the numbers of faint QSOs that are classified as extended objects in the SDSS, and consequent uncertainties that follow.

  7. External Compton emission from relativistic jets in Galactic black hole candidates and ultraluminous X-ray sources

    CERN Document Server

    Georganopoulos, M; Kirk, J G

    2002-01-01

    Galactic binary systems that contain a black hole candidate emit hard X-rays in their low luminosity mode. We show that this emission can be understood as due to the Compton scattering of photons from the companion star and/or the accretion disk by relativistic electrons in a jet. The same electrons are also responsible for the radio emission. Two sources -- XTE J1118+480 and Cygnus X-1 -- are modelled as representatives of black holes with low and high luminosity companion stars respectively. We further show that the ultraluminous compact X-ray sources observed in nearby galaxies have the properties expected of stellar mass black holes with high luminosity companions in which the jet is oriented close to our line of sight.

  8. Swift follow-up observations of the new outburst of the black hole candidate V4641 Sgr

    Science.gov (United States)

    Altamirano, D.; Bahramian, A.; Sivakoff, G.; Middleton, M.; Knigge, C.; Gandhi, P.; Hynes, R.; Johnson, C.; Casella, P.; Motta, S.; Miller-Jones, J.; Neilsen, J.

    2015-08-01

    The MAXI team has recently reported on the outburst onset of the black hole candidate V4641 Sgr as detected with MAXI/GSC (ATEL #7858). In order to confirm the outburst and characterize its current accretion state, a Swift/XRT PC-mode pointed observation was performed on UT 07:31:00 02/08/2015 for a total of 435 seconds.

  9. Discovery and X-ray Monitoring of a New Black Hole Candidate XTE J1752-223

    Science.gov (United States)

    Shaposhnikov, Nikolai; Swank, J. H.; Markwardt, C. B.; Krimm, H.

    2010-03-01

    On October 23, 2009 a new X-ray transient source XTE J1752-223 was discovered by RXTE during observations scanning the Galactic Bulge region. Source identification in the optical, infra-red, and radio immediately followed. The first pointed RXTE observation, three days after the discovery, revealed a very hard non-thermal energy spectrum and strong iron line emission. After the initial rise the source flux leveled off and showed very stable properties for more than a month of monitoring observations until the Sun was too close for RXTE to observe. We analyzed RXTE data collected during this monitoring campaign. The aperiodic fast variability properties are strongly reminiscent of the extreme hard states shown by the well known black hole binary Cygnus X-1, as well as several other black hole candidates. The overall similarity of the source properties to those of other Galactic black holes classify XTE J1752-223 as a new stellar black hole candidate. We compare spectral and variability properties of XTE J1752-223 to Cygnus X-1 and discuss possible implications for various mechanisms of non-thermal emission.

  10. A second black hole candidate in a M31 globular cluster is identified with XMM-Newton

    CERN Document Server

    Barnard, R

    2009-01-01

    We use arguments developed in previous work to identify a second black hole candidate associated with a M31 globular cluster, Bo 144, on the basis of X-ray spectral and timing properties. The 2002 XMM-Newton observation of the associated X-ray source (hereafter XBo 144) revealed behaviour that is common to all low-mass X-ray binaries (LMXBs) in the low-hard state. Studies have shown that neutron star LMXBs exhibit this behaviour at 0.01-1000 keV luminosities <=10% of the Eddington limit (L_Edd). However, the unabsorbed 0.3-10 keV XBo 144 luminosity was ~0.30 L_Edd for a 1.4 M_sun neutron star, and the expected 0.01-1000 keV luminosity is 3-7 times higher. We therefore identify XBo 144 as a black hole candidate. Furthermore, it is the second black hole candidate to be consistent with formation via tidal capture of a mean sequence donor in a GC; such systems were previously though non-existent, because the donor was thought to be disrupted during the capture process.

  11. SDSS IV MaNGA: Discovery of an Hα Blob Associated with a Dry Galaxy Pair—Ejected Gas or a “Dark” Galaxy Candidate?

    Science.gov (United States)

    Lin, Lihwai; Lin, Jing-Hua; Hsu, Chin-Hao; Fu, Hai; Huang, Song; Sánchez, Sebastián F.; Gwyn, Stephen; Gelfand, Joseph D.; Cheung, Edmond; Masters, Karen; Peirani, Sébastien; Rujopakarn, Wiphu; Stark, David V.; Belfiore, Francesco; Bothwell, M. S.; Bundy, Kevin; Hagen, Alex; Hao, Lei; Huang, Shan; Law, David; Li, Cheng; Lintott, Chris; Maiolino, Roberto; Roman-Lopes, Alexandre; Wang, Wei-Hao; Xiao, Ting; Yuan, Fangting; Bizyaev, Dmitry; Malanushenko, Elena; Drory, Niv; Fernández-Trincado, J. G.; Pace, Zach; Pan, Kaike; Thomas, Daniel

    2017-03-01

    We report the discovery of a mysterious giant Hα blob that is ˜8 kpc away from the main MaNGA target 1-24145, one component of a dry galaxy merger, and has been identified in the first-year SDSS-IV MaNGA data. The size of the Hα blob is ˜3-4 kpc in radius, and the Hα distribution is centrally concentrated. However, there is no optical continuum counterpart in the deep broadband images reaching ˜26.9 mag arcsec-2 in surface brightness. We estimate that the masses of the ionized and cold gases are 3.3× {10}5 {M}⊙ and MaNGA 1-24145 to the Hα blob, suggesting that the primary ionizing source may come from MaNGA 1-24145, likely a low-activity AGN. Possible explanations for this Hα blob include the AGN outflow, the gas remnant being tidally or ram-pressure stripped from MaNGA 1-24145, or an extremely low surface brightness galaxy. However, the stripping scenario is less favored according to galaxy merger simulations and the morphology of the Hα blob. With the current data, we cannot distinguish whether this Hα blob is ejected gas due to a past AGN outburst, or a special category of “ultra-diffuse galaxy” interacting with MaNGA 1-24145 that further induces the gas inflow to fuel the AGN in MaNGA 1-24145.

  12. SDSS J143030.22-001115.1: A Misclassified Narrow-line Seyfert 1 Galaxy with Flat X-ray Spectrum

    Institute of Scientific and Technical Information of China (English)

    Wei-Hao Bian; Quan-Ling Cui; Li-Hua Chao

    2006-01-01

    We used multi-component profiles to model the Hβ and [O Ⅲ]λλ4959,5007 lines of SDSS J143030.22-001115.1, a narrow-line Seyfert 1 galaxy (NLS1) in a sample of 150 NLS1 candidates selected from the Sloan Digital Sky Survey (SDSS), Early Data Release (EDR). After subtracting the Hβ contribution from narrow line regions (NLRs), we found that its full width half maximum (FWHM) of broad Hβ line is nearly 2900km s-1, significantly larger than the customarily adopted criterion of 2000km s-1. With its weak Fe Ⅱ multiples,we believe that SDSS J143030.22-001115.1 should not be classified as a genuine NLS1.When we calculate the virial black hole masses of NLS1s, we should use the Hβ linewidth after subtracting the NLR component.

  13. A quasar companion to the puzzling quasar SDSS J0927+2943

    OpenAIRE

    Decarli, R.; Falomo, R.; Treves, A.; Barattini, M

    2010-01-01

    We report the discovery of a quasar close to SDSS J0927+2943 (z = 0.713), which is a massive binary / recoiling black hole candidate. The companion quasar is at a projected distance of 125 h_70^{-1} kpc and exhibits a radial velocity difference of ~1400 km/s with respect to the known quasar. We discuss the nature of this peculiar quasar pair and the properties of its environment. We propose that the overall system is caught in the process of ongoing structure formation.

  14. First Identification of Direct Collapse Black Hole Candidates in the Early Universe in CANDELS/GOODS-S

    CERN Document Server

    Pacucci, Fabio; Grazian, Andrea; Fiore, Fabrizio; Giallongo, Emanuele

    2016-01-01

    The first black hole seeds, formed when the Universe was younger than 500 Myr, are recognized to play an important role for the growth of early (z ~ 7) super-massive black holes. While progresses have been made in understanding their formation and growth, their observational signatures remain largely unexplored. As a result, no detection of such sources has been confirmed so far. Supported by numerical simulations, we present a novel photometric method to identify black hole seed candidates in deep multi-wavelength surveys. We predict that these highly-obscured sources are characterized by a steep spectrum in the infrared (1.6-4.5 micron), i.e. by very red colors. The method selects the only 2 objects with a robust X-ray detection found in the CANDELS/GOODS-S survey with a photometric redshift z > 6. Fitting their infrared spectra only with a stellar component would require unrealistic star formation rates (>2000 solar masses per year). To date, the selected objects represent the most promising black hole see...

  15. Period doubling and non-linear resonance in the black hole candidate IGR J17091-3624 ?

    CERN Document Server

    Rebusco, P; Kluzniak, W; Abramowicz, M A

    2012-01-01

    The two high frequency quasi periodic oscillations (HFQPOs) recently reported in the black hole candidate IGR J17091-3624 by Altamirano and Belloni (2012) are in a 5:2 frequency ratio (164 Hz to 66 Hz). This ratio is strongly suggestive of period doubling and nonlinear resonance analogous to phenomena known in RV Tauri-type pulsating stars (and recently discovered also in oscillations of RR Lyrae-type and of BL Herculis-type variables). An interpretation of the frequency ratio in terms of nonlinear interactions and a comparison with the HFQPOs reported in GRS 1915+105 may imply a mass of about 6 solar masses for the black hole in IGR J17091- 3624.

  16. Estimation of Mass of the Black Hole Candidate MAXI J1659-152 using TCAF and POS Models

    CERN Document Server

    Molla, Aslam Ali; Chakrabarti, Sandip K; Mondal, Santanu; Jana, Arghajit

    2016-01-01

    The Galactic transient black hole candidate (BHC) MAXI~J1659-152 exhibited temporal and spectral evolution during its very first X-ray outburst (2010) after its discovery on 25th Sept. 2010. Our recent studies of a few transient BHCs including MAXI~J1659-152 using Chakrabarti-Titarchuk two-component advective flow (TCAF) solution as an additive table local model in XSPEC revealed details of accretion flow dynamics around the black hole (BH). The TCAF model fitted normalization (N) comes out to be almost constant throughout the entire outburst consisting of several spectral states. We introduce two independent methods to determine the mass ($M_{BH}$) of the BHC, namely, {\\it $i)$ keeping TCAF fitted normalization parameter in a narrow range}, and {\\it $ii)$ studying evolution of the Quasi-Periodic Oscillation frequency ($\

  17. The rate of stellar tidal disruption flares from SDSS data

    Directory of Open Access Journals (Sweden)

    van Velzen S.

    2012-12-01

    Full Text Available We have searched for flares due to the tidal disruption of stars by supermassive black holes in archival Sloan Digital Sky Survey (SDSS multi-epoch imaging data. Our pipeline takes advantage of the excellent astrometry of SDSS to separate nuclear flares from supernovae. The 10 year baseline and the high cadence of the observations facilitate a clear-cut identification of variable active galactic nuclei. We found 186 nuclear flares, of which two are strong stellar tidal disruption flare (TDF candidates. To compute the rate of these events, we simulated our entire pipeline to obtain the efficiency of detection for a given light curve. We compute a model-independent upper limit to the TDF rate of Ṅ < 3 × 10−4 yr−1galaxy−1 (90% CL. Using a simple model to extrapolate the observed light curve forward and backward in time, we find our best-estimate of the rate: Ṅ = 3-3+5 × 10−5 yr−1galaxy−1.

  18. Baryons in the relativistic jets of the stellar-mass black-hole candidate 4U 1630-47.

    Science.gov (United States)

    Trigo, María Díaz; Miller-Jones, James C A; Migliari, Simone; Broderick, Jess W; Tzioumis, Tasso

    2013-12-12

    Accreting black holes are known to power relativistic jets, both in stellar-mass binary systems and at the centres of galaxies. The power carried away by the jets, and, hence, the feedback they provide to their surroundings, depends strongly on their composition. Jets containing a baryonic component should carry significantly more energy than electron-positron jets. Energetic considerations and circular-polarization measurements have provided conflicting circumstantial evidence for the presence or absence of baryons in jets, and the only system in which they have been unequivocally detected is the peculiar X-ray binary SS 433 (refs 4, 5). Here we report the detection of Doppler-shifted X-ray emission lines from a more typical black-hole candidate X-ray binary, 4U 1630-47, coincident with the reappearance of radio emission from the jets of the source. We argue that these lines arise from baryonic matter in a jet travelling at approximately two-thirds the speed of light, thereby establishing the presence of baryons in the jet. Such baryonic jets are more likely to be powered by the accretion disk than by the spin of the black hole, and if the baryons can be accelerated to relativistic speeds, the jets should be strong sources of γ-rays and neutrino emission.

  19. Event-horizon-scale structure in the supermassive black hole candidate at the Galactic Centre

    CERN Document Server

    Doeleman, Sheperd; Rogers, Alan E E; Plambeck, Richard; Freund, Robert; Tilanus, Remo P J; Friberg, Per; Ziurys, Lucy M; Moran, James M; Corey, Brian; Young, Ken H; Smythe, Daniel L; Titus, Michael; Marrone, Daniel P; Cappallo, Roger J; Bock, Douglas C J; Bower, Geoffrey C; Chamberlin, Richard; Davis, Gary R; Krichbaum, Thomas P; Lamb, James; Maness, Holly; Niell, Arthur E; Roy, Alan; Strittmatter, Peter; Werthimer, Daniel; Whitney, Alan R; Woody, David

    2008-01-01

    The cores of most galaxies are thought to harbour supermassive black holes, which power galactic nuclei by converting the gravitational energy of accreting matter into radiation (ref 1). Sagittarius A*, the compact source of radio, infrared and X-ray emission at the centre of the Milky Way, is the closest example of this phenomenon, with an estimated black hole mass that is 4 million times that of the Sun (refs. 2,3). A long-standing astronomical goal is to resolve structures in the innermost accretion flow surrounding Sgr A* where strong gravitational fields will distort the appearance of radiation emitted near the black hole. Radio observations at wavelengths of 3.5 mm and 7 mm have detected intrinsic structure in Sgr A*, but the spatial resolution of observations at these wavelengths is limited by interstellar scattering (refs. 4-7). Here we report observations at a wavelength of 1.3 mm that set a size of 37 (+16, -10; 3-sigma) microarcseconds on the intrinsic diameter of Sgr A*. This is less than the expe...

  20. Origin of X-ray Emission from Transient Black Hole Candidates in Quiescence

    CERN Document Server

    Pszota, Gabor; Yuan, Feng; Cui, Wei

    2008-01-01

    We report results from a systematic study of X-ray emission from black hole transients in quiescence. In this state mass accretion is thought to follow the geometry of an outer optically thick, geometrically thin disc and an inner optically thin, geometrically thick radiatively inefficient accretion flow (RIAF). The inner flow is likely also coupled to the jets near the black hole that are often seen in such systems. The goal of the study is to see whether the X-ray emission in the quiescent state is mainly powered by the accretion flow or the jets. Using data from deep XMM-Newton observations of selected black hole transients, we have found that the quiescent X-ray spectra are, to a high precision, of power-law shape in the cases of GRO J1655-40 and V404 Cyg. Such spectra deviate significantly from the expected X-ray spectrum of the RIAF at very low accretion rates. On the other hand, they can naturally be explained by emission from the jets, if the emitting electrons follow a power-law spectral distribution...

  1. Relativistic smearing of the reflection spectrum in Galactic Black Hole Candidates

    CERN Document Server

    Done, C; Smith, D A

    1997-01-01

    We identify the reflected component in the GINGA spectra of Nova Muscae, a Black Hole transient system which has been used as the prototype for the recent advection dominated disk models. We see that the reflected spectrum is generally significantly relativistically smeared, and use this and the amount of reflection to track the innermost extent of the accretion disk. We see that the optically thick disk does retreat during the decline, but more slowly than predicted by the advective models, posing problems for this description of the accretion flow.

  2. An eclipsing binary black hole candidate system in the blazar Mrk 421

    CERN Document Server

    Benitez, E; Fraija, N; Hernandez, X; Lopez-Corona, O; Lora-Clavijo, F D; Mendoza, S

    2015-01-01

    Removing strong outbursts from multiwavelength light curves of the blazar Mrk 421, we construct outburstless time series for this system. A model-independent power spectrum light curve analysis in the optical, hard X-ray and gamma-rays of this outburstless state shows clear evidence for a periodicity of \\approx 400 days. A subsequent full maximum likelihood analysis fitting an eclipse model confirms a periodicity of 387.16 days. The power spectrum of the signal in the outburstless state of the source does not follow a flicker noise behaviour and so, the system producing it is not self-organised. This means that the periodicity is not produced by any internal physical processes associated to the central engine. The simplest physical mechanism to which this periodicity could be ascribed is a dynamical effect produced by an orbiting supermassive black hole companion of mass \\sim 10^7 M_\\odot eclipsing the central black hole, which has a mass \\sim 10^8 M_\\odot. The optimal model restricts the physics of the eclip...

  3. The soft spectral state of the black hole candidate IGR J17091-3624 observed by INTEGRAL and Swift

    DEFF Research Database (Denmark)

    Del Santo, M.; Kuulkers, E.; Bozzo, E.

    2011-01-01

    The currently on-going outburst of the black hole candidate (BHC) IGR J17091-3624 (ATel #3144, #3159, #3167) has been recently observed simultaneously with INTEGRAL and Swift. The source was in the IBIS FOV on 2011 Feb. 28 from 17:45 to 21:23 (UTC; exposure time 7.7 ks) during the Galactic Bulge......, a better description of the spectrum (confirmed by the F-test) can be obtained adding a disk black-body component (red. chi^2=1.1 (302 d.o.f.)). The fit of the joint XRT+IBIS/ISGRI broad-band spectrum (0.8-200 keV) gives an absorption column density of N_H=1.00+/-0.06, a disc black-body temperature of 1...

  4. The soft spectral state of the black hole candidate IGR J17091-3624 observed by INTEGRAL and Swift

    DEFF Research Database (Denmark)

    Del Santo, M.; Kuulkers, E.; Bozzo, E.

    2011-01-01

    The currently on-going outburst of the black hole candidate (BHC) IGR J17091-3624 (ATel #3144, #3159, #3167) has been recently observed simultaneously with INTEGRAL and Swift. The source was in the IBIS FOV on 2011 Feb. 28 from 17:45 to 21:23 (UTC; exposure time 7.7 ks) during the Galactic Bulge......, a better description of the spectrum (confirmed by the F-test) can be obtained adding a disk black-body component (red. chi^2=1.1 (302 d.o.f.)). The fit of the joint XRT+IBIS/ISGRI broad-band spectrum (0.8-200 keV) gives an absorption column density of N_H=1.00+/-0.06, a disc black-body temperature of 1...

  5. Do Black Hole Candidates Have Magnetic Moments Instead of Event Horizons?

    CERN Document Server

    Robertson, S L; Robertson, Stanley L.; Leiter, Darryl J.

    2003-01-01

    In previous work we found that many of the spectral properties of low mass x-ray binaries (LMXB), including galactic black hole candiates (GBHC) were consistent with the existence of intrinsically magnetized central objects. We review and extend these findings and show that the existence of intrisically magnetic BHC is consistent with a new class of solutions of the Einstein field equations of General Relativity. These solutions are based on a strict adherence to the Strong Principle of Equivalence (SPOE) requirement that the world lines of physical matter must remain timelike in all regions of spacetime. The new solutions emerge when the structure and radiation transfer properties of the energy momentum tensor on the right hand side of the Einstein field equations are appropriately chosen to dynamically enforce the SPOE requirement of timelike world line completeness. In this context, we find that the Einstein field equations allow the existence of highly red shifted, Magnetospheric, Eternally Collapsing Obj...

  6. A Population of Short-Period Variable Quasars from PTF as Supermassive Black Hole Binary Candidates

    CERN Document Server

    Charisi, M; Haiman, Z; Price-Whelan, A M; Graham, M J; Bellm, E C; Laher, R R; Marka, S

    2016-01-01

    Supermassive black hole binaries (SMBHBs) at sub-parsec separations should be common in galactic nuclei, as a result of frequent galaxy mergers. Hydrodynamical simulations of circumbinary discs predict strong periodic modulation of the mass accretion rate on time-scales comparable to the orbital period of the binary. As a result, SMBHBs may be recognized by the periodic modulation of their brightness. We conducted a statistical search for periodic variability in a sample of 35,383 spectroscopically confirmed quasars in the photometric database of the Palomar Transient Factory (PTF). We analysed Lomb-Scargle periodograms and assessed the significance of our findings by modeling each individual quasar's variability as a damped random walk (DRW). We identified 50 quasars with significant periodicity beyond the DRW model, typically with short periods of a few hundred days. We find 33 of these to remain significant after a re-analysis of their periodograms including additional optical data from the intermediate-PT...

  7. Viscosity profile and Quasi Periodic Oscillation frequency of few transient black hole candidates

    Science.gov (United States)

    Mondal, Santanu; Debnath, Dipak; Chakrabarti, Sandip Kumar; Jana, Arghajit; Chatterjee, Debjit; Molla, Aslam Ali

    2016-07-01

    Matters enter into the potential well formed by the compact objects due to the transport of angular momentum by viscosity. We compute the amount of viscosity during the outburst time of the transient sources. In the progressive days as the viscosity increases inner edge of the Keplerian disc moves closer to the black holes. Thus the size of the Compton cloud reduces and the frequency of the Quasi Periodic Oscillations increases. We also compute the Compton cooling day by day, which is responsible for the movement of the shock both in rising and declining phases of the outburst. Our viscosity value rises/decays monotonically during the rising/declining phases of the outburst, well within the range proposed by magneto-rotational instability. For that we solve the Rankine-Hugoniot conditions and derive the condition of shock formation in presence of Compton cooling.

  8. NuSTAR observations of black hole binary candidates in the Galactic Center and its environs

    Science.gov (United States)

    Hailey, Charles James; Mori, Kaya

    2017-08-01

    The recent discovery of a diffuse, hard X-ray emission in the central 10 pc (Perez et al. 2015) interpreted as magnetic cataclysmic variables (Hailey et al. 2017) leaves open the question of whether a sub-dominant population of sources could exist much closer to the supermassive black hole (SMBH), which NuSTAR could not resolve. Here we report the recent NuSTAR observations of two new transient hard X-ray sources within ~ 1 pc of the Galactic Center, which were discovered by Swift. These sources have no known counterparts at other energies. The spectral properties of these sources rule out NS-HMXBs. Continuous monitoring of the Galactic Center by Swift, combined with the known short (report recent results from the NuSTAR Galactic Legacy Survey of a larger region, ~ 0.7 square degrees, focusing on the search for more BHCs.

  9. VLBA 24 and 43 GHz observations of massive binary black hole candidate PKS 1155 + 251

    Science.gov (United States)

    Yang, Xiaolong; Liu, Xiang; Yang, Jun; Mi, Ligong; Cui, Lang; An, Tao; Hong, Xiaoyu; Ho, Luis C.

    2017-10-01

    PKS 1155+251 is a radio-loud quasar source at z = 0.203. Observations using very long baseline interferometry (VLBI) at ∼2, 5, 8 and 15 GHz show that the structure of the radio source is quite complicated on parsec scales and that the outer hotspots are apparently undergoing a significant contraction. Because these results cannot be fully explained based on the compact symmetric object (CSO) scenario with a radio core located between the northern and southern complexes, we made observations with the Very Long Baseline Array (VLBA) at 24 and 43 GHz to search for compact substructures and alternative interpretations. The results show that the radio core revealed in the previous VLBI observations remains compact with a flat spectrum in our sub-milli-arcsecond-resolution images; the northern lobe emission becomes faint at 24 GHz and is mostly resolving out at 43 GHz; the southern complex is more bright but has been resolved into the brightest southern-end (S1) and jet or tail alike components westwards. Explaining the southern components aligned westward with a standard CSO scenario alone remains a challenge. As for the flatter spectral index of the southern-end component S1 between 24 and 43 GHz in our observations and the significant 15 GHz VLBA flux variability of S1, an alternative scenario is that the southern complex may be powered by a secondary black hole residing at S1. But more sensitive and high-resolution VLBI monitoring is required to discriminate the CSO and the binary black hole scenarios.

  10. Observations of the Black Hole candidate GX339-4 with the TTM telescope of the "KVANT" module on board the "MIR" orbital station

    Science.gov (United States)

    Lavrov, S. V.; Borozdin, K. N.; Alexandrovich, N. L.

    TTM device of the "KVANT" module onboard the "MIR" russian space station had obtained two series observations of the X-ray source Black Hole candidate GX339-4 in 1989-1994. Soft state of source, in wich source spectrum (2-28 keV) was approximated by the multi-color accretion disk model with absorption, has been founded in March 1989. Hard state of source with spectrum approximated by the power law with absorption and transfer from the hard to the soft state has been observed in the March 1994. Various source spectrum states are the prove of its belonging to the Black Hole candidates class.

  11. THE FAINT 'HEARTBEATS' OF IGR J17091-3624: AN EXCEPTIONAL BLACK HOLE CANDIDATE

    Energy Technology Data Exchange (ETDEWEB)

    Altamirano, D.; Van der Klis, M.; Wijnands, R.; Kalamkar, M. [Astronomical Institute, ' Anton Pannekoek' , University of Amsterdam, Science Park 904, 1098XH, Amsterdam (Netherlands); Belloni, T.; Stiele, H.; Motta, S.; Munoz-Darias, T. [INAF-Osservatorio Astronomico di Brera, Via E. Bianchi 46, I-23807 Merate (Italy); Linares, M. [Massachusetts Institute of Technology-Kavli Institute for Astrophysics and Space Research, Cambridge, MA 02139 (United States); Curran, P. A. [Laboratoire AIM, CEA DSM/IRFU/SAp, Centre de Saclay, F-91191 Gif-sur-Yvette (France); Casella, P. [School of Physics and Astronomy, University of Southampton, Southampton, Hampshire, SO17 1BJ (United Kingdom); Krimm, H., E-mail: d.altamirano@uva.nl [CRESST and NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2011-12-15

    We report on the first 180 days of Rossi X-Ray Timing Explorer observations of the outburst of the black hole candidate IGR J17091-3624. This source exhibits a broad variety of complex light curve patterns including periods of strong flares alternating with quiet intervals. Similar patterns in the X-ray light curves have been seen in the (up to now) unique black hole system GRS 1915+105. In the context of the variability classes defined by Belloni et al. for GRS 1915+105, we find that IGR J17091-3624 shows the {nu}, {rho}, {alpha}, {lambda}, {beta}, and {mu} classes as well as quiet periods which resemble the {chi} class, all occurring at 2-60 keV count rate levels which can be 10-50 times lower than observed in GRS 1915+105. The so-called {rho} class 'heartbeats' occur as fast as every few seconds and as slow as {approx}100 s, tracing a loop in the hardness-intensity diagram which resembles that previously seen in GRS 1915+105. However, while GRS 1915+105 traverses this loop clockwise, IGR J17091-3624 does so in the opposite sense. We briefly discuss our findings in the context of the models proposed for GRS 1915+105 and find that either all models requiring near Eddington luminosities for GRS 1915+105-like variability fail, or IGR J17091-3624 lies at a distance well in excess of 20 kpc, or it harbors one of the least massive black holes known (<3 M{sub Sun }).

  12. Testing the Kerr nature of black hole candidates using iron line reverberation mapping in the Cardoso-Pani-Rico framework

    Science.gov (United States)

    Jiang, Jiachen; Bambi, Cosimo; Steiner, James F.

    2016-06-01

    The iron K α line commonly observed in the x-ray spectrum of black hole candidates is produced by x-ray fluorescence of the inner accretion disk. This line can potentially be quite a powerful tool to probe the spacetime geometry around these objects and test the Kerr black hole hypothesis. In a previous paper, we studied the ability to constrain possible deviations from the Kerr solution from the standard time-integrated iron line spectrum within the Cardoso-Pani-Rico framework. In the present work, we expand on that study and consider iron line reverberation mapping in the Cardoso-Pani-Rico framework. That is, we consider the time evolution of the iron line profile in response to fluctuations in the x-ray primary source. Our simulations clearly show that the time information in reverberation mapping can better constrain the background metric than the time-integrated approach, and this is true, notably, for the deformation parameter ɛ3r, which is only weakly informed by a time-integrated observation.

  13. Testing the Kerr nature of black hole candidates using iron line reverberation mapping in the CPR framework

    CERN Document Server

    Jiang, Jiachen; Steiner, James F

    2016-01-01

    The iron K$\\alpha$ line commonly observed in the X-ray spectrum of black hole candidates is produced by X-ray fluorescence of the inner accretion disk. This line can potentially be quite a powerful tool to probe the spacetime geometry around these objects and test the Kerr black hole hypothesis. In a previous paper, we studied the ability to constrain possible deviations from the Kerr solution from the standard time-integrated iron line spectrum within the Cardoso-Pani-Rico framework. In the present work, we expand on that study and consider iron line reverberation mapping in the CPR framework. That is, we consider the time-evolution of the iron line profile in response to fluctuations in the X-ray primary source. Our simulations clearly show that the time information in reverberation mapping can better constrain the background metric than the time-integrated approach, and this is true, notably, for the deformation parameter $\\epsilon^r_3$, which is only weakly informed by a time-integrated observation.

  14. Baryons in the relativistic jets of the stellar-mass black hole candidate 4U 1630-47

    CERN Document Server

    Trigo, María Díaz; Migliari, Simone; Broderick, Jess W; Tzioumis, Tasso

    2013-01-01

    Accreting black holes are known to power relativistic jets, both in stellar-mass binary systems and at the centres of galaxies. The power carried away by the jets, and hence the feedback they provide to their surroundings, depends strongly on their composition. Jets containing a baryonic component should carry significantly more energy than electron-positron jets. While energetic considerations and circular polarisation measurements have provided conflicting circumstantial evidence for the presence or absence of baryons, the only system in which baryons have been unequivocally detected in the jets is the X-ray binary SS 433. Here we report the detection of Doppler-shifted X-ray emission lines from a more typical black hole candidate X-ray binary, 4U1630-47, coincident with the reappearance of radio emission from the jets of the source. We argue that these lines arise in a jet with velocity 0.66c, thereby establishing the presence of baryons in the jet. Such baryonic jets are more likely to be powered by the a...

  15. NuSTAR and Swift observations of the black hole candidate XTE J1908+094 during its 2013 outburst

    CERN Document Server

    Tao, Lian; Walton, Dominic J; Furst, Felix; Kennea, Jamie; Miller, Jon M; Boggs, Steven E; Christensen, Finn E; Craig, William W; Gandhi, Poshak; Grefenstette, Brian W; Hailey, Charles J; Harrison, Fiona A; Krimm, Hans A; Pottschmidt, Katja; Stern, Daniel; Tendulkar, Shriharsh P; Zhang, William W

    2015-01-01

    The black hole candidate XTE J1908+094 went into outburst for the first time since 2003 in October 2013. We report on an observation with the Nuclear Spectroscopic Telescope Array (NuSTAR) and monitoring observations with Swift during the outburst. NuSTAR caught the source in the soft state: the spectra show a broad relativistic iron line, and the light curves reveal a ~40 ks flare with the count rate peaking about 40% above the non-flare level and with significant spectral variation. A model combining a multi-temperature thermal component, a power-law, and a reflection component with an iron line provides a good description of the NuSTAR spectrum. Although relativistic broadening of the iron line is observed, it is not possible to constrain the black hole spin with these data. The variability of the power-law component, which can also be modeled as a Comptonization component, is responsible for the flux and spectral change during the flare, suggesting that changes in the corona (or possibly continued jet act...

  16. Application of the Nonballistic Model to the Black Hole Candidate XTE J1752-223 and the Quasar NRAO 150

    Science.gov (United States)

    Zheng, T. Y.; Gong, B. P.

    2017-02-01

    Optical and radio observations of the black hole candidate XTE J1752-223 have exhibited a slightly curved motion of the jet components, which is associated with its radio light curve. In addition, observations of the quasar NRAO 150 have revealed a core–jet structure wobbling with a high angular speed. In this paper, the phenomena displayed in these two different sources are interpreted as the precession of a bent jet. In such a scenario, hot spots reproduced at different separations from the core precess on the same precession cone, in which different components correspond to different propagation times to the observer. By fitting the kinematics of the components of XTE J1752-223 and its light curve with a curved pattern of precession period 314 days, we find that the propagation time can make an earlier event appear later, and the jet axis can oscillate during its precession. Simulating the quasar NRAO 150 with the same scenario reveals that the knots at larger separation from the core precess at a slower speed than those closer in. A possible mechanism relating to the cooling time of a component is proposed. These three new results are of importance in understanding the physics underlying the curved jet as well as the activity of the central engine of different black hole systems.

  17. Disc-jet coupling in the 2009 outburst of the black hole candidate H1743-322

    CERN Document Server

    Miller-Jones, J C A; Altamirano, D; Coriat, M; Corbel, S; Dhawan, V; Krimm, H A; Remillard, R A; Rupen, M P; Russell, D M; Fender, R P; Heinz, S; Körding, E G; Maitra, D; Markoff, S; Migliari, S; Sarazin, C L; Tudose, V

    2012-01-01

    We present an intensive radio and X-ray monitoring campaign on the 2009 outburst of the Galactic black hole candidate X-ray binary H1743-322. With the high angular resolution of the Very Long Baseline Array, we resolve the jet ejection event and measure the proper motions of the jet ejecta relative to the position of the compact core jets detected at the beginning of the outburst. This allows us to accurately couple the moment when the jet ejection event occurred with X-ray spectral and timing signatures. We find that X-ray timing signatures are the best diagnostic of the jet ejection event in this outburst, which occurred as the X-ray variability began to decrease and the Type C quasi-periodic oscillations disappeared from the X-ray power density spectrum. However, this sequence of events does not appear to be replicated in all black hole X-ray binary outbursts, even within an individual source. In our observations of H1743-322, the ejection was contemporaneous with a quenching of the radio emission, prior t...

  18. Following the 2008 outburst decay of the black hole candidate H1743-322 in X-ray and radio

    CERN Document Server

    Jonker, P G; Homan, J; Gallo, E; Rupen, M; Tomsick, J; Fender, R P; Kaaret, Philip; Steeghs, D T H; Torres, M A P; Wijnands, R; Markoff, S; Lewin, W H G

    2009-01-01

    In this Paper we report on radio (VLA and ATCA) and X-ray (RXTE, Chandra and Swift) observations of the outburst decay of the transient black hole candidate H1743-322 in early 2008. We find that the X-ray light curve followed an exponential decay, leveling off towards its quiescent level. The exponential decay timescale is ~4 days and the quiescent flux corresponds to a luminosity of 3x10^32 (d/7.5 kpc)^2 erg/s. This together with the relation between quiescent X-ray luminosity and orbital period reported in the literature suggests that H1743-322 has an orbital period longer than ~10 hours. Both the radio and X-ray light curve show evidence for flares. The radio - X-ray correlation can be well described by a power-law with index ~0.18. This is much lower than the index of 0.6-0.7 found for the decay of several black hole transients before. The radio spectral index measured during one of the radio flares while the source is in the low-hard state, is -0.5+-0.15, which indicates that the radio emission is optica...

  19. Red bulgeless galaxies in SDSS DR7. Are there any AGN hosts?

    CERN Document Server

    Coelho, Bruno; Lobo, Catarina; Ribeiro, Bruno

    2013-01-01

    With the main goal of finding bulgeless galaxies harbouring super massive black holes and showing, at most, just residual star formation activity, we have selected a sample of massive bulgeless red sequence galaxies from the SDSS-DR7, based on the NYU-VAGC catalogue. Multivavelength data were retrieved using EURO-VO tools, and the objects are characterised in terms of degree of star formation and the presence of an AGN. We have found seven objects that are quenched massive galaxies, that have no prominent bulge and that show signs of extra activity in their nuclei, five of them being central in their halo. These objects are rather robust candidates for rare systems that, though devoid of a significant bulge, harbor a supermassive black hole with an activity level likely capable of having halted the star formation through feedback.

  20. VVV Survey Observations of a Microlensing Stellar Mass Black Hole Candidate in the Field of the Globular Cluster NGC 6553

    CERN Document Server

    Minniti, D; Alonso-Garcia, J; Anguita, T; Catelan, M; Gran, F; Motta, V; Muro, G; Rojas, K; Saito, R K

    2015-01-01

    We report the discovery of a large timescale candidate microlensing event of a bulge stellar source based on near-infrared observations with the VISTA Variables in the Via Lactea Survey (VVV). The new microlensing event is projected only 3.5 arcmin away from the center of the globular cluster NGC 6553. The source appears to be a bulge giant star with magnitude Ks = 13.52, based on the position in the color-magnitude diagram. The foreground lens may be located in the globular cluster, which has well-known parameters such as distance and proper motions. If the lens is a cluster member, we can directly estimate its mass simply following Paczynski et al. (1996) which is a modified version of the more general case due to Refsdal. In that case, the lens would be a massive stellar remnant, with M = 1.5-3.5 Msun. If the blending fraction of the microlensing event appears to be small, and this lens would represent a good isolated black hole (BH) candidate, that would be the oldest BH known. Alternative explanations (w...

  1. The nature of massive black hole binary candidates: II. Spectral energy distribution atlas

    CERN Document Server

    Lusso, Elisabeta; Dotti, Massimo; Montuori, Carmen; Hogg, David W; Tsalmantza, Paraskevi; Fumagalli, Michele; Prochaska, Jason X

    2014-01-01

    Recoiling supermassive black holes (SMBHs) are considered one plausible physical mechanism to explain high velocity shifts between narrow and broad emission lines sometimes observed in quasar spectra. If the sphere of influence of the recoiling SMBH is such that only the accretion disc is bound, the dusty torus would be left behind, hence the SED should then present distinctive features (i.e. a mid-infrared deficit). Here we present results from fitting the Spectral Energy Distributions (SEDs) of 32 Type-1 AGN with high velocity shifts between broad and narrow lines. The aim is to find peculiar properties in the multi-wavelength SEDs of such objects by comparing their physical parameters (torus and disc luminosity, intrinsic reddening, and size of the 12$\\mu$m emitter) with those estimated from a control sample of $\\sim1000$ \\emph{typical} quasars selected from the Sloan Digital Sky Survey in the same redshift range. We find that all sources, with the possible exception of J1154+0134, analysed here present a ...

  2. Recurring flares from supermassive black hole binaries: implications for tidal disruption candidates and OJ 287

    CERN Document Server

    Tanaka, Takamitsu L

    2013-01-01

    I discuss the possibility that accreting, supermassive black hole (SMBH) binaries with sub-parsec separations produce luminous, periodically recurring outbursts that interrupt periods of relative quiescence. This hypothesis is motivated by two characteristics found in simulations of binaries embedded in prograde accretion discs: (i) the formation of a central, low-density cavity, and (ii) the leakage of circumbinary gas into this cavity, occurring once per orbit, via discrete streams on nearly radial trajectories. The first feature will diminish the emergent optical/UV flux of the system relative to active galactic nuclei (AGN) powered by single SMBHs, while the second is likely to trigger periodic fluctuations in the emergent flux. I propose a simple toy model in which a leaked stream crosses its own orbit and shocks, converting its bulk kinetic energy to heat. The result is a hot, optically thick flow that is quickly accreted and produces a flare with an AGN-like spectrum that peaks in the UV and ranges fro...

  3. A population of short-period variable quasars from PTF as supermassive black hole binary candidates

    Science.gov (United States)

    Charisi, M.; Bartos, I.; Haiman, Z.; Price-Whelan, A. M.; Graham, M. J.; Bellm, E. C.; Laher, R. R.; Márka, S.

    2016-12-01

    Supermassive black hole binaries (SMBHBs) at sub-parsec separations should be common in galactic nuclei, as a result of frequent galaxy mergers. Hydrodynamical simulations of circum-binary discs predict strong periodic modulation of the mass accretion rate on time-scales comparable to the orbital period of the binary. As a result, SMBHBs may be recognized by the periodic modulation of their brightness. We conducted a statistical search for periodic variability in a sample of 35 383 spectroscopically confirmed quasars in the photometric data base of the Palomar Transient Factory (PTF). We analysed Lomb-Scargle periodograms and assessed the significance of our findings by modelling each individual quasar's variability as a damped random walk (DRW). We identified 50 quasars with significant periodicity beyond the DRW model, typically with short periods of a few hundred days. We find 33 of these to remain significant after a re-analysis of their periodograms including additional optical data from the intermediate-PTF and the Catalina Real-Time Transient Survey. Assuming that the observed periods correspond to the redshifted orbital periods of SMBHBs, we conclude that our findings are consistent with a population of unequal-mass SMBHBs, with a typical mass ratio as low as q ≡ M2/M1 ≈ 0.01.

  4. VLT spectroscopy of the Black Hole Candidate Swift J1357.2-0933 in Quiescence

    CERN Document Server

    Torres, M A P; Miller-Jones, J C A; Steeghs, D; Repetto, S; Wu, Jianfeng

    2015-01-01

    We present time-resolved optical spectroscopy of the counterpart to the high-inclination black hole low-mass X-ray binary Swift J1357.2-0933 in quiescence. Absorption features from the mass donor star were not detected. Instead the spectra display prominent broad double-peaked Halpha emission and weaker HeI emission lines. From the Halpha peak-to-peak separation we constrain the radial velocity semi-amplitude of the donor star to > 789 km/s. Further analysis through radial velocity and equivalent width measurements indicates that the Halpha line is free of variability due to S-wave components or disc eclipses. From our data and previous observations during outburst, we conclude that long-term radial velocity changes ascribed to a precessing disc were of low amplitude or not present. This implies that the centroid position of the line should closely represent the systemic radial velocity. Using the derived systemic velocity of -150 km/s and the best available limits on the source distance, we infer that the bl...

  5. A strong and broad Fe line in the XMM-Newton spectrum of the new X-ray transient and black hole candidate XTE J1652-453

    NARCIS (Netherlands)

    Hiemstra, Beike; Méndez, Mariano; Done, Chris; Díaz Trigo, María; Altamirano, Diego; Casella, Piergiorgio

    2011-01-01

    We observed the new X-ray transient and black hole candidate XTE J1652-453 simultaneously with XMM-Newton and the Rossi X-ray Timing Explorer (RXTE). The observation was done during the decay of the 2009 outburst, when XTE J1652-453 was in the hard-intermediate state. The spectrum shows a strong and

  6. Discovery of a broad iron line in the black hole candidate Swift J1753.5-0127, and the disc emission in the low/hard state revisited

    NARCIS (Netherlands)

    Hiemstra, Beike; Soleri, Paolo; Mendez, Mariano; Belloni, Tomaso; Mostafa, Reham; Wijnands, Rudy

    2009-01-01

    We analysed simultaneous archival XMM-Newton and Rossi X-ray Timing Explorer observations of the X-ray binary and black hole candidate Swift J1753.5-0127. In a previous analysis of the same data, a soft thermal component was found in the X-ray spectrum, and the presence of an accretion disc extendin

  7. A strong and broad Fe line in the XMM-Newton spectrum of the new X-ray transient and black hole candidate XTEJ1652-453

    NARCIS (Netherlands)

    Hiemstra, Beike; Méndez, Mariano; Done, Chris; Díaz Trigo, María; Altamirano, Diego; Casella, Piergiorgio

    2011-01-01

    We observed the new X-ray transient and black hole candidate XTEJ1652-453 simultaneously with XMM-Newton and the Rossi X-ray Timing Explorer (RXTE). The observation was done during the decay of the 2009 outburst, when XTEJ1652-453 was in the hard-intermediate state. The spectrum shows a strong and b

  8. The Search for Binary Black holes in Seyferts with Double Peaked Emission Lines

    CERN Document Server

    Kharb, P; Subramanian, S; Paragi, Z

    2015-01-01

    We discuss results from very long baseline interferometry (VLBI) observations of two Seyfert galaxies with double peaked emission lines in their SDSS optical spectra. Such AGN are potential candidates for the presence of binary black holes, which can be resolved on parsec-scales with VLBI. Our observations do not detect twin radio cores but rather nuclear outflows in these Seyferts. These outflows could be interacting with the emission line clouds producing the double peaks in the emission lines.

  9. Harnessing the full power of the widest Chandra field: average accretion rates of black holes in SDSS galaxies through X-ray stacking

    Science.gov (United States)

    Goulding, Andy D.; Greene, Jenny E.; Hickox, Ryan C.; Alexander, David M.; Forman, William R.; Jones, Christine; Lehmer, Bret

    2017-08-01

    Galaxy-scale bars are expected to provide an effective means for driving material towards the central region in spiral galaxies, and possibly feeding supermassive black holes (BHs). I will present our latest results on a statistically-complete study of the effect of bars on average BH accretion. From a well-selected sample of over 50,000 spiral galaxies extracted from the Sloan Digital Sky Survey, we separate those sources considered to contain galaxy-scale bars from those that do not. Using the first 16 years worth of data taken by the Chandra X-ray Observatory, we identify X-ray luminous AGN and perform the widest-area X-ray stacking analysis to date on the remaining X-ray undetected sources. Through our X-ray stacking, we derive a time-averaged look at accretion for galaxies at fixed stellar mass and star formation rate, finding that the average nuclear accretion rates of galaxies with bar structures are fully consistent with those lacking bars, and robustly concluding that large-scale bars have little or no effect on the average growth of BHs in nearby (z < 0.15) galaxies over gigayear timescales.

  10. Disc-jet Coupling in the 2009 Outburst of the Black Hole Candidate H1743-322

    Science.gov (United States)

    Miller-Jones, J. C. A.; Sivakoff, G. R.; Altamirano, D.; Coriat, M.; Corbel, S.; Dhawan, V.; Krimm, H. A.; Remillard, R. A.; Rupen, M. P.; Russell, D. M.; Fender, R. P.; Heinz, S.; Kording, E. G.; Maitra, D.; Markoff, S.; Migliari, S.; Sarazin, C. L.; Tudose, V.

    2012-01-01

    We present an intensive radio and X-ray monitoring campaign on the 2009 outburst of the Galactic black hole candidate X-ray binary H1743-322. With the high angular resolution of the Very Long Baseline Array, we resolve the jet ejection event and measure the proper motions of the jet ejecta relative to the position of the compact core jets detected at the beginning of the outburst. This allows us to accurately couple the moment when the jet ejection event occurred with X-ray spectral and timing signatures. We find that X-ray timing signatures are the best diagnostic of the jet ejection event in this outburst, which occurred as the X-ray variability began to decrease and the Type C quasi-periodic oscillations disappeared from the X-ray power density spectrum. However, this sequence of events does not appear to be replicated in all black hole X-ray binary outbursts, even within an individual source. In our observations of H1743-322, the ejection was contemporaneous with a quenching of the radio emission, prior to the start of the major radio flare. This contradicts previous assumptions that the onset of the radio flare marks the moment of ejection. The jet speed appears to vary between outbursts with a positive correlation outburst luminosity. The compact core radio jet reactivated on transition to the hard intermediate state at the end of the outburst and not when the source reached the low hard spectral state. Comparison with the known near-infrared behaviour of the compact jets suggests a gradual evolution of the compact jet power over a few days near beginning the and end of an outburst

  11. Halo Structure Traced by SDSS RR Lyrae

    CERN Document Server

    Ivezic, Z; Schlegel, D J; Smolcic, V; Johnston, D; Gunn, J E; Knapp, G R; Strauss, M A; Rockosi, C M

    2003-01-01

    We discuss the density and radial velocity distributions of over 3000 candidate RR Lyrae stars selected by various methods using Sloan Digital Sky Survey data for about 1000 deg^2 of sky. This is more than 20 times larger sample than previously reported by SDSS (Ivezic et al. 2000), and includes candidate RR Lyrae stars out to the sample limit of 100 kpc. A cutoff in the radial distribution of halo RR Lyrae at ~50-60 kpc that was suggested by the early SDSS data appears to be a statistical anomaly confined to a small region (~100 deg^2). Despite the large increase in observed area, the most prominent features remain to be those associated with the Sgr dwarf tidal stream. We find multiple number density peaks along three lines of sight in the Sgr dwarf tidal stream plane, that may indicate several perigalactic passages of the Sgr dwarf galaxy.

  12. High-energy observations of the state transition of the X-ray nova and black hole candidate XTE J1720-318

    DEFF Research Database (Denmark)

    Bel, M.C.; Rodriguez, J.; Sizun, P.

    2004-01-01

    We report the results of extensive high-energy observations of the X-ray transient and black hole candidate XTE J1720-318 performed with INTEGRAL, XMM-Newton and RXTE. The source, which underwent an X-ray outburst in 2003 January, was observed in February in a spectral state dominated by a soft......, typical of a black-hole binary in the so-called High/Soft State. We then followed the evolution of the source outburst over several months using the INTEGRAL Galactic Centre survey observations. The source became active again at the end of March: it showed a clear transition towards a much harder state...... of the black hole X-ray novae class which populate our galactic bulge and we discuss its properties in the frame of the spectral models used for transient black hole binaries....

  13. LOW LUMINOSITY AGN CANDIDATES IN SDSS

    Directory of Open Access Journals (Sweden)

    J. P. Torres-Papaqui

    2011-01-01

    Full Text Available En una muestra de 476931 galaxias con l neas de emisi n agostas del Sloan Digital Sky Survey Data Release 5, identificamos y estudiamos galaxias de las cuales algunas importantes l neas de emisi n usadas para determinar la naturaleza de su actividad ([OIII]h5007 A, H , o ambas no est an presentes. Este fen meno afecta al 22% de las galaxias con l neas de emisi n y no esta relacionado con una baja raz n de se al a ruido. En el diagrama comparando el ancho equivalente EW([NII]h6584 con la raz n de l nea [NII]h6584/H , la mayor a de estas galaxias se clasifica como AGN. El FWHM de la l nea H es del orden de 400 km s-1 y la luminosidad mediana es 5.6 1039 erg s-1, lo cual justifica la clasificaci n de estas galaxias como AGN de baja luminosidad. Un estudio en sus historias de formaci n estelar usando starlight revela que no existe formaci n estelar en el ltimo Giga a o. Las galaxias anfitrionas de las LLAGNs son de tipo morfol gico temprano con bulbos m s masivos que los de AGN luminosas.

  14. Discovery and evolution of the new black hole candidate Swift J1539.2-6227 during its 2008 outburst

    CERN Document Server

    Krimm, H A; Markwardt, C B; Brocksopp, C; Grise, F; Kaaret, P; Romano, P

    2011-01-01

    We report on the discovery by the Swift Gamma-Ray Burst Explorer of the black hole candidate Swift J1539.2-6227 and the subsequent course of an outburst beginning in November 2008 and lasting at least seven months. The source was discovered during normal observations with the Swift Burst Alert Telescope (BAT) on 2008 November 25. An extended observing campaign with the Rossi X-Ray Timing Explorer (RXTE) and Swift provided near-daily coverage over 176 days, giving us a good opportunity to track the evolution of spectral and timing parameters with fine temporal resolution through a series of spectral states. The source was first detected in a hard state during which strong low-frequency quasi-periodic oscillations (QPOs) were detected. The QPOs persisted for about 35 days and a signature of the transition from the hard to soft intermediate states was seen in the timing data. The source entered a short-lived thermal state about 40 days after the start of the outburst. There were variations in spectral hardness a...

  15. MAXI GSC observations of a spectral state transition in the black hole candidate XTE J1752-223

    CERN Document Server

    Nakahira, Satoshi; Sugizaki, Mutsumi; Ueda, Yoshihiro; Negoro, Hitoshi; Ebisawa, Ken; Kawai, Nobuyuki; Matsuoka, Masaru; Tsunemi, Hiroshi; Daikyuji, Arata; Eguchi, Satoshi; Hiroi, Kazuo; Ishikawa, Masaki; Ishiwata, Ryoji; Isobe, Naoki; Kawasaki, Kazuyoshi; Kimura, Masashi; Kohama, Mitsuhiro; Mihara, Tatehiro; Miyoshi, Sho; Morii, Mikio; Nakagawa, Yujin E; Nakajima, Motoki; Ozawa, Hiroshi; Sootome, Tetsuya; Sugimori, Kousuke; Suzuki, Motoko; Tomida, Hiroshi; Ueno, Shiro; Yamamoto, Takayuki; Yoshida, Atsumasa

    2010-01-01

    We present the first results on the black hole candidate XTE J1752-223 from the Gas Slit Camera (GSC) on-board the Monitor of All-sky X-ray Image (MAXI) on the International Space Station. Including the onset of the outburst reported by the Proportional Counter Array on-board the Rossi X-ray Timing Explorer on 2009 October 23, the MAXI/GSC has been monitoring this source approximately 10 times per day with a high sensitivity in the 2-20 keV band. XTE J1752-223 was initially in the low/hard state during the first 3 months. An anti-correlated behavior between the 2-4 keV and 4-20 keV bands were observed around January 20, 2010, indicating that the source exhibited the spectral transition to the high/soft state. A transient radio jet may have been ejected when the source was in the intermediate state where the spectrum was roughly explained by a power-law with a photon index of 2.5-3.0. The unusually long period in the initial low/hard state implies a slow variation in the mass accretion rate, and the dramatic s...

  16. A late jet rebrightening revealed from multi-wavelength monitoring of the black hole candidate XTE J1752-223

    CERN Document Server

    Russell, D M; Muñoz-Darias, T; Lewis, F; Motta, S; Stiele, H; Belloni, T; Miller-Jones, J C A; Jonker, P G; O'Brien, K; Homan, J; Casella, P; Gandhi, P; Soleri, P; Markoff, S; Maitra, D; Gallo, E; Bel, M Cadolle

    2011-01-01

    We present optical monitoring of the black hole candidate XTE J1752-223 during its 2009 - 2010 outburst and decay to quiescence. The optical light curve can be described by an exponential decay followed by a plateau, then a more rapid fade towards quiescence. The plateau appears to be due to an extra component of optical emission that brightens and then fades over ~ 40 days. We show evidence for the origin of this optical 'flare' to be the synchrotron jet during the decaying hard state, and we identify and isolate both disc and jet components in the spectral energy distributions. The optical flare has the same morphology and amplitude as a contemporaneous X-ray rebrightening. This suggests a common origin, but no firm conclusions can be made favouring or disfavouring the jet producing the X-ray flare. The quiescent optical magnitudes are B >= 20.6, V >= 21.1, R >= 19.5, i' >= 19.2. From the optical outburst amplitude we estimate a likely orbital period of < 22 h. We also present near-infrared (NIR) photome...

  17. Discovery of high-frequency quasi-periodic oscillations in the black-hole candidate IGR J17091-3624

    CERN Document Server

    Altamirano, Diego

    2012-01-01

    We report the discovery of 8.5 sigma high-frequency quasi-periodic oscillations (HFQPOs) at 66 Hz in the RXTE data of the black hole candidate IGR J17091-3624, a system whose X-ray properties are very similar to those of microquasar GRS 1915+105. The centroid frequency of the strongest peak is ~66 Hz, its quality factor above 5 and its rms is between 4 and 10%. We found a possible additional peak at 164 Hz when selecting a subset of data; however, at 4.5 sigma level we consider this detection marginal. These QPOs have hard spectrum and are stronger in observations performed between September and October 2011, during which IGR J17091-3624 displayed for the first time light curves which resemble those of the gamma variability class in GRS 1915+105. We find that the 66 Hz QPO is also present in previous observations (4.5 sigma), but only when averaging ~235 ksec of relatively high count rate data. The fact that the HFQPOs frequency in IGR J17091-3624 matches surprisingly well that seen in GRS 1915+105 raises que...

  18. DISCOVERY OF HIGH-FREQUENCY QUASI-PERIODIC OSCILLATIONS IN THE BLACK HOLE CANDIDATE IGR J17091-3624

    Energy Technology Data Exchange (ETDEWEB)

    Altamirano, D. [Astronomical Institute, ' Anton Pannekoek' , University of Amsterdam, Science Park 904, 1098XH Amsterdam (Netherlands); Belloni, T., E-mail: d.altamirano@uva.nl [INAF-Osservatorio Astronomico di Brera, Via E. Bianchi 46, I-23807 Merate (Italy)

    2012-03-15

    We report the discovery of 8.5{sigma} high-frequency quasi-periodic oscillations (HFQPOs) at 66 Hz in the Rossi X-ray Timing Explorer data of the black hole candidate IGR J17091-3624, a system whose X-ray properties are very similar to those of microquasar GRS 1915+105. The centroid frequency of the strongest peak is {approx}66 Hz, its quality factor above five, and its rms is between 4% and 10%. We found a possible additional peak at 164 Hz when selecting a subset of the data; however, at the 4.5{sigma} level we consider this detection marginal. These QPOs have hard spectrum and are stronger in observations performed between 2011 September and October, during which IGR J17091-3624 displayed for the first time light curves that resemble those of the {gamma} variability class in GRS 1915+105. We find that the 66 Hz QPO is also present in previous observations (4.5{sigma}), but only when averaging {approx}235 ks of relatively high count rate data. The fact that the HFQPOs frequency in IGR J17091-3624 matches surprisingly well with that seen in GRS 1915+105 raises questions on the mass scaling of QPOs frequency in these two systems. We discuss some possible interpretations; however, they all strongly depend on the distance and mass of IGR J17091-3624, both completely unconstrained today.

  19. Spectral and Temporal Behavior of the Black Hole Candidate XTE J1118+480 as Observed with BeppoSAX

    CERN Document Server

    Frontera, F; Zdziarski, A A; Belloni, T; Del Sordo, S; Masetti, N; Orlandini, M; Palazzi, E

    2003-01-01

    XTE J1118+480 is a well established black hole candidate with a mass estimate in the range from 7 to 10 solar masses. With BeppoSAX we observed the source 4 times, from April to December 2000. Results of the firs t observation were already reported (Frontera et al. 2001). Here we report spectral results of the later observations, performed in May, June and December 2000 and compare them with the results obtained from the 2000 April observation. We observe a decrease of the column density from a value consistent with the Galactic N_H obtained from radio measurement s to a value a factor 2 lower. The spectra are well fit with a thermal Comptonization plus a blackbody model. The blackbody luminosity decreases with time, while the electron temperature of the Comptonizing electron s does not show significant changes. A Compton reflection component is apparent and stable, although weak (mean value of Omega/2pi = 0.21[-0.04,+0.05]). The reflector shows a low metallicity (mean value of Z/Zsun = 0.13[-0.04,+0.06]). On...

  20. Broad-Band Spectrum of The Black Hole Candidate IGR J17497-2821 Studied with Suzaku

    CERN Document Server

    Paizis, A; Takahashi, H; Dotani, T; Kohmura, T; Kokubun, M; Rodríguez, J; Ueda, Y; Walter, R; Yamada, S; Yamaoka, K; Yuasa, T

    2008-01-01

    The broad-band 1-300 keV Suzaku spectrum of IGR J17497-2821, the X-ray transient discovered by INTEGRAL in September 2006, is presented. Suzaku observed IGR J17497-2821 on September 25, eight days after its discovery, for a net exposure of about 53 ksec. During the Suzaku observation, IGR J17497-2821 is very bright, 2 x 10^37 erg/s at 8 kpc in the 1-300 keV range, and shows a hard spectrum, typical of black hole candidates in the low-hard state. Despite the multi-mission X-ray monitoring of the source, only with Suzaku is it possible to obtain a broad-band spectrum in the 1-300 keV range with a very high signal to noise ratio. A sum of a multi-color disc (DISKBB) and a thermal Comptonization component (COMPPS) with mild reflection is a good representation of our IGR J17497-2821 Suzaku spectrum. The spectral properties of the accretion disc as well as the cut-off energy in the spectrum at about 150 keV are clearly detected and constrained. We discuss the implications on the physical model used to interpret the...

  1. Molecular hydrogen absorption systems in SDSS

    CERN Document Server

    Balashev, S A; Ivanchik, A V; Varshalovich, D A; Petitjean, P; Noterdaeme, P

    2014-01-01

    We present a systematic search for molecular hydrogen absorption systems at high redshift in quasar spectra from the Sloan Digital Sky Survey (SDSS) II Data Release 7 and SDSS-III Data Release 9. We have selected candidates using a modified profile fitting technique taking into account that the Ly$\\alpha$ forest can effectively mimic H$_2$ absorption systems at the resolution of SDSS data. To estimate the confidence level of the detections, we use two methods: a Monte-Carlo sampling and an analysis of control samples. The analysis of control samples allows us to define regions of the spectral quality parameter space where H$_2$ absorption systems can be confidently identified. We find that H$_2$ absorption systems with column densities $\\log {\\rm N_{H_2}} > 19$ can be detected in only less than 3% of SDSS quasar spectra. We estimate the upper limit on the detection rate of saturated H$_2$ absorption systems ($\\log {\\rm N_{H_2}} > 19$) in Damped Ly-$\\alpha$ (DLA) systems to be about 7%. We provide a sample of ...

  2. Testing the space-time geometry around black hole candidates with the analysis of the broad K$\\alpha$ iron line

    CERN Document Server

    Bambi, Cosimo

    2012-01-01

    Astrophysical black hole candidates are thought to be the Kerr black holes predicted by General Relativity, but there is not yet a clear evidence that the geometry of the space-time around these objects is really described by the Kerr metric. In order to confirm the Kerr black hole hypothesis, we have to observe strong gravity features and check they are in agreement with the ones predicted by General Relativity. In this paper, I study what kind of information can be extracted by analyzing the broad K$\\alpha$ iron line, which is often seen in the X-ray spectrum of both stellar-mass and super-massive black hole candidates and whose shape is supposed to be strongly affected by the space-time geometry. I extend previous studies in the literature. It turns out that there is a strong degeneracy between the spin parameter and the deformation parameter; that is, the line emitted around a Kerr black hole with a certain spin can be very similar to the one coming from the space-time around a non-Kerr object with a quit...

  3. Evidence of Spin and Energy Extraction in a Galactic Black Hole Candidate: The XMM-NEWTON/EPIC SPECTRUM of XTE 11650-500

    Science.gov (United States)

    Miller, J. M.; Fabian, A. C.; Wunands, R.; Reynolds, C. S.; Ehle, M.; Freyberg, M. J.; VanDerKlis, M.; Lewin, W. H. G.; Sanchez-Fernandez, C.; Castro-Tirado, A. J.

    2002-01-01

    We observed the Galactic black hole candidate XTE J1650-500 early in its fall of 2001 outburst with the XMM-Newton European Photon Imaging pn Camera (EPIC-pn). The observed spectrum is consistent with the source having been in the very high state. We h d a broad, skewed Fe Kar emission line that suggests the primary in this system may be a Kerr black hole and that indicates a steep disk emissivity profile that is hard to explain in terms of a standard accretion disk model. These results are quantitatively and qualitatively similar to those from an XMM-Newton observation of the Seyfert galaxy MCG -6-30-15. The steep emissivity in MCG -6-30-15 may be explained by the extraction and dissipation of rotational energy from a black hole with nearly maximal angular momentum or from material in the plunging region via magnetic connections to the inner accretion disk. If this process is at work in both sources, an exotic but fundamental general relativistic prediction may be confirmed across a factor of l0(exp 6) in black hole mass. We discuss these results in terms of the accretion flow geometry in stellar-mass black holes and the variety of enigmatic phenomena often observed in the very high state.

  4. Unusual double-peaked emission in the SDSS quasar J093201.60 + 031858.7

    Science.gov (United States)

    Barrows, R. S.; Lacy, C. H. S.; Kennefick, D.; Kennefick, J.; Seigar, M. S.

    2011-02-01

    We examine spectral properties of the SDSS quasar J093201.60 + 031858.7, in particular the presence of strong blue peaks in the Balmer emission lines offset from the narrow lines by approximately 4200 km s -1. Asymmetry in the broad central component of the H β line indicates the presence of a double-peaked emitter. However, the strength and sharpness of the blue H β and blue H γ peaks make this quasar spectrum unique among double-peaked emitters identified from SDSS spectra. We fit a disk model to the H β line and compare this object with other unusual double-peaked quasar spectra, particularly candidate binary supermassive black holes (SMBHs). Under the binary SMBH scenario, we test the applicability of a model in which a second SMBH may produce the strong blue peak in the Balmer lines of a double-peaked emitter. If there were only one SMBH, a circular, Keplerian disk model fit would be insufficient, indicating some sort of asymmetry is required to produce the strength of the blue peak. In either case, understanding the nature of the complex line emission in this object will aid in further discrimination between a single SMBH with a complex accretion disk and the actual case of a binary SMBH.

  5. Unusual Double-peaked Emission in the SDSS Quasar J093201.60+031858.7

    CERN Document Server

    Barrows, R Scott; Kennefick, Daniel; Kennefick, Julia

    2010-01-01

    We examine spectral properties of the SDSS quasar J093201.60+031858.7, in particular the presence of strong blue peaks in the Balmer emission lines offset from the narrow lines by approximately 4200 km s$^{-1}$. Asymmetry in the broad central component of the H$\\beta$ line indicates the presence of a double-peaked emitter. However, the strength and sharpness of the blue H$\\beta$ and blue H$\\gamma$ peaks make this quasar spectrum unique amongst double-peaked emitters identified from SDSS spectra. We fit a disk model to the H$\\beta$ line and compare this object with other unusual double-peaked quasar spectra, particularly candidate binary supermassive black holes (SMBHs). Under the binary SMBH scenario, we test the applicability of a model in which a second SMBH may produce the strong blue peak in the Balmer lines of a double-peaked emitter. If there were only one SMBH, a circular, Keplerian disk model fit would be insufficient, indicating some sort of asymmetry is required to produce the strength of the blue p...

  6. The Fall 2004 SDSS Supernova Survey

    CERN Document Server

    Sako, M; Frieman, J A; Adelman-McCarthy, J; Becker, A; De Jongh, F; Dilday, B; Estrada, J; Hendry, J; Holtzman, J; Kaplan, J; Kessler, R; Lampeitl, H; Marriner, J P; Miknaitis, G; Riess, A; Tucker, D; Barentine, J; Blandford, R D; Brewington, H; Dembicky, J; Harvanek, M; Hawley, S; Hogan, C; Johnston, D; Kahn, S; Ketzeback, B; Kleinman, S; Krzesínski, J; Lamenti, D; Long, D; McMillan, R; Newman, P; Nitta, A; Nichol, R; Scranton, R; Sheldon, E S; Snedden, S A; Stoughton, C; York, D; Sako, Masao; Romani, Roger; Frieman, Josh; Carthy, Jen Adelman-Mc; Becker, Andrew; Jongh, Fritz De; Dilday, Ben; Estrada, Juan; Hendry, John; Holtzman, Jon; Kaplan, Jared; Kessler, Rick; Lampeitl, Hubert; Marriner, John; Miknaitis, Gajus; Riess, Adam; Tucker, Douglas

    2005-01-01

    In preparation for the Supernova Survey of the Sloan Digital Sky Survey (SDSS) II, a proposed 3-year extension to the SDSS, we have conducted an early engineering and science run during the fall of 2004, which consisted of approximately 20 scheduled nights of repeated imaging of half of the southern equatorial stripe. Transient supernova-like events were detected in near real-time and photometric measurements were made in the five SDSS filter bandpasses with a cadence of ~2 days. Candidate type Ia supernovae (SNe) were pre-selected based on their colors, light curve shape, and the properties of the host galaxy. Follow-up spectroscopic observations were performed with the Astrophysical Research Consortium 3.5m telescope and the 9.2m Hobby-Eberly Telescope to confirm their types and measure the redshifts. The 2004 campaign resulted in 22 spectroscopically confirmed SNe, which includes 16 type Ia, 5 type II, and 1 type Ib/c. These SN Ia will help fill in the sparsely sampled redshift interval of z = 0.05 - 0.35,...

  7. The (w)hole survey: an unbiased sample study of transition disk candidates based on Spitzer catalogs

    CERN Document Server

    van der Marel, Nienke; van Terwisga, Sierk; Merin, Bruno; Herczeg, Gregory; Ligterink, Niels F W; van Dishoeck, Ewine F

    2016-01-01

    Understanding disk evolution and dissipation is essential for studies of planet formation. Transition disks, i.e., disks with large dust cavities and gaps, are promising candidates of active evolution. About two dozen SED-selected candidates have been confirmed to have dust cavities through millimeter interferometric imaging, but this sample is biased towards the brightest disks. The Spitzer surveys of nearby low-mass star forming regions have resulted in more than 4000 Young Stellar Objects (YSOs). Using color criteria we have selected a sample of ~150 candidates, and an additional 40 candidates and known transition disks from the literature. The Spitzer data were complemented by new observations at longer wavelengths, including new JCMT and APEX submillimeter photometry, and WISE and Herschel-PACS mid and far-infrared photometry. Furthermore, optical spectroscopy was obtained and stellar types were derived for 85% of the sample, including information from the literature. The SEDs were fit to a grid of RADMC...

  8. The evolution of the X-ray phase lags during the outbursts of the black hole candidate GX 339-4

    CERN Document Server

    Altamirano, Diego

    2015-01-01

    Owing to the frequency and reproducibility of its outbursts, the black-hole candidate GX 339-4 has become the standard against which the outbursts of other black-hole candidate are matched up. Here we present the first systematic study of the evolution of the X-ray lags of the broad-band variability component (0.008-5 Hz) in GX 339-4 as a function of the position of the source in the hardness-intensity diagram. The hard photons always lag the soft ones, consistent with previous results. In the low-hard state the lags correlate with X-ray intensity, and as the source starts the transition to the intermediate/soft states, the lags first increase faster, and then appear to reach a maximum, although the exact evolution depends on the outburst and the energy band used to calculate the lags. The time of the maximum of the lags appears to coincide with a sudden drop of the Optical/NIR flux, the fractional RMS amplitude of the broadband component in the power spectrum, and the appearance of a thermal component in the...

  9. Evidence for Spin and Energy Extraction in a Galactic Black Hole Candidate The XMM-Newton\\/EPIC-pn Spectrum of XTE J1650-500

    CERN Document Server

    Miller, J M; Wijnands, R; Reynolds, C S; Ehle, M; Freyberg, M J; Van der Klis, M; Lewin, W H G; Sánchez-Fernández, C; Castro-Tirado, A J

    2002-01-01

    We observed the Galactic black hole candidate XTE J1650-500 early in its Fall, 2001 outburst with the XMM-Newton European Photon Imaging pn Camera (EPIC-pn). The observed spectrum is consistent with the source having been in the "very high" state. We find a broad, skewed Fe K-alpha emission line which suggests that the primary in this system may be a Kerr black hole, and which indicates a steep emissivity profile that is hard to explain in terms of a standard accretion disk model. These results are quantitatively and qualitatively similar to those from an XMM-Newton observation of the Seyfert galaxy MCG--6-30-15. The steep emissivity in MCG--6-30-15 may be explained by the extraction and dissipation of rotational energy from a black hole with nearly- maximal angular momentum or material in the plunging region via magnetic connections to the inner accretion disk. If this process is at work in both sources, an exotic but fundamental general relativistic prediction may be confirmed across a factor of 10^6 in bla...

  10. A broadband X-ray spectral study of the intermediate-mass black hole candidate M82 X-1 with NuSTAR, Chandra and Swift

    CERN Document Server

    Brightman, Murray; Barret, Didier; Davis, Shane W; Fürst, Felix; Madsen, Kristin K; Middleton, Matthew; Miller, Jon M; Stern, Daniel; Tao, Lian; Walton, Dominic J

    2016-01-01

    M82 X-1 is one of the brightest ultraluminous X-ray sources (ULXs) known, which, assuming Eddington-limited accretion and other considerations, makes it one of the best intermediate-mass black hole (IMBH) candidates. However, the ULX may still be explained by super-Eddington accretion onto a stellar-remnant black hole. We present simultaneous NuSTAR, Chandra and Swift/XRT observations during the peak of a flaring episode with the aim of modeling the emission of M82 X-1 and yielding insights into its nature. We find that thin-accretion disk models all require accretion rates at or above the Eddington limit in order to reproduce the spectral shape, given a range of black hole masses and spins. Since at these high Eddington ratios the thin-disk model breaks down due to radial advection in the disk, we discard the results of the thin-disk models as unphysical. We find that the temperature profile as a function of disk radius ($T(r)\\propto r^{-p}$) is significantly flatter ($p=0.55^{+ 0.07}_{- 0.04}$) than expecte...

  11. The surface density profile of NGC 6388 : a good candidate for harboring an intermediate-mass black hole

    CERN Document Server

    Lanzoni, B; Ferraro, F R; Miocchi, P; Valenti, E; Rood, R T

    2007-01-01

    We have used a combination of high resolution (HST ACS-HRC, ACS-WFC, and WFPC2) and wide-field (ESO-WFI) observations of the galactic globular cluster NGC 6388 to derive its center of gravity, projected density profile, and central surface brightness profile. While the overall projected profiles are well fit by a King model with intermediate concentration (c=1.8) and sizable core radius (rc=7"), a significant power law (with slope \\alpha=-0.2) deviation from a flat core behavior has been detected within the inner 1 arcsecond. These properties suggest the presence of a central intermediate mass black hole. The observed profiles are well reproduced by a multi-mass isotropic, spherical model including a black hole with a mass of ~5.7x10^3 Msol.

  12. Spectroscopic Analysis of Subluminous B Stars in Binaries - Four Candidate Systems with Neutron Star/Black Hole Companions Discovered

    CERN Document Server

    Geier, S; Edelmann, H; Heber, U; Napiwotzki, R

    2006-01-01

    The masses of compact objects like white dwarfs, neutron stars and black holes are fundamental to astrophysics, but very difficult to measure. We present the results of an analysis of subluminous B (sdB) stars in close binary systems with unseen compact companions to derive their masses and clarify their nature. Radial velocity curves were obtained from time resolved spectroscopy. The atmospheric parameters were determined in a quantitative spectral analysis. With high resolution spectra we were able to measure the projected rotational velocity of the stars with high accuracy. The assumption of orbital synchronization made it possible to constrain inclination angle and companion mass of the binaries. Five invisible companions have masses that are compatible with white dwarfs or late type main sequence stars. But four sdBs have very massive companions like heavy white dwarfs, neutron stars or even black holes. Such a high fraction of massive compact companions can not be explained with current models of binary...

  13. A Thermote, a Novel Thermal Element Simplifying the Finding of a Medium's Entropy Emerges as a Sensible Dark Matter Candidate from Primordial Black Holes with a Mass in Range of Axion's, a Leading Candidate

    Science.gov (United States)

    Feria, Erlan H.

    2017-06-01

    Black holes acting as dark matter have been predicted, e.g., via a duality theory in (Feria 2011, Proc. IEEE Int’l Conf. on SMC, Alaska, USA) and via observations in (Kashlinsky 2016, AJL). Here a thermote, a novel thermal element simplifying the finding of a medium’s entropy, emerges as a dark matter candidate from primordial black holes with a mass in range of axion's, a leading candidate. The thermote energy, eT, is defined as the average thermal energy contributed to a particle’s motion by the medium’s degrees of freedom (DoF) and is thus given by eT=NDoFkBT/2 where NDoF is the DoF number (e.g., NDoF=2 for a black-hole since only in its event-horizon particle motions can occur) and kBT/2 is the thermal energy contributed by each degree of freedom (kB is the Boltzmann constant and T is temperature). The entropy S of a spherical homogeneous medium is then simply stated as S=(kB/2)E/eT where E=Mc2 is the medium's rest-energy, with M its point-mass and c the speed of light, and eT=NDoFkBT/2 is the thermote's kinetic-energy. This simple equation naturally surfaced from a rest/kinetic or retention/motion mass-energy duality theory where, e.g., black-holes and vacuums form together such a duality with black holes offering the least resistance to mass-energy rest, or retention, and vacuums offering the least resistance to mass-energy kinetics, or motions. In turn, this duality theory has roots in the universal cybernetics duality principle (UCDP) stating “synergistic physical and mathematical dualities arise in efficient system designs” (Feria 2014, http://dx.doi.org/10.1117/2.1201407.005429, SPIE Newsroom). Our thermote based entropy finding method is applicable to spherical homogeneous mediums such as black-holes, photon-gases, and flexible-phase (Feria 2016, Proc. IEEE Int’l Conf. on Smart Cloud, Columbia University, NY, USA), where the thermote of a primordial black hole, with NDoF=2 and a CMB radiation temperature of T=2.725 kelvin, emerges as a

  14. A Search for Periodicity in the X-Ray Spectrum of Black Hole Candidate A0620-00

    Science.gov (United States)

    1991-06-01

    Dispersion M inimization ............................... 44 4.2 Results ................................................................. 48 4.2.1...the hole was assumed to be nottrotating, so the inner edge of •he disk was it r1 - 6M. Model (a) corresponds to a - 0 3 W. - W 10- .If) yrr’ - Ldd ...fits with error bars. (h) The error dispersion . The curve is the minimum X2 fit to a Gaussian. 2.2 Systematic Corrections 29 We now construct the

  15. X-Ray Timing and Spectral Observations of Galactic Black Hole Candidate XTE J1550--564 During Outburst

    Energy Technology Data Exchange (ETDEWEB)

    Reilly, Kaice T

    2002-12-11

    Soft X-ray transients (SXTs), a sub-class of low-mass X-ray binaries (LMXBs), provide a unique opportunity to test General Relativity and to probe fundamental physics under conditions terrestrially unattainable. SXT outbursts are of great interest because they allow the study of LMXBs under a wide range of accretion rates. The majority of known SXTs contain black holes, therefore SXT outbursts are key to understanding accretion physics around black holes and in active galactic nuclei, which are thought to contain supermassive, M {approx} 10{sup 6} - 10{sup 10} M{circle_dot}, where M{circle_dot} is one solar mass, central compact objects. These compact objects are most likely black holes, which exhibit, on a much larger scale, accretion physics similar to that around black holes in SXTs. In this work, the timing and spectral properties of the SXT and microquasar XTE J1550-564 during outburst are studied. Observations made by the Unconventional Stellar Aspect (USA) Experiment on board the Advanced Research and Global Observation Satellite (ARGOS) are emphasized. USA data show a low-frequency quasi-periodic oscillation (LFQPO) with a centroid frequency that tends to increase with increasing USA flux and a fractional rms amplitude which is correlated with the USA hardness ratio (4-16 keV/1-4 keV). Several high-frequency quasi-periodic oscillations (HFQPOs) were detected by the Rossi X-ray Timing Explorer (RXTE), during periods where the LFQPO is seen to be weakening or not detectable at all. The evolution of the USA hardness ratio with time and source flux is examined. The hardness-intensity diagram shows counterclockwise cyclical evolution and possibly indicates the presence of two independent accretion flows: a geometrically thin, optically thick accretion disk and a hot sub-Keplerian flow.

  16. FIRST LONG-TERM OPTICAL SPECTRAL MONITORING OF A BINARY BLACK HOLE CANDIDATE E1821+643. I. VARIABILITY OF SPECTRAL LINES AND CONTINUUM

    Energy Technology Data Exchange (ETDEWEB)

    Shapovalova, A. I.; Burenkov, A. N.; Zhdanova, V. E. [Special Astrophysical Observatory of the Russian AS, Nizhnij Arkhyz, Karachaevo-Cherkesia 369167 (Russian Federation); Popović, L. Č. [Astronomical Observatory, Volgina 7, 11160 Belgrade 74 (Serbia); Chavushyan, V. H.; Valdés, J. R.; Patiño-Álvarez, V.; León-Tavares, J.; Torrealba, J. [Instituto Nacional de Astrofísica, Óptica y Electrónica, Apartado Postal 51-216, 72000 Puebla, Puebla, México (Mexico); Ilić, D.; Kovačević, A. [Department of Astronomy, Faculty of Mathematics, University of Belgrade, Studentski trg 16, 11000 Belgrade (Serbia); Kollatschny, W., E-mail: ashap@sao.ru [Institut für Astrophysik, Georg-August-Universität Göttingen (Germany)

    2016-02-15

    We report the results of the first long-term (1990–2014) optical spectrophotometric monitoring of a binary black hole candidate QSO E1821+643, a low-redshift, high-luminosity, radio-quiet quasar. In the monitored period, the continua and Hγ fluxes changed about two times, while the Hβ flux changed about 1.4 times. We found periodical variations in the photometric flux with periods of 1200, 1850, and 4000 days, and 4500-day periodicity in the spectroscopic variations. However, the periodicity of 4000–4500 days covers only one cycle of variation and should be confirmed with a longer monitoring campaign. There is an indication of the period around 1300 days in the spectroscopic light curves, buts with small significance level, while the 1850-day period could not be clearly identified in the spectroscopic light curves. The line profiles have not significantly changed, showing an important red asymmetry and broad line peak redshifted around +1000 km s{sup −1}. However, Hβ shows a broader mean profile and has a larger time lag (τ ∼ 120 days) than Hγ (τ ∼ 60 days). We estimate that the mass of the black hole is ∼2.6 × 10{sup 9} M{sub ⊙}. The obtained results are discussed in the frame of the binary black hole hypothesis. To explain the periodicity in the flux variability and high redshift of the broad lines, we discuss a scenario where dense, gas-rich, cloudy-like structures are orbiting around a recoiling black hole.

  17. Correlated X-ray Spectral and Timing Behavior of the Black Hole Candidate XTE J1550-564

    CERN Document Server

    Homan, J; Van der Klis, M; Belloni, T; Van Paradijs, J; Klein-Wolt, M; Fender, R P; Méndez, M; Homan, Jeroen; Wijnands, Rudy; Klis, Michiel van der; Belloni, Tomaso; Paradijs, Jan van; Klein-Wolt, Marc; Fender, Robert P; Mendez, Mariano

    2000-01-01

    We present an analysis of data of the black hole X-ray transient XTE J1550-564, taken with RXTE between 1998 Nov 22 and 1999 May 20. The source went through several different states, which were divided into soft and hard states, based on the relative strength of the high energy power law tail. The states showed up as distinct branches in the color-color diagram, connecting to form a structure with a comb-like topology, the branch corresponding to the soft state forming the spine and the branches corresponding to the various hard states forming the teeth of the comb. The power spectral properties of each branch were correlated with their spectral properties. Three types of QPOs were found: 1-18 Hz and 100-285 Hz QPOs on the hard branches, and 15-18 Hz QPOs on and near the soft branch. The frequency of the high and low frequency QPOs on the hard branches were correlated with each other, and with spectral hardness. The behavior of the XTE J1550-564 strongly favors a two-dimensional description of black hole beha...

  18. On the radio properties of the intermediate-mass black hole candidate ESO 243-49 HLX-1

    CERN Document Server

    Cseh, D; Godet, O; Barret, D; Corbel, S; Coriat, M; Falcke, H; Farrell, S A; Koerding, E; Lenc, E; Wrobel, J M

    2014-01-01

    We present follow-up radio observations of ESO 243-49 HLX-1 from 2012 using the Australia Telescope Compact Array (ATCA) and the Karl G. Jansky Very Large Array (VLA). We report the detection of radio emission at the location of HLX-1 during its hard X-ray state using the ATCA. Assuming that the `Fundamental Plane' of accreting black holes is applicable, we provide an independent estimate of the black hole mass of $M_{\\rm{BH}}\\leq2.8^{+7.5}_{-2.1} \\times 10^{6}$ M$_{\\odot}$ at 90% confidence. However, we argue that the detected radio emission is likely to be Doppler-boosted and our mass estimate is an upper limit. We discuss other possible origins of the radio emission such as being due to a radio nebula, star formation, or later interaction of the flares with the large-scale environment. None of these were found adequate. The VLA observations were carried out during the X-ray outburst. However, no new radio flare was detected, possibly due to a sparse time sampling. The deepest, combined VLA data suggests a ...

  19. The enigmatic black-hole candidate and X-ray transient IGR J17091-3624 in its quiescent state as seen with XMM-Newton

    CERN Document Server

    Wijnands, Rudy; Altamirano, Diego

    2012-01-01

    We report on two short XMM-Newton observations performed in August 2006 and February 2007 during the quiescence state of the enigmatic black hole candidate system IGR J17091-3624. During both observations the source was clearly detected. Although the errors on the estimated fluxes are large, the source appears to be brighter by several tens of percents during the February 2007 observation compared to the August 2006 observation. During both observations the 2-10 keV luminosity of the source was close to ~10^{33} erg/s for an assumed distance of 10 kpc. However, we note that the distance to this source is not well constrained and it has been suggested it might be as far as 35 kpc which would result in an order of magnitude higher luminosities. If the empirically found relation between the orbital period and the quiescence luminosity of black hole transients is also valid for IGR J17091-3624, then we can estimate an orbital period of >100 hours (>4 days) for a distance of 10 kpc but it could be as large as tens...

  20. Broadband monitoring tracing the evolution of the jet and disk in the black hole candidate X-ray binary MAXI J1659-152

    CERN Document Server

    van der Horst, A J; Miller-Jones, J C A; Linford, J D; Gorosabel, J; Russell, D M; Postigo, A de Ugarte; Lundgren, A A; Taylor, G B; Maitra, D; Guziy, S; Belloni, T M; Kouveliotou, C; Jonker, P G; Kamble, A; Paragi, Z; Homan, J; Kuulkers, E; Granot, J; Altamirano, D; Buxton, M M; Castro-Tirado, A; Fender, R P; Garrett, M A; Gehrels, N; Hartmann, D H; Kennea, J A; Krimm, H A; Mangano, V; Ramirez-Ruiz, E; Romano, P; Wijers, R A M J; Wijnands, R; Yang, Y J

    2013-01-01

    MAXI J1659-152 was discovered on 2010 September 25 as a new X-ray transient, initially identified as a gamma-ray burst, but was later shown to be a new X-ray binary with a black hole as the most likely compact object. Dips in the X-ray light curves have revealed that MAXI J1659-152 is the shortest period black hole candidate identified to date. Here we present the results of a large observing campaign at radio, sub-millimeter, near-infrared (nIR), optical and ultraviolet (UV) wavelengths. We have combined this very rich data set with the available X-ray observations to compile a broadband picture of the evolution of this outburst. We have performed broadband spectral modeling, demonstrating the presence of a spectral break at radio frequencies and a relationship between the radio spectrum and X-ray states. Also, we have determined physical parameters of the accretion disk and put them into context with respect to the other parameters of the binary system. Finally, we have investigated the radio-X-ray and nIR/...

  1. Investigating the disc-jet coupling in accreting compact objects using the black hole candidate Swift J1753.5-0127

    CERN Document Server

    Soleri, P; Tudose, V; Maitra, D; Bell, M; Linares, M; Altamirano, D; Wijnands, R; Belloni, T; Casella, P; Miller-Jones, J C A; Muxlow, T; Klein-Wolt, M; Garrett, M; van der Klis, M

    2010-01-01

    In studies of accreting black holes in binary systems, empirical relations have been proposed to quantify the coupling between accretion processes and ejection mechanisms. These processes are probed respectively by means of X-ray and radio/optical-infrared observations. The relations predict, given certain accretion conditions, the expected energy output in the form of a jet. We investigated this coupling by studying the black hole candidate Swift J1753.5-0127, via multiwavelength coordinated observations over a period of ~4 years. We present the results of our campaign showing that, all along the outburst, the source features a jet that is fainter than expected from the empirical correlation between the radio and the X-ray luminosities in hard spectral state. Because the jet is so weak in this system the near-infrared emission is, unusually for this state and luminosity, dominated by thermal emission from the accretion disc. We briefly discuss the importance and the implications of a precise determination of...

  2. Spatially-Resolved Spectroscopy of SDSS J0952+2552: a confirmed Dual AGN

    CERN Document Server

    McGurk, R C; Rosario, D J; Shields, G A; Smith, K L; Wright, S A

    2011-01-01

    Most massive galaxies contain supermassive black holes (SMBHs) in their cores. When galaxies merge, gas is driven to nuclear regions and can accrete onto the central black hole. Thus one expects to see dual AGN in a fraction of galaxy mergers. Candidates for galaxies containing dual AGN have been identified by the presence of double-peaked narrow [O III] emission lines and by high spatial resolution images of close galaxy pairs. Spatially-resolved spectroscopy is needed to confirm these galaxy pairs as systems with spatially-separated double SMBHs. With the Keck 2 Laser Guide Star Adaptive Optics system and the OSIRIS near-infrared integral field spectrograph, we obtained spatially-resolved spectra for SDSS J09527.62+255257.2, a radio-quiet quasar shown by previous imaging to consist of a galaxy and its close (1.0") companion. We find that the main galaxy is a Type 1 AGN with both broad and narrow AGN emission lines in its spectrum, while the companion galaxy is a Type 2 AGN with narrow emission lines only. T...

  3. Detecting active comets with SDSS

    Energy Technology Data Exchange (ETDEWEB)

    Solontoi, Michael; Ivezic, Zeljko; /Washington U., Seattle, Astron. Dept.; West, Andrew A.; /MIT, MKI; Claire, Mark; /Washington U., Seattle, Astron. Dept.; Juric, Mario; /Princeton U. Observ.; Becker, Andrew; Jones, Lynne; /Washington U., Seattle, Astron. Dept.; Hall, Patrick B.; /York U., Canada; Kent, Steve; /Fermilab; Lupton, Robert H.; /Princeton U. Observ.; Quinn, Tom; /Washington U., Seattle, Astron. Dept. /Princeton U. Observ.

    2010-12-01

    Using a sample of serendipitously discovered active comets in the Sloan Digital Sky Survey (SDSS), we develop well-controlled selection criteria for greatly increasing the efficiency of comet identification in the SDSS catalogs. After follow-up visual inspection of images to reject remaining false positives, the total sample of SDSS comets presented here contains 19 objects, roughly one comet per 10 million other SDSS objects. The good understanding of selection effects allows a study of the population statistics, and we estimate the apparent magnitude distribution to r {approx} 18, the ecliptic latitude distribution, and the comet distribution in SDSS color space. The most surprising results are the extremely narrow range of colors for comets in our sample (e.g. root-mean-square scatter of only {approx}0.06 mag for the g-r color), and the similarity of comet colors to those of jovian Trojans. We discuss the relevance of our results for upcoming deep multi-epoch optical surveys such as the Dark Energy Survey, Pan-STARRS, and the Large Synoptic Survey Telescope (LSST), and estimate that LSST may produce a sample of about 10,000 comets over its 10-year lifetime.

  4. The phase lags of high-frequency quasi-periodic oscillations in four black-hole candidates

    CERN Document Server

    Mendez, Mariano; Belloni, Tomaso; Sanna, Andrea

    2013-01-01

    We measured the phase-lag spectrum of the high-frequency quasi-periodic oscillations (QPO) in the black hole systems (at QPO frequencies) GRS 1915+105 (35 Hz and 67 Hz), GRO J1655-40 (300 Hz and 450 Hz), XTE J1550-564 (180 Hz and 280 Hz), and IGR J17091-3624 (67 Hz). The lag spectra of the 67-Hz QPO in, respectively, GRS 1915+105 and IGR J17091-3624, and the 450-Hz QPO in GRO J1655-40 are hard (hard photons lag the soft ones) and consistent with each other, with the hard lags increasing with energy. On the contrary, the lags of the 35-Hz QPO in GRS 1915+105 are soft, with the lags becoming softer as the energy increases; the lag spectrum of the 35-Hz QPO is inconsistent with that of the 67-Hz QPO. The lags of the 300-Hz QPO in GRO J1655-40, and the 180-Hz and the 280-Hz QPO in XTE J1550-564 are independent of energy, consistent with each other and with being zero or slightly positive (hard lags). For GRO J1655-40 the lag spectrum of the 300-Hz QPO differs significantly from that of the 450-Hz QPOs. The simila...

  5. Color-Induced Displacement double stars in SDSS

    CERN Document Server

    Pourbaix, D; Knapp, G R; Gunn, J E

    2004-01-01

    We report the first successful application of the astrometric color-induced displacement technique (CID, the displacement of the photocenter between different bandpasses due to a varying contribution of differently colored components to the total light), originally proposed by Wielen (1996) for discovering unresolved binary stars. Using the Sloan Digital Sky Survey (SDSS) Data Release 1 with 2.5 million stars brighter than 21m in the u and g bands, we select 419 candidate binary stars with CID greater than 0.5 arcsec. The SDSS colors of the majority of these candidates are consistent with binary systems including a white dwarf and any main sequence star with spectral type later than ~K7. The astrometric CID method discussed here is complementary to the photometric selection of binary stars in SDSS discussed by Smolcic et al. (2004), but there is considerable overlap (15%) between the two samples of selected candidates. This overlap testifies both to the physical soundness of both methods, as well as to the as...

  6. The SDSS High Latitude Cloud Survey

    Science.gov (United States)

    McGehee, P. M.

    2009-01-01

    The high latitude clouds (|b| > 30) are primarily translucent molecular clouds and diffuse Galactic cirrus with the majority of them seen at high latitude simply due to their proximity to the Sun. The rare exceptions are those, like the Draco and other intermediate or high velocity clouds, found significantly above or below the Galactic plane. To date, star formation has only been verified in MBM 12 and MBM 20, which are two of the densest high latitude molecular clouds. We present results from an ongoing study of high latitude clouds based on the Sloan Digital Sky Survey (SDSS) and the Two Micron All-Sky Survey (2MASS). This study consists of two major efforts, the first (described here) to provide a 3-D mapping of the interstellar dust using a color-excess technique, the second to identify candidate low-mass Classical T Tauri stars in the field.

  7. A strong and broad iron line in the XMM-Newton spectrum of the new X-ray transient and black-hole candidate XTE J1652-453

    NARCIS (Netherlands)

    Hiemstra, Beike; Mendez, Mariano; Done, Chris; Trigo, Maria Diaz; Altamirano, Diego; Casella, Piergiorgio

    2010-01-01

    ABSTRACT We observed the new X-ray transient and black-hole candidate XTE J1652−453 si- multaneously with XMM-Newton and the Rossi X-ray Timing Explorer (RXTE). The observation was done during the decay of the 2009 outburst, when XTE J1652−453 was in the hard-intermediate state. The spectrum shows a

  8. Discovery and Monitoring of a New Black Hole Candidate XTE J1752-223 with RXTE: RMS Spectrum Evolution, BH Mass and the Source Distance

    Science.gov (United States)

    Shaposhinikov, Nikolai; Markwardt, Craig; Swank, Jean; Krimm, Hans

    2010-01-01

    We report on the discovery and monitoring observations of a new galactic black hole candidate XTE J1752-223 by Rossi X-ray Timing Explorer (RXTE). The new source appeared on the X-ray sky on October 21 2009 and was active for almost 8 months. Phenomenologically, the source exhibited the low-hard/highsoft spectral state bi-modality and the variability evolution during the state transition that matches standard behavior expected from a stellar mass black hole binary. We model the energy spectrum throughout the outburst using a generic Comptonization model assuming that part of the input soft radiation in the form of a black body spectrum gets reprocessed in the Comptonizing medium. We follow the evolution of fractional root-mean-square (RMS) variability in the RXTE/PCA energy band with the source spectral state and conclude that broad band variability is strongly correlated with the source hardness (or Comptonized fraction). We follow changes in the energy distribution of rms variability during the low-hard state and the state transition and find further evidence that variable emission is strongly concentrated in the power-law spectral component. We discuss the implication of our results to the Comptonization regimes during different spectral states. Correlations of spectral and variability properties provide measurements of the BH mass and distance to the source. The spectral-timing correlation scaling technique applied to the RXTE observations during the hardto- soft state transition indicates a mass of the BH in XTE J1752-223 between 8 and 11 solar masses and a distance to the source about 3.5 kiloparsec.

  9. Type Ia supernova rate studies from the SDSS-II Supernova Study

    Energy Technology Data Exchange (ETDEWEB)

    Dilday, Benjamin [Univ. of Chicago, IL (United States)

    2008-08-01

    The author presents new measurements of the type Ia SN rate from the SDSS-II Supernova Survey. The SDSS-II Supernova Survey was carried out during the Fall months (Sept.-Nov.) of 2005-2007 and discovered ~ 500 spectroscopically confirmed SNe Ia with densely sampled (once every ~ 4 days), multi-color light curves. Additionally, the SDSS-II Supernova Survey has discovered several hundred SNe Ia candidates with well-measured light curves, but without spectroscopic confirmation of type. This total, achieved in 9 months of observing, represents ~ 15-20% of the total SNe Ia discovered worldwide since 1885. The author describes some technical details of the SN Survey observations and SN search algorithms that contributed to the extremely high-yield of discovered SNe and that are important as context for the SDSS-II Supernova Survey SN Ia rate measurements.

  10. Quasar feedback in the early Universe: the case of SDSS J1148+5251

    NARCIS (Netherlands)

    Valiante, Rosa; Schneider, Raffaella; Maiolino, Roberto; Salvadori, Stefania; Bianchi, Simone

    2012-01-01

    Galaxy-scale gas outflows triggered by active galactic nuclei have been proposed as a key physical process to regulate the co-evolution of nuclear black holes and their host galaxies. The recent detection of a massive gas outflow in one of the most distant quasars, SDSS J1148+5251 at z= 6.4,

  11. Quasar feedback in the early Universe : The case of SDSS J1148+5251

    NARCIS (Netherlands)

    Valiante, Rosa; Schneider, Raffaella; Maiolino, Roberto; Salvadori, Stefania; Bianchi, Simone

    2012-01-01

    Galaxy-scale gas outflows triggered by active galactic nuclei have been proposed as a key physical process to regulate the co-evolution of nuclear black holes and their host galaxies. The recent detection of a massive gas outflow in one of the most distant quasars, SDSS J1148+5251 at z = 6.4,

  12. First long-term optical spectro-photometric monitoring of a binary black hole candidate E1821+643: I. Variability of spectral lines and continuum

    CERN Document Server

    Shapovalova, A I; Chavushyan, V H; Burenkov, A N; Ilic, D; Kollatschny, W; Kovacevic, A; Valdes, J R; Patino-Alvarez, V; Leon-Tavares, J; Torrealba, J; Zhdanova, V E

    2016-01-01

    We report the results of the first long-term (1990-2014) optical spectro-photometric monitoring of a binary black hole candidate QSO E1821+643, a low-redshift high-luminosity radio-quiet quasar. In the monitored period the continua and H$\\gamma$ fluxes changed for around two times, while the H$\\beta$ flux changed around 1.4 times. We found the periodical variations in the photometric flux with the periods of 1200, 1850 and 4000 days, and 4500 days periodicity in the spectroscopic variations. However, the periodicity of 4000-4500 days covers only one cycle of variation and should be confirmed with a longer monitoring campaign. There is an indication of the period around 1300 days in the spectroscopic light curves, but with small significance level, while the 1850 days period could not be clearly identified in the spectroscopic light curves. The line profiles have not significantly changed, showing an important red asymmetry and broad line peak redshifted around +1000 km s$^{-1}$. However, H$\\beta$ shows broade...

  13. A Spectral Study of the Black Hole Candidate XTE J1752-223 in the High/Soft State with MAXI, Suzaku and Swift

    CERN Document Server

    Nakahira, Satoshi; Uedu, Yoshihiro; Yamaoka, Kazutaka; Sugizaki, Mutsumi; Mihara, Tatehiro; Matsuoka, Masaru; Yoshida, Atsumasa; Makishima, Kazuo; Ebisawa, Ken; Kubota, Aya; Yamada, Shin'ya; Negoro, Hitoshi; Hiroi, Kazuo; Ishikawa, Masaki; Kawai, Nobuyuki; Kimura, Masashi; Kitayama, Hiroki; Kohama, Mitsuhiro; Matsumura, Takanori; Morii, Mikio; Nakajima, Motoki; Serino, Motoko; Shidatsu, Megumi; Sootome, Tetsuya; Sugimori, Kousuke; Suwa, Fumitoshi; Tomida, Hiroshi; Tsuboi, Yoko; Tsunemi, Hiroshi; Ueno, Shiro; Usui, Ryuichi; Yamamoto, Takayuki; Yamazaki, Kyohei; Tashiro, Makoto S; Terada, Yukikatsu; Seta, Hiromi

    2011-01-01

    We report on the X-ray spectral analysis of the black hole candidate XTE\\ J1752--223 in the 2009--2010 outburst, utilizing data obtained with the MAXI/Gas Slit Camera (GSC), the Swift/XRT, and Suzaku, which work complementarily. As already reported by Nakahira et al. (2010) MAXI monitored the source continuously throughout the entire outburst for about eight months. All the MAXI/GSC energy spectra in the high/soft state lasting for 2 months are well represented by a multi-color disk plus power-law model. The innermost disk temperature changed from $\\sim$0.7 keV to $\\sim$0.4 keV and the disk flux decreased by an order of magnitude. Nevertheless, the innermost radius is constant at $\\sim$41 $D_{3.5}(\\cos{\\it i})^{-1/2}$ km, where $D_{3.5}$ is the source distance in units of 3.5 kpc and $i$ the inclination. The multi-color disk parameters obtained with the MAXI/GSC are consistent with those with the Swift/XRT and Suzaku. The Suzaku data also suggests a possibility that the disk emission is slightly Comptonized, ...

  14. SDSS1133: an unusually persistent transient in a nearby dwarf galaxy

    Science.gov (United States)

    Koss, Michael; Blecha, Laura; Mushotzky, Richard; Hung, Chao Ling; Veilleux, Sylvain; Trakhtenbrot, Benny; Schawinski, Kevin; Stern, Daniel; Smith, Nathan; Li, Yanxia; Man, Allison; Filippenko, Alexei V.; Mauerhan, Jon C.; Stanek, Kris; Sanders, David

    2014-11-01

    While performing a survey to detect recoiling supermassive black holes, we have identified an unusual source having a projected offset of 800 pc from a nearby dwarf galaxy. The object, SDSS J113323.97+550415.8, exhibits broad emission lines and strong variability. While originally classified as a supernova (SN) because of its non-detection in 2005, we detect it in recent and past observations over 63 yr and find over a magnitude of rebrightening in the last 2 yr. Using high-resolution adaptive optics observations, we constrain the source emission region to be ≲12 pc and find a disturbed host-galaxy morphology indicative of recent merger activity. Observations taken over more than a decade show narrow [O III] lines, constant ultraviolet emission, broad Balmer lines, a constant putative black hole mass over a decade of observations despite changes in the continuum, and optical emission-line diagnostics consistent with an active galactic nucleus (AGN). However, the optical spectra exhibit blueshifted absorption, and eventually narrow Fe II and [Ca II] emission, each of which is rarely found in AGN spectra. While this peculiar source displays many of the observational properties expected of a potential black hole recoil candidate, some of the properties could also be explained by a luminous blue variable star (LBV) erupting for decades since 1950, followed by a Type IIn SN in 2001. Interpreted as an LBV followed by an SN analogous to SN 2009ip, the multidecade LBV eruptions would be the longest ever observed, and the broad Hα emission would be the most luminous ever observed at late times (>10 yr), larger than that of unusually luminous SNe such as SN 1988Z, suggesting one of the most extreme episodes of pre-SN mass-loss ever discovered.

  15. White Dwarfs in SDSS DR9 and DR10

    Science.gov (United States)

    Gentile Fusillo, Nicola Pietro; Gänsicke, Boris; Koester, Detlev

    2015-06-01

    Currently the largest catalogue of spectroscopically identified WDs is based on the 7th Data Release (DR) of the Sloan Digital Sky Survey and contains over 20000 WDs (Kleinman et al. 2013). However, only a fraction of all WDs in the photometric footprint of SDSS have been spectroscopically followed up. Using DR7 spectroscopy as a training sample, we developed a method to select high confidence photometric WD candidates. The novelty of our selection is that it allows us to assign to any object with multi-colour and proper motion data a well-defined "probability of being a white dwarf" (or a contaminant). Exploiting this selection method we compiled a catalogue (Gentile Fusillo et al. in prep) which currently covers the entire photometric footprint of SDSS, 14555sq deg, with a limiting magnitude of g ≤ 19. The catalogue contains over 20000 high-confidence WDs and WD candidates 11500 of which have not yet been followed up with Sloan spectroscopy. Even though, so far, our catalogue relies only SDSS we plan to extend the sky coverage as additional deep multi-colour large area surveys become available. DR10 includes over 1.4 million spectra taken with the new BOSS spectrograph, which improves over the original SDSS spectograph in both resolution and wavelength coverage, but has so far not been systematically mined for WD science. As part of this project, we also inspected over 8000 BOSS spectra of bright (g ≤ 19) colour selected sources and classified 1765 new WDs. We used this independent, spectroscopically confirmed sample to further validate our selection method. Finally we discuss possible application of our catalogue , focusing on the selection and follow up of 9 new DZs which show strong pollution from elements other than Ca and IR excess emission emission consistent with the presence of debris discs.

  16. A comparison of multifractal behavior in galaxy samples from SDSS

    Science.gov (United States)

    García-Farieta, J. E.; Casas-Miranda, R. A.

    2017-07-01

    We studied the spatial distribution of galaxies with samples from the Sloan Digital Sky Survey (SDSS) including observational holes in the masks. From a multifractal formalism and using the sliding window technique for each sample, we have determined the fractal dimension and the lacunarity spectrum. Aditionally, the scale of homogeneity was determined for each struture parameter. Our results show that the galaxy clustering exhibits a behavior that depends on the radial distance, revealing that the hierarchical distribution is not a fractal at large-scales, with a transition to homogeneity on large scales below 130 Mpc/h.

  17. Multiwavelength View of SDSS Galaxies

    CERN Document Server

    Obric, M; Kauffmann, G; Lupton, R H; Tremonti, C A; Brinchmann, J; Charlot, S; Knapp, G R; Gunn, J E; Rockosi, C M; Schlegel, D J; Strauss, M A; Gacesa, M; Smolcic, V; Anderson, S; Voges, W; Blanton, M R; Eisenstein, D J

    2004-01-01

    We summarize the detection rates at wavelengths other than optical for \\~99,000 galaxies from the Sloan Digital Sky Survey (SDSS) Data Release 1 ``main'' spectroscopic sample. The analysis is based on positional cross-correlation with source catalogs from ROSAT, 2MASS, IRAS, GB6, FIRST, NVSS and WENSS surveys. We find that the rest-frame UV-IR broad-band galaxy SEDs form a remarkably uniform, nearly one parameter, family. As an example, the SDSS u and r band data, supplemented with redshift, can be used to predict K band magnitudes measured by 2MASS with an rms scatter of only 0.2 mag; when measurement uncertainties are taken into account, the astrophysical scatter appears not larger than ~0.1 mag.

  18. A Systematic Search for Changing-Look Quasars in SDSS

    CERN Document Server

    MacLeod, Chelsea L; Lawrence, Andy; Goad, Mike; Horne, Keith; Burgett, William; Chambers, Ken C; Flewelling, Heather; Hodapp, Klaus; Kaiser, Nick; Magnier, Eugene; Wainscoat, Richard; Waters, Christopher

    2015-01-01

    We present a systematic search for changing-look quasars based on repeat photometry from SDSS and Pan-STARRS1, along with repeat spectra from SDSS and SDSS-III BOSS. Objects with large, $|\\Delta g|>1$~mag photometric variations in their light curves are selected as candidates to look for changes in broad emission line (BEL) features. Out of a sample of 1011 objects that satisfy our selection criteria and have more than one epoch of spectroscopy, we find 10 examples of quasars that have variable and/or "changing-look'' BEL features. Four of our objects have emerging BELs; five have disappearing BELs, and one object shows tentative evidence for having both emerging and disappearing BELs. With redshifts in the range 0.2012% of luminous quasars that vary by |\\Delta g|>1 mag display changing-look BEL features on rest-frame timescales of 8 to 10 years. We discuss the possibilities for the origin of such BEL changes, such as a change in obscuration or in the central engine.

  19. A systematic search for changing-look quasars in SDSS

    Science.gov (United States)

    MacLeod, Chelsea L.; Ross, Nicholas P.; Lawrence, Andy; Goad, Mike; Horne, Keith; Burgett, William; Chambers, Ken C.; Flewelling, Heather; Hodapp, Klaus; Kaiser, Nick; Magnier, Eugene; Wainscoat, Richard; Waters, Christopher

    2016-03-01

    We present a systematic search for changing-look quasars based on repeat photometry from Sloan Digital Sky Survey (SDSS) and Pan-STARRS1, along with repeat spectra from SDSS and SDSS-III Baryon Oscillation Spectroscopic Survey. Objects with large, |Δg| > 1 mag photometric variations in their light curves are selected as candidates to look for changes in broad emission line (BEL) features. Out of a sample of 1011 objects that satisfy our selection criteria and have more than one epoch of spectroscopy, we find 10 examples of quasars that have variable and/or `changing-look' BEL features. Four of our objects have emerging BELs, five have disappearing BELs, and one object shows tentative evidence for having both emerging and disappearing BELs. With redshifts in the range 0.20 15 per cent of strongly variable luminous quasars display changing-look BEL features on rest-frame time-scales of 8 to 10 yr. Plausible time-scales for variable dust extinction are factors of 2-10 too long to explain the dimming and brightening in these sources, and simple dust reddening models cannot reproduce the BEL changes. On the other hand, an advancement such as disc reprocessing is needed if the observed variations are due to accretion rate changes.

  20. NTT and NOT spectroscopy of SDSS-II supernovae

    CERN Document Server

    Ostman, L; Goobar, A; Amanullah, R; Smith, M; Sollerman, J; Stanishev, V; Stritzinger, M D; Bassett, B A; Davis, T M; Edmondson, E; Frieman, J A; Garnavich, P M; Lampeitl, H; Leloudas, G; Marriner, J; Nichol, R C; Romer, K; Sako, M; Schneider, D P; Zheng, C

    2010-01-01

    Context. The SDSS-II Supernova Survey, conducted between 2005 and 2007, was designed to detect a large number of Type Ia supernovae (SNe Ia) around z~0.2, the redshift “gap” between low-z and high-z SN searches. The survey has provided multi-band photometric lightcurves for variable targets, and SN candidates were scheduled for spectroscopic observations, primarily to provide SN classification and accurate redshifts. We present SN spectra obtained in 2006 and 2007 using the NTT and the NOT. Aims. We provide an atlas of SN spectra in the range z =0.03-0.32 that complements the well-sampled lightcurves from SDSS-II in the forthcoming three-year SDSS SN cosmology analysis. The sample can, for example, be used for spectral studies of SNe Ia, which are critical for understanding potential systematic effects when SNe are used to determine cosmological distances. Methods. The spectra were reduced in a uniform manner, and special care was taken in estimating the uncertainties for the different processing st...

  1. Purple dwarfs: New L subdwarfs from UKIDSS and SDSS

    Directory of Open Access Journals (Sweden)

    Marocco F.

    2013-04-01

    Full Text Available The first L subdwarf was a discovered only ten years ago. Less than ten L subdwarfs been published in the literature to date. Metal-poor ultracool atmospheres has not been well understood. Halo mass function cross substellar limit has not been measured. We used UKIDSS and SDSS to search for L subdwarfs. We have confirmed some new L subdwarfs and are following up more candidates with ground based large telescopes. We discussed spectral features of L subdwarfs and halo brown dwarfs.

  2. The SDSS data archive server

    Energy Technology Data Exchange (ETDEWEB)

    Neilsen, Eric H., Jr.; /Fermilab

    2007-10-01

    The Sloan Digital Sky Survey (SDSS) Data Archive Server (DAS) provides public access to data files produced by the SDSS data reduction pipeline. This article discusses challenges in public distribution of data of this volume and complexity, and how the project addressed them. The Sloan Digital Sky Survey (SDSS)1 is an astronomical survey of covering roughly one quarter of the night sky. It contains images of this area, a catalog of almost 300 million objects detected in those images, and spectra of more than a million of these objects. The catalog of objects includes a variety of data on each object. These data include not only basic information but also fit parameters for a variety of models, classifications by sophisticated object classification algorithms, statistical parameters, and more. If the survey contains the spectrum of an object, the catalog includes a variety of other parameters derived from its spectrum. Data processing and catalog generation, described more completely in the SDSS Early Data Release2 paper, consists of several stages: collection of imaging data, processing of imaging data, selection of spectroscopic targets from catalogs generated from the imaging data, collection of spectroscopic data, processing of spectroscopic data, and loading of processed data into a database. Each of these stages is itself a complex process. For example, the software that processes the imaging data determines and removes some instrumental signatures in the raw images to create 'corrected frames', models the point spread function, models and removes the sky background, detects objects, measures object positions, measures the radial profile and other morphological parameters for each object, measures the brightness of each object using a variety of methods, classifies the objects, calibrates the brightness measurements against survey standards, and produces a variety of quality assurance plots and diagnostic tables. The complexity of the spectroscopic

  3. Exploring the SDSS Data Set with Linked Scatter Plots. I. EMP, CEMP, and CV Stars

    Science.gov (United States)

    Carbon, Duane F.; Henze, Christopher; Nelson, Bron C.

    2017-02-01

    We present the results of a search for extremely metal-poor (EMP), carbon-enhanced metal-poor (CEMP), and cataclysmic variable (CV) stars using a new exploration tool based on linked scatter plots (LSPs). Our approach is especially designed to work with very large spectrum data sets such as the SDSS, LAMOST, RAVE, and Gaia data sets, and it can be applied to stellar, galaxy, and quasar spectra. As a demonstration, we conduct our search using the SDSS DR10 data set. We first created a 3326-dimensional phase space containing nearly 2 billion measures of the strengths of over 1600 spectral features in 569,738 SDSS stars. These measures capture essentially all the stellar atomic and molecular species visible at the resolution of SDSS spectra. We show how LSPs can be used to quickly isolate and examine interesting portions of this phase space. To illustrate, we use LSPs coupled with cuts in selected portions of phase space to extract EMP stars, CEMP stars, and CV stars. We present identifications for 59 previously unrecognized candidate EMP stars and 11 previously unrecognized candidate CEMP stars. We also call attention to 2 candidate He ii emission CV stars found by the LSP approach that have not yet been discussed in the literature.

  4. SDSS spectroscopic survey of stars

    CERN Document Server

    Ivezic, Z; Uomoto, A; Bond, N; Beers, T; Allende-Prieto, C; Wilhelm, R; Lee, Y S; Sivarani, T; Juric, M; Lupton, R; Rockosi, C M; Knapp, G; Gunn, J; Yanny, B; Jester, S; Kent, S; Pier, J; Munn, J A; Richards, G; Newberg, H; Blanton, M; Eisenstein, D; Hawley, S; Anderson, S; Harris, H; Kiuchi, F; Chen, A; Bushong, J; Sohi, H; Haggard, D; Kimball, A; Barentine, J; Brewington, H; Harvanek, M; Kleinman, S; Krzesínski, J; Long, D; Nitta, A; Snedden, S A

    2007-01-01

    In addition to optical photometry of unprecedented quality, the Sloan Digital Sky Survey (SDSS) is also producing a massive spectroscopic database. We discuss determination of stellar parameters, such as effective temperature, gravity and metallicity from SDSS spectra, describe correlations between kinematics and metallicity, and study their variation as a function of the position in the Galaxy. We show that stellar parameter estimates by Beers et al. show a good correlation with the position of a star in the g-r vs. u-g color-color diagram, thereby demonstrating their robustness as well as a potential for photometric parameter estimation methods. Using Beers et al. parameters, we find that the metallicity distribution of the Milky Way stars at a few kpc from the galactic plane is bimodal with a local minimum at [Z/Zo]~ -1.3. The median metallicity for the low-metallicity [Z/Zo] -1.3 sample. We also find that the low-metallicity sample has ~2.5 times larger velocity dispersion and that it does not rotate (at ...

  5. The SDSS-III BOSS quasar lens survey: discovery of 13 gravitationally lensed quasars

    Science.gov (United States)

    More, Anupreeta; Oguri, Masamune; Kayo, Issha; Zinn, Joel; Strauss, Michael A.; Santiago, Basilio X.; Mosquera, Ana M.; Inada, Naohisa; Kochanek, Christopher S.; Rusu, Cristian E.; Brownstein, Joel R.; da Costa, Luiz N.; Kneib, Jean-Paul; Maia, Marcio A. G.; Quimby, Robert M.; Schneider, Donald P.; Streblyanska, Alina; York, Donald G.

    2016-02-01

    We report the discovery of 13 confirmed two-image quasar lenses from a systematic search for gravitationally lensed quasars in the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS). We adopted a methodology similar to that used in the SDSS Quasar Lens Search (SQLS). In addition to the confirmed lenses, we report 11 quasar pairs with small angular separations ( ≲ 2 arcsec) confirmed from our spectroscopy, which are either projected pairs, physical binaries, or possibly quasar lens systems whose lens galaxies have not yet been detected. The newly discovered quasar lens system, SDSS J1452+4224 at zs ≈ 4.8 is one of the highest redshift multiply imaged quasars found to date. Furthermore, we have over 50 good lens candidates yet to be followed up. Owing to the heterogeneous selection of BOSS quasars, the lens sample presented here does not have a well-defined selection function.

  6. The SDSS-III BOSS quasar lens survey: discovery of thirteen gravitationally lensed quasars

    CERN Document Server

    More, Anupreeta; Kayo, Issha; Zinn, Joel; Strauss, Michael A; Santiago, Basilio X; Mosquera, Ana M; Inada, Naohisa; Kochanek, Christopher S; Rusu, Cristian E; Brownstein, Joel R; da Costa, Luiz N; Kneib, Jean-Paul; Maia, Marcio A G; Quimby, Robert M; Schneider, Donald P; Streblyanska, Alina; York, Donald G

    2015-01-01

    We report the discovery of 13 confirmed two-image quasar lenses from a systematic search for gravitationally lensed quasars in the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS). We adopted a methodology similar to that used in the SDSS Quasar Lens Search (SQLS). In addition to the confirmed lenses, we report 11 quasar pairs with small angular separations ($\\lesssim$2") confirmed from our spectroscopy, which are either projected pairs, physical binaries, or possibly quasar lens systems whose lens galaxies have not yet been detected. The newly discovered quasar lens system, SDSS J1452+4224 at zs$\\approx$4.8 is one of the highest redshift multiply imaged quasars found to date. Furthermore, we have over 50 good lens candidates yet to be followed up. Owing to the heterogeneous selection of BOSS quasars, the lens sample presented here does not have a well-defined selection function.

  7. Quasar SDSS J142507.32+323137.4: dual AGNs?

    Institute of Scientific and Technical Information of China (English)

    Zhi-Xin Peng; Yan-Mei Chen; Qiu-Sheng Gu; Chen Hu

    2011-01-01

    We analyze the optical spectrum of type 1 QSO SDSS J1425+3231. This object is interesting since its narrow emission lines, such as [O Ⅲ]λλ4959, 5007, are double-peaked, and the line structure can be modeled well by three Gaussian components: two components for the two peaks (we refer to the peaks at low/high redshift as “the blue/red component”) and another one for the line wing which has the same line center as that of the blue component, but is ~ 3 times broader. The separation between the blue and red components is ~ 500km s-1 with the blue component being ~2 times broader than the red one. The Hβ emission can be separated into four components: two for the double-peaked narrow line and two for the broad line which comes from the broad line regions. The black hole mass estimated from the broad Hβ emission line using the typical reverberation mapping relation is 0.85 × 108 M⊙, which is consistent with that derived from parameters of [O Ⅲ]λ 5007 of the blue component.We suggest that this QSO might be a dual AGN system; the broad Hβ emission line is mainly contributed by the primary black hole (traced by the blue component) while the broad Hβ component of the secondary black hole (traced by the red component)is hard to be separated out considering a resolution of ~ 2000 for SDSS spectra or it may be totally obscured by the dusty torus.

  8. A Nearby Old Halo White Dwarf Candidate from the Sloan Digital Sky Survey

    Science.gov (United States)

    2008-07-01

    2008 May 27 ABSTRACT We report the discovery of a nearby old halo white dwarf (WD) candidate from the Sloan Digital Sky Survey ( SDSS ). SDSS J110217.48...411315.4 has a proper motion of 1′′.75 yr−1 and redder optical colors than all other known featureless (type DC) WDs. We present SDSS imaging and...complicated physics of the dense atmospheres of cool WDs. Key words: stars: individual ( SDSS J110217.48+411315.4) – white dwarfs Online-only material

  9. Spectral Synthesis of SDSS Galaxies

    CERN Document Server

    Sodre, J; Mateus, A; Stasinska, G; Gomes, J M

    2005-01-01

    We investigate the power of spectral synthesis as a mean to estimate physical properties of galaxies. Spectral synthesis is nothing more than the decomposition of an observed spectrum in terms of a superposition of a base of simple stellar populations of various ages and metallicities (here from Bruzual & Charlot 2003), producing as output the star-formation and chemical histories of a galaxy, its extinction and velocity dispersion. We discuss the reliability of this approach and apply it to a volume limited sample of 50362 galaxies from the SDSS Data Release 2, producing a catalog of stellar population properties. A comparison with recent estimates of both observed and physical properties of these galaxies obtained by other groups shows good qualitative and quantitative agreement, despite substantial differences in the method of analysis. The confidence in the method is further strengthened by several empirical and astrophysically reasonable correlations between synthesis results and independent quantiti...

  10. SDSS spectroscopy for blazars in the Fermi LAT bright AGN sample

    Institute of Scientific and Technical Information of China (English)

    Zhao-Yu Chen; Min-Feng Gu; Zhong-Hui Fan; Xin-Wu Cao

    2009-01-01

    We have collected all available spectra and photometric data from the SDSS catalog for bright AGNs complied from the first three months of the Fermi large area telescope all-sky survey.Based on the 106 high-confidence and 11 low-confidence associated bright AGN list,the photometry data are collected from SDSS DR7 for 28 sources (12 BL Lacs and 16 FSRQs),two of which are low-confidence associated bright AGNs.Among these 28 SDSS photometric sources,SDSS spectra are available for 20 sources (6 BL Lacs and 14 FSRQs).The black hole masses MBH and the broad line region (BLR) luminosity were obtained for 14 FSRQs by measuring the line-widths and strengths of broad emission lines from the SDSS spectra.The broad emission line measurements of five FSRQs are presented for the first time in this work.The optical continuum emission of these 14 FSRQs is found to be likely dominated by the non-thermal jet emission by comparing the relationship between the broad Mg Ⅱ line and continuum luminosity to that of radio-quiet AGNs.The black hole mass of the 14 FSRQs ranges from 10~(8.2) M_⊙ to 10~(9.9) M_⊙,with most of the sources larger than 10~9 M_⊙.The Eddington ratio L_(bol)/L_(Edd) ranges from 10~(-1.5) to~1.This implies that an optically thin,geometrically thick accretion disk may exist in these FSRQs.

  11. Mini-Survey on SDSS OIII AGN with Swift

    Science.gov (United States)

    Angelini, Lorella

    2008-01-01

    The number of AGN and their luminosity distribution are crucial parameters for our understanding of the AGN phenomenon. There is a common wisdom that every massive galaxy has a massive black hole. However, most of these objects either are not radiating or until recently have been very difficult to detect. The Sloan Digital Sky Survey (SDSS) data, based on the [OIII] line indicate that perhaps up to 20% of all galaxies may be classified as AGN a surprising result that must be checked with independent data. X-ray surveys have revealed that hard X-ray selected AGN show a strong luminosity dependent evolution and their luminosity function (LF) shows a dramatic break towards low $L_X$ (at all $z$). This is seen for all types of AGN, but is stronger for the broad-line objects. In sharp contrast, the local LF of {it optically-selected samples} shows no such break and no differences between narrow and broad-line objects. Assuming both hard X-ray and [O{\\sc iii}] emission are fair indicators of AGN activity, it is important to understand this discrepancy. We present here the results of a min-survey done with Swift on a selected sample of SDSS selected AGN. The objects have been sampled at different L([O{\\sc iii}]) to check the relation with the $L_X$ observed with Swift.

  12. Mini-Survey of SDSS OIII AGN with Swift

    Science.gov (United States)

    Angelina, Lorella; George, Ian

    2007-01-01

    There is a common wisdom that every massive galaxy has a massive block hole. However, most of these objects either are not radiating or until recently have been very difficult to detect. The Sloan Digital Sky Survey (SDSS) data, based on the [OIII] line indicate that perhaps up to 20% of all galaxies may be classified as AGN a surprising result that must be checked with independent data. X-ray surveys have revealed that hard X-ray selected AGN show a strong luminosity dependent evolution and their luminosity function (LF) shows a dramatic break towards low Lx (at all z). This is seen for all types of AGN, but is stronger for the broad-line objects. In sharp contrast, the local LF of (optically-selected samples) shows no such break and no differences between narrow and broad-line objects. Assuming both hard X-ray and [OIII] emission are fair indicators of AGN activity, it is important to understand this discrepancy. We present here the results of a mini-survey done with Swift on a selected sample of SDSS selected AGN. The objects have been sampled at different L([OIII]) to check the relation with the Lx observed with Swift.

  13. High-energy observations of the state transition of the X-ray nova and black hole candidate XTE J1720-318

    DEFF Research Database (Denmark)

    Bel, M.C.; Rodriguez, J.; Sizun, P.

    2004-01-01

    , typical of a black-hole binary in the so-called High/Soft State. We then followed the evolution of the source outburst over several months using the INTEGRAL Galactic Centre survey observations. The source became active again at the end of March: it showed a clear transition towards a much harder state...

  14. ATCA radio detection of MAXI J1535-571 indicates it is a strong black hole X-ray binary candidate

    Science.gov (United States)

    Russell, T. D.; Miller-Jones, J. C. A.; Sivakoff, G. R.; Tetarenko, A. J.; Jacpot Xrb Collaboration

    2017-09-01

    MAXI J1535-571 is a newly discovered Galactic hard X-ray transient (GCN #21788, ATels #10699, 10700). Following its identification as a potential hard-state low-mass X-ray binary (ATel #10702) and a potential black hole system (ATel #10708), we conducted target of opportunity observations of this source with the Australia Telescope Compact Array (ATCA).

  15. Investigating the disc-jet coupling in accreting compact objects using the black hole candidate Swift J1753.5-0127

    NARCIS (Netherlands)

    Soleri, P.; Fender, R.; Tudose, V.; Maitra, D.; Bell, M.; Linares, M.; Altamirano, D.; Wijnands, R.; Belloni, T.; Casella, P.; Miller-Jones, J. C. A.; Muxlow, T.; Klein-Wolt, M.; Garrett, M.; van der Klis, M.

    2010-01-01

    In studies of accreting black holes in binary systems, empirical relations have been proposed to quantify the coupling between accretion processes and ejection mechanisms. These processes are probed, respectively, by means of X-ray and radio/optical-infrared observations. The relations predict, give

  16. The black hole candidate XTE J1752-223 towards and in quiescence: optical and simultaneous X-ray-radio observations

    NARCIS (Netherlands)

    Ratti, E.M.; Jonker, P.G.; Miller-Jones, J.C.A.; Torres, M.A.P.; Homan, J.; Markoff, S.; Tomsick, J.; Kaaret, P.; Wijnands, R.; Gallo, E.; Özel, F.; Steeghs, D.T.H.; Fender, R.P.

    2012-01-01

    We present optical, X-ray and radio observations of the black hole transient (BHT) XTE J1752−223 towards and in quiescence. Optical photometry shows that the quiescent magnitude of XTE J1752−223 is fainter than 24.4 mag in the i′ band. A comparison with measurements of the source during its 2009-201

  17. Cataclysmic Variables from SDSS. VIII. The Final Year (2007-2008)

    CERN Document Server

    Szkody, Paula; Brooks, Keira; Gaensicke, Boris T; Kronberg, Martin; Riecken, Thomas; Ross, Nicholas P; Schmidt, Gary D; Schneider, Donald P; Agueros, Marcel A; Gomez-Moran, Ada N; Knapp, Gillian R; Schreiber, Matthias R; Schwope, Axel D

    2011-01-01

    This paper completes the series of cataclysmic variables (CVs) identified from the Sloan Digital Sky Survey I/II. The coordinates, magnitudes and spectra of 33 CVs are presented. Among the 33 are eight systems known previous to SDSS (CT Ser, DO Leo, HK Leo, IR Com, V849 Her, V405 Peg, PG1230+226 and HS0943+1404), as well as nine objects recently found through various photometric surveys. Among the systems identified since the SDSS are two polar candidates, two intermediate polar candidates and one candidate for containing a pulsating white dwarf. Our followup data have confirmed a polar candidate from Paper VII and determined tentative periods for three of the newly identified CVs. A complete summary table of the 285 CVs with spectra from SDSS I/II is presented as well as a link to an online table of all known CVs from both photometry and spectroscopy that will continue to be updated as future data appear.

  18. THE z = 5 QUASAR LUMINOSITY FUNCTION FROM SDSS STRIPE 82

    Energy Technology Data Exchange (ETDEWEB)

    McGreer, Ian D.; Fan Xiaohui [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721-0065 (United States); Jiang Linhua [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287 (United States); Richards, Gordon T. [Department of Physics, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104 (United States); Strauss, Michael A. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Ross, Nicholas P.; White, Martin [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 92420 (United States); Shen Yue [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Schneider, Donald P.; Brandt, W. Niel [Department of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802 (United States); Myers, Adam D. [Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071 (United States); DeGraf, Colin [McWilliams Center for Cosmology, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213 (United States); Glikman, Eilat [Department of Physics and Yale Center for Astronomy and Astrophysics, Yale University, P.O. Box 208121, New Haven, CT 06520-8121 (United States); Ge Jian [Department of Astronomy, University of Florida, 211 Bryant Space Science Center, Gainesville, FL 32611 (United States); Streblyanska, Alina, E-mail: imcgreer@as.arizona.edu [Instituto de Astrofisica de Canarias (IAC), E-38200 La Laguna, Tenerife (Spain)

    2013-05-10

    We present a measurement of the Type I quasar luminosity function at z = 5 using a large sample of spectroscopically confirmed quasars selected from optical imaging data. We measure the bright end (M{sub 1450} < -26) with Sloan Digital Sky Survey (SDSS) data covering {approx}6000 deg{sup 2}, then extend to lower luminosities (M{sub 1450} < -24) with newly discovered, faint z {approx} 5 quasars selected from 235 deg{sup 2} of deep, coadded imaging in the SDSS Stripe 82 region (the celestial equator in the Southern Galactic Cap). The faint sample includes 14 quasars with spectra obtained as ancillary science targets in the SDSS-III Baryon Oscillation Spectroscopic Survey, and 59 quasars observed at the MMT and Magellan telescopes. We construct a well-defined sample of 4.7 < z < 5.1 quasars that is highly complete, with 73 spectroscopic identifications out of 92 candidates. Our color selection method is also highly efficient: of the 73 spectra obtained, 71 are high-redshift quasars. These observations reach below the break in the luminosity function (M{sub 1450}{sup *}{approx}-27). The bright-end slope is steep ({beta} {approx}< -4), with a constraint of {beta} < -3.1 at 95% confidence. The break luminosity appears to evolve strongly at high redshift, providing an explanation for the flattening of the bright-end slope reported previously. We find a factor of {approx}2 greater decrease in the number density of luminous quasars (M{sub 1450} < -26) from z = 5 to z = 6 than from z = 4 to z = 5, suggesting a more rapid decline in quasar activity at high redshift than found in previous surveys. Our model for the quasar luminosity function predicts that quasars generate {approx}30% of the ionizing photons required to keep hydrogen in the universe ionized at z = 5.

  19. A strong and broad iron line in the XMM-Newton spectrum of the new X-ray transient and black-hole candidate XTE J1652-453

    CERN Document Server

    Hiemstra, Beike; Done, Chris; Trigo, Maria Diaz; Altamirano, Diego; Casella, Piergiorgio

    2010-01-01

    We observed the new X-ray transient and black-hole candidate XTE J1652-453 simultaneously with XMM-Newton and the Rossi X-ray Timing Explorer (RXTE). The observation was done during the decay of the 2009 outburst, when XTE J1652-453 was in the hard-intermediate state. The spectrum shows a strong and broad iron emission line with an equivalent width of ~ 450 eV. The profile is consistent with that of a line being produced by reflection off the accretion disk, broadened by relativistic effects close to the black hole. The best-fitting inner radius of the accretion disk is ~ 4 gravitational radii. Assuming that the accretion disk is truncated at the radius of the innermost stable circular orbit, the black hole in XTE J1652-453 has a spin parameter of ~ 0.5. The power spectrum of the RXTE observation has an additional variability component above 50 Hz, which is typical for the hard-intermediate state. No coherent quasi-periodic oscillations at low frequency are apparent in the power spectrum, which may imply that...

  20. REVEALING THE NATURE OF EXTREME CORONAL-LINE EMITTER SDSS J095209.56+214313.3

    Energy Technology Data Exchange (ETDEWEB)

    Palaversa, Lovro; Holl, Berry [Observatoire astronomique de l’Université de Genève, 51 chemin des Maillettes, CH-1290 Sauverny (Switzerland); Gezari, Suvi [Department of Astronomy, University of Maryland, College Park, MD 20742-2421 (United States); Sesar, Branimir [Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany); Stuart, J. Scott [Lincoln Laboratory, Massachusetts Institute of Technology, 244 Wood Street, Lexington, MA 02420-9108 (United States); Wozniak, Przemyslaw [Los Alamos National Laboratory, 30 Bikini Atoll Road, Los Alamos, NM 87545-0001 (United States); Ivezić, Željko, E-mail: lovro.palaversa@unige.ch [University of Washington, Department of Astronomy, P.O. Box 351580, Seattle, WA 98195-1580 (United States)

    2016-03-10

    Extreme coronal-line emitter (ECLE) SDSS J095209.56+214313.3, known by its strong, fading, high-ionization lines, has been a long-standing candidate for a tidal disruption event; however, a supernova (SN) origin has not yet been ruled out. Here we add several new pieces of information to the puzzle of the nature of the transient that powered its variable coronal lines: (1) an optical light curve from the Lincoln Near Earth Asteroid Research (LINEAR) survey that serendipitously catches the optical flare, and (2) late-time observations of the host galaxy with the Swift Ultraviolet and Optical Telescope (UVOT) and X-ray telescope (XRT) and the ground-based Mercator telescope. The well-sampled, ∼10 yr long, unfiltered LINEAR light curve constrains the onset of the flare to a precision of ±5 days and enables us to place a lower limit on the peak optical magnitude. Difference imaging allows us to estimate the location of the flare in proximity of the host galaxy core. Comparison of the GALEX data (early 2006) with the recently acquired Swift UVOT (2015 June) and Mercator observations (2015 April) demonstrates a decrease in the UV flux over a ∼10 yr period, confirming that the flare was UV-bright. The long-lived UV-bright emission, detected 1.8 rest-frame years after the start of the flare, strongly disfavors an SN origin. These new data allow us to conclude that the flare was indeed powered by the tidal disruption of a star by a supermassive black hole and that tidal disruption events are in fact capable of powering the enigmatic class of ECLEs.

  1. The 2dF-SDSS LRG and QSO Survey: The spectroscopic QSO catalogue

    CERN Document Server

    Croom, Scott M; Shanks, Tom; Boyle, Brian J; Sharp, Robert G; Bland-Hawthorn, Joss; Bridges, Terry; Brunner, Robert J; Cannon, Russell; Carson, Daniel; Chiu, Kuenley; Colless, Matthew; Couch, Warrick; De Propris, Roberto; Drinkwater, Michael J; Edge, Alastair; Fine, Stephen; Loveday, Jon; Miller, Lance; Myers, Adam D; Nichol, Robert C; Outram, Phil; Pimbblet, Kevin; Roseboom, Isaac; Ross, Nicholas; Schneider, Donald P; Smith, Allyn; Stoughton, Chris; Strauss, Michael A; Wake, David

    2008-01-01

    We present the final spectroscopic QSO catalogue from the 2dF-SDSS LRG and QSO (2SLAQ) Survey. This is a deep, 18candidate QSOs were selected from SDSS photometry and observed spectroscopically with the 2dF spectrograph on the Anglo-Australian Telescope. This sample covers an area of 191.9 deg^2 and contains new spectra of 16326 objects, of which 8764 are QSOs, and 7623 are newly discovered (the remainder were previously identified by the 2QZ and SDSS surveys). The full QSO sample (including objects previously observed in the SDSS and 2QZ surveys) contains 12702 QSOs. The new 2SLAQ spectroscopic data set also contains 2343 Galactic stars, including 362 white dwarfs, and 2924 narrow emission line galaxies with a median redshift of z=0.22. We present detailed completeness estimates for the survey, based on modelling of QSO colours, including host galaxy contributi...

  2. WISE Photometry for 400 Million SDSS Sources

    Science.gov (United States)

    Lang, Dustin; Hogg, David W.; Schlegel, David J.

    2016-02-01

    We present photometry of images from the Wide-Field Infrared Survey Explorer (WISE) of over 400 million sources detected by the Sloan Digital Sky Survey (SDSS). We use a “forced photometry” technique, using measured SDSS source positions, star-galaxy classification, and galaxy profiles to define the sources whose fluxes are to be measured in the WISE images. We perform photometry with The Tractor image modeling code, working on our “unWISE” coaddds and taking account of the WISE point-spread function and a noise model. The result is a measurement of the flux of each SDSS source in each WISE band. Many sources have little flux in the WISE bands, so often the measurements we report are consistent with zero given our uncertainties. However, for many sources we get 3σ or 4σ measurements; these sources would not be reported by the “official” WISE pipeline and will not appear in the WISE catalog, yet they can be highly informative for some scientific questions. In addition, these small-signal measurements can be used in stacking analyses at the catalog level. The forced photometry approach has the advantage that we measure a consistent set of sources between SDSS and WISE, taking advantage of the resolution and depth of the SDSS images to interpret the WISE images; objects that are resolved in SDSS but blended together in WISE still have accurate measurements in our photometry. Our results, and the code used to produce them, are publicly available at http://unwise.me.

  3. WISE PHOTOMETRY FOR 400 MILLION SDSS SOURCES

    Energy Technology Data Exchange (ETDEWEB)

    Lang, Dustin [Department of Astronomy and Astrophysics and Dunlap Institute, University of Toronto, 50 Saint George Street, Toronto, ON, M5S 3H4 (Canada); Hogg, David W. [Center for Cosmology and Particle Physics, Department of Physics, New York University, 4 Washington Place, New York, NY 10003 (United States); Schlegel, David J., E-mail: dstndstn@gmail.com [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States)

    2016-02-15

    We present photometry of images from the Wide-Field Infrared Survey Explorer (WISE) of over 400 million sources detected by the Sloan Digital Sky Survey (SDSS). We use a “forced photometry” technique, using measured SDSS source positions, star–galaxy classification, and galaxy profiles to define the sources whose fluxes are to be measured in the WISE images. We perform photometry with The Tractor image modeling code, working on our “unWISE” coaddds and taking account of the WISE point-spread function and a noise model. The result is a measurement of the flux of each SDSS source in each WISE band. Many sources have little flux in the WISE bands, so often the measurements we report are consistent with zero given our uncertainties. However, for many sources we get 3σ or 4σ measurements; these sources would not be reported by the “official” WISE pipeline and will not appear in the WISE catalog, yet they can be highly informative for some scientific questions. In addition, these small-signal measurements can be used in stacking analyses at the catalog level. The forced photometry approach has the advantage that we measure a consistent set of sources between SDSS and WISE, taking advantage of the resolution and depth of the SDSS images to interpret the WISE images; objects that are resolved in SDSS but blended together in WISE still have accurate measurements in our photometry. Our results, and the code used to produce them, are publicly available at http://unwise.me.

  4. Magnetic White Dwarf Stars in the SDSS

    CERN Document Server

    Kepler, S O; Jordan, Stefan; Kleinman, Scot J; Kulebi, Baybars; Koester, Detlev; Peçanha, Viviane; Castanheira, Bárbara G; Nitta, Atsuko; Costa, José Eduardo da Silveira; Winget, Don Earl; Kanaan, Antonio; Fraga, Luciano

    2012-01-01

    To obtain a better statistics on the occurrence of magnetism among white dwarfs, we searched the spectra of the hydrogen atmosphere white dwarf stars (DAs) in the Data Release 7 of the Sloan Digital Sky Survey (SDSS) for Zeeman splittings and estimated the magnetic fields. We found 521 DAs with detectable Zeeman splittings, with fields in the range from around 1 MG to 733 MG, which amounts to 4% of all DAs observed. As the SDSS spectra have low signal-to-noise ratios, we carefully investigated by simulations with theoretical spectra how reliable our detection of magnetic field was.

  5. Growth of Primordial Black Holes

    Science.gov (United States)

    Harada, Tomohiro

    Primordial black holes have important observational implications through Hawking evaporation and gravitational radiation as well as being a candidate for cold dark matter. Those black holes are assumed to have formed in the early universe typically with the mass scale contained within the Hubble horizon at the formation epoch and subsequently accreted mass surrounding them. Numerical relativity simulation shows that primordial black holes of different masses do not accrete much, which contrasts with a simplistic Newtonian argument. We see that primordial black holes larger than the 'super-horizon' primordial black holes have decreasing energy and worm-hole like struture, suggesting the formation through quamtum processes.

  6. VizieR Online Data Catalog: Exploring the SDSS data set. I. EMP & CV stars (Carbon+, 2017)

    Science.gov (United States)

    Carbon, D. F.; Henze, C.; Nelson, B. C.

    2017-08-01

    We present the results of a search for extremely metal-poor (EMP), carbon-enhanced metal-poor (CEMP), and cataclysmic variable (CV) stars using a new exploration tool based on linked scatter plots (LSPs). Our approach is especially designed to work with very large spectrum data sets such as the SDSS, LAMOST, RAVE, and Gaia data sets, and it can be applied to stellar, galaxy, and quasar spectra. As a demonstration, we conduct our search using the SDSS DR10 data set. We first created a 3326-dimensional phase space containing nearly 2 billion measures of the strengths of over 1600 spectral features in 569738 SDSS stars. These measures capture essentially all the stellar atomic and molecular species visible at the resolution of SDSS spectra. We show how LSPs can be used to quickly isolate and examine interesting portions of this phase space. To illustrate, we use LSPs coupled with cuts in selected portions of phase space to extract EMP stars, CEMP stars, and CV stars. We present identifications for 59 previously unrecognized candidate EMP stars and 11 previously unrecognized candidate CEMP stars. We also call attention to 2 candidate He II emission CV stars found by the LSP approach that have not yet been discussed in the literature. (3 data files).

  7. A Periodically Varying Luminous Quasar at z=2 from the Pan-STARRS1 Medium Deep Survey: A Candidate Supermassive Black Hole Binary in the Gravitational Wave-Driven Regime

    CERN Document Server

    Liu, Tingting; Heinis, Sebastien; Magnier, Eugene A; Burgett, William S; Chambers, Kenneth; Flewelling, Heather; Huber, Mark; Hodapp, Klaus W; Kaiser, Nicholas; Kudritzki, Rolf-Peter; Tonry, John L; Wainscoat, Richard J; Waters, Christopher

    2015-01-01

    Supermassive black hole binaries (SMBHBs) should be an inevitable consequence of the hierarchical growth of massive galaxies through mergers, and the strongest sirens of gravitational waves (GWs) in the cosmos. And yet, their direct detection has remained elusive due to the compact (sub-parsec) orbital separations of gravitationally bound SMBHBs. Here we exploit a theoretically predicted signature of a SMBHB in the time domain: periodic variability caused by a mass accretion rate that is modulated by the binary's orbital motion. We report our first significant periodically varying quasar detection from the systematic search in the Pan-STARRS1 (PS1) Medium Deep Survey. Our SMBHB candidate, PSO J334.2028+01.4075, is a luminous radio-loud quasar at $z=2.060$, with extended baseline photometry from the Catalina Real-Time Transient Survey, as well as archival spectroscopy from the FIRST Bright Quasar Survey. The observed period ($542 \\pm 15$ days) and estimated black hole mass ($\\log (M_{\\rm BH}/M_\\odot) = 9.97 \\p...

  8. Braneworld Black Holes

    CERN Document Server

    Whisker, Richard

    2008-01-01

    In this thesis we investigate black holes in the Randall-Sundrum braneworld scenario. We begin with an overview of extra-dimensional physics, from the original proposal of Kaluza and Klein up to the modern braneworld picture of extra dimensions. A detailed description of braneworld gravity is given, with particular emphasis on its compatibility with experimental tests of gravity. We then move on to a discussion of static, spherically symmetric braneworld black hole solutions. Assuming an equation of state for the ``Weyl term'', which encodes the effects of the extra dimension, we are able to classify the general behaviour of these solutions. We then use the strong field limit approach to investigate the gravitational lensing properties of some candidate braneworld black hole solutions. It is found that braneworld black holes could have significantly different observational signatures to the Schwarzschild black hole of standard general relativity. Rotating braneworld black hole solutions are also discussed, an...

  9. Accretion, primordial black holes and standard cosmology

    Indian Academy of Sciences (India)

    B Nayak; P Singh

    2011-01-01

    Primordial black holes evaporate due to Hawking radiation. We find that the evaporation times of primordial black holes increase when accretion of radiation is included. Thus, depending on accretion efficiency, more primordial black holes are existing today, which strengthens the conjecture that the primordial black holes are the proper candidates for dark matter.

  10. Detailed modelling of a large sample of Herschel sources in the Lockman Hole: identification of cold dust and of lensing candidates through their anomalous SEDs

    CERN Document Server

    Rowan-Robinson, Michael; Wardlow, Julie; Farrah, Duncan; Oliver, Seb; Bock, Jamie; Clarke, Charlotte; Clements, David; Ibar, Edo; Gonzalez-Solares, Eduardo; Marchetti, Lucia; Scott, Douglas; Smith, Anthony; Vaccari, Mattia; Valtchanov, Ivan

    2014-01-01

    We have studied in detail a sample of 967 SPIRE sources with 5-sigma detections at 350 and 500 micron and associations with Spitzer-SWIRE 24 micron galaxies in the HerMES-Lockman survey area, fitting their mid- and far-infrared, and submillimetre, SEDs in an automatic search with a set of six infrared templates. For almost 300 galaxies we have modelled their SEDs individually to ensure the physicality of the fits. We confirm the need for the new cool and cold cirrus templates, and also of the young starburst template, introduced in earlier work. We also identify 109 lensing candidates via their anomalous SEDs and provide a set of colour-redshift constraints which allow lensing candidates to be identified from combined Herschel and Spitzer data. The picture that emerges of the submillimetre galaxy population is complex, comprising ultraluminous and hyperluminous starbursts, lower luminosity galaxies dominated by interstellar dust emission, lensed galaxies and galaxies with surprisingly cold (10-13K) dust. 11 %...

  11. Spectral Energy Distributions of SDSS Blazars

    Indian Academy of Sciences (India)

    H. Z. Li; L. E. Chen

    2014-09-01

    We compiled the radio, optical and X-ray data for SDSS sample, and presented broad band spectral index. The broad band energy distribution reveals that FSRQs and LBLs objects have similar spectral properties. However, HBLs have a separate distinct property. Even so, a unified scheme was also revealed from colour–colour diagram.

  12. Host Galaxy Spectra and Consequences for SN Typing from the SDSS SN Survey

    Energy Technology Data Exchange (ETDEWEB)

    Olmstead, Matthew D.; Brown, Peter J.; Sako, Masao; Bassett, Bruce; Bizyaev, Dmitry; Brinkmann, J.; Brownstein, Joel R.; Brewington, Howard; Campbell, Heather; D’Andrea, Chris B.; Dawson, Kyle S.; Ebelke, Garrett L.; Frieman, Joshua A.; Galbany, Lluís; Garnavich, Peter; Gupta, Ravi R.; Hlozek, Renee; Jha, Saurabh W.; Kunz, Martin; Lampeitl, Hubert; Malanushenko, Elena; Malanushenko, Viktor; Marriner, John; Miquel, Ramon; Montero-Dorta, Antonio D.; Nichol, Robert C.; Oravetz, Daniel J.; Pan, Kaike; Schneider, Donald P.; Simmons, Audrey E.; Smith, Mathew; Snedden, Stephanie A.

    2014-03-06

    We present the spectroscopy from 5254 galaxies that hosted supernovae (SNe) or other transient events in the Sloan Digital Sky Survey II (SDSS-II). Obtained during SDSS-I, SDSS-II, and the Baryon Oscillation Spectroscopic Survey (BOSS), this sample represents the largest systematic, unbiased, magnitude limited spectroscopic survey of supernova (SN) host galaxies. Using the host galaxy redshifts, we test the impact of photometric SN classification based on SDSS imaging data with and without using spectroscopic redshifts of the host galaxies. Following our suggested scheme, there are a total of 1166 photometrically classified SNe Ia when using a flat redshift prior and 1126 SNe Ia when the host spectroscopic redshift is assumed. For 1024 (87.8%) candidates classified as likely SNe Ia without redshift information, we find that the classification is unchanged when adding the host galaxy redshift. Using photometry from SDSS imaging data and the host galaxy spectra, we also report host galaxy properties for use in future nalysis of SN astrophysics. Finally, we investigate the differences in the interpretation of the light curve properties with and without knowledge of the redshift. When using the SALT2 light curve fitter, we find a 21% increase in the number of fits that converge when using the spectroscopic redshift. Without host galaxy redshifts, we find that SALT2 light curve fits are systematically biased towards lower photometric redshift estimates and redder colors in the limit of low signal-to-noise data. The general improvements in performance of the light curve fitter and the increased diversity of the host galaxy sample highlights the importance of host galaxy spectroscopy for current photometric SN surveys such as the Dark Energy Survey and future surveys such as the Large Synoptic Survey Telescope.

  13. THE SWIFT AGN AND CLUSTER SURVEY. II. CLUSTER CONFIRMATION WITH SDSS DATA

    Energy Technology Data Exchange (ETDEWEB)

    Griffin, Rhiannon D.; Dai, Xinyu [Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, OK 73019 (United States); Kochanek, Christopher S. [Department of Astronomy, Ohio State University, Columbus, OH 43210 (United States); Bregman, Joel N., E-mail: Rhiannon.D.Griffin-1@ou.edu, E-mail: xdai@ou.edu, E-mail: ckochanek@astronomy.ohio-state.edu, E-mail: jbregman@umich.edu [Department of Astronomy, University of Michigan, Ann Arbor, MI 48109 (United States)

    2016-01-15

    We study 203 (of 442) Swift AGN and Cluster Survey extended X-ray sources located in the SDSS DR8 footprint to search for galaxy over-densities in three-dimensional space using SDSS galaxy photometric redshifts and positions near the Swift cluster candidates. We find 104 Swift clusters with a >3σ galaxy over-density. The remaining targets are potentially located at higher redshifts and require deeper optical follow-up observations for confirmation as galaxy clusters. We present a series of cluster properties including the redshift, brightest cluster galaxy (BCG) magnitude, BCG-to-X-ray center offset, optical richness, and X-ray luminosity. We also detect red sequences in ∼85% of the 104 confirmed clusters. The X-ray luminosity and optical richness for the SDSS confirmed Swift clusters are correlated and follow previously established relations. The distribution of the separations between the X-ray centroids and the most likely BCG is also consistent with expectation. We compare the observed redshift distribution of the sample with a theoretical model, and find that our sample is complete for z ≲ 0.3 and is still 80% complete up to z ≃ 0.4, consistent with the SDSS survey depth. These analysis results suggest that our Swift cluster selection algorithm has yielded a statistically well-defined cluster sample for further study of cluster evolution and cosmology. We also match our SDSS confirmed Swift clusters to existing cluster catalogs, and find 42, 23, and 1 matches in optical, X-ray, and Sunyaev–Zel’dovich catalogs, respectively, and so the majority of these clusters are new detections.

  14. XMM-Newton and Chandra observations of the M31 globular cluster black hole candidate XB135: a heavyweight contender cut down to size

    CERN Document Server

    Barnard, R; Garcia, M R; Kolb, U C; Murray, S S

    2015-01-01

    CXOM31 J004252.030+413107.87 is one of the brightest X-ray sources within the D_25 region of M31, and associated with a globular cluster (GC) known as B135; we therefore call this X-ray source XB135. XB135 is a low mass X-ray binary (LMXB) that apparently exhibited hard state characteristics at 0.3--10 keV luminosities 4--6 E+38 erg/s, and the hard state is only observed below ~10% Eddington. If true, the accretor would be a high mass black hole (BH) (> ~50 M_Sun); such a BH may be formed from direct collapse of a metal-poor, high mass star, and the very low metalicity of B135 (0.015 Z_Sun) makes such a scenario plausible. We have obtained new XMM-Newton and Chandra HRC observations to shed light on the nature of this object. We find from the HRC observation that XB135 is a single point source located close to the center of B135. The new XMM-Newton spectrum is consistent with a rapidly spinning ~10--20 M_Sun BH in the steep power law or thermal dominant state, but inconsistent with the hard state that we prev...

  15. The black hole candidate XTE J1752-223 towards and in quiescence: optical and simultaneous X-ray - radio observations

    CERN Document Server

    Ratti, E M; Miller-Jones, J C A; Torres, M A P; Homan, J; Markoff, S; Tomsick, J A; Kaaret, P; Wijnands, R; Gallo, E; Ozel, F; Steeghs, D T H; Fender, R P

    2012-01-01

    We present optical, X-ray and radio observations of the black hole transient (BHT) XTE J1752-223 towards and in quiescence. Optical photometry shows that the quiescent magnitude of XTE J1752-223 is fainter than 24.4 magnitudes in the i'-band. A comparison with measurements of the source during its 2009-2010 outburst shows that the outburst amplitude is more than 8 magnitudes in the i'-band. Known X-ray properties of the source combined with the faintness of the quiescence optical counterpart and the large outburst optical amplitude point towards a short orbital period system (Porb<~6.8 h) with an M type (or later) mass donor, at a distance of 3.5<~d<~8 kpc. Simultaneous X-ray and radio data were collected with Chandra and the EVLA, allowing constraints to be placed on the quiescent X-ray and radio flux of XTE J1752-223. Furthermore, using data covering the final stage of the outburst decay, we investigated the low luminosity end of the X-ray - radio correlation for this source and compared it with ot...

  16. Repeated Short-term Spectral Softening in the Low/Hard State of the Galactic Black-Hole Candidate Swift J1753.5-0127

    CERN Document Server

    Yoshikawa, Akifumi; Nakahira, Satoshi; Matsuoka, Masaru; Negoro, Hitoshi; Mihara, Tatehiro; Tamagawa, Toru

    2015-01-01

    We report MAXI and Swift observations of short-term spectral softenings of the galactic black-hole X-ray binary Swift J1753.5-0127 in the low/hard state. These softening events are characterized by a simultaneous increase of soft X-rays (2-4 keV) and a decrease of hard X-rays (15-50 keV) lasting for a few tens of days. The X-ray energy spectra during the softening periods can be reproduced with a model consisting of a multi-color disk blackbody and its Comptonized component. The fraction of the Comptonized component decreased from 0.30 to 0.15 when the spectrum became softer; meanwhile the inner disk temperature (Tin) increased from 0.2 to 0.45 keV. These results imply that the softening events are triggered by a short-term increase of the mass accretion rate. During the observed spectral softening events, the disk flux (F) and Tin did not obey the relation: F is proportional to Tin^4, suggesting that the inner disk radius does not reach the innermost stable circular orbit.

  17. XMM-Newton and optical follow-up observations of SDSS J093249.57+472523.0 and SDSS J102347.67+003841.2

    CERN Document Server

    Homer, L; Chen, B; Henden, A; Schmidt, G; Anderson, S F; Silvestri, N M; Brinkmann, J; Homer, Lee; Szkody, Paula; Chen, Bing; Henden, Arne; Schmidt, Gary; Anderson, Scott F.; Silvestri, Nicole M.

    2005-01-01

    We report follow-up XMM-Newton and ground-based optical observations of the unusual X-ray binary SDSS J102347.67+003841.2 (=FIRST J102347.6+003841), and a new candidate intermediate polar found in the Sloan Digital Sky Survey: SDSS J093249.57+472523.0. SDSS J1023 was observed in its low-state, with similar magnitude/color (V=17.4 and B=17.9), and smooth orbital modulation as seen in most previous observations. We further refine the ephemeris (for photometric minimum) to: HJD(TT)_min= 2453081.8546(3) + E* 0.198094(1) d. It is easily detected in X-rays at an unabsorbed flux (0.01-10.0 keV) of 5x10e-13 erg/cm^2/s. Fitting a variety of models we find that: (i) either a hot (kT>~15 keV) optically thin plasma emission model (bremsstrahlung or MEKAL) or a simple power law can provide adequate fits to the data; (ii) these models prefer a low column density ~10e19 cm^-2; (iii) a neutron star atmosphere plus power law model (as found for quiescent low-mass X-ray binaries) can also produce a good fit (for plausible dist...

  18. The black hole candidate XTE J1752-223 towards and in quiescence: optical and simultaneous X-ray-radio observations

    Science.gov (United States)

    Ratti, E. M.; Jonker, P. G.; Miller-Jones, J. C. A.; Torres, M. A. P.; Homan, J.; Markoff, S.; Tomsick, J. A.; Kaaret, P.; Wijnands, R.; Gallo, E.; Özel, F.; Steeghs, D. T. H.; Fender, R. P.

    2012-07-01

    We present optical, X-ray and radio observations of the black hole transient (BHT) XTE J1752-223 towards and in quiescence. Optical photometry shows that the quiescent magnitude of XTE J1752-223 is fainter than 24.4 mag in the i' band. A comparison with measurements of the source during its 2009-2010 outburst shows that the outburst amplitude is more than 8 mag in the i' band. Known X-ray properties of the source combined with the faintness of the quiescence optical counterpart and the large outburst optical amplitude point towards a short orbital-period system (Porb≲ 6.8 h) with an M type (or later) mass donor, at a distance of 3.5 ≲d≲ 8 kpc. Simultaneous X-ray and radio data were collected with Chandra and the Expanded Very Large Array (EVLA), allowing constraints to be placed on the quiescent X-ray and radio flux of XTE J1752-223. Furthermore, using data covering the final stage of the outburst decay, we investigated the low-luminosity end of the X-ray-radio correlation for this source and compared it with other BHTs. We found that XTE J1752-223 adds to the number of outliers with respect to the 'standard' X-ray-radio luminosity relation. Furthermore, XTE J1752-223 is the second source, after the BHT H1743-322, that shows a transition from the region of the outliers towards the 'standard' correlation at low luminosity. Finally, we report on a faint, variable X-ray source we discovered with Chandra at an angular distance of ˜2.9 arcsec to XTE J1752-223 and at a position angle consistent with that of the radio jets previously observed from the BHT. We discuss the possibility that we detected X-ray emission associated with a jet from XTE J1752-223.

  19. Dynamical Black Hole Masses of BL Lac Objects from the Sloan Digital Sky Survey

    NARCIS (Netherlands)

    Plotkin, Richard M.; Markoff, Sera; Trager, Scott C.; Anderson, Scott F.

    2012-01-01

    We measure black hole masses for 71 BL Lac objects from the Sloan Digital Sky Survey (SDSS) with redshifts out to z ∼ 0.4. We perform spectral decompositions of their nuclei from their host galaxies and measure their stellar velocity dispersions. Black hole masses are then derived from the black

  20. Dynamical Black Hole Masses of BL Lac Objects from the Sloan Digital Sky Survey

    NARCIS (Netherlands)

    Plotkin, Richard M.; Markoff, Sera; Trager, Scott C.; Anderson, Scott F.

    2012-01-01

    We measure black hole masses for 71 BL Lac objects from the Sloan Digital Sky Survey (SDSS) with redshifts out to z ∼ 0.4. We perform spectral decompositions of their nuclei from their host galaxies and measure their stellar velocity dispersions. Black hole masses are then derived from the black hol

  1. Galaxy Zoo: finding offset discs and bars in SDSS galaxies★

    Science.gov (United States)

    Kruk, Sandor J.; Lintott, Chris J.; Simmons, Brooke D.; Bamford, Steven P.; Cardamone, Carolin N.; Fortson, Lucy; Hart, Ross E.; Häußler, Boris; Masters, Karen L.; Nichol, Robert C.; Schawinski, Kevin; Smethurst, Rebecca J.

    2017-08-01

    We use multiwavelength Sloan Digital Sky Survey (SDSS) images and Galaxy Zoo morphologies to identify a sample of ∼270 late-type galaxies with an off-centre bar. We measure offsets in the range 0.2-2.5 kpc between the photometric centres of the stellar disc and stellar bar. The measured offsets correlate with global asymmetries of the galaxies, with those with largest offsets showing higher lopsidedness. These findings are in good agreement with predictions from simulations of dwarf-dwarf tidal interactions producing off-centre bars. We find that the majority of galaxies with off-centre bars are of Magellanic type, with a median mass of 109.6 M⊙, and 91 per cent of them having M⋆ < 3 × 1010 M⊙, the characteristic mass at which galaxies start having higher central concentrations attributed to the presence of bulges. We conduct a search for companions to test the hypothesis of tidal interactions, but find that a similar fraction of galaxies with offset bars have companions within 100 kpc as galaxies with centred bars. Although this may be due to the incompleteness of the SDSS spectroscopic survey at the faint end, alternative scenarios that give rise to offset bars such as interactions with dark companions or the effect of lopsided halo potentials should be considered. Future observations are needed to confirm possible low-mass companion candidates and to determine the shape of the dark matter halo, in order to find the explanation for the off-centre bars in these galaxies.

  2. SDSS1133: An Unusually Persistent Transient in a Nearby Dwarf Galaxy

    CERN Document Server

    Koss, Michael; Mushotzky, Richard; Hung, Chao Ling; Veilleux, Sylvain; Trakhtenbrot, Benny; Schawinski, Kevin; Stern, Daniel; Smith, Nathan; Li, Yanxia; Man, Allison; Filippenko, Alexei V; Mauerhan, Jon C; Stanek, Kris; Sanders, David

    2014-01-01

    We have discovered an unusual source offset by 0.8 kpc from a nearby dwarf galaxy while performing a survey to detect recoiling black holes. The object, SDSS J113323.97+550415.8, exhibits broad emission lines and strong variability. While originally classified as a supernova (SN) because of its nondetection in 2005, we detect it in recent and past observations over 63 yr. Using high-resolution adaptive optics observations, we constrain the source emission region to be 10 yr), larger than that of unusually luminous supernovae such as SN 1988Z, suggesting one of the most extreme episodes of pre-SN mass loss ever discovered.

  3. Update on the SDSS-III MARVELS data pipeline development

    Science.gov (United States)

    Li, Rui; Ge, J.; Thomas, N. B.; Petersen, E.; Wang, J.; Ma, B.; Sithajan, S.; Shi, J.; Ouyang, Y.; Chen, Y.

    2014-01-01

    MARVELS (Multi-object APO Radial Velocity Exoplanet Large-area Survey), as one of the four surveys in the SDSS-III program, has monitored over 3,300 stars during 2008-2012, with each being visited an average of 26 times over a 2-year window. Although the early data pipeline was able to detect over 20 brown dwarf candidates and several hundreds of binaries, no giant planet candidates have been reliably identified due to its large systematic errors. Learning from past data pipeline lessons, we re-designed the entire pipeline to handle various types of systematic effects caused by the instrument (such as trace, slant, distortion, drifts and dispersion) and observation condition changes (such as illumination profile and continuum). We also introduced several advanced methods to precisely extract the RV signals. To date, we have achieved a long term RMS RV measurement error of 14 m/s for HIP-14810 (one of our reference stars) after removal of the known planet signal based on previous HIRES RV measurement. This new 1-D data pipeline has been used to robustly identify four giant planet candidates within the small fraction of the survey data that has been processed (Thomas et al. this meeting). The team is currently working hard to optimize the pipeline, especially the 2-D interference-fringe RV extraction, where early results show a 1.5 times improvement over the 1-D data pipeline. We are quickly approaching the survey baseline performance requirement of 10-35 m/s RMS for 8-12 solar type stars. With this fine-tuned pipeline and the soon to be processed plates of data, we expect to discover many more giant planet candidates and make a large statistical impact to the exoplanet study.

  4. Performance of the SDSS-III MARVELS New Data Pipeline

    Science.gov (United States)

    Li, Rui; Ge, J.; Thomas, N. B.; Shi, J.; Petersen, E.; Ouyang, Y.; Wang, J.; Ma, B.; Sithajan, S.

    2013-01-01

    As one of the four surveys in the SDSS-III program, MARVELS (Multi-object APO Radial Velocity Exoplanet Large-area Survey) had monitored over 3,300 stars during 2008-2012 with each observed about 27 times over a 2-year window. MARVELS has successfully produced over 20 brown dwarf candidates and several hundreds of binaries. However, the early data pipeline has large long term systematic errors and cannot reliably produce giant planet candidates. Our new MARVELS pipeline team, with the assistance of UF Department of Mathematics, has made great progress in dealing with the long-term systematic errors over the past 9 months. We redesigned the entire pre-processing procedure to handle various types of systematic effects caused by the instrument (such as trace, slant and distortion) and observation condition changes (such as illumination profile). We explored several advanced methods to precisely extract the RV signal from the processed spectra. We also developed a new simulation program to model all of these effects and used it to test the performance of our new pipeline. Our goal is to deliver a new pipeline to meet the survey baseline performance 10-35 m/s for the survey stars) by the end of 2012. We will report the fundamental performance of the pipeline and lessons learned from the pipeline development.

  5. New ultracool subdwarfs identified in large-scale surveys using Virtual Observatory tools: II. SDSS DR7 vs UKIDSS LAS DR6, SDSS DR7 vs UKIDSS LAS DR8, SDSS DR9 vs UKIDSS LAS DR10, and SDSS DR7 vs 2MASS

    CERN Document Server

    Lodieu, N; Osorio, M R Zapatero; Solano, E; Aberasturi, M; Martin, E L; Rodrigo, C

    2016-01-01

    We aim at developing an efficient method to search for late-type subdwarfs (metal-depleted dwarfs with spectral types >M5) to improve the current statistics. Our objectives are: improve our knowledge of metal-poor low-mass dwarfs, bridge the gap between the late-M and L types, determine their surface density, and understand the impact of metallicity on the stellar and substellar mass function. We carried out a search cross-matching the SDSS, 2MASS, and UKIDSS using STILTS, Aladin, and Topcat. We considered different photometric and proper motion criteria for our selection. We identified 29 and 71 late-type subdwarf candidates in each cross-correlation over 8826 and 3679 square degrees, respectively. We obtained low-resolution optical spectra for 71 of our candidates with GTC, NOT, and VLT and retrieved spectra for 30 candidates from the SDSS spectroscopic database. We classified 92 candidates based on 101 optical spectra using two methods: spectral indices and comparison with templates of known subdwarfs. We ...

  6. A Statistical Study of Brown Dwarf Companions from the SDSS-III MARVELS Survey

    Science.gov (United States)

    Grieves, Nolan; Ge, Jian; Thomas, Neil; Ma, Bo; De Lee, Nathan M.; Lee, Brian L.; Fleming, Scott W.; Sithajan, Sirinrat; Varosi, Frank; Liu, Jian; Zhao, Bo; Li, Rui; Agol, Eric; MARVELS Team

    2016-01-01

    We present 23 new Brown Dwarf (BD) candidates from the Multi-object APO Radial-Velocity Exoplanet Large-Area Survey (MARVELS) of the Sloan Digital Sky Survey III (SDSS-III). The BD candidates were selected from the processed MARVELS data using the latest University of Florida 2D pipeline, which shows significant improvement and reduction of systematic errors over the 1D pipeline results included in the SDSS Data Release 12. This sample is the largest BD yield from a single radial velocity survey. Of the 23 candidates, 18 are around main sequence stars and 5 are around giant stars. Given a giant contamination rate of ~24% for the MARVELS survey, we find a BD occurrence rate around main sequence stars of ~0.7%, which agrees with previous studies and confirms the BD desert, while the BD occurrence rate around the MARVELS giant stars is ~0.6%. Preliminary results show that our new candidates around solar type stars support a two population hypothesis, where BDs are divided at a mass of ~42.5 MJup. BDs less massive than 42.5 MJup have eccentricity distributions consistent with planet-planet scattering models, where BDs more massive than 42.5 MJup have both period and eccentricity distributions similar to that of stellar binaries. Special Brown Dwarf systems such as multiple BD systems and highly eccentric BDs will also be presented.

  7. Hunting for Extremely Faint Planetary Nebulae in the SDSS Spectroscopic Database

    CERN Document Server

    Yuan, Haibo

    2013-01-01

    Using ~1,700,000 target- and sky-fiber spectra from the SDSS, we have carried out a systematic search for Galactic planetary nebulae (PNe) via detections of the [OIII] 4959, 5007 lines. Thanks to the excellent sensitivity of the SDSS spectroscopic surveys, this is by far the deepest search for PNe ever taken, reaching a surface brightness of the [OIII] 5007 line down to about 29.0 mag./arcsec^2. The search recovers 13 previously known PNe in the Galactic Caps. In total, 44 new PN candidates are identified, including 7 candidates of multiple detections and 37 candidates of single detection. The 7 candidates of multiple detections are all extremely large (between 21' - 154') and faint, located mostly in the low Galactic latitude region and with a kinematics similar to disk stars. After checking their images in Ha and other bands, three of them are probably HII regions, one is probably associated with a new supernova remnant, another one is possibly a true PN, and the remaining two could be either PNe or superno...

  8. SDSS-II Supernova Survey: An Analysis of the Largest Sample of Type Ia Supernovae and Correlations with Host-Galaxy Spectral Properties

    CERN Document Server

    Wolf, Rachel C; Gupta, Ravi R; Sako, Masao; Fischer, John A; Kessler, Rick; Jha, Saurabh W; March, Marisa C; Scolnic, Daniel M; Fischer, Johanna-Laina; Campbell, Heather; Nichol, Robert C; Olmstead, Matthew D; Richmond, Michael; Schneider, Donald P; Smith, Mathew

    2016-01-01

    Using the largest single-survey sample of Type Ia supernovae (SNe Ia) to date, we study the relationship between properties of SNe Ia and those of their host galaxies, focusing primarily on correlations with Hubble residuals (HR). Our sample consists of 345 photometrically-classified or spectroscopically-confirmed SNeIa discovered as part of the SDSS-II Supernova Survey (SDSS-SNS). This analysis utilizes host-galaxy spectroscopy obtained during the SDSS-I/II spectroscopic survey and from an ancillary program on the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS) that obtained spectra for nearly all host galaxies of SDSS-II SN candidates. In addition, we use photometric host-galaxy properties from the SDSS-SNS data release (Sako et al. 2014) such as host stellar mass and star-formation rate. We confirm the well-known relation between HR and host-galaxy mass and find a 3.6{\\sigma} significance of a non-zero linear slope. We also recover correlations between HR and host-galaxy gas-phase metallicity and s...

  9. SDSS-II Supernova survey. An analysis of the largest sample of type IA supernovae and correlations with host-galaxy spectral properties

    Energy Technology Data Exchange (ETDEWEB)

    Wolf, Rachel C.; D’Andrea, Chris B.; Gupta, Ravi R.; Sako, Masao; Fischer, John A.; Kessler, Rick; Jha, Saurabh W.; March, Marisa C.; Scolnic, Daniel M.; Fischer, Johanna-Laina; Campbell, Heather; Nichol, Robert C.; Olmstead, Matthew D.; Richmond, Michael; Schneider, Donald P.; Smith, Mathew

    2016-04-20

    Using the largest single-survey sample of Type Ia supernovae (SNe Ia) to date, we study the relationship between properties of SNe Ia and those of their host galaxies, focusing primarily on correlations with Hubble residuals (HR). Our sample consists of 345 photometrically-classified or spectroscopicallyconfirmed SNe Ia discovered as part of the SDSS-II Supernova Survey (SDSS-SNS). This analysis utilizes host-galaxy spectroscopy obtained during the SDSS-I/II spectroscopic survey and from an ancillary program on the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS) that obtained spectra for nearly all host galaxies of SDSS-II SN candidates. In addition, we use photometric hostgalaxy properties from the SDSS-SNS data release (Sako et al. 2014) such as host stellar mass and star-formation rate. We confirm the well-known relation between HR and host-galaxy mass and find a 3.6σ significance of a non-zero linear slope. We also recover correlations between HR and hostgalaxy gas-phase metallicity and specific star-formation rate as they are reported in the literature. With our large dataset, we examine correlations between HR and multiple host-galaxy properties simultaneously and find no evidence of a significant correlation. We also independently analyze our spectroscopically-confirmed and photometrically-classified SNe Ia and comment on the significance of similar combined datasets for future surveys.

  10. SN Typing for the SDSS SN Survey

    Energy Technology Data Exchange (ETDEWEB)

    Rivers, Elizabeth S.; /Wellesley Coll. /SLAC

    2005-12-15

    In the fall of 2004 the Sloan Digital Sky Survey (SDSS) 2.5m telescope scanned the southern equatorial stripe for approximately 20 nights over the space of two months. Light curves for over four dozen supernovae (SNe) were collected over time using five colored filters ugriz that together had a range of approximately 3000{angstrom} to 10500{angstrom}. 22 SNe were spectroscopically confirmed with follow-up observation. Using the data obtained in the Fall 2004 campaign, preparations are now being made for the Supernova Survey of the SDSS II, a three-year extension of the original project. One main goal of the Supernova Survey will be to identify and study type Ia SNe of up to redshift {approx}0.4, the intermediate ''redshift desert'', as well as enabling further study of other types of SNe including type 1b/c and peculiar SNe. Most of the SNe found will not have spectra taken, due to time and cost constraints. Thus it would be advantageous to be able to robustly type SNe solely from the light curves obtained by the SDSS telescope prior to, or even without ever obtaining a spectrum. Using light curves of well-observed SNe templates were constructed for comparison with unknown SNe in order to photometrically type them.

  11. WISE photometry for 400 million SDSS sources

    CERN Document Server

    Lang, Dustin; Schlegel, David J

    2014-01-01

    We present photometry of images from the Wide-Field Infrared Survey Explorer (WISE; Wright et al. 2010) of over 400 million sources detected by the Sloan Digital Sky Survey (SDSS; York et al. 2000). We use a "forced photometry" technique, using measured SDSS source positions, star-galaxy separation and galaxy profiles to define the sources whose fluxes are to be measured in the WISE images. We perform photometry with The Tractor image modeling code, working on our "unWISE" coaddds and taking account of the WISE point-spread function and a noise model. The result is a measurement of the flux of each SDSS source in each WISE band. Many sources have little flux in the WISE bands, so often the measurements we report are consistent with zero. However, for many sources we get three- or four-sigma measurements; these sources would not be reported by the WISE pipeline and will not appear in the WISE catalog, yet they can be highly informative for some scientific questions. In addition, these small-signal measurements...

  12. Clusters of Galaxies in the SDSS

    CERN Document Server

    Nichol, R C

    2003-01-01

    I review here past and present research on clusters and groups of galaxies within the Sloan Digital Sky Survey (SDSS). In particular, I discuss the C4 algorithm which is designed to search for clusters within a 7-dimensional data-space, i.e., simultaneous in both color & space. The C4 catalog has a well defined selection function based on mock SDSS galaxy catalogs constructed from the Hubble Volume simulation, and is >90% complete, with 10^14 Msolar at z<0.14. Furthermore, the observed summed r-band luminosity of C4 clusters is linearly related to M200 with <30% scatter at any given halo mass. I also briefly review the selection and observation of Luminous Red Galaxies (LRGs) and demonstrate that these galaxies have a similar clustering strength as clusters and groups of galaxies. I outline a new collaboration planning to obtain redshifts for 10,000 LRGs at 0.4SDSS photometric data and the AAT 2dF instrument. Finally, I review the role of clusters and groups of galaxies in th...

  13. A DESCRIPTION OF QUASAR VARIABILITY MEASURED USING REPEATED SDSS AND POSS IMAGING

    Energy Technology Data Exchange (ETDEWEB)

    MacLeod, Chelsea L.; Ivezic, Zeljko; Becker, Andrew C.; Anderson, Scott F. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Sesar, Branimir [Division of Physics, Mathematics and Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States); De Vries, Wim [Department of Physics, University of California, One Shields Ave, Davis, CA 95616 (United States); Kochanek, Christopher S. [Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States); Kelly, Brandon C. [Department of Physics, University of California, Santa Barbara, CA 93106 (United States); Lupton, Robert H. [Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544 (United States); Hall, Patrick B. [Department of Physics and Astronomy, York University, Toronto, ON M3J 1P3 (Canada); Richards, Gordon T. [Department of Physics, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104 (United States); Schneider, Donald P. [Department of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802 (United States)

    2012-07-10

    We provide a quantitative description and statistical interpretation of the optical continuum variability of quasars. The Sloan Digital Sky Survey (SDSS) has obtained repeated imaging in five UV-to-IR photometric bands for 33,881 spectroscopically confirmed quasars. About 10,000 quasars have an average of 60 observations in each band obtained over a decade along Stripe 82 (S82), whereas the remaining {approx}25,000 have 2-3 observations due to scan overlaps. The observed time lags span the range from a day to almost 10 years, and constrain quasar variability at rest-frame time lags of up to 4 years, and at rest-frame wavelengths from 1000 A to 6000 A. We publicly release a user-friendly catalog of quasars from the SDSS Data Release 7 that have been observed at least twice in SDSS or once in both SDSS and the Palomar Observatory Sky Survey, and we use it to analyze the ensemble properties of quasar variability. Based on a damped random walk (DRW) model defined by a characteristic timescale and an asymptotic variability amplitude that scale with the luminosity, black hole mass, and rest wavelength for individual quasars calibrated in S82, we can fully explain the ensemble variability statistics of the non-S82 quasars such as the exponential distribution of large magnitude changes. All available data are consistent with the DRW model as a viable description of the optical continuum variability of quasars on timescales of {approx}5-2000 days in the rest frame. We use these models to predict the incidence of quasar contamination in transient surveys such as those from the Palomar Transient Factory and Large Synoptic Survey Telescope.

  14. The Radio-Loud Narrow-Line Quasar SDSS J172206.03+565451.6

    Science.gov (United States)

    Komossa, Stefanie; Voges, Wolfgang; Adorf, Hans-Martin; Xu, Dawei; Mathur, Smita; Anderson, Scott F.

    2006-03-01

    We report identification of the radio-loud narrow-line quasar SDSS J172206.03+565451.6, which we found in the course of a search for radio-loud narrow-line active galactic nuclei (AGNs). SDSS J172206.03+565451.6 is only about the fourth securely identified radio-loud narrow-line quasar and the second-most radio loud, with a radio index R1.4~100-700. Its black hole mass, MBH~=(2-3)×107 Msolar estimated from Hβ line width and 5100 Å luminosity, is unusually small given its radio loudness, and the combination of mass and radio index puts SDSS J172206.03+565451.6 in a scarcely populated region of MBH-R diagrams. SDSS J172206.03+565451.6 is a classical narrow-line Seyfert 1-type object with FWHMHβ~=1490 km s-1, an intensity ratio of [O III]/Hβ~=0.7, and Fe II emission complexes with Fe II λ4570/Hβ~=0.7. The ionization parameter of its narrow-line region, estimated from the line ratio [O II]/[O III], is similar to Seyferts, and its high ratio of [Ne V]/[Ne III] indicates a strong EUV-to-soft X-ray excess. We advertise the combined usage of [O II]/[O III] and [Ne V]/[Ne III] diagrams as a useful diagnostic tool to estimate ionization parameters and to constrain the EUV-soft X-ray continuum shape relatively independently from other parameters.

  15. GRB Afterglows and Other Transients in the SDSS

    OpenAIRE

    Lee, Brian C.; Reichart, Daniel E.

    2003-01-01

    The Sloan Digital Sky Survey (SDSS) will image one quarter of the sky centered on the northern galactic cap and produce a 3-D map of galaxies and quasars found in the sample. An additional 225 deg^2 southern survey will be imaged repeatedly on varying timescales. Here we discuss both archival searches in the SDSS catalog (such as SDSS J24602.54+011318.8) and active searches with the SDSS instruments (such as for GRB 010222) for GRB afterglows and other transient objects.

  16. The Swift AGN and Cluster Survey. II. Cluster Confirmation with SDSS Data

    CERN Document Server

    Griffin, Rhiannon D; Kochanek, Christopher S; Bregman, Joel N

    2015-01-01

    We study 203 extended X-ray sources in the Swift GRB fields that are located within the Sloan Digital Sky Survey (SDSS) DR8 footprint. We search for galaxy over-densities in three-dimensional space using SDSS galaxies and their photometric redshifts near the Swift cluster candidates. We find 103 Swift clusters with a >3 sigma over-density. The remaining targets are potentially located at higher redshifts and require deeper optical follow-up observations for confirmations as galaxy clusters. We present a series of cluster properties including the redshift, BCG magnitude, BCG-to-X-ray center offset, optical richness, and X-ray luminosity. We also detect red sequences in almost half of the 103 confirmed clusters. The X-ray luminosity and optical richness for the SDSS confirmed Swift clusters are correlated and follow previously established relations. The distribution of the separations between the X-ray centroids and the most likely BCG is also consistent with expectation. We compare the observed redshift distri...

  17. Constraining sub-Parsec Binary Supermassive Black Holes in Quasars with Multi-Epoch Spectroscopy. I. The General Quasar Population

    CERN Document Server

    Shen, Yue; Loeb, Abraham; Tremaine, Scott

    2013-01-01

    We perform a systematic search for sub-parsec binary supermassive black holes (BHs) in normal broad line quasars at z<0.8, using multi-epoch SDSS spectroscopy of the broad Hbeta line. Our working model is that: only one of the two BHs in the binary is active, and dynamically dominates its own broad line region (BLR); the inactive companion BH is orbiting at a distance of a few R_BLR, where R_BLR~0.01-0.1 pc is the BLR size. We search for the expected line-of-sight acceleration of the broad line velocity from binary orbital motion by cross-correlating SDSS spectra from two epochs separated by up to several years in the quasar restframe. Out of ~700 pairs of spectra for which we have good measurements of the velocity shift between two epochs (1-sigma error~40 km/s), we detect 28 systems with significant velocity shifts in broad Hbeta, among which seven are the best candidates for the hypothesized binaries. We use the distribution of the observed accelerations (mostly non-detections) to place constraints on t...

  18. Binary Active Galactic Nuclei in Stripe 82: Constraints on Synchronized Black Hole Accretion in Major Mergers

    CERN Document Server

    Fu, Hai; Myers, A D; Djorgovski, S G; Yan, Lin

    2015-01-01

    Representing simultaneous black hole accretion during a merger, binary active galactic nuclei (AGNs) could provide valuable observational constraints to models of galaxy mergers and AGN triggering. High-resolution radio interferometer imaging offers a promising method to identify a large and uniform sample of binary AGNs, because it probes a generic feature of nuclear activity and is free from dust obscuration. Our previous search yielded 52 strong candidates of kpc-scale binaries over the 92 deg^2 of the Sloan Digital Sky Survey (SDSS) Stripe 82 area with 2"-resolution Very Large Array (VLA) images. Here we present 0.3"-resolution VLA 6 GHz observations for six candidates that have complete optical spectroscopy. The new data confirm the binary nature of four candidates and identify the other two as line-of-sight projections of radio structures from single AGNs. The four binary AGNs at z ~ 0.1 reside in major mergers with projected separations of 4.2-12 kpc. Optical spectral modeling shows that their hosts ha...

  19. Optically selected BL Lacertae candidates from the Sloan Digital Sky Survey Data Release Seven

    NARCIS (Netherlands)

    R.M. Plotkin; S.F. Anderson; W.N. Brandt; A.M. Diamond-Stanic; X. Fan; P.B. Hall; A.E. Kimball; M.W. Richmond; D.P. Schneider; O. Shemmer; W. Voges; D.G. York; N.A. Bahcall; S. Snedden; D. Bizyaev; H. Brewington; V. Malanushenko; E. Malanushenko; D. Oravetz; K. Pan; A. Simmons

    2010-01-01

    We present a sample of 723 optically selected BL Lac candidates from the Sloan Digital Sky Survey Data Release 7 (SDSS DR7) spectroscopic database encompassing 8250 deg(2) of sky; our sample constitutes one of the largest uniform BL Lac samples yet derived. Each BL Lac candidate has a high-quality S

  20. The WIRED Survey II: Infrared Excesses in the SDSS DR7 White Dwarf Catalog

    CERN Document Server

    Debes, J H; Wachter, S; Leisawitz, D T; Cohen, M

    2011-01-01

    With the launch of the {\\em Wide-field Infrared Survey Explorer} ({\\em WISE}), a new era of detecting planetary debris and brown dwarfs around white dwarfs (WDs) has begun with the {\\em WISE} InfraRed Excesses around Degenerates (WIRED) Survey. The WIRED Survey is sensitive to substellar objects and dusty debris around WDs out to distances exceeding 100 pc, well beyond the completeness level of local WDs. In this paper, we present a cross-correlation of the preliminary Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7) WD Catalog between the {\\em WISE}, Two-Micron All Sky Survey (2MASS), UKIRT Infrared Deep Sky Survey (UKIDSS), and SDSS DR7 photometric catalogs. From $\\sim18,000$ input targets, there are {\\em WISE} detections comprising 344 "naked" WDs (detection of the WD photosphere only), 1020 candidate WD+M dwarf binaries, 42 candidate WD+brown dwarf (BD) systems, 52 candidate WD+dust disk systems, and 69 targets with indeterminate infrared excess. We classified all of the detected targets through spect...

  1. The connection between black hole mass and Doppler boosted emission in BL Lacertae type objects

    OpenAIRE

    Leon-Tavares, J.; Valtaoja, E.; V. H. Chavushyan; Tornikoski, M.; Anorve, C.; Nieppola, E.; Lahteenmaki, A.

    2010-01-01

    We investigate the relationship between black hole mass (MBH) and Doppler boosted emission for BL Lacertae type objects (BL Lacs) detected in the SDSS and FIRST surveys. The synthesis of stellar population and bidimensional decomposition methods allows us to disentangle the components of the host galaxy from that of the nuclear black hole in their optical spectra and images, respectively. We derive estimates of black hole masses via stellar velocity dispersion and bulge luminosity. We find th...

  2. Data Mining for Dwarf Novae in SDSS, GALEX and Astrometric Catalogues

    CERN Document Server

    Wils, Patrick; Drake, Andrew J; Southworth, John

    2009-01-01

    By cross matching blue objects from SDSS with GALEX and the astrometric catalogues USNO-B1.0, GSC2.3 and CMC14, 64 new dwarf nova candidates with one or more observed outbursts have been identified. 14 of these systems are confirmed as cataclysmic variables through existing and follow-up spectroscopy. A study of the amplitude distribution and an estimate of the outburst frequency of these new dwarf novae and those discovered by the Catalina Real-time Transient Survey (CRTS) indicates that besides systems that are faint because they are farther away, there also exists a population of intrinsically faint dwarf novae with rare outbursts.

  3. The WIRED Survey. 2; Infrared Excesses in the SDSS DR7 White Dwarf Catalog

    Science.gov (United States)

    Debes, John H.; Hoard, D. W.; Wachter, Stefanie; Leisawitz, David T.; Cohen, Martin

    2011-01-01

    With the launch of the Wide-field Infrar.ed Survey Explorer (WISE), a new era of detecting planetary debris and brown dwarfs (BDs) around white dwarfs (WDs) has begun with the WISE InfraRed Excesses around Degenerates (WIRED) Survey. The WIRED Survey is sensitive to substellar objects and dusty debris around WDs out to distances exceeding 100 pc, well beyond the completeness level of local WDs. In this paper, we present a cross-correlation of the preliminary Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7) WD catalog between the WISE, Two-Micron All Sky Survey (2MASS), UKIRT Infrared Deep Sky Survey (UKIDSS), and SDSS DR7 photometric catalogs. From -18,000 input targets, there are WISE detections comprising 344 "naked" WDs (detection of the WD photosphere only), 1020 candidate WD+M dwarf binaries, 42 candidate WD+BD systems, 52 candidate WD+dust disk systems, and 69 targets with indeterminate infrared excess. We classified all of the detected targets through spectral energy distribution model fitting of the merged optical, near-IR, and WISE photometry. Some of these detections could be the result of contaminating sources within the large (approx. 6") WISE point-spread function; we make a preliminary estimate for the rates of contamination for our WD+BD and WD+disk candidates and provide notes for each target of interest. Each candidate presented here should be confirmed with higher angular resolution infrared imaging or infrared spectroscopy. We also present an overview of the observational characteristics of the detected WDs in the WISE photometric bands, including the relative frequencies of candidate WD+M, WD+BD, and WD+disk systems.

  4. THE WIRED SURVEY. II. INFRARED EXCESSES IN THE SDSS DR7 WHITE DWARF CATALOG

    Energy Technology Data Exchange (ETDEWEB)

    Debes, John H.; Leisawitz, David T. [Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Hoard, D. W. [Spitzer Science Center, California Institute of Technology, Pasadena, CA 91125 (United States); Wachter, Stefanie [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States); Cohen, Martin [Monterey Institute for Research in Astronomy, Marina, CA 93933 (United States)

    2011-12-01

    With the launch of the Wide-field Infrared Survey Explorer (WISE), a new era of detecting planetary debris and brown dwarfs (BDs) around white dwarfs (WDs) has begun with the WISE InfraRed Excesses around Degenerates (WIRED) Survey. The WIRED Survey is sensitive to substellar objects and dusty debris around WDs out to distances exceeding 100 pc, well beyond the completeness level of local WDs. In this paper, we present a cross-correlation of the preliminary Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7) WD catalog between the WISE, Two-Micron All Sky Survey (2MASS), UKIRT Infrared Deep Sky Survey (UKIDSS), and SDSS DR7 photometric catalogs. From {approx}18,000 input targets, there are WISE detections comprising 344 'naked' WDs (detection of the WD photosphere only), 1020 candidate WD+M dwarf binaries, 42 candidate WD+BD systems, 52 candidate WD+dust disk systems, and 69 targets with indeterminate infrared excess. We classified all of the detected targets through spectral energy distribution model fitting of the merged optical, near-IR, and WISE photometry. Some of these detections could be the result of contaminating sources within the large ( Almost-Equal-To 6'') WISE point-spread function; we make a preliminary estimate for the rates of contamination for our WD+BD and WD+disk candidates and provide notes for each target of interest. Each candidate presented here should be confirmed with higher angular resolution infrared imaging or infrared spectroscopy. We also present an overview of the observational characteristics of the detected WDs in the WISE photometric bands, including the relative frequencies of candidate WD+M, WD+BD, and WD+disk systems.

  5. The FAST Initiative: Fostering a More Inclusive SDSS Collaboration

    Science.gov (United States)

    Holley-Bockelmann, Kelly; Chanover, Nancy J.; Burgasser, Adam J.; Cruz, Kelle L.; Liu, Charles; Mason, Paul A.; Pando, Jesus; Rice, Emily L.; Schmidt, Sarah J.; Sanchez-Gallego, Jose Ramon; Lucatello, Sara; Aragon-Salamanca, Alfonso; Belfiore, Francesco; Cherinka, Brian; Feuillet, Diane; Jones, Amy; Masters, Karen; Simmons, Audrey; Ross, Ashley; Stassun, Keivan G.; Tayar, Jamie

    2017-01-01

    The success of the Sloan Digital Sky Survey (SDSS) hinges on tapping into a diverse talent base. From our experience, however, it is clear that simply allowing access to SDSS data is not enough to increase the participation of underrepresented minorities in the collaboration. For this reason, the SDSS collaboration instituted the Faculty and Student Team (FAST) Program, which pairs teams of faculty and students from underrepresented groups with SDSS partners to build serious, long-term research collaborations. Our intent is to build capacity at the faculty level to propagate SDSS research to students in the long-term. We present the FAST initiative in detail and outline results from the first 1.5 years of the program.

  6. Target Selection for the SDSS-III MARVELS Survey

    CERN Document Server

    Paegert, Martin; De Lee, Nathan; Pepper, Joshua; Fleming, Scott W; Sivarani, Thirupathi; Mahadevan, Suvrath; Mack, Claude E; Dhital, Saurav; Hebb, Leslie; Ge, Jian

    2015-01-01

    We present the target selection process for the Multi-object APO Radial Velocity Exoplanets Large-area Survey (MARVELS), which is part of the Sloan Digital Sky Survey (SDSS) III. MARVELS is a medium-resolution ($R \\sim 11000$) multi-fiber spectrograph capable of obtaining radial velocities for 60 objects at a time in order to find brown dwarfs and giant planets. The survey was configured to target dwarf stars with effective temperatures approximately between $4500$ and $6250 \\, \\mbox{K}$. For the first 2 years MARVELS relied on low-resolution spectroscopic pre-observations to estimate the effective temperature and $\\log(g)$ for candidate stars and then selected suitable dwarf stars from this pool. Ultimately, the pre-observation spectra proved ineffective at filtering out giant stars; many giants were incorrectly classified as dwarfs, resulting in a giant contamination rate of $\\sim$30\\% for the first phase of the MARVELS survey. Thereafter, the survey instead applied a reduced proper motion cut to eliminate ...

  7. Target Selection for the SDSS-III MARVELS Survey

    Science.gov (United States)

    Paegert, Martin; Stassun, Keivan G.; De Lee, Nathan; Pepper, Joshua; Fleming, Scott W.; Sivarani, Thirupathi; Mahadevan, Suvrath; Mack, Claude E., III; Dhital, Saurav; Hebb, Leslie; Ge, Jian

    2015-06-01

    We present the target selection process for the Multi-object APO Radial Velocity Exoplanets Large-area Survey (MARVELS), which is part of the Sloan Digital Sky Survey (SDSS) III. MARVELS is a medium-resolution (R ∼ 11,000) multi-fiber spectrograph capable of obtaining radial velocities for 60 objects at a time in order to find brown dwarfs and giant planets. The survey was configured to target dwarf stars with effective temperatures approximately between 4500 and 6250 K. For the first 2 years MARVELS relied on low-resolution spectroscopic pre-observations to estimate the effective temperature and log (g) for candidate stars and then selected suitable dwarf stars from this pool. Ultimately, the pre-observation spectra proved ineffective at filtering out giant stars; many giants were incorrectly classified as dwarfs, resulting in a giant contamination rate of ∼30% for the first phase of the MARVELS survey. Thereafter, the survey instead applied a reduced proper motion cut to eliminate giants and used the Infrared Flux Method to estimate effective temperatures, using only extant photmetric and proper-motion catalog information. The target selection method introduced here may be useful for other surveys that need to rely on extant catalog data for selection of specific stellar populations.

  8. Spectroscopy of supernova host galaxies from the SDSS-II SN survey with the SDSS and BOSS spectrographs

    Science.gov (United States)

    Olmstead, Matthew Dwaune

    Type Ia supernovae (SNeIa) have been used as standard candles to measure cosmological distances. The initial discovery of the accelerated expansion of the universe was performed using ~50 SNe Ia. Large SNe surveys have increased the number of spectroscopically-confirmed SNe Ia to over a thousand with redshift coverage beyond z = 1. We are now in the age of abundant photometry without the ability for full follow-up spectroscopy of all SN candidates. SN cosmology using these large samples will increasingly rely on robust photometric classification of SN candidates. Photometric classification will increase the sample by including faint SNe as these are preferentially not observed with follow-up spectroscopy. The primary concern with using photometrically classified SNe Ia in cosmology is when a core-collapse SNe is incorrectly classified as an SN Ia. This can be mitigated by obtaining the host galaxy redshift of each SN candidate and using this information as a prior in the photometric classification, removing one degree of freedom. To test the impact of redshift on photometric classification, I have performed an assessment on photometric classification of candidates from the Sloan Digital Sky Survey-II (SDSS-II) SN Survey. I have tested the classification with and without redshift priors by looking at the change of photometric classification, the effect of data quality on photometric classification, and the effect of SN light curve properties on photometric classification. Following our suggested classification scheme, there are a total of 1038 photometrically classified SNe Ia when using a flat redshift prior and 1002 SNe~Ia with the spectroscopic redshift. For 912 (91.0%) candidates classified as likely SNe Ia without redshift information, the classification is unchanged when adding the host galaxy redshift. Finally, I investigate the differences in the interpretation of the light curve properties with and without knowledge of the redshift. When using the SALT2

  9. Multipole moments of bumpy black holes

    CERN Document Server

    Vigeland, Sarah J

    2010-01-01

    General relativity predicts the existence of black holes, compact objects whose spacetimes depend on only their mass and spin (the famous "no hair" theorem). As various observations probe deeper into the strong fields of black hole candidates, it is becoming possible to test this prediction. Previous work suggested that such tests can be performed by measuring whether the multipolar structure of black hole candidates has the form that general relativity demands, and introduced a family of "bumpy black hole" spacetimes to be used for making these measurements. These spacetimes are black holes with the "wrong" multipoles, where the deviation from general relativity depends on the spacetime's "bumpiness." In this paper, we show how to compute the Geroch-Hansen moments of a bumpy black hole, demonstrating that there is a clean mapping between the deviations used in the bumpy black hole formalism and the Geroch-Hansen moments. We also extend our previous results to define bumpy black holes whose {\\it current} mome...

  10. SDSS DR7 WHITE DWARF CATALOG

    Energy Technology Data Exchange (ETDEWEB)

    Kleinman, S. J.; Nitta, A. [Gemini Observatory, 670 North A' ohoku Place, Hilo, HI 96720 (United States); Kepler, S. O.; Pelisoli, Ingrid; Pecanha, Viviane; Costa, J. E. S. [Instituto de Fisica, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS (Brazil); Koester, D. [Institut fuer Theoretische Physik und Astrophysik, Universitaet Kiel, D-24098 Kiel (Germany); Krzesinski, J. [Mt. Suhora Observatory, Pedagogical University of Cracow, ul. Podchorazych 2, 30-084 Cracow (Poland); Dufour, P.; Lachapelle, F.-R.; Bergeron, P. [Departement de Physique, Universite de Montreal, C. P. 6128, Succ. Centre-Ville, Montreal, Quebec H3C 3J7 (Canada); Yip, Ching-Wa [Department of Physics and Astronomy, The Johns Hopkins University, 3701 San Martin Drive, Baltimore, MD 21218 (United States); Harris, Hugh C. [United States Naval Observatory, Flagstaff Station, 10391 West Naval Observatory Road, Flagstaff, AZ 86001-8521 (United States); Eisenstein, Daniel J. [Harvard Smithsonian Center for Astrophysics, 60 Garden Street, MS 20, Cambridge, MA 02138 (United States); Althaus, L.; Corsico, A., E-mail: hch@nofs.navy.mil [Facultad de Ciencias Astronomicas y Geofisicas, Paseo del Bosque S/N, (1900) La Plata (Argentina)

    2013-01-15

    We present a new catalog of spectroscopically confirmed white dwarf stars from the Sloan Digital Sky Survey (SDSS) Data Release 7 spectroscopic catalog. We find 20,407 white dwarf spectra, representing 19,712 stars, and provide atmospheric model fits to 14,120 DA and 1011 DB white dwarf spectra from 12,843 and 923 stars, respectively. These numbers represent more than a factor of two increase in the total number of white dwarf stars from the previous SDSS white dwarf catalogs based on DR4 data. Our distribution of subtypes varies from previous catalogs due to our more conservative, manual classifications of each star in our catalog, supplementing our automatic fits. In particular, we find a large number of magnetic white dwarf stars whose small Zeeman splittings mimic increased Stark broadening that would otherwise result in an overestimated log g if fit as a non-magnetic white dwarf. We calculate mean DA and DB masses for our clean, non-magnetic sample and find the DB mean mass is statistically larger than that for the DAs.

  11. SDSS, LSST, and Gaia: Lessons and Synergies

    CERN Document Server

    Juric, Mario

    2011-01-01

    The advent of deep, wide, accurate, digital photometric surveys exemplified by the Sloan Digital Sky Survey (SDSS) has had a profound impact on studies of the Milky Way. In the past decade, we have transitioned from a scarcity to an (over)abundance of precise, well calibrated, observations of stars over a large fraction of the Galaxy. The avalanche of data will continue throughout this decade, culminating with Gaia and LSST. This new reality will necessitate changes in methodology, habits, and expectations both on the side of the large survey projects as well as the astrophysics community at large. We argue, based on the experience with SDSS, that surveys should release data as early and often as possible incorporating incremental improvements in each subsequent release, as opposed to holding off for a single, big, final release. The scientific community will need to reciprocate by performing analyses and (re-analyses) appropriate to the current fidelity of the released data, understanding that these are cont...

  12. The 3D skeleton of the SDSS

    CERN Document Server

    Sousbie, T; Courtois, H; Colombi, S; Novikov, D; Sousbie, Thierry; Pichon, Christophe; Colombi, St\\'ephane; Novikov, Dmitri

    2006-01-01

    The length of the three-dimensional filaments observed in the fourth public data-release of the SDSS is measured using the {\\em local skeleton} method. It consists in defining the set of points where the gradient of the smoothed density field is extremal along its isocontours, with some additional constraints on local curvature to probe actual ridges in the galaxy distribution. A good fit to the mean filament length per unit volume, $\\cal{L}$, in the SDSS survey is found to be ${\\cal{L}}=(52500\\pm6500) (L/{\\rm Mpc})^{-1.75\\pm0.06}\\rm{Mpc}/(100 \\rm{Mpc})^{3}$ for $8.2 \\leq L \\leq 16.4$ Mpc, where $L$ is the smoothing length in Mpc. This result, which deviates only slightly, as expected, from the trivial behavior ${\\cal{L}} \\propto L^{-2}$, is in excellent agreement with a $\\Lambda$CDM cosmology, as long as the matter density parameter remains in the range $0.25 < \\Omega_{\\rm matter} < 0.4$ at one sigma confidence level, considering the universe is flat. These measurements, which are in fact dominated by ...

  13. The Formation of COINS: Equity and Inclusion in SDSS

    Science.gov (United States)

    Schmidt, Sarah J.; Sanchez-Gallego, Jose Ramon; Chanover, Nancy J.; Holley-Bockelmann, Kelly; Lucatello, Sara; Aragon-Salamanca, Alfonso; Belfiore, Francesco; Cherinka, Brian; Feuillet, Diane; Jones, Amy; Masters, Karen; Simmons, Audrey; Ross, Ashley; Stassun, Keivan G.; Tayar, Jamie

    2017-01-01

    In the era of large surveys, collaborations like the Sloan Digital Sky Survey (SDSS) are becoming a new normal for many scientists, and collaboration policies and climate have a considerable affect on scientific careers. As such, it is essential that collaborations actively strive to include all scientists regardless of gender, gender identity, race, ethnicity, sexual orientation, disability, career stage, geographic location, economic background, social and cultural backgrounds, and all possible intersections thereof. We report on the formation and progress of the Committee On INclusiveness in the SDSS (COINS). COINS was formed to assess the SDSS-IV project and collaboration's climate and demographics, to recommend new policies or practices with regard to increasing inclusiveness, and to assist in the implementation of these new activities where necessary. We report on our current activities, which include ongoing support for the SDSS Research Experience for Undergraduates program, support for the SDSS Faculty and Student Teams initiative, administering and analyzing the SDSS demographic surveys, working towards collaboration meeting inclusiveness and accessibility, and adopting strategies for integrating and mentoring new members. We welcome input from SDSS members and non-members about how to work towards a more equitable and inclusive collaboration.

  14. Quasar Absorption Lines and SDSS Galaxies

    Science.gov (United States)

    Shoemaker, Emileigh Suzanne; Scott, Jennifer E.; Oldak, Katarzyna

    2017-01-01

    We present the results of a study of the sightlines of 45 low redshift quasars (0.06 COS that lie within the footprint of the Sloan Digital Sky Survey. We use both the SDSS DR12 galaxy photometric data, including photometric redshifts, and the measured properties of the absorbers along with the known absorption characteristics of the intergalactic medium and the circumgalactic medium of galaxies to assign the most probable galaxy matches for each absorber in the sample, using estimated galaxy luminosities and virial radii as a discriminator. We show that the scheme can recover known galaxy-absorber matches found from spectroscopic data and thus provides a method for identifying likely pairs in photometric data sets as well as targets for spectroscopic follow up.

  15. Searching for Binary Supermassive Black Holes via Variable Broad Emission Line Shifts: Low Binary Fraction

    CERN Document Server

    Wang, Lile; Ju, Wenhua; Rafikov, Roman R; Ruan, John J; Schneider, Donald P

    2016-01-01

    Supermassive black hole binaries (SMBHs) are expected to result from galaxy mergers, and thus are natural byproducts (and probes) of hierarchical structure formation in the Universe. They are also the primary expected source of low-frequency gravitational wave emission. We search for binary BHs using time-variable velocity shifts in broad Mg II emission lines of quasars with multi-epoch observations. First, we inspect velocity shifts of the binary SMBH candidates identified in Ju et al. (2013), using SDSS spectra with an additional epoch of data that lengthens the typical baseline to ~10 yr. We find variations in the line-of-sight velocity shifts over 10 years that are comparable to the shifts observed over 1-2 years, ruling out the binary model for the bulk of our candidates. We then analyze 1438 objects with 8 yr median time baselines, from which we would expect to see velocity shifts >1000 km/s from sub-pc binaries. We find only one object with an outlying velocity of 448 km/s, indicating, based on our mod...

  16. Black Holes

    Science.gov (United States)

    Luminet, Jean-Pierre

    1992-09-01

    Foreword to the French edition; Foreword to the English edition; Acknowledgements; Part I. Gravitation and Light: 1. First fruits; 2. Relativity; 3. Curved space-time; Part II. Exquisite Corpses: 4. Chronicle of the twilight years; 5. Ashes and diamonds; 6. Supernovae; 7. Pulsars; 8. Gravitation triumphant; Part III. Light Assassinated: 9. The far horizon; 10. Illuminations; 11. A descent into the maelstrom; 12. Map games; 13. The black hole machine; 14. The quantum black hole; Part IV. Light Regained: 15. Primordial black holes; 16. The zoo of X-ray stars; 17. Giant black holes; 18. Gravitational light; 19. The black hole Universe; Appendices; Bibliography; Name index; Subject index.

  17. SDSS DR6 Data for Photometric Redshift Calculations

    Data.gov (United States)

    National Aeronautics and Space Administration — Subject Area: Astronomical data Description: The Sloan Digital Sky Survey (SDSS) is a multi-organization effort to gather deep, multi-color images covering more than...

  18. Emission line taxonomy and the nature of AGN-looking galaxies in the SDSS

    CERN Document Server

    Fernandes, Roberto Cid; Asari, Natalia Vale; Mateus, Abilio; Schlickmann, Marielli; Schoenell, William

    2009-01-01

    Massive spectroscopic surveys like the SDSS have revolutionized the way we study AGN and their relations to the galaxies they live in. A first step in any such study is to define samples of different types of AGN on the basis of emission line ratios. This deceivingly simple step involves decisions on which classification scheme to use and data quality censorship. Galaxies with weak emission lines are often left aside or dealt with separately because one cannot fully classify them onto the standard Star-Forming, Seyfert of LINER categories. This contribution summarizes alternative classification schemes which include this very numerous population. We then study how star-formation histories and physical properties of the hosts vary from class to class, and present compelling evidence that the emission lines in the majority of LINER-like systems in the SDSS are not powered by black-hole accretion. The data are fully consistent with them being galaxies whose old stars provide all the ionizing power needed to expl...

  19. Emission-Line Taxonomy and the Nature of AGN-Looking Galaxies in the SDSS

    Science.gov (United States)

    Cid Fernandes, Roberto; Stasińska, Grażyna; Vale Asari, Natalia; Mateus, Abílio; Schlickmann, Marielli S.; Schoenell, William; Schoenell

    2010-05-01

    Massive spectroscopic surveys like the SDSS have revolutionized the way we study AGN and their relations to the galaxies they live in. A first step in any such study is to define samples of different types of AGN on the basis of emission-line ratios. This deceivingly simple step involves decisions on which classification scheme to use and data quality censorship. Galaxies with weak emission lines are often left aside or dealt with separetely because one cannot fully classify them onto the standard star-forming, Seyfert, or LINER categories. This contribution summarizes alternative classification schemes which include this very numerous population. We then study how star-formation histories and physical properties of the hosts vary from class to class, and present compelling evidence that the emission lines in the majority of LINER-like systems in the SDSS are not powered by black-hole accretion. The data are fully consistent with them being galaxies whose old stars provide all the ionizing power needed to explain their line ratios and luminosities. Such retired galaxies deserve a place in the emission-line taxonomy.

  20. Grey Milky Way Extinction from SDSS Stellar Photometry

    OpenAIRE

    Gorbikov, Evgeny; Brosch, Noah

    2009-01-01

    We report results concerning the distribution and properties of galactic extinction at high galactic latitudes derived from stellar statistics using the Sloan Digital Sky Survey (SDSS). We use the classical Wolf diagram method to identify regions with extinction, and derive the extinction and the extinction law of the dust using all five SDSS spectral bands. We estimate the distance to the extinguishing medium using simple assumptions about the stellar populations in the line of sight. We rep...

  1. WHT follow-up observations of extremely metal-poor stars identified from SDSS and LAMOST

    Science.gov (United States)

    Aguado, D. S.; González Hernández, J. I.; Allende Prieto, C.; Rebolo, R.

    2017-09-01

    Aims: We have identified several tens of extremely metal-poor star candidates from SDSS and LAMOST, which we follow up with the 4.2 m William Herschel Telescope (WHT) telescope to confirm their metallicity. Methods: We followed a robust two-step methodology. We first analyzed the SDSS and LAMOST spectra. A first set of stellar parameters was derived from these spectra with the FERRE code, taking advantage of the continuum shape to determine the atmospheric parameters, in particular, the effective temperature. Second, we selected interesting targets for follow-up observations, some of them with very low-quality SDSS or LAMOST data. We then obtained and analyzed higher-quality medium-resolution spectra obtained with the Intermediate dispersion Spectrograph and Imaging System (ISIS) on the WHT to arrive at a second more reliable set of atmospheric parameters. This allowed us to derive the metallicity with accuracy, and we confirm the extremely metal-poor nature in most cases. In this second step we also employed FERRE, but we took a running mean to normalize both the observed and the synthetic spectra, and therefore the final parameters do not rely on having an accurate flux calibration or continuum placement. We have analyzed with the same tools and following the same procedure six well-known metal-poor stars, five of them at [Fe/H] http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/605/A40

  2. VizieR Online Data Catalog: SDSS/3XMM X-ray-selected LINERs (Nisbet+, 2016)

    Science.gov (United States)

    Nisbet, D. M.; Best, P. N.

    2016-07-01

    This research has been carried out on a data base of LINERs, for which both X-ray and radio luminosity information and black hole mass estimates are available. The sample was constructed by cross-matching the fourth data release of the 3XMM Serendipitous Source catalogue of X-ray sources (released by the XMM-Newton Survey Science Centre; XMM-SSC 2013, Cat. IX/44) with the seventh data release from the SDSS-DR7; Abazajian et al. (2009ApJS..182..543A) and then adding in radio luminosity data obtained from the FIRST catalogue (Becker, White & Helfand, 1995ApJ...450..559B, Cat. VIII/92). (1 data file).

  3. The Most Massive Galaxies and Black Holes Allowed by $\\Lambda$CDM

    CERN Document Server

    Behroozi, Peter

    2016-01-01

    Given a galaxy's stellar mass, its host halo mass has a lower limit from the cosmic baryon fraction and known baryonic physics. At $z>4$, galaxy stellar mass functions place lower limits on halo number densities that approach expected $\\Lambda$CDM halo mass functions. High-redshift galaxy stellar mass functions can thus place interesting limits on number densities of massive haloes, which are otherwise very difficult to measure. While halo mass functions at $z95% confidence. Similar arguments apply to black holes; using number density constraints alone, the most massive observed black holes at $z>5$ must lie above the median $z=0$ black hole mass - bulge mass relation. If their virial mass estimates are accurate, the quasars SDSS J1044$-$0125 and SDSS J010013.02$+$280225.8 must both have black hole mass - stellar mass ratios of at least 2%, equaling the recent $z=0$ record for central galaxies in NGC 1600.

  4. Close supermassive binary black holes

    Science.gov (United States)

    Gaskell, C. Martin

    2010-01-01

    It has been proposed that when the peaks of the broad emission lines in active galactic nuclei (AGNs) are significantly blueshifted or redshifted from the systemic velocity of the host galaxy, this could be a consequence of orbital motion of a supermassive blackhole binary (SMB). The AGN J1536+0441 (=SDSS J153636.22+044127.0) has recently been proposed as an example of this phenomenon. It is proposed here instead that 1536+044 is an example of line emission from a disc. If this is correct, the lack of clear optical spectral evidence for close SMBs is significant and argues either that the merging of close SMBs is much faster than has generally been hitherto thought, or if the approach is slow, that when the separation of the binary is comparable to the size of the torus and broad-line region, the feeding of the black holes is disrupted.

  5. SLoWPoKES-II: 100,000 WIDE BINARIES IDENTIFIED IN SDSS WITHOUT PROPER MOTIONS

    Energy Technology Data Exchange (ETDEWEB)

    Dhital, Saurav [Department of Physical Sciences, Embry-Riddle Aeronautical University, 600 South Clyde Morris Blvd., Daytona Beach, FL 32114 (United States); West, Andrew A.; Schluns, Kyle J.; Massey, Angela P. [Department of Astronomy, Boston University, 725 Commonwealth Avenue, Boston, MA 02215 (United States); Stassun, Keivan G., E-mail: dhitals@erau.edu [Department of Physics and Astronomy, Vanderbilt University, 6301 Stevenson Center, Nashville, TN, 37235 (United States)

    2015-08-15

    We present the Sloan Low-mass Wide Pairs of Kinematically Equivalent Stars (SLoWPoKES)-II catalog of low-mass visual binaries identified from the Sloan Digital Sky Survey (SDSS) by matching photometric distances. The candidate pairs are vetted by comparing the stellar information. The candidate pairs are vetted by comparing the stellar density at their respective Galactic positions to Monte Carlo realizations of a simulated Milky Way. In this way, we are able to identify large numbers of bona fide wide binaries without the need for proper motions. Here, 105,537 visual binaries with angular separations of ∼1–20″ were identified, each with a probability of chance alignment of ≤5%. This is the largest catalog of bona fide wide binaries to date, and it contains a diversity of systems—in mass, mass ratios, binary separations, metallicity, and evolutionary states—that should facilitate follow-up studies to characterize the properties of M dwarfs and white dwarfs. There is a subtle but definitive suggestion of multiple populations in the physical separation distribution, supporting earlier findings. We suggest that wide binaries are composed of multiple populations, most likely representing different formation modes. There are 141 M7 or later wide binary candidates, representing a seven-fold increase over the number currently known. These binaries are too wide to have been formed via the ejection mechanism. Finally, we found that 6% of spectroscopically confirmed M dwarfs are not included in the SDSS STAR catalog; they are misclassified as extended sources due to the presence of a nearby or partially resolved companion. The SLoWPoKES-II catalog is publicly available to the entire community on the World Wide Web via the Filtergraph data visualization portal.

  6. Runaway M Dwarf Candidates from the Sloan Digital Sky Survey

    CERN Document Server

    Favia, Andrej; Theissen, Christopher A

    2015-01-01

    We present a sample of 20 runaway M dwarf candidates (RdMs) within 1 kpc of the Sun whose Galactocentric velocities exceed 400 km s$^{-1}$. The candidates were selected from the SDSS DR7 M Dwarf Catalog of West et al. (2011). Our RdMs have SDSS+USNO-B proper motions that are consistent with those recorded in the PPMXL, LSPM, and combined WISE+SDSS+2MASS catalogs. Sixteen RdMs are classified as dwarfs, while the remaining four RdMs are subdwarfs. We model the Galactic potential using a bulge-disk-halo profile (Kenyon et al. 2008; Brown et al. 2014). Our fastest RdM, with Galactocentric velocity 658.5 $\\pm$ 236.9 km s$^{-1}$, is a possible hypervelocity candidate, as it is unbound in 77% of our simulations. About half of our RdMs have kinematics that are consistent with ejection from the Galactic center. Seven of our RdMs have kinematics consistent with an ejection scenario from M31 or M32 to within 2{\\sigma}, although our distance-limited survey makes such a realization unlikely. No more than four of our RdMs ...

  7. SDSS DR7 White Dwarf Catalog

    CERN Document Server

    Kleinman, S J; Koester, D; Pelisoli, Ingrid; Peçanha, Viviane; Nitta, A; Costa, J E S; Krzesinski, J; Dufour, P; Lachapelle, F -R; Bergeron, P; Yip, Ching-Wa; Harris, Hugh C; Eisenstein, Daniel J; Althaus, L; Córsico, A

    2012-01-01

    We present a new catalog of spectroscopically-confirmed white dwarf stars from the Sloan Digital Sky Survey Data Release 7 spectroscopic catalog. We find 20,407 white dwarf spectra, representing 19,712 stars, and provide atmospheric model fits to 14,120 DA and 1011 DB white dwarf spectra from 12,843 and 923 stars, respectively. These numbers represent a more than factor of two increase in the total number of white dwarf stars from the previous SDSS white dwarf catalog based on DR4 data. Our distribution of subtypes varies from previous catalogs due to our more conservative, manual classifications of each star in our catalog, supplementing our automatic fits. In particular, we find a large number of magnetic white dwarf stars whose small Zeeman splittings mimic increased Stark broadening that would otherwise result in an overestimated log(g) if fit as a non-magnetic white dwarf. We calculate mean DA and DB masses for our clean, non-magnetic sample and find the DB mean mass is statistically larger than that for...

  8. Galaxy Clustering in Early SDSS Redshift Data

    CERN Document Server

    Zehavi, I.; Frieman, Joshua A.; Weinberg, David H.; Mo, Houjun J.; Anderson, Scott F.; Strauss, Michael A.; Annis, James; Bahcall, Neta A.; Bernardi, Mariangela; Briggs, John W.; Brinkmann, Jon; Burles, Scott; Carey, Larry; Castander, Francisco J.; Connolly, J.; Csabai, Istvan; Dalcanton, Julianne J.; Dodelson,Scott; Doi,Mamoru; Eisenstein, Daniel; Evans, Michael L.; Finkbeiner, Douglas P.; Friedman, Scott; Fukugita, Masataka; Gunn, James E.; Hennessy, Greg S.; Hindsley, Robert B.; Ivezic, Zeljko; Kent,Stephen; Knapp, Gillian R.; Kron, Richard; Kunszt, Peter; Lamb, Donald; French Leger, R.; Long, Daniel C.; Loveday, Jon.; Lupton, Robert H.; McKay, Timothy; Meiksin, Avery; Merrelli, Aronne; Munn, Jeffrey A.; Narayanan, Vijay; Newcomb, Matt; Nichol, Robert C.; Owen, Russell; Peoples, John; Pope, Adrian; Rockosi, Constance M.; Schlegel, David; Schneider, Donald P.; Scoccimarro, Roman; Sheth, Ravi K.; Siegmund, Walter; Smee, Stephen; Snir, Yehuda; Stebbins, Albert; Stoughton, Christopher; SubbaRao, Mark; Szalay, Alexander S.; Szapudi, Istvan; Tegmark, Max; Tucker, Douglas L.; Uomoto, Alan; Vanden Berk, Dan; Vogeley, Michael S.; Waddell,Patrick; Yanny, Brian; York, Donald G.; Zehavi, Idit; Blanton, Michael R.; Frieman, Joshua A.; Weinberg, David H.; Mo, Houjun J.; Strauss, Michael A.

    2002-01-01

    We present the first measurements of clustering in the Sloan Digital Sky Survey (SDSS) galaxy redshift survey. Our sample consists of 29,300 galaxies with redshifts 5,700 km/s < cz < 39,000 km/s, distributed in several long but narrow (2.5-5 degree) segments, covering 690 square degrees. For the full, flux-limited sample, the redshift-space correlation length is approximately 8 Mpc/h. The two-dimensional correlation function \\xi(r_p,\\pi) shows clear signatures of both the small-scale, ``fingers-of-God'' distortion caused by velocity dispersions in collapsed objects and the large-scale compression caused by coherent flows, though the latter cannot be measured with high precision in the present sample. The inferred real-space correlation function is well described by a power law, \\xi(r)=(r/6.1+/-0.2 Mpc/h)^{-1.75+/-0.03}, for 0.1 Mpc/h < r < 16 Mpc/h. The galaxy pairwise velocity dispersion is \\sigma_{12} ~ 600+/-100 km/s for projected separations 0.15 Mpc/h < r_p < 5 Mpc/h. When we divide the...

  9. Long Term Variability of SDSS Quasars

    CERN Document Server

    De Vries, W; White, R; Becker, Bob; Vries, Wim de; White, Rick

    2003-01-01

    We use a sample of 3791 quasars from the Sloan Digital Sky Survey (SDSS) Early Data Release (EDR), and compare their photometry to historic plate material for the same set of quasars in order to study their variability properties. The time base-line we attain this way ranges from a few months to up to 50 years. In contrast to monitoring programs, where relatively few quasars are photometrically measured over shorter time periods, we utilize existing databases to extend this base-line as much as possible, at the cost of sampling per quasar. Our method, however, can easily be extended to much larger samples. We construct variability Structure Functions and compare these to the literature and model functions. From our modeling we conclude that 1) quasars are more variable toward shorter wavelengths, 2) their variability is consistent with an exponentially decaying light-curve with a typical time-scale of ~2 years, 3) these outbursts occur on typical time-scales of ~200 years. With the upcoming first data release...

  10. Characterization of Dwarf Novae Using SDSS Colors

    CERN Document Server

    Kato, Taichi; Uemura, Makoto

    2011-01-01

    We have developed a method for estimating orbital periods of dwarf novae from SDSS colors in quiescence using an artificial neural network. For typical objects below the period gap with good photometric accuracy, we could estimate orbital periods to a 1-sigma error of 22%. The error of estimation is worse for systems with longer periods. We have also developed a neural network-based method for categorical classification. This method has been proven to be efficient in classifying objects into three categories (WZ Sge-type, SU UMa-type and SS Cyg/Z Cam-type) and works for very faint objects down to g=21. Using these methods, we have investigated the distribution of orbital periods of dwarf novae from a modern transient survey (Catalina Real-Time Survey). Using Bayesian analysis developed by Uemura et al. (2010, arXiv:1003.0945), the present sample tends to give a flatter distribution toward the shortest period and a shorter estimate of the period minimum, which may have been resulted from the uncertainties in t...

  11. Component masses of young, wide, non-magnetic white dwarf binaries in the SDSS DR7

    CERN Document Server

    Baxter, R B; Parker, Q A; Casewell, S L; Lodieu, N; Burleigh, M R; Lawrie, K A; Kulebi, B; Koester, D; Holland, B R

    2014-01-01

    We present a spectroscopic component analysis of 18 candidate young, wide, non-magnetic, double-degenerate binaries identified from a search of the Sloan Digital Sky Survey Data Release 7 (DR7). All but two pairings are likely to be physical systems. We show SDSS J084952.47+471247.7 + SDSS J084952.87+471249.4 to be a wide DA+DB binary, only the second identified to date. Combining our measurements for the components of 16 new binaries with results for three similar, previously known systems within the DR7, we have constructed a mass distribution for the largest sample to date (38) of white dwarfs in young, wide, non-magnetic, double-degenerate pairings. This is broadly similar in form to that of the isolated field population with a substantial peak around M~0.6 Msun. We identify an excess of ultra-massive white dwarfs and attribute this to the primordial separation distribution of their progenitor systems peaking at relatively larger values and the greater expansion of their binary orbits during the final sta...

  12. Reddening Behaviors of Galaxies in the SDSS Photometric System

    CERN Document Server

    Kim, Sungsoo S

    2008-01-01

    We analyze the behaviors of reddening vectors in the SDSS photometric system for galaxies of different morphologies, ages, and redshifts. As seen in other photometric systems, the dependence of reddening on the spectral energy distribution (SED) and the nonlinearity of reddening are likewise non-negligible for the SDSS system if extinction is significant (~> 1 mag). These behaviors are most significant for the g filter, which has the largest bandwidth-to-central wavelength ratio among SDSS filters. The SDSS colors involving adjacent filters show greater SED-dependence and nonlinearity. A procedure for calculating the correct amount of extinction from an observed color excess is provided. The relative extinctions between (i.e., the extinction law for) SDSS filters given by Schlegel et al., which were calculated with an older version of filter response functions, would underestimate the amount of extinction in most cases by ~5 to 10 % (maximum ~20 %). We recommend A/A_{5500} values of 1.574, 1.191, 0.876, 0.671...

  13. The SDSS DR6 Luminosity Functions of Galaxies

    CERN Document Server

    Montero-Dorta, Antonio D

    2008-01-01

    We present number counts, luminosity functions (LFs) and luminosity densities of galaxies obtained using the Sloan Digital Sky Survey Sixth Data Release in all SDSS photometric bands. Thanks to the SDSS DR6, galaxy statistics have increased by a factor of ~9 in the u-band and by a factor of ~4-5 in the rest of the SDSS bands with respect to the previous work of Blanton et al. (2003b). In addition, we have achieved a high redshift completeness in our galaxy samples. Firstly, by making use of the survey masks, provided by the NYU-VAGC DR6, we have been able to define an area on the sky of high angular redshift completeness. Secondly, we guarantee that brightness-dependent redshift incompleteness is small within the magnitude ranges that define our galaxy samples. With these advances, we have estimated very accurate SDSS DR6 LFs in both the bright and the faint end. In the {0.1}^r-band, our SDSS DR6 luminosity function is well fitted by a Schechter LF with parameters Phi_{*}=0.90 +/- 0.07$, M_{*}-5log_{10}h=-20....

  14. VizieR Online Data Catalog: SDSS-RM project: peak velocities of QSOs (Shen+, 2016)

    Science.gov (United States)

    Shen, Y.; Brandt, W. N.; Richards, G. T.; Denney, K. D.; Greene, J. E.; Grier, C. J.; Ho, L. C.; Peterson, B. M.; Petitjean, P.; Schneider, D. P.; Tao, C.; Trump, J. R.

    2017-01-01

    The SDSS-RM quasar sample includes 849 broad-line quasars at 0.1SDSS-RM project within the SDSS-III (Eisenstein+ 2011AJ....142...72E) Baryon Oscillation Spectroscopic Survey (BOSS, Dawson+ 2013AJ....145...10D), using the BOSS spectrograph on the 2.5m SDSS telescope. The wavelength coverage of BOSS spectroscopy is ~3650-10400Å, with a spectral resolution of R~2000. (1 data file).

  15. Millijansky Radio Variability in SDSS Stripe 82

    Science.gov (United States)

    Hodge, J. A.; Becker, R. H.; White, R. L.; Richards, G. T.

    2013-06-01

    We report on a blind survey for extragalactic radio variability that was carried out by comparing two epochs of data from the Faint Images of the Radio Sky at Twenty centimeters survey with a third epoch from a new 1.4 GHz survey of SDSS Stripe 82. The three epochs are spaced seven years apart and have an overlapping area of 60 deg2. We uncover 89 variable sources down to the millijansky level, 75 of which are newly identified, and we find no evidence for transient phenomena. This new sample of variable sources allows us to infer an upper limit to the mean characteristic timescale of active galactic nucleus radio variability of 14 yr. We find that only 1% of extragalactic sources have fractional variability f var > 3, while 44% of Galactic sources vary by this much. The variable sample contains a larger fraction of quasars than a comparable non-variable control sample, though the majority of the variable sources appear to be extended galaxies in the optical. This implies that either quasars are not the dominant contributor to the variability of the sample, or that the deep optical data allow us to detect the host galaxies of some low-z quasars. We use the new, higher resolution data to report on the morphology of the variable sources. Finally, we show that the fraction of sources that are variable remains constant or increases at low flux densities. This may imply that next generation radio surveys with telescopes like Australian Square Kilometer Array Pathfinder and MeerKAT will see a constant or even increasing fraction of variable sources down into the sub-millijansky regime.

  16. Mass Models and Environment of the New Quadruply Lensed Quasar SDSS J1330+1810

    Energy Technology Data Exchange (ETDEWEB)

    Oguri, Masamune; Inada, Naohisa; Blackburne, Jeffrey A.; Shin, Min-Su; Kayo, Issha; Strauss, Michael A.; Schneider, Donald P.; York, Donald G.

    2008-09-09

    We present the discovery of a new quadruply lensed quasar. The lens system, SDSS J1330+1810 at z{sub s} = 1.393, was identified as a lens candidate from the spectroscopic sample of the Sloan Digital Sky Survey. Optical and near-infrared images clearly show four quasar images with a maximum image separation of 1.76 inch, as well as a bright lensing galaxy. We measure a redshift of the lensing galaxy of z{sub 1} = 0.373 from absorption features in the spectrum. We find a foreground group of galaxies at z = 0.31 centred {approx} 120 inch southwest of the lens system. Simple mass models fit the data quite well, including the flux ratios between images, although the lens galaxy appears to be {approx} 1 mag brighter than expected by the Faber-Jackson relation. Our mass modeling suggests that shear from nearby structure is affecting the lens potential.

  17. Variability-based AGN selection using image subtraction in the SDSS and LSST era

    CERN Document Server

    Choi, Yumi; Becker, Andrew C; Ivezić, \\vZeljko; Connolly, Andrew J; MacLeod, Chelsea L; Ruan, John J; Anderson, Scott F

    2013-01-01

    With upcoming all sky surveys such as LSST poised to generate a deep digital movie of the optical sky, variability-based AGN selection will enable the construction of highly-complete catalogs with minimum contamination. In this study, we generate $g$-band difference images and construct light curves for QSO/AGN candidates listed in SDSS Stripe 82 public catalogs compiled from different methods, including spectroscopy, optical colors, variability, and X-ray detection. Image differencing excels at identifying variable sources embedded in complex or blended emission regions such as Type II AGNs and other low-luminosity AGNs that may be omitted from traditional photometric or spectroscopic catalogs. To separate QSOs/AGNs from other sources using our difference image light curves, we explore several light curve statistics and parameterize optical variability by the characteristic damping timescale ($\\tau$) and variability amplitude. By virtue of distinguishable variability parameters of AGNs, we are able to select...

  18. A Cross-Match of 2MASS and SDSS: Newly-Found L and T Dwarfs and an Estimate of the Space Densitfy of T Dwarfs

    CERN Document Server

    Metchev, Stanimir; Berriman, G Bruce; Looper, Dagny

    2007-01-01

    We report new L and T dwarfs found in a cross-match of the SDSS Data Release 1 and 2MASS. Our simultaneous search of the two databases effectively allows us to relax the criteria for object detection in either survey and to explore the combined databases to a greater completeness level. We find two new T dwarfs in addition to the 13 already known in the SDSS DR1 footprint. We also identify 22 new candidate and bona-fide L dwarfs, including a new young L2 dwarf and a peculiar L2 dwarf with unusually blue near-IR colors: potentially the result of mildly sub-solar metallicity. These discoveries underscore the utility of simultaneous database cross-correlation in searching for rare objects. Our cross-match completes the census of T dwarfs within the joint SDSS and 2MASS flux limits to the 97% level. Hence, we are able to accurately infer the space density of T dwarfs. We employ Monte Carlo tools to simulate the observed population of SDSS DR1 T dwarfs with 2MASS counterparts and find that the space density of T0-...

  19. The SDSS-IV in 2014: A Demographic Snapshot

    CERN Document Server

    Lundgren, Britt; Zasowski, Gail; Lucatello, Sara; Diamond-Stanic, Aleksandar M; Tremonti, Christy A; Myers, Adam D; Aragon-Salamanca, Alfonso; Gillespie, Bruce; Ho, Shirley; Gallagher, John S

    2015-01-01

    Many astronomers now participate in large international collaborations, and it is important to examine whether these structures foster a scientific climate that is inclusive and diverse. The Committee on the Participation of Women in the Sloan Digital Sky Survey (CPWS) was formed to evaluate the demographics and gender climate within SDSS-IV, one of the largest and most geographically distributed astronomical collaborations. In April 2014, the CPWS administered a demographic survey to establish a baseline for the incipient SDSS-IV. We received responses from 250 participants (46% of the active membership). Half of the survey respondents were located in the US or Canada and 30% were based in Europe. Eleven percent of survey respondents considered themselves to be an ethnic minority at their current institution. Twenty-five percent of the SDSS-IV collaboration members are women, a fraction that is consistent with the US astronomical community, but substantially higher than the fraction of women in the IAU (16%)...

  20. Photometric asymmetry between clockwise and counterclockwise spiral galaxies in SDSS

    CERN Document Server

    Shamir, Lior

    2016-01-01

    While galaxies with clockwise and counterclockwise handedness are visually different, they are expected to be symmetric in all of their other characteristics. Previous experiments using both manual analysis and machine vision have shown that the handedness of Sloan Digital Sky Survey (SDSS) galaxies can be predicted with accuracy significantly higher than mere chance using its photometric data alone, showing that SDSS photometry pipeline is sensitive to the handedness of the galaxy. However, some of these previous experiments were based on manually classified galaxies, and the results may therefore be subjected to bias originated from the human perception. This paper describes an experiment based on a set of 162,514 celestial objects classified as clockwise and counterclockwise spiral galaxies in a fully automatic process, showing that the source of the asymmetry is more than the human perception bias. The results are compared to two smaller datasets, and confirm the observation that the handedness of SDSS ga...

  1. New resources to explore the old galaxy: Mining the SDSS

    Energy Technology Data Exchange (ETDEWEB)

    C. Allende Prieto et al.

    2003-07-01

    The Sloan Digital Sky Survey (SDSS) is collecting photometry and intermediate resolution spectra for {approx} 10{sup 5} stars in the thick-disk and stellar halo of the Milky Way. This massive dataset can be used to infer the properties of the stars that make up these structures, and considerably deepen our vision of the old components of the Galaxy. We devise tools for automatic analysis of the SDSS photometric and spectroscopic data based on plane-parallel line-blanketed LTE model atmospheres and fast optimization algorithms. A preliminary study of about 5000 stars in the Early Data Release gives a hint of the vast amount of information that the SDSS stellar sample contains.

  2. An Active Black Hole in a Compact Dwarf

    Science.gov (United States)

    Kohler, Susanna

    2016-05-01

    A new type of galaxy has just been added to the galaxy zoo: a small, compact, and old elliptical galaxy that shows signs of a monster black hole actively accreting material in its center. What can this unusual discovery tell us about how compact elliptical galaxies form?A New Galactic BeastCompact elliptical galaxies are an extremely rare early-type dwarf galaxy. Consistent with their name, compact ellipticals are small, very compact collections of ancient stars; these galaxies exhibit a high surface brightness and arent actively forming stars.Optical view of the ancient compact elliptical galaxy SDSS J085431.18+173730.5 (center of image) in an SDSS color composite image. [Adapted from Paudel et al. 2016]Most compact ellipticals are found in dense environments, particularly around massive galaxies. This has led astronomers to believe that compact ellipticals might form via the tidal stripping of a once-large galaxy in interactions with another, massive galaxy. In this model, once the original galaxys outer layers are stripped away, the compact inner bulge component would be left behind as a compact elliptical galaxy. Recent discoveries of a few isolated compact ellipticals, however, have strained this model.Now a new galaxy has been found to confuse our classification schemes: the first-ever compact elliptical to also display signs of an active galactic nucleus. Led by Sanjaya Paudel (Korea Astronomy and Space Science Institute), a team of scientists discovered SDSS J085431.18+173730.5 serendipitously in Sloan Digital Sky Survey data. The team used SDSS images and spectroscopy in combination with data from the Canada-France-Hawaii Telescope to learn more about this unique galaxy.Puzzling CharacteristicsSDSS J085431.18+173730.5 presents an interesting conundrum. Ancient compact ellipticals are supposed to be devoid of gas, with no fuel left to trigger nuclear activity. Yet SDSS J085431.18+173730.5 clearly shows the emission lines that indicate active accretion onto

  3. The milky way tomography with sdss

    Energy Technology Data Exchange (ETDEWEB)

    Juric, Mario; Ivezic, Zeljko; Brooks, Alyson; Lupton, Robert H.; Schlegel, David; Finkbeiner, Douglas; Padmanabhan, Nikhil; Bond, Nicholas; Rockosi, Constance M.; Knapp,; Gunn, James E.; Sumi, Takahiro; Schneider, Donald; Barentine, J.C.; Brewington, Howard J.; Brinkmann, J.; Fukugita, Masataka; Harvanek, Michael; Kleinman, S.J.; Krzesinski, Jurek; Long, Dan; /Princeton U. Observ. /Washington U., Seattle, Astron. Dept. /Princeton U. /Penn State U., Astron. Astrophys. /Apache Point Observ. /Tokyo U., ICRR

    2005-10-01

    Using the photometric parallax method, we estimate the distances to {approx}48 million stars detected by the Sloan Digital Sky Survey (SDSS), and map their three-dimensional number density distribution in the Galaxy. The currently available data sample the distance range from 100 pc to 15 kpc and cover 6,500 deg{sup 2} of sky, mostly at high galactic latitudes (|b| > 25). These stellar number density maps allow an investigation of the Galactic structure without any a priori assumptions about its components. The data show strong evidence for a Galaxy consisting of an oblate halo, disk components, and a number of localized overdensities. The number density distribution of stars in the Solar neighborhood (D < 1.5kpc) favors a model having a ''thin'' and a ''thick'' exponential disk, with scale heights and lengths of H{sub 1} {approx} 280 pc and L{sub 1} {approx} 2400pc, and H{sub 2} {approx} 1200pc and L{sub 2} {approx} 3500pc, respectively, and local thick-to-thin disk normalization {rho}{sub thick} (R{sub {circle_dot}})/{rho}{sub thin}(R{sub {circle_dot}}) = 4%. Fits applied to the entire dataset are significantly more uncertain due to the presence of clumps and overdensities. The halo power law index is very poorly constrained, but we find an oblate halo with c/a {approx} 0.5 to be strongly preferred. While roughly consistent with this simple model, the measured density distribution shows a number of statistically significant deviations from the model predictions. In addition to known features, such as the Monoceros stream, a remarkable density enhancement covering over a thousand square degrees of sky is detected towards the constellation of Virgo, at distances of {approx} 5-15 kpc. Compared to counts in a region symmetric with respect to the l = 0 line and with the same Galactic latitude, it is responsible for a factor of 2 number density excess, and may be a nearby tidal stream or a low-surface brightness dwarf galaxy

  4. X-ray survey of galaxy clusters in the SDSS Stripe 82 region

    Science.gov (United States)

    Durret, Florence; Takey, Ali

    2016-07-01

    We conducted a survey of galaxy clusters detected from XMM-Newton observations covering an area of 11.25 deg^2 in the Stripe 82 region of the Sloan Digital Sky Survey (SDSS). We found 94 X-ray cluster candidates from the third XMM-Newton serendipitous source catalogue (3XMM-DR5) and correlated this list with recently published X-ray and optically selected cluster catalogues to obtain optical confirmations and redshifts (between 0.05 and 1.19, with a median of 0.36) for 54 galaxy groups/clusters. Of these, 17 are newly X-ray discovered clusters and 45 systems with spectroscopic confirmations. Among the remaining candidates, 25 sources are distant cluster candidates (beyond a redshift of 0.6). We will present preliminary results on the X-ray and optical properties of these clusters: luminosities and temperatures of the X-ray gas, and optical properties of the galaxies (morphology, luminosity functions).

  5. Red Runaways II: Low mass Hills stars in SDSS Stripe 82

    CERN Document Server

    Zhang, Yanqiong; Carlin, Jeffrey L

    2016-01-01

    Stars ejected from the Galactic centre can be used to place important constraints on the Milky Way potential. Since existing hypervelocity stars are too distant to accurately determine orbits, we have conducted a search for nearby candidates using full three-dimensional velocities. Since the efficacy of such studies are often hampered by deficiencies in proper motion catalogs, we have chosen to utilize the reliable, high-precision SDSS Stripe 82 proper motion catalog. Although we do not find any candidates which have velocities in excess of the escape speed, we identify 226 stars on orbits that are consistent with Galactic centre ejection. This number is significantly larger than what we would expect for halo stars on radial orbits and cannot be explained by disk or bulge contamination. If we restrict ourselves to metal-rich stars, we find 29 candidates with [Fe/H] > -0.8 dex and 10 with [Fe/H] > -0.6 dex. Their metallicities are more consistent with what we expect for bulge ejecta, and so we believe these ca...

  6. Incidence of WISE -selected obscured AGNs in major mergers and interactions from the SDSS

    Science.gov (United States)

    Weston, Madalyn E.; McIntosh, Daniel H.; Brodwin, Mark; Mann, Justin; Cooper, Andrew; McConnell, Adam; Nielsen, Jennifer L.

    2017-02-01

    We use the Wide-field Infrared Survey Explorer (WISE) and the Sloan Digital Sky Survey (SDSS) to confirm a connection between dust-obscured active galactic nuclei (AGNs) and galaxy merging. Using a new, volume-limited (z ≤ 0.08) catalogue of visually selected major mergers and galaxy-galaxy interactions from the SDSS, with stellar masses above 2 × 1010 M⊙, we find that major mergers (interactions) are 5-17 (3-5) times more likely to have red [3.4] - [4.6] colours associated with dust-obscured or `dusty' AGNs, compared to non-merging galaxies with similar masses. Using published fibre spectral diagnostics, we map the [3.4] - [4.6] versus [4.6] - [12] colours of different emission-line galaxies and find that one-quarter of Seyferts have colours indicative of a dusty AGN. We find that AGNs are five times more likely to be obscured when hosted by a merging galaxy, half of AGNs hosted by a merger are dusty, and we find no enhanced frequency of optical AGNs in merging over non-merging galaxies. We conclude that undetected AGNs missed at shorter wavelengths are at the heart of the ongoing AGN-merger connection debate. The vast majority of mergers hosting dusty AGNs are star forming and located at the centres of Mhalo < 1013 M⊙ groups. Assuming plausibly short-duration dusty-AGN phases, we speculate that a large fraction of gas-rich mergers experience a brief obscured AGN phase, in agreement with the strong connection between central star formation and black hole growth seen in merger simulations.

  7. SDSS-III : massive spectroscopic surveys of the distant universe, the Milk Way, and extra-solar planetary systems

    OpenAIRE

    Eisenstein, Daniel J; Weinberg, David H.; Agol, Eric; Aihara, Hiroaki; Allende Prieto, Carlos; Anderson, Scott F.; Arns, James A.; Aubourg, Éric; Bailey, Stephen; Balbinot, Eduardo; Barkhouser, Robert; Beers, Timothy C.; Berlind, Andreas A.; Bickerton, Steven J.; Bizyaev, Dmitry

    2011-01-01

    Building on the legacy of the Sloan Digital Sky Survey (SDSS-I and II), SDSS-III is a program of four spectroscopic surveys on three scientific themes: dark energy and cosmological parameters, the history and structure of the Milky Way, and the population of giant planets around other stars. In keeping with SDSS tradition, SDSS-III will provide regular public releases of all its data, beginning with SDSS Data Release 8 (DR8), which was made public in 2011 January and includes SDSS-I and SDSS-...

  8. The SDSS Coadd: A Galaxy Photometric Redshift Catalog

    Energy Technology Data Exchange (ETDEWEB)

    Reis, Ribamar R.R.; /Fermilab /Rio de Janeiro Federal U.; Soares-Santos, Marcelle; /Fermilab /Inst. Geo. Astron., Havana /Sao Paulo U.; Annis, James; /Fermilab; Dodelson, Scott; /Fermilab /Chicago U. /Chicago U., KICP; Hao, Jiangang; /Fermilab; Johnston, David; /Fermilab; Kubo, Jeffrey; /Fermilab; Lin, Huan; /Fermilab; Seo, Hee-Jong; /UC, Berkeley; Simet, Melanie; /Chicago U.

    2011-11-01

    We present and describe a catalog of galaxy photometric redshifts (photo-z's) for the Sloan Digital Sky Survey (SDSS) Coadd Data. We use the Artificial Neural Network (ANN) technique to calculate photo-z's and the Nearest Neighbor Error (NNE) method to estimate photo-z errors for {approx} 13 million objects classified as galaxies in the coadd with r < 24.5. The photo-z and photo-z error estimators are trained and validated on a sample of {approx} 89, 000 galaxies that have SDSS photometry and spectroscopic redshifts measured by the SDSS Data Release 7 (DR7), the Canadian Network for Observational Cosmology Field Galaxy Survey (CNOC2), the Deep Extragalactic Evolutionary Probe Data Release 3(DEEP2 DR3), the SDSS-III's Baryon Oscillation Spectroscopic Survey (BOSS), the Visible imaging Multi-Object Spectrograph - Very Large Telescope Deep Survey (VVDS) and the WiggleZ Dark Energy Survey. For the best ANN methods we have tried, we find that 68% of the galaxies in the validation set have a photo-z error smaller than {sigma}{sub 68} = 0.036. After presenting our results and quality tests, we provide a short guide for users accessing the public data.

  9. Measuring Quasar Variability with Pan-STARRS1 and SDSS

    CERN Document Server

    Morganson, E; Chambers, K C; Green, P J; Kaiser, N; Magnier, E A; Marshall, P J; Morgan, J S; Price, P A; Rix, H -W; Chlafly, E F S; Tonry, J L; Walter, F

    2014-01-01

    We measure quasar variability using the Panoramic Survey Telescope and Rapid Response System 1 Survey (Pan-STARRS1 or PS1) and the Sloan Digital Sky Survey (SDSS) and establish a method of selecting quasars via their variability in 10,000 square degree surveys. We use 100,000 spectroscopically confirmed quasars that have been well measured in both PS1 and SDSS and take advantage of the decadal time scales that separate SDSS measurements and PS1 measurements. A power law model fits the data well over the entire time range tested, 0.01 to 10 years. Variability in the current PS1-SDSS dataset can efficiently distinguish between quasars and non-varying objects. It improves the purity of a griz quasar color cut from 4.1% to 48% while maintaining 67% completeness. Variability will be very effective at finding quasars in datasets with no u band and in redshift ranges where exclusively photometric selection is not efficient. We show that quasars' rest-frame ensemble variability, measured as a root mean squared in del...

  10. Scalelength of 30000 SDSS disc galaxies (Fathi+, 2010)

    NARCIS (Netherlands)

    Fathi, K.; Allen, M.; Boch, T.; Hatziminaoglou, E.; Peletier, R. F.

    2012-01-01

    Disc scalelength (h) for 30000 galaxies from the Sloan Digitized Sky Survey (SDSS) Data Release 7, in the r-band. Also included is the Asymmetry parameter for each galaxy. Virtual Observatory methods and tools were used to define, retrieve and analyze the images for this unprecedentedly large sample

  11. SSGSS : The Spitzer-SDSS-GALEX Spectroscopic Survey

    NARCIS (Netherlands)

    O'Dowd, Matthew J.; Schiminovich, David; Johnson, Benjamin D.; Treyer, Marie A.; Martin, Christopher D.; Wyder, Ted K.; Charlot, Stephane; Heckman, Timothy M.; Martins, Lucimara P.; Seibert, Mark; van der Hulst, J. M.

    2011-01-01

    The Spitzer-SDSS-GALEX Spectroscopic Survey (SSGSS) provides a new sample of 101 star-forming galaxies at z <0.2 with unprecedented multi-wavelength coverage. New mid-to far-infrared spectroscopy from the Spitzer Space Telescope is added to a rich suite of previous imaging and spectroscopy, includin

  12. Black Holes versus Supersymmetry at the LHC

    Science.gov (United States)

    Roy, Arunava; Cavaglia, Marco

    2007-11-01

    Supersymmetry and extra dimensions are the two most promising candidates for new physics at the TeV scale. Supersymmetric particles or extra-dimensional effects could soon be observed at the Large Hadron Collider. In this paper we assess the distinguishability of supersymmetry and black hole events at the LHC. Black hole events are simulated with the CATFISH black hole generator. Supersymmetry simulations use a combination of PYTHIA and ISAJET, the latter providing the mass spectrum. Our analysis shows that supersymmetry and black hole events at the Large Hadron Collider can be easily discriminated.

  13. Black holes

    CERN Document Server

    Chrúsciel, P T

    2002-01-01

    This paper is concerned with several not-quantum aspects of black holes, with emphasis on theoretical and mathematical issues related to numerical modeling of black hole space-times. Part of the material has a review character, but some new results or proposals are also presented. We review the experimental evidence for existence of black holes. We propose a definition of black hole region for any theory governed by a symmetric hyperbolic system of equations. Our definition reproduces the usual one for gravity, and leads to the one associated with the Unruh metric in the case of Euler equations. We review the global conditions which have been used in the Scri-based definition of a black hole and point out the deficiencies of the Scri approach. Various results on the structure of horizons and apparent horizons are presented, and a new proof of semi-convexity of horizons based on a variational principle is given. Recent results on the classification of stationary singularity-free vacuum solutions are reviewed. ...

  14. The SDSS-IV in 2014: A Demographic Snapshot

    Science.gov (United States)

    Lundgren, Britt; Kinemuchi, Karen; Zasowski, Gail; Lucatello, Sara; Diamond-Stanic, Aleksandar M.; Tremonti, Christy A.; Myers, Adam D.; Aragón-Salamanca, Alfonso; Gillespie, Bruce; Ho, Shirley; Gallagher, John S.

    2015-08-01

    Many astronomers now participate in large international scientific collaborations, and it is important to examine whether these structures foster a healthy scientific climate that is inclusive and diverse. The Committee on the Participation of Women in the Sloan Digital Sky Survey (CPWS) was formed to evaluate the demographics and gender climate within SDSS-IV, one of the largest and most geographically distributed astronomical collaborations. In 2014 April, the CPWS administered a voluntary demographic survey to establish a baseline for the incipient SDSS-IV, which began observations in 2014 July. We received responses from 250 participants (46% of the active membership). Half of the survey respondents were located in the United States or Canada and 30% were based in Europe. Approximately 65% were faculty or research scientists and 31% were postdocs or graduate students. Eleven percent of survey respondents considered themselves to be an ethnic minority at their current institution. Twenty-five percent of the SDSS-IV collaboration members are women, a fraction that is consistent with the U.S. astronomical community, but substantially higher than the fraction of women in the International Astronomical Union (16%). Approximately equal fractions of men and women report holding positions of leadership in the collaboration. When binned by academic age and career level, men and women also assume leadership roles at approximately equal rates, in a way that increases steadily for both genders with increasing seniority. In this sense, SDSS-IV has been successful in recruiting leaders that are representative of the collaboration. That said, it is clear that more progress needs to be made toward achieving gender balance and increasing diversity in the field of astronomy, and there is still room for improvement in the membership and leadership of SDSS-IV. For example, at the highest level of SDSS-IV leadership, women disproportionately assume roles related to education and

  15. The Rate of Type Ia Supernovae at z~0.2 from SDSS-I Overlapping Fields

    CERN Document Server

    Horesh, Assaf; Ofek, Eran O; Maoz, Dan

    2008-01-01

    In the course of the Sloan Digital Sky Survey (SDSS-I), a large fraction of the surveyed area was observed more than once due to field tiling overlap, usually at different epochs. We utilize some of these data to perform a supernova (SN) survey at a mean redshift of z=0.2. Our archival search, in ~ 5% of the SDSS-I overlap area, produces 29 SN candidates clearly associated with host galaxies. Using the Bayesian photometric classification algorithm of Poznanski et al., and correcting for classification bias, we find 17 of the 29 candidates are likely Type Ia SNe. Accounting for the detection efficiency of the survey and for host extinction, this implies a Type Ia SN rate of R=14.0+(2.5,1.4}-(2.5,1.1}+/-2.5 10^-14 h(70)^2 yr^-1 L_sun^-1, where the errors are Poisson error, systematic detection efficiency error, and systematic classification error, respectively. The volumetric rate is R=1.89+(0.42,0.18)-(0.34,0.15)+/-0.42 10^-5 yr^-1 h(70)^3 Mpc^-3. Our measurement is consistent with other rate measurements at l...

  16. Characterizing RR Lyraes using SDSS, Single-Epoch Spectroscopy

    Science.gov (United States)

    Long, Stacy Scott; Wilhelm, Ronald J.; De Lee, Nathan M.

    2017-01-01

    Starting with Data Release-7, the Sloan Digital Sky Survey (SDSS) has made available the single-epoch spectra (SES) that were previously combined to produce the final composite spectra available for stars and galaxies. These SES can be used to probe time-variability through spectral line strength variations. RR Lyrae stars (RRL) have typically been identified using periodic variations in their light curves. Today, using the SDSS-SES it is possible to, in some cases, identify RRL from changes in the line strengths of the Ca-IIK, H-$\\beta$, H-$\\gamma$, and H-$\\delta$ lines. Similarly, it is possible to construct composite spectra that are free of phase-blending, by grouping SES that have similar spectral line strengths, for an individual star. We have developed a method for comparing SES with synthetic spectra spanning a range of T = [5500,8500]K, log g = [1.0-4.0] and [Fe/H]=[-3.0-0.0] to produce temperatures, surface gravities and metallicities for all SES taken for a given star. Using this method we are able to search for variations in temperature that are 2-sigma beyond the computed uncertainty, indicating that spectral variation is occurring. We will show results using a sample of bright RRL stars of known pulsation phase and stars from SDSS-Stripe82 which have published light curves for several hundred RRLs. We will also present a temperature-phase diagram that shows stars with consistent phases can be produced allowing us to construct composite spectra that are of the same phase for a given star. This is crucially important to the accurate determination of metal abundance for stars in the SDSS spectral foot-print. We will also show details of the compiled Catalina Surveys for stars with SDSS spectroscopy.

  17. On the fairness of the main galaxy sample of SDSS

    Institute of Scientific and Technical Information of China (English)

    Ke-Lai Meng; Bin Ma; Jun Pan; Long-Long Feng

    2011-01-01

    Flux-limited and volume-limited galaxy samples are constructed from the Sloan Digital Sky Survey (SDSS) data releases DR4, DR6 and DR7 for statistical analysis. The two-point correlation functions ξ(s), monopole of three-point correlation functions ζ0, projected two-point correlation function Wp and pairwise velocity dispersion σ12 are measured to test if galaxy samples are fair for these statistics. We find that with the increment of sky coverage of subsequent data releases in SDSS,ξ(s) of the flux-limited sample is extremely robust and insensitive to local structures at low redshift. However, for volume-limited samples fainter than L* at large scales s >~ 10 h-1 Mpc, the deviation of ξ(s) from different SDSS data releases (DR7, DR6 and DR4) increases with the increment of absolute magnitude. The case of ζ0(s) is similar to that of ξ(s). In the weakly nonlinear regime, there is no agreement between ζ0 of different data releases in all luminosity bins. Furthermore, Wp of volume-limited samples of DR7 in luminosity bins fainter than -Mr,0.1 = [18.5, 19.5] are significantly larger and σ12 of the two faintest volume-limited samples of DR7 display a very different scale dependence than results from DR4 and DR6. Our findings call for caution in understanding clustering analysis results of SDSS faint galaxy samples and higher order statistics of SDSS volume-limited samples in the weakly nonlinear regime. The first zero-crossing points of ξ(s) from volume-limited samples are also investigated and discussed.

  18. A TARGETED SEARCH FOR PECULIARLY RED L AND T DWARFS IN SDSS, 2MASS, AND WISE: DISCOVERY OF A POSSIBLE L7 MEMBER OF THE TW HYDRAE ASSOCIATION

    Energy Technology Data Exchange (ETDEWEB)

    Kellogg, Kendra; Metchev, Stanimir [Western University, Centre for Planetary and Space Exploration, 1151 Richmond St, London, ON N6A 3K7 (Canada); Geißler, Kerstin; Hicks, Shannon [Stony Brook University, Stony Brook, NY 11790 (United States); Kirkpatrick, J. Davy [Infrared Processing and Analysis Center, Mail Code 100-22, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125 (United States); Kurtev, Radostin, E-mail: kkellogg@uwo.ca, E-mail: smetchev@uwo.ca [Instituto de Física y Astronomía, Facultad de Ciencias, Universidad de Valparaíso, Ave. Gran Bretaña 1111, Playa Ancha, Casilla 53, Valparaíso (Chile)

    2015-12-15

    We present the first results from a targeted search for brown dwarfs with unusual red colors indicative of peculiar atmospheric characteristics. These include objects with low surface gravities or with unusual dust content or cloud properties. From a positional cross-match of SDSS, 2MASS, and WISE, we have identified 40 candidate peculiar early-L to early-T dwarfs that are either new objects or have not been identified as peculiar through prior spectroscopy. Using low-resolution spectra, we confirm that 10 of the candidates are either peculiar or potential L/T binaries. With a J − K{sub s} color of 2.62 ± 0.15 mag, one of the new objects—the L7 dwarf 2MASS J11193254–1137466—is among the reddest field dwarfs currently known. Its proper motion and photometric parallax indicate that it is a possible member of the TW Hydrae moving group. If confirmed, it would be the lowest-mass (5–6 M{sub Jup}) free-floating member. We also report a new T dwarf, 2MASS J22153705+2110554, that was previously overlooked in the SDSS footprint. These new discoveries demonstrate that despite the considerable scrutiny already devoted to the SDSS and 2MASS surveys, our exploration of these data sets is not yet complete.

  19. Observational Constraints on Quasar Black Hole Mass Distributions, Eddington Ratio Distributions, and Lifetimes

    DEFF Research Database (Denmark)

    Kelly, Brandon C.; Vestergaard, Marianne; Fan, X.

    2010-01-01

    I will present the black hole mass function (BHMF) of broad line quasars in the SDSS DR3. We employ a powerful Bayesian statistical technique that corrects for incompleteness and the statistical uncertainty in the mass estimates. We find evidence that the most massive black hole appeared as quasars...... earlier in the universe, and that most quasars are not radiating at or near the Eddington limit. I will also present constraints on the quasar lifetime and maximum black hole mass, derived from the mass functions....

  20. Observational Constraints on Quasar Black Hole Mass Distributions, Eddington Ratio Distributions, and Lifetimes

    DEFF Research Database (Denmark)

    Kelly, Brandon C.; Vestergaard, Marianne; Fan, X.

    2010-01-01

    I will present the black hole mass function (BHMF) of broad line quasars in the SDSS DR3. We employ a powerful Bayesian statistical technique that corrects for incompleteness and the statistical uncertainty in the mass estimates. We find evidence that the most massive black hole appeared as quasars...... earlier in the universe, and that most quasars are not radiating at or near the Eddington limit. I will also present constraints on the quasar lifetime and maximum black hole mass, derived from the mass functions....

  1. Coronal Holes

    Directory of Open Access Journals (Sweden)

    Steven R. Cranmer

    2009-09-01

    Full Text Available Coronal holes are the darkest and least active regions of the Sun, as observed both on the solar disk and above the solar limb. Coronal holes are associated with rapidly expanding open magnetic fields and the acceleration of the high-speed solar wind. This paper reviews measurements of the plasma properties in coronal holes and how these measurements are used to reveal details about the physical processes that heat the solar corona and accelerate the solar wind. It is still unknown to what extent the solar wind is fed by flux tubes that remain open (and are energized by footpoint-driven wave-like fluctuations, and to what extent much of the mass and energy is input intermittently from closed loops into the open-field regions. Evidence for both paradigms is summarized in this paper. Special emphasis is also given to spectroscopic and coronagraphic measurements that allow the highly dynamic non-equilibrium evolution of the plasma to be followed as the asymptotic conditions in interplanetary space are established in the extended corona. For example, the importance of kinetic plasma physics and turbulence in coronal holes has been affirmed by surprising measurements from the UVCS instrument on SOHO that heavy ions are heated to hundreds of times the temperatures of protons and electrons. These observations point to specific kinds of collisionless Alfvén wave damping (i.e., ion cyclotron resonance, but complete theoretical models do not yet exist. Despite our incomplete knowledge of the complex multi-scale plasma physics, however, much progress has been made toward the goal of understanding the mechanisms ultimately responsible for producing the observed properties of coronal holes.

  2. M Dwarfs From The SDSS, 2MASS and WISE Surveys: Identification, Characterisation and Unresolved Ultracool Companionship

    Science.gov (United States)

    Cook, Neil James

    2016-08-01

    The aim of this thesis is to use a cross-match between WISE, 2MASS and SDSS to identify a large sample of M dwarfs. Through the careful characterisation and quality control of these M dwarfs I aim to identify rare systems (i.e. unresolved UCD companions, young M dwarfs, late M dwarfs and M dwarfs with common proper motion companions). Locating ultracool companions to M dwarfs is important for constraining low-mass formation models, the measurement of substellar dynamical masses and radii, and for testing ultracool evolutionary models. This is done by using an optimised method for identifying M dwarfs which may have unresolved ultracool companions. To do this I construct a catalogue of 440 694 M dwarf candidates, from WISE, 2MASS and SDSS, based on optical- and near-infrared colours and reduced proper motion. With strict reddening, photometric and quality constraints I isolate a sub-sample of 36 898 M dwarfs and search for possible mid-infrared M dwarf + ultracool dwarf candidates by comparing M dwarfs which have similar optical/near-infrared colours (chosen for their sensitivity to effective temperature and metallicity). I present 1 082 M dwarf + ultracool dwarf candidates for follow-up. Using simulated ultracool dwarf companions to M dwarfs, I estimate that the occurrence of unresolved ultracool companions amongst my M dwarf + ultracool dwarf candidates should be at least four times the average for my full M dwarf catalogue. I discuss yields of candidates based on my simulations. The possible contamination and bias from misidentified M dwarfs is then discussed, from chance alignments with other M dwarfs and UCDs, from chance alignments with giant stars, from chance alignments with galaxies, and from blended systems (via visual inspection). I then use optical spectra from LAMOST to spectral type a subset of my M dwarf + ultracool dwarf candidates. These candidates need confirming as true M dwarf + ultracool dwarf systems thus I present a new method I developed to

  3. DISCOVERY OF DRAMATIC OPTICAL VARIABILITY IN SDSS J1100+4421: A PECULIAR RADIO-LOUD NARROW-LINE SEYFERT 1 GALAXY?

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, Masaomi [National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan); Morokuma, Tomoki; Doi, Mamoru; Kikuchi, Yuki [Institute of Astronomy, School of Science, University of Tokyo, Mitaka, Tokyo 181-0015 (Japan); Itoh, Ryosuke [Department of Physical Sciences, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Akitaya, Hiroshi; Tanaka, Yasuyuki T.; Kawabata, Koji S. [Hiroshima Astrophysical Science Center, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Tominaga, Nozomu [Department of Physics, Faculty of Science and Engineering, Konan University, Kobe, Hyogo 658-8501 (Japan); Saito, Yoshihiko; Kawai, Nobuyuki [Department of Physics, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8551 (Japan); Stawarz, Łukasz [Institute of Space and Astronautical Science, JAXA, Sagamihara, Kanagawa 252-5210 (Japan); Gandhi, Poshak [Department of Physics, Durham University, Durham DH1-3LE (United Kingdom); Ali, Gamal; Essam, Ahmad; Hamed, Gamal [National Research Institute of Astronomy and Geophysics, Helwan, Cairo (Egypt); Aoki, Tsutomu [Kiso Observatory, Institute of Astronomy, School of Science, The University of Tokyo, Kiso, Nagano 397-0101 (Japan); Contreras, Carlos; Hsiao, Eric Y. [Carnegie Observatories, Las Campanas Observatory, Colina El Pino, Casilla 601 (Chile); Iwata, Ikuru, E-mail: masaomi.tanaka@nao.ac.jp [Subaru Telescope, National Astronomical Observatory of Japan, Hilo, HI 96720 (United States); and others

    2014-10-01

    We present our discovery of dramatic variability in SDSS J1100+4421 by the high-cadence transient survey Kiso Supernova Survey. The source brightened in the optical by at least a factor of three within about half a day. Spectroscopic observations suggest that this object is likely a narrow-line Seyfert 1 galaxy (NLS1) at z = 0.840, however, with unusually strong narrow emission lines. The estimated black hole mass of ∼10{sup 7} M {sub ☉} implies bolometric nuclear luminosity close to the Eddington limit. SDSS J1100+4421 is also extremely radio-loud, with a radio loudness parameter of R ≅ 4 × 10{sup 2}-3 × 10{sup 3}, which implies the presence of relativistic jets. Rapid and large-amplitude optical variability of the target, reminiscent of that found in a few radio- and γ-ray-loud NLS1s, is therefore produced most likely in a blazar-like core. The 1.4 GHz radio image of the source shows an extended structure with a linear size of about 100 kpc. If SDSS J1100+4421 is a genuine NLS1, as suggested here, this radio structure would then be the largest ever discovered in this type of active galaxies.

  4. Discovery of Dramatic Optical Variability in SDSS J1100+4421: A Peculiar Radio-Loud Narrow-Line Seyfert 1 Galaxy?

    CERN Document Server

    Tanaka, Masaomi; Itoh, Ryosuke; Akitaya, Hiroshi; Tominaga, Nozomu; Saito, Yoshihiko; Stawarz, Lukasz; Tanaka, Yasuyuki T; Gandhi, Poshak; Ali, Gamal; Aoki, Tsutomu; Contreras, Carlos; Doi, Mamoru; Essam, Ahmad; Hamed, Gamal; Hsiao, Eric Y; Iwata, Ikuru; Kawabata, Koji S; Kawai, Nobuyuki; Kikuchi, Yuki; Kobayashi, Naoto; Kuroda, Daisuke; Maehara, Hiroyuki; Matsumoto, Emiko; Mazzali, Paolo A; Minezaki, Takeo; Mito, Hiroyuki; Miyata, Takashi; Miyazaki, Satoshi; Mori, Kensho; Moritani, Yuki; Morokuma-Matsui, Kana; Morrell, Nidia; Nagao, Tohru; Nakada, Yoshikazu; Nakata, Fumiaki; Noma, Chinami; Ohsuga, Ken; Okada, Norio; Phillips, Mark M; Pian, Elena; Richmond, Michael W; Sahu, Devendra; Sako, Shigeyuki; Sarugaku, Yuki; Shibata, Takumi; Soyano, Takao; Stritzinger, Maximilian D; Tachibana, Yutaro; Taddia, Francesco; Takaki, Katsutoshi; Takey, Ali; Tarusawa, Ken'ichi; Ui, Takahiro; Ukita, Nobuharu; Urata, Yuji; Walker, Emma S; Yoshii, Taketoshi

    2014-01-01

    We present our discovery of dramatic variability in SDSS J1100+4421 by the high-cadence transient survey Kiso Supernova Survey (KISS). The source brightened in the optical by at least a factor of three within about half a day. Spectroscopic observations suggest that this object is likely a narrow-line Seyfert 1 galaxy (NLS1) at z=0.840, however with unusually strong narrow emission lines. The estimated black hole mass of ~ 10^7 Msun implies bolometric nuclear luminosity close to the Eddington limit. SDSS J1100+4421 is also extremely radio-loud, with a radio loudness parameter of R ~ 4 x 10^2 - 3 x 10^3, which implies the presence of relativistic jets. Rapid and large-amplitude optical variability of the target, reminiscent of that found in a few radio- and gamma-ray loud NLS1s, is therefore produced most likely in a blazar-like core. The 1.4 GHz radio image of the source shows an extended structure with a linear size of about 100 kpc. If SDSS J1100+4421 is a genuine NLS1, as suggested here, this radio structu...

  5. A new catalogue of polar-ring galaxies selected from the SDSS

    CERN Document Server

    Moiseev, Alexei; Smirnova, Aleksandrina; Reshetnikov, Vladimir

    2011-01-01

    (Abridged) Galaxies with polar rings (PRGs) are a unique class of extragalactic objects allowing to investigate a wide range of problems, linked with the formation and evolution of galaxies, and to study the properties of their dark haloes. The progress in the study of PRGs is constrained by a small number of known objects of this type. Up to date, we can only attribute about two dozens of kinematically-confirmed galaxies to this class, mostly from Whitmore et al. (1990) catalogue. We present a new catalogue of PRGs based on the results of the original Galaxy Zoo project. Based on the preliminary classification of the Galaxy Zoo, we viewed more than 40000 images of the Sloan Digital Sky Survey (SDSS) and selected 275 galaxies, included in our catalogue. Our Sloan-based Polar Ring Catalog (SPRC) contains 70 galaxies that we classified as "the best candidates", among which we expect to have a very high proportion of true PRGs, and 115 good PRG candidates. 53 galaxies are classified as PRG related objects.We ide...

  6. Revisiting the Hubble sequence in the SDSS DR7

    Science.gov (United States)

    Huertas-Company, M.; Aguerri, J. A. L.; Bernardi, M.; Mei, S.; S´Nchez Almeida, J.

    2011-11-01

    We present an automated morphological classification in 4 types (E, S0, Sab, Scd) of ˜ 700,000 galaxies from the SDSS DR7 spectroscopic sample based on support vector machines. The main new property of the classification is that we associate a probability to each galaxy of being in the four morphological classes instead of assigning a single class. The classification is therefore better adapted to nature where we expect a continuous transition between different morphological types. The algorithm is trained with a visual classification and then compared to several independent visual classifications including the Galaxy Zoo first-release catalog. We find a very good correlation between the automated classification and classical visual ones. The compiled catalog is intended for use in different applications and is therefore publicly available through a dedicated webpage (http://gepicom04.obspm.fr/sdss_morphology/Morphology_2010.html)

  7. Quasar Variability Measurements With SDSS Repeated Imaging and POSS Data

    CERN Document Server

    Ivezic, Z; Juric, M; Anderson, S; Hall, P B; Richards, G T; Rockosi, C M; Vanden Berk, Daniel E; Turner, E L; Knapp, G R; Gunn, J E; Schlegel, D J; Strauss, M A; Schneider, D P

    2004-01-01

    We analyze the properties of quasar variability using repeated SDSS imaging data in five UV-to-far red photometric bands, accurate to 0.02 mag, for 13,000 spectroscopically confirmed quasars. The observed time lags span the range from 3 hours to over 3 years, and constrain the quasar variability for rest-frame time lags of up to two years, and at rest-frame wavelengths from 1000 Ang. to 6000 Ang. We demonstrate that 66,000 SDSS measurements of magnitude differences can be described within the measurement noise by a simple function of only three free parameters. The addition of POSS data constrains the long-term behavior of quasar variability and provides evidence for a turn-over in the structure function. This turn-over indicates that the characteristic time scale for optical variability of quasars is of the order 1 year.

  8. Coronal Holes

    CERN Document Server

    Cranmer, Steven R

    2009-01-01

    Coronal holes are the darkest and least active regions of the Sun, as observed both on the solar disk and above the solar limb. Coronal holes are associated with rapidly expanding open magnetic fields and the acceleration of the high-speed solar wind. This paper reviews measurements of the plasma properties in coronal holes and how these measurements are used to reveal details about the physical processes that heat the solar corona and accelerate the solar wind. It is still unknown to what extent the solar wind is fed by flux tubes that remain open (and are energized by footpoint-driven wave-like fluctuations), and to what extent much of the mass and energy is input intermittently from closed loops into the open-field regions. Evidence for both paradigms is summarized in this paper. Special emphasis is also given to spectroscopic and coronagraphic measurements that allow the highly dynamic non-equilibrium evolution of the plasma to be followed as the asymptotic conditions in interplanetary space are establish...

  9. Changing Ionization Conditions in SDSS Galaxies with AGN as a Function of Environment from Pairs to Clusters

    CERN Document Server

    Khabiboulline, Emil T; Silverman, John D; Ellison, Sara L; Mendel, J Trevor; Patton, David R

    2014-01-01

    We study how AGN activity changes across environments from galaxy pairs to clusters using $143\\, 843$ galaxies with $z<0.2$ from the Sloan Digital Sky Survey (SDSS). Using a refined technique, we apply a continuous measure of AGN activity, characteristic of the ionization state of the narrow-line emitting gas. Changes in key emission-line ratios ([NII]$\\lambda6548$/H$\\alpha$, [OIII]$\\lambda5007$/H$\\beta$) between different samples allow us to disentangle different environmental effects while removing contamination. We confirm that galaxy interactions enhance AGN activity. However, conditions in the central regions of clusters are inhospitable for AGN activity even if galaxies are in pairs. These results can be explained through models of gas dynamics in which pair interactions stimulate the transfer of gas to the nucleus and clusters suppress gas availability for accretion onto the central black hole.

  10. Rλ3-inspired black holes

    Science.gov (United States)

    Kováčik, Samuel

    2017-08-01

    We study a black hole with a blurred mass density instead of a singular one, which is caused by the noncommutativity of three-space. Depending on its mass, such object has either none, one or two event horizons. It possesses properties, which become important on a microscopic scale, in particular, the Hawking temperature does not increase indefinitely as the mass goes to zero, but vanishes instead. Such frozen and extremely dense pieces of matter are good dark matter candidates.

  11. The Milky Way Tomography with SDSS: II. Stellar Metallicity

    CERN Document Server

    Ivezic, Zeljko; Juric, Mario; Bond, Nicholas; Dalcanton, Julianne; Rockosi, Constance M; Yanny, Brian; Newberg, Heidi J; Beers, Timothy C; Prieto, Carlos Allende; Wilhelm, Ron; Lee, Young Sun; Sivarani, Thirupathi; Norris, John E; Bailer-Jones, Coryn A L; Fiorentin, Paola Re; Schlegel, David; Uomoto, Alan; Lupton, Robert H; Knapp, Gillian R; Gunn, James E; Covey, Kevin R; Smith, J Allyn; Miknaitis, Gajus; Doi, Mamoru; Tanaka, Masayuki; Fukugita, Masataka; Kent, Steve; Finkbeiner, Douglas; Munn, Jeffrey A; Pier, Jeffrey R; Quinn, Tom; Hawley, Suzanne; Anderson, Scott; Kiuchi, Furea; Chen, Alex; Bushong, James; Sohi, Harkirat; Haggard, Daryl; Kimball, Amy; Barentine, John; Brewington, Howard; Harvanek, Mike; Kleinman, Scott; Krzesinski, Jurek; Long, Dan; Nitta, Atsuko; Snedden, Stephanie; Lee, Brian; Harris, Hugh; Brinkmann, Jonathan; Schneider, Donald P; York, Donald G

    2008-01-01

    Using effective temperature and metallicity derived from SDSS spectra for ~60,000 F and G type main sequence stars (0.2SDSS u-g and g-r colors. We apply this method to SDSS photometric data for about 2 million F/G stars and measure the unbiased metallicity distribution for a complete volume-limited sample of stars at distances between 500 pc and 8 kpc. The metallicity distribution can be exquisitely modeled using two components with a spatially varying number ratio, that correspond to disk and halo. The two components also possess the kinematics expected for disk and halo stars. The metallicity of the halo component is spatially invariant, while the median disk metallicity smoothly decreases with distance from the Galactic plane from -0.6 at 500 pc to -0.8 beyond several kpc. The absence of a correlation between metallicity and kinematics for disk stars is in a conflict with the traditional decomposition in terms of thin an...

  12. Photometric redshifts for the SDSS Data Release 12

    Science.gov (United States)

    Beck, Róbert; Dobos, László; Budavári, Tamás; Szalay, Alexander S.; Csabai, István

    2016-08-01

    We present the methodology and data behind the photometric redshift data base of the Sloan Digital Sky Survey (SDSS) Data Release 12. We adopt a hybrid technique, empirically estimating the redshift via local regression on a spectroscopic training set, then fitting a spectrum template to obtain K-corrections and absolute magnitudes. The SDSS spectroscopic catalogue was augmented with data from other, publicly available spectroscopic surveys to mitigate target selection effects. The training set is comprised of 1976 978 galaxies, and extends up to redshift z ≈ 0.8, with a useful coverage of up to z ≈ 0.6. We provide photometric redshifts and realistic error estimates for the 208 474 076 galaxies of the SDSS primary photometric catalogue. We achieve an average bias of overline{Δ z_{norm}} = {5.84 × 10^{-5}}, a standard deviation of σ(Δznorm) = 0.0205, and a 3σ outlier rate of Po = 4.11 per cent when cross-validating on our training set. The published redshift error estimates and photometric error classes enable the selection of galaxies with high-quality photometric redshifts. We also provide a supplementary error map that allows additional, sophisticated filtering of the data.

  13. Photometric redshifts for the SDSS Data Release 12

    CERN Document Server

    Beck, Róbert; Budavári, Tamás; Szalay, Alexander S; Csabai, István

    2016-01-01

    We present the methodology and data behind the photometric redshift database of the Sloan Digital Sky Survey Data Release 12 (SDSS DR12). We adopt a hybrid technique, empirically estimating the redshift via local regression on a spectroscopic training set, then fitting a spectrum template to obtain K-corrections and absolute magnitudes. The SDSS spectroscopic catalog was augmented with data from other, publicly available spectroscopic surveys to mitigate target selection effects. The training set is comprised of $1,976,978$ galaxies, and extends up to redshift $z\\approx 0.8$, with a useful coverage of up to $z\\approx 0.6$. We provide photometric redshifts and realistic error estimates for the $208,474,076$ galaxies of the SDSS primary photometric catalog. We achieve an average bias of $\\overline{\\Delta z_{\\mathrm{norm}}} = -0.0012$, a standard deviation of $\\sigma \\left(\\Delta z_{\\mathrm{norm}}\\right)=0.0249$, and a $3\\sigma$ outlier rate of $P_o=1.6\\%$ when cross-validating on our training set. The published...

  14. Photometric Asymmetry Between Clockwise and Counterclockwise Spiral Galaxies in SDSS

    Science.gov (United States)

    Shamir, Lior

    2017-02-01

    While galaxies with clockwise and counterclockwise handedness are visually different, they are expected to be symmetric in all of their other characteristics. Previous experiments using both manual analysis and machine vision have shown that the handedness of Sloan Digital Sky Survey galaxies can be predicted with accuracy significantly higher than mere chance using its photometric data alone. However, some of these previous experiments were based on manually classified galaxies, and the results may therefore be subjected to bias originated from the human perception. This paper describes an experiment based on a set of 162,514 galaxies classified automatically to clockwise and counterclockwise spiral galaxies, showing that the source of the asymmetry in Sloan Digital Sky Survey (SDSS) database is not the human perception bias. The results are compared to two smaller datasets, and confirm the observation that the handedness of SDSS galaxies can be predicted by their photometry. The experiment also shows statistically significant differences in the measured magnitude of SDSS galaxies, according which galaxies with clockwise patterns are brighter than galaxies with counterclockwise patterns. The magnitude of that difference changes across RA ranges, and exhibits a strong correlation with the cosine of the right ascension.

  15. Cataclysmic Variables from SDSS II. The Second Year

    CERN Document Server

    Szkody, P; Silvestri, N M; Henden, A A; Anderson, S F; Frith, W J; Lawton, B; Owens, E; Raymond, S; Schmidt, G; Wolfe, M; Bochanski, J J; Covey, K; Harris, H; Hawley, S; Knapp, G R; Margon, B; Voges, W; Walkowicz, L; Brinkmann, J; Lamb, D Q; Anderson, Scott F.; Bochanski, John; Covey, Kevin; Fraser, Oliver; Frith, James; Harris, Hugh; Hawley, Suzanne; Henden, Arne; Knapp, Gillian R.; Lawton, Brandon; Margon, Bruce; Owens, Ethan; Raymond, Sean; Schmidt, Gary; Silvestri, Nicole; Szkody, Paula; Voges, Wolfgang; Walkowicz, Lucianne; Wolfe, Michael

    2003-01-01

    The first full year of operation following the commissioning year of the Sloan Digital Sky Survey has revealed a wide variety of newly discovered cataclysmic variables. We show the SDSS spectra of forty-two cataclysmic variables observed in 2002, of which thirty-five are new classifications, four are known dwarf novae (CT Hya, RZ Leo, T Leo and BZ UMa), one is a known CV identified from a previous quasar survey (Aqr1) and two are known ROSAT or FIRST discovered CVs (RX J09445+0357, FIRST J102347.6+003841). The SDSS positions, colors and spectra of all forty-two systems are presented. In addition, the results of follow-up studies of several of these objects identify the orbital periods, velocity curves and polarization that provide the system geometry and accretion properties. While most of the SDSS discovered systems are faint (>18th mag) with low accretion rates (as implied from their spectral characteristics), there are also a few bright objects which may have escaped previous surveys due to changes in the ...

  16. LasDamas Mock Galaxy Catalogs for SDSS

    Science.gov (United States)

    McBride, Cameron; Berlind, A.; Scoccimarro, R.; Wechsler, R.; Busha, M.; Gardner, J.; van den Bosch, F.

    2009-01-01

    The statistical strength of galaxy redshift surveys, such as the Sloan Digital Sky Survey (SDSS), have ushered us into the era of precision measurements of galaxy clustering. We are now fitting physical models to measured clustering statistics. Galaxy clustering is thus in a position to directly constrain cosmological and galaxy formation theories. This paradigm shift from qualitative to quantitative demands that we understand the statistical and systematic errors in our measurements. Moreover, we must quantify the theoretical uncertainties in our models, which are no longer clearly sub-dominant to observational errors. We address this emerging need with the LasDamas project (LArge Suite of DArk MAtter Simulations) by producing an unprecedented number of independent and realistic mock galaxy catalogs. To date, we have run over 100 independent N-body realizations using a fixed cosmology and initialized using 2nd order Lagrangian perturbation theory. We populate overdensities of dark matter using the halo occupation distribution framework, designed to match both small and large scale clustering of the observed SDSS data. A series of mock galaxy catalogs matching the geometry of the final SDSS release (DR7) are created over a wide luminosity range to correspond to Main and LRG volume-limited samples. We include important observational effects, such as redshift distortions and fiber collisions. These galaxy mocks are publicly available.

  17. Dumb holes: analogues for black holes.

    Science.gov (United States)

    Unruh, W G

    2008-08-28

    The use of sonic analogues to black and white holes, called dumb or deaf holes, to understand the particle production by black holes is reviewed. The results suggest that the black hole particle production is a low-frequency and low-wavenumber process.

  18. The Hunt for Red Quasars: Luminous Obscured Black Hole Growth Unveiled in the Stripe 82 X-Ray Survey

    Science.gov (United States)

    LaMassa, Stephanie M.; Glikman, Eilat; Brusa, Marcella; Rigby, Jane R.; Tasnim Ananna, Tonima; Stern, Daniel; Lira, Paulina; Urry, C. Megan; Salvato, Mara; Alexandroff, Rachael; Allevato, Viola; Cardamone, Carolin; Civano, Francesca; Coppi, Paolo; Farrah, Duncan; Komossa, S.; Lanzuisi, Giorgio; Marchesi, Stefano; Richards, Gordon; Trakhtenbrot, Benny; Treister, Ezequiel

    2017-10-01

    We present results of a ground-based near-infrared campaign with Palomar TripleSpec, Keck NIRSPEC, and Gemini GNIRS to target two samples of reddened active galactic nucleus (AGN) candidates from the 31 deg2 Stripe 82 X-ray survey. One sample, which is ∼89% complete to K 4, Vega). The fainter sample (K> 17, Vega) represents a pilot program to follow-up four sources from a parent sample of 34 that are not detected in the single-epoch SDSS catalog and have WISE quasar colors. All 12 sources are broad-line AGNs (at least one permitted emission line has an FWHM exceeding 1300 km s‑1) and span a redshift range 0.59 0.5), and a greater percentage have high X-ray luminosities ({L}{{X},{full}}> {10}44 erg s‑1). Such outflows and high luminosities may be consistent with the paradigm that reddened broad-line AGNs represent a transitory phase in AGN evolution as described by the major merger model for black hole growth. Results from our pilot program demonstrate proof of concept that our selection technique is successful in discovering reddened quasars at z> 1 missed by optical surveys.

  19. KILOPARSEC-SCALE SPATIAL OFFSETS IN DOUBLE-PEAKED NARROW-LINE ACTIVE GALACTIC NUCLEI. I. MARKERS FOR SELECTION OF COMPELLING DUAL ACTIVE GALACTIC NUCLEUS CANDIDATES

    Energy Technology Data Exchange (ETDEWEB)

    Comerford, Julia M. [Astronomy Department, University of Texas at Austin, Austin, TX 78712 (United States); Gerke, Brian F. [Kavli Institute for Particle Astrophysics and Cosmology, M/S 29, Stanford Linear Accelerator Center, 2575 Sand Hill Road, Menlo Park, CA 94725 (United States); Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, MS 169-221, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Cooper, Michael C. [Center for Galaxy Evolution, Department of Physics and Astronomy, University of California, Irvine, 4129 Frederick Reines Hall, Irvine, CA 92697 (United States); Weiner, Benjamin J. [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Newman, Jeffrey A. [Department of Physics and Astronomy, Pittsburgh Particle Physics, Astrophysics, and Cosmology Center, University of Pittsburgh, Pittsburgh, PA 15260 (United States); Madsen, Kristin [Space Radiation Laboratory, California Institute of Technology, MS 105-24, Pasadena, CA 91125 (United States); Barrows, R. Scott [Arkansas Center for Space and Planetary Sciences, University of Arkansas, Fayetteville, AR 72701 (United States)

    2012-07-01

    Merger-remnant galaxies with kiloparsec (kpc) scale separation dual active galactic nuclei (AGNs) should be widespread as a consequence of galaxy mergers and triggered gas accretion onto supermassive black holes, yet very few dual AGNs have been observed. Galaxies with double-peaked narrow AGN emission lines in the Sloan Digital Sky Survey (SDSS) are plausible dual AGN candidates, but their double-peaked profiles could also be the result of gas kinematics or AGN-driven outflows and jets on small or large scales. To help distinguish between these scenarios, we have obtained spatial profiles of the AGN emission via follow-up long-slit spectroscopy of 81 double-peaked narrow-line AGNs in SDSS at 0.03 {<=} z {<=} 0.36 using Lick, Palomar, and MMT Observatories. We find that all 81 systems exhibit double AGN emission components with {approx}kpc projected spatial separations on the sky (0.2 h{sup -1}{sub 70} kpc <{Delta}x < 5.5 h{sup -1}{sub 70} kpc; median {Delta}x = 1.1 h{sup -1}{sub 70} kpc), which suggests that they are produced by kiloparsec-scale dual AGNs or kiloparsec-scale outflows, jets, or rotating gaseous disks. Further, the objects split into two subpopulations based on the spatial extent of the double emission components and the correlation between projected spatial separations and line-of-sight velocity separations. These results suggest that the subsample (58{sup +5}{sub -6}%) of the objects with spatially compact emission components may be preferentially produced by dual AGNs, while the subsample (42{sup +6}{sub -5}%) with spatially extended emission components may be preferentially produced by AGN outflows. We also find that for 32{sup +8}{sub -6}% of the sample the two AGN emission components are preferentially aligned with the host galaxy major axis, as expected for dual AGNs orbiting in the host galaxy potential. Our results both narrow the list of possible physical mechanisms producing the double AGN components, and suggest several observational

  20. Pruning The ELM Survey: Characterizing Candidate Low-mass White Dwarfs through Photometric Variability

    Science.gov (United States)

    Bell, Keaton J.; Gianninas, A.; Hermes, J. J.; Winget, D. E.; Kilic, Mukremin; Montgomery, M. H.; Castanheira, B. G.; Vanderbosch, Z.; Winget, K. I.; Brown, Warren R.

    2017-02-01

    We assess the photometric variability of nine stars with spectroscopic Teff and log g values from the ELM Survey that locates them near the empirical extremely low-mass (ELM) white dwarf instability strip. We discover three new pulsating stars: SDSS J135512.34+195645.4, SDSS J173521.69+213440.6, and SDSS J213907.42+222708.9. However, these are among the few ELM Survey objects that do not show radial velocity (RV) variations that confirm the binary nature expected of helium-core white dwarfs. The dominant 4.31 hr pulsation in SDSS J135512.34+195645.4 far exceeds the theoretical cut-off for surface reflection in a white dwarf, and this target is likely a high-amplitude δ Scuti pulsator with an overestimated surface gravity. We estimate the probability to be less than 0.0008 that the lack of measured RV variations in four of eight other pulsating candidate ELM white dwarfs could be due to low orbital inclination. Two other targets exhibit variability as photometric binaries. Partial coverage of the 19.342 hr orbit of WD J030818.19+514011.5 reveals deep eclipses that imply a primary radius >0.4 R⊙—too large to be consistent with an ELM white dwarf. The only object for which our time series photometry adds support to ELM white dwarf classification is SDSS J105435.78‑212155.9, which has consistent signatures of Doppler beaming and ellipsoidal variations. We conclude that the ELM Survey contains multiple false positives from another stellar population at Teff ≲ 9000 K, possibly related to the sdA stars recently reported from SDSS spectra.

  1. The Intrinsic Eddington Ratio Distribution of Active Galactic Nuclei in Young Galaxies from SDSS

    Science.gov (United States)

    Jones, Mackenzie L.; Hickox, Ryan C.; Black, Christine; Hainline, Kevin Nicholas; DiPompeo, Michael A.

    2016-04-01

    An important question in extragalactic astronomy concerns the distribution of black hole accretion rates, i.e. the Eddington ratio distribution, of active galactic nuclei (AGN). Specifically, it is matter of debate whether AGN follow a broad distribution in accretion rates, or if the distribution is more strongly peaked at characteristic Eddington ratios. Using a sample of galaxies from SDSS DR7, we test whether an intrinsic Eddington ratio distribution that takes the form of a broad Schechter function is in fact consistent with previous work that suggests instead that young galaxies in optical surveys have a more strongly peaked lognormal Eddington ratio distribution. Furthermore, we present an improved method for extracting the AGN distribution using BPT diagnostics that allows us to probe over one order of magnitude lower in Eddington ratio, counteracting the effects of dilution by star formation. We conclude that the intrinsic Eddington ratio distribution of optically selected AGN is consistent with a power law with an exponential cutoff, as is observed in the X-rays. This work was supported in part by a NASA Jenkins Fellowship.

  2. A Full Year's Chandra Exposure on SDSS Quasars from the Chandra Multiwavelength Project

    CERN Document Server

    Green, Paul J; Richards, G T; Barkhouse, W A; Constantin, A; Haggard, D; Karovska, M; Kim, D -W; Kim, M; Vikhlinin, A; Mossman, A; Silverman, J D; Anderson, S F; Kashyap, V; Wilkes, B J; Tananbaum, H

    2008-01-01

    We study the spectral energy distributions and evolution of a large sample of optically selected quasars from the Sloan Digital Sky Survey (SDSS) that were observed in 323 Chandra images analyzed by the Chandra Multiwavelength Project (ChaMP). Our highest-confidence matched sample includes 1135 X-ray detected quasars in the redshift range 0.23 QSOs detected, we find no evidence for evolution out to z~5 for either the X-ray photon index Gamma or for the ratio of optical/UV to X-ray flux alpha_ox. About 10% of detected QSOs are obscured (Nh>1E22), but the fraction might reach ~1/3 if most non-detections are absorbed. We confirm a significant correlation between alpha_ox and optical luminosity, but it flattens or disappears for fainter AGN alone. Gamma hardens significantly both towards higher X-ray luminosity, and for relatively X-ray loud quasars. These trends may represent a relative increase in non-thermal X-ray emission, and our findings thereby strengthen analogies between Galactic black hole binaries and ...

  3. Herschel Far-IR counterparts of SDSS galaxies: Analysis of commonly used Star Formation Rate estimates

    CERN Document Server

    Sánchez, H Domínguez; Lara-López, M A; Oteo, I; Cepa, J; García, A M Pérez; Sánchez-Portal, M; Ederoclite, A; Lutz, D; Cresci, G; Delvecchio, I; Berta, S; Magnelli, B; Popesso, P; Pozzi, F; Riguccini, L

    2014-01-01

    We study a hundred of galaxies from the spectroscopic Sloan Digital Sky Survey with individual detections in the Far-Infrared Herschel PACS bands (100 or 160 $\\mu$m) and in the GALEX Far-UltraViolet band up to z$\\sim$0.4 in the COSMOS and Lockman Hole fields. The galaxies are divided into 4 spectral and 4 morphological types. For the star forming and unclassifiable galaxies we calculate dust extinctions from the UV slope, the H$\\alpha$/H$\\beta$ ratio and the $L_{\\rm IR}/L_{\\rm UV}$ ratio. There is a tight correlation between the dust extinction and both $L_{\\rm IR}$ and metallicity. We calculate SFR$_{total}$ and compare it with other SFR estimates (H$\\alpha$, UV, SDSS) finding a very good agreement between them with smaller dispersions than typical SFR uncertainties. We study the effect of mass and metallicity, finding that it is only significant at high masses for SFR$_{H\\alpha}$. For the AGN and composite galaxies we find a tight correlation between SFR and L$_{IR}$ ($\\sigma\\sim$0.29), while the dispersion...

  4. The Hypervelocity Star SDSS J090745.0+024507 is a Short-Period Variable

    CERN Document Server

    Fuentes, C I; Gaudi, B S; McLeod, B A; Bogdanov, S B; Hartman, J D; Hickox, R C; Holman, M J; Fuentes, Cesar I.; Leod, Brian A. Mc; Bogdanov, Slavko B.; Hartman, Joel D.; Hickox, Ryan C.; Holman, Matthew J.

    2005-01-01

    We present high-precision photometry of the hypervelocity star SDSS J090745.0+024507 (HVS), which has a Galactic rest-frame radial velocity of v=709 km/s, and so has likely been ejected from the supermassive black hole in the Galactic center. Our data were obtained on two nights using the MMT 6.5m telescope, and is supplemented by lower precision photometry obtained on four nights using the FLWO 1.2m telescope. The high-precision photometry indicates that the HVS is a short-period, low-amplitude variable, with period P=0.2-2 days and amplitude A = 2-10%. Together with the known effective temperature of T_eff ~ 10,500 K (spectral type B9), this variability implies that the HVS is a member of the class of slowly pulsating B-type main sequence stars, thus resolving the previously-reported two-fold degeneracy in the luminosity and distance of the star. The HVS has a heliocentric distance of 71 kpc, and an age of ~0.35 Gyr. The time of ejection from the center of the Galaxy is < 100 Myr, and thus the existence ...

  5. Low redshift quasars in the SDSS Stripe 82. The local environments

    CERN Document Server

    Karhunen, K; Falomo, R; Bettoni, D

    2014-01-01

    We study the environments of low redshift (z < 0.5) quasars based on a large and homogeneous dataset from the Stripe 82 region of the Sloan Digital Sky Survey (SDSS). We have compared the < 1 Mpc scale envi- ronments of 302 quasars that were resolved in our recent study to those of 288 inactive galaxies with closely matched redshifts. Crucially, the lu- minosities of the inactive galaxies and the quasar host galaxies are also closely matched, unlike in most previous studies. The environmental overdensities were studied by measuring the num- ber density of galaxies within a projected distance of 200 kpc to 1 Mpc. The galaxy number density of the quasar environments is comparable to that of the inactive galaxies with similar luminosities, both classes of ob- jects showing significant excess compared to the background galaxy density for distances < 400 kpc. There is no significant dependence of the galaxy number density on redshift, quasar or host galaxy luminosity, black hole mass or radio loudness. Th...

  6. Constraining sub-parsec binary supermassive black holes in quasars with multi-epoch spectroscopy. II. The population with kinematically offset broad Balmer emission lines

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xin [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States); Shen, Yue [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Bian, Fuyan [Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611 (Australia); Loeb, Abraham [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Tremaine, Scott, E-mail: xinliu@astro.ucla.edu [Institute for Advanced Study, Princeton, NJ 08540 (United States)

    2014-07-10

    A small fraction of quasars have long been known to show bulk velocity offsets (of a few hundred to thousands of km s{sup –1}) in the broad Balmer lines with respect to the systemic redshift of the host galaxy. Models to explain these offsets usually invoke broad-line region gas kinematics/asymmetry around single black holes (BHs), orbital motion of massive (∼sub-parsec (sub-pc)) binary black holes (BBHs), or recoil BHs, but single-epoch spectra are unable to distinguish between these scenarios. The line-of-sight (LOS) radial velocity (RV) shifts from long-term spectroscopic monitoring can be used to test the BBH hypothesis. We have selected a sample of 399 quasars with kinematically offset broad Hβ lines from the Sloan Digital Sky Survey (SDSS) Seventh Data Release quasar catalog, and have conducted second-epoch optical spectroscopy for 50 of them. Combined with the existing SDSS spectra, the new observations enable us to constrain the LOS RV shifts of broad Hβ lines with a rest-frame baseline of a few years to nearly a decade. While previous work focused on objects with extreme velocity offset (>10{sup 3} km s{sup –1}), we explore the parameter space with smaller (a few hundred km s{sup –1}) yet significant offsets (99.7% confidence). Using cross-correlation analysis, we detect significant (99% confidence) radial accelerations in the broad Hβ lines in 24 of the 50 objects, of ∼10-200 km s{sup –1} yr{sup –1} with a median measurement uncertainty of ∼10 km s{sup –1} yr{sup –1}, implying a high fraction of variability of the broad-line velocity on multi-year timescales. We suggest that 9 of the 24 detections are sub-pc BBH candidates, which show consistent velocity shifts independently measured from a second broad line (either Hα or Mg II) without significant changes in the broad-line profiles. Combining the results on the general quasar population studied in Paper I, we find a tentative anti-correlation between the velocity offset in the

  7. Unveiling the AGN activity in multiple SMBH systems: the remarkable case of SDSS J0959+1259

    Science.gov (United States)

    De Rosa, A.; Magna Team

    2016-06-01

    In this talk we will present results from the MAGNA (Multiple AGN Activity) project focused on the detection and study of multiple supermassive BH systems. We aim at studying the physical properties of multiple AGN candidates in interacting/disturbed systems from both an observational and a theoretical point of view. The final goal is to understand the possible mechanisms that could relate the triggering of AGN activity with the different stages of galaxies mergers. The MAGNA project includes the study of several samples of dual AGN, extracted from different wavebands, supplied by an extensive set of multiwavelength observations granted to our team by MUSE, XMM, VLA as well as available in archives. This strategy allowed us to identify a galaxy compact group (CG SDSS J0959+1259) that appears exceptional having a high concentration of nuclear activity. We present here the multi-wavelength study of this CG through XMM, SDSS and BUSCA data. The XMM analysis extends and modifies the previous identification of the members of this group, which is composed of 3 Compton thin AGN, 2 LINERs and 3 star forming region.

  8. High-Resolution Spectroscopy of Extremely Metal-Poor Stars from SDSS/SEGUE: I. Atmospheric Parameters and Chemical Compositions

    CERN Document Server

    Aoki, Wako; Lee, Young Sun; Honda, Satoshi; Ito, Hiroko; Takada-Hidai, Masahide; Frebel, Anna; Suda, Takuma; Fujimoto, Masatuki Y; Carollo, Daniela; Sivarani, Thirupathi

    2012-01-01

    Chemical compositions are determined based on high-resolution spectroscopy for 137 candidate extremely metal-poor (EMP) stars selected from the Sloan Digital Sky Survey (SDSS) and its first stellar extension, the Sloan Extension for Galactic Understanding and Exploration (SEGUE). High-resolution spectra with moderate signal-to-noise (S/N) ratios were obtained with the High Dispersion Spectrograph of the Subaru Telescope. Most of the sample (approximately 80%) are main-sequence turn-off stars, including dwarfs and subgiants. Four cool main-sequence stars, the most metal-deficient such stars known, are included in the remaining sample. Good agreement is found between effective temperatures estimated by the SEGUE stellar parameter pipeline, based on the SDSS/SEGUE medium-resolution spectra, and those estimated from the broadband $(V-K)_0$ and $(g-r)_0$ colors. Our abundance measurements reveal that 70 stars in our sample have [Fe/H] $ +0.7$) among the 25 giants in our sample is as high as 36%, while only a lowe...

  9. On gravitomagnetic precession around black holes

    CERN Document Server

    Merloni, A; Stella, L; Bini, D

    1998-01-01

    We compute exactly the Lense-Thirring precession frequency for point masses in the Kerr metric, for arbitrary black hole mass and specific angular momentum. We show that this frequency, for point masses at or close to the innermost stable orbit, and for holes with moderate to extreme rotation, is less than, but comparable to the rotation frequency. Thus, if the quasi periodic oscillations (QPOs) observed in the modulation of the X-ray flux from some black holes candidates are due to Lense-Thirring precession of orbiting material, we predict that a separate, distinct QPO ought to be observed in each object.

  10. On Quantum Contributions to Black Hole Growth

    CERN Document Server

    Spaans, Marco

    2013-01-01

    The effects of Wheeler's quantum foam on black hole growth are explored from an astrophysical perspective. Quantum fluctuations in the form of mini (10^-5 g) black holes can couple to macroscopic black holes and allow the latter to grow exponentially in mass on a time scale of ~10^9 years. Consequently, supermassive black holes can acquire a lot of their mass through these quantum contributions over the life time of the universe. This alleviates the need for very efficient forms of baryonic matter accretion more recent than a redshift z~6. Sgr A* in the Milky Way center is a candidate to verify this quantum space-time effect, with a predicted mass growth rate of 4x10^-3 Mo yr^-1. A few comments on the possibility and consequences of dark matter as quantum grown black holes are made, with a big crunch fate of the universe.

  11. New ultracool subdwarfs identified in large-scale surveys using Virtual Observatory tools: Part I: UKIDSS LAS DR5 vs SDSS DR7

    CERN Document Server

    Lodieu, N; Osorio, M R Zapatero; Solano, E; Aberasturi, M; Martín, E L

    2012-01-01

    The aim of the project is to improve our knowledge on the low-mass and low-metallicity population to investigate the influence of metallicity of the stellar (and substellar) mass function. We present the results of a photometric and proper motion search aimed at unearthing ultracool subdwarfs in large-scale surveys. We employed and combined the UKIDSS LAS DR5 and the SDSS DR7 complemented with ancillary data from 2MASS, DENIS and SuperCOSMOS. The SDSS DR7 vs UKIDSS LAS DR5 search returned a total of 32 ultracool subdwarf candidates, only two being recognised as a subdwarf in the literature. Twenty-seven candidates were followed-up spectroscopically in the optical between 600 and 1000 nm. We confirmed 20 candidates as subdwarfs, extreme subdwarfs or ultra-subdwarfs with spectral types later than M5; this represents a success rate of ~60%. Among those 20 new subdwarfs, we identified 2 early-L subdwarfs very likely located within 100 pc that we propose as templates for future searches because they are the first ...

  12. Selection bias in dynamically-measured super-massive black hole samples: dynamical masses and dependence on Sérsic index

    Science.gov (United States)

    Shankar, Francesco; Bernardi, Mariangela; Sheth, Ravi K.

    2017-01-01

    We extend the comparison between the set of local galaxies having dynamically measured black holes with galaxies in the Sloan Digital Sky Survey (SDSS). We first show that the most up-to-date local black hole samples of early-type galaxies with measurements of effective radii, luminosities, and Sérsic indices of the bulges of their host galaxies, have dynamical mass and Sérsic index distributions consistent with those of SDSS early-type galaxies of similar bulge stellar mass. The host galaxies of local black hole samples thus do not appear structurally different from SDSS galaxies, sharing similar dynamical masses, light profiles and light distributions. Analysis of the residuals reveals that velocity dispersion is more fundamental than Sérsic index nsph in the scaling relations between black holes and galaxies. Indeed, residuals with nsph could be ascribed to the (weak) correlation with bulge mass or even velocity dispersion. Finally, targetted Monte Carlo simulations that include the effects of the sphere of influence of the black hole, and tuned to reproduce the observed residuals and scaling relations in terms of velocity dispersion and stellar mass, show that, at least for galaxies with Mbulge ≳ 1010 M⊙ and nsph ≳ 5, the observed mean black hole mass at fixed Sérsic index is biased significantly higher than the intrinsic value.

  13. A Precision Photometric Comparison between SDSS-II and CSP Type Ia Supernova Data

    DEFF Research Database (Denmark)

    Mosher, J.; Sako, M.; Corlies, L.

    2012-01-01

    Consistency between Carnegie Supernova Project (CSP) and SDSS-II Supernova Survey ugri measurements has been evaluated by comparing Sloan Digital Sky Survey (SDSS) and CSP photometry for nine spectroscopically confirmed Type Ia supernova observed contemporaneously by both programs. The CSP data w...

  14. A Precision Photometric Comparison between SDSS-II and CSP Type Ia Supernova Data

    DEFF Research Database (Denmark)

    Mosher, J.; Sako, M.; Corlies, L.;

    2012-01-01

    Consistency between Carnegie Supernova Project (CSP) and SDSS-II Supernova Survey ugri measurements has been evaluated by comparing Sloan Digital Sky Survey (SDSS) and CSP photometry for nine spectroscopically confirmed Type Ia supernova observed contemporaneously by both programs. The CSP data...

  15. Improved cosmological constraints from a joint analysis of the SDSS-II and SNLS supernova samples

    CERN Document Server

    Betoule, M; Guy, J; Mosher, J; Hardin, D; Biswas, R; Astier, P; El-Hage, P; Konig, M; Kuhlmann, S; Marriner, J; Pain, R; Regnault, N; Balland, C; Bassett, B A; Brown, P J; Campbell, H; Carlberg, R G; Cellier-Holzem, F; Cinabro, D; Conley, A; D'Andrea, C B; DePoy, D L; Doi, M; Ellis, R S; Fabbro, S; Filippenko, A V; Foley, R J; Frieman, J A; Fouchez, D; Galbany, L; Goobar, A; Gupta, R R; Hill, G J; Hlozek, R; Hogan, C J; Hook, I M; Howell, D A; Jha, S W; Guillou, L Le; Leloudas, G; Lidman, C; Marshall, J L; Möller, A; Mourão, A M; Neveu, J; Nichol, R; Olmstead, M D; Palanque-Delabrouille, N; Perlmutter, S; Prieto, J L; Pritchet, C J; Richmond, M; Riess, A G; Ruhlmann-Kleider, V; Sako, M; Schahmaneche, K; Schneider, D P; Smith, M; Sollerman, J; Sullivan, M; Walton, N A; Wheeler, C J

    2014-01-01

    We present cosmological constraints from a joint analysis of type Ia supernova (SN Ia) observations obtained by the SDSS-II and SNLS collaborations. The data set includes several low-redshift samples (z<0.1), all 3 seasons from the SDSS-II (0.05 < z < 0.4), and 3 years from SNLS (0.2

  16. Kiloparsec-scale Spatial Offsets in Double-peaked Narrow-line AGNs. I. Markers for Selection of Compelling Dual AGN Candidates

    CERN Document Server

    Comerford, Julia M; Stern, Daniel; Cooper, Michael C; Weiner, Benjamin J; Newman, Jeffrey A; Harrison, Fiona; Madsen, Kristin; Barrows, R Scott

    2011-01-01

    Merger-remnant galaxies with kpc-scale separation dual active galactic nuclei (AGNs) should be widespread as a consequence of galaxy mergers and triggered gas accretion onto supermassive black holes, yet very few dual AGNs have been observed. Galaxies with double-peaked narrow AGN emission lines in the Sloan Digital Sky Survey are plausible dual AGN candidates, but their double-peaked profiles could also be the result of gas kinematics or AGN-driven outflows and jets on small or large scales. To help distinguish between these scenarios, we have obtained spatial profiles of the AGN emission via follow-up longslit spectroscopy of 81 double-peaked narrow-line AGNs in SDSS at 0.03 < z < 0.36 using Lick, Palomar, and MMT Observatories. We find that all 81 systems exhibit double AGN emission components with ~kpc projected spatial separations on the sky, which suggests that they are produced by kpc-scale dual AGNs or kpc-scale outflows, jets, or rotating gaseous disks. In addition, we find that the subsample (...

  17. The velocity distribution of SDSS satellites in MOND

    CERN Document Server

    Angus, Garry; Tiret, Olivier; Combes, Francoise; Zhao, HongSheng

    2007-01-01

    The recent SDSS measured velocity distribution of satellite galaxies has been modelled in the context of MOND. We show that even when the extra constraint of adhering to the projected satellite number density profile is added, the two line of sight (los) velocity dispersion profiles presented in Klypin & Prada (2007) can be matched simply with a radially varying anisotropy. Interestingly, the anisotropies required to fit the los velocity dispersions are remarkably similar to the anisotropies generated by dissipationless collapse simulations in MOND. The mass-to-light ratios of the two host galaxies used are sensible and positivity of the distribution function is satisfied.

  18. Metallicity Calibration and Photometric Parallax Estimation: II. SDSS photometry

    CERN Document Server

    Guctekin, S Tuncel; Karaali, S; Plevne, O; Ak, S; Ak, T; Bostanci, Z F

    2016-01-01

    We used the updated [Fe/H] abundances of 168 F-G type dwarfs and calibrated them to a third order polynomial in terms of reduced ultraviolet excess, $\\delta_{0.41}$ defined with $ugr$ data in the SDSS. We estimated the $M_g$ absolute magnitudes for the same stars via the re-reduced Hipparcos parallaxes and calibrated the absolute magnitude offsets, $\\Delta M_g$, relative to the intrinsic sequence of Hyades to a third order polynomial in terms of $\\delta_{0.41}$. The ranges of the calibrations are $-218$ mag).

  19. Photometric Redshift Estimation on SDSS Data Using Random Forests

    CERN Document Server

    Carliles, Samuel; Heinis, Sebastien; Priebe, Carey; Szalay, Alexander

    2007-01-01

    Given multiband photometric data from the SDSS DR6, we estimate galaxy redshifts. We employ a Random Forest trained on color features and spectroscopic redshifts from 80,000 randomly chosen primary galaxies yielding a mapping from color to redshift such that the difference between the estimate and the spectroscopic redshift is small. Our methodology results in tight RMS scatter in the estimates limited by photometric errors. Additionally, this approach yields an error distribution that is nearly Gaussian with parameter estimates giving reliable confidence intervals unique to each galaxy photometric redshift.

  20. SDSS J102146.44+234926.3: New WZ Sge-type dwarf nova

    CERN Document Server

    Golovin, Alex; Pavlenko Elena P; Tom, Krajci; Yuliana, Kuznyetsova; Arne, Henden; Victoria, Krushevska; Shawn, Dvorak; Kirill, Sokolovsky; Sergeeva Tatyana P; Robert, James; Tim, Crawford; Laurent, Corp

    2007-01-01

    We report CCD photometry and spectroscopy during 2006 outburst of the dwarf nova SDSS J102146.44+234926.3 (SDSS J1021). The photographic plates from the MAO, SAI and CrAO plate archives, which cover the position of the SDSS J1021, were inspected for the presence of previous outbursts. We also present the BVRcIc photometric calibration of 52 stars in SDSS J1021 vicinity, which have V-magnitude in the range of 11.21-17.23m and can serve as comparison stars. The large amplitude of the SDSS J1021 outburst of 7m, superhumps with a period below the ''period gap'', rebrightening during the declining stage of superoutburst, rarity of outbursts and obtained spectrum allow to classify this object as a WZ Sge type dwarf nova.

  1. Local stars formed at z>10: a sample extracted from the SDSS

    CERN Document Server

    Sbordone, Luca; Caffau, Elisabetta; Ludwig, Hans-Guenter

    2010-01-01

    As the Universe emerged from its initial hot and dense phase, its chemical composition was extremely simple, being limited to stable H and He isotopes, and traces of Li. The first stars that formed had such initial composition. However, they quickly began to produce a whole array of heavier nuclei, polluting the interstellar medium. While none among these first stars has been detected to date, an increasing sample exists of their direct descendant, stars with heavy elements content of the order of 1/1000 of the solar value, or less. In most cases, such stars should have formed at redshift of about 10 or beyond, and their chemical composition can provide crucial constraints to the nature of the very first stars. Extremely metal poor (EMP) stars are exceedingly rare. We used the low resolution spectra obtained by the Sloan Digital Sky Survey (SDSS) to search for EMP candidates: results of VLT-UVES high resolution follow-up for 16 of them is presented here. A newly developed automatic abundance analysis and para...

  2. ENVIRONMENTAL DEPENDENCE OF ALL FIVE BAND LUMINOSITIES FOR SDSS-III/BOSS GALAXIES IN THE SDSS DR9

    Directory of Open Access Journals (Sweden)

    Xin-Fa Deng

    2014-01-01

    Full Text Available Utilizamos la muestra CMMASS con corrimientos al rojo entre 0.44 y 0.5 9 para investigar la dependencia ambiental de las luminosidades en cinco bandas de esta mues- tra proveniente del Sloan Digital Sky Survey Versi ́on 9 (SDSS DR9. Para dismi nuir el efecto de selecci ́on radial dividimos la muestra CMASS en diferentes submuestras con corrimientos al rojo agrupados en celdas con △ z = 0 . 01 y analizamos para cada sub- muestra la dependencia ambiental de las luminosidades en cinco bandas. Encontramos que todas las luminosidades est ́an d ́ebilmente correlacionadascon el ambiente lo cal.

  3. Cosmological Constraints From SDSS MaxBCG Cluster Abundances

    Energy Technology Data Exchange (ETDEWEB)

    Rozo, Eduardo; /Ohio State U. /Chicago U. /KICP, Chicago; Wechsler, Risa H.; /KICP, Chicago /KIPAC, Menlo Park; Koester, Benjamin P.; /Chicago U., Astron. Astrophys. Ctr.; McKay, Timothy A.; Evrard, August E.; /Michigan U.; Johnston, David; /Caltech, JPL; Sheldon, Erin S.; /CCPP, New York; Annis, James; /Fermilab; Frieman, Joshua A.; /KICP,

    2007-03-26

    We perform a maximum likelihood analysis of the cluster abundance measured in the SDSS using the maxBCG cluster finding algorithm. Our analysis is aimed at constraining the power spectrum normalization {sigma}{sub 8}, and assumes flat cosmologies with a scale invariant spectrum, massless neutrinos, and CMB and supernova priors {Omega}{sub m}h{sup 2} = 0.128 {+-} 0.01 and h = 0.72 {+-} 0.05 respectively. Following the method described in the companion paper Rozo et al. (2007), we derive {sigma}{sub 8} = 0.92 {+-} 0.10 (1{sigma}) after marginalizing over all major systematic uncertainties. We place strong lower limits on the normalization, {sigma}{sub 8} > 0.76 (95% CL) (> 0.68 at 99% CL). We also find that our analysis favors relatively low values for the slope of the Halo Occupation Distribution (HOD), {alpha} = 0.83 {+-} 0.06. The uncertainties of these determinations will substantially improve upon completion of an ongoing campaign to estimate dynamical, weak lensing, and X-ray cluster masses in the SDSS maxBCG cluster sample.

  4. The Alignment effect of brightest cluster galaxies in the SDSS

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Rita S.J.; Annis, Jim; Strauss, Michael A.; Lupton, Robert H.; Bahcall, Neta A.; Gunn, James E.; Kepner, Jeremy V.; Postman, Marc

    2001-10-01

    One of the most vital observational clues for unraveling the origin of Brightest Cluster Galaxies (BCG) is the observed alignment of the BCGs with their host cluster and its surroundings. We have examined the BCG-cluster alignment effect, using clusters of galaxies detected from the Sloan Digital Sky Survey (SDSS). We find that the BCGs are preferentially aligned with the principal axis of their hosts, to a much higher redshift (z >~ 0.3) than probed by previous studies (z <~ 0.1). The alignment effect strongly depends on the magnitude difference of the BCG and the second and third brightest cluster members: we find a strong alignment effect for the dominant BCGs, while less dominant BCGs do not show any departure from random alignment with respect to the cluster. We therefore claim that the alignment process originates from the same process that makes the BCG grow dominant, be it direct mergers in the early stage of cluster formation, or a later process that resembles the galactic cannibalism scenario. We do not find strong evidence for (or against) redshift evolution between 0SDSS cluster catalogs, which will provide us with better statistics for systematic investigations of the alignment with redshift, richness and morphology of both the cluster and the BCG.

  5. Isolated Main Galaxy Pairs from the SDSS Data Release 4

    Institute of Scientific and Technical Information of China (English)

    Xin-Fa Deng; Yi-Qing Chen; Ping Wu; Cheng-Hong Luo; Ji-Zhou He

    2006-01-01

    From the Main galaxy data of the SDSS Data Release 4 (SDSS4), we have identified close galaxy pairs at neighbourhood radius R = 100 kpc by three-dimensional cluster analysis. Using the criterion that an "isolated galaxy pair" must be separated from its "nearest neighbor" by more than 500 kpc, we constructed an isolated galaxy pair sample of 1158 pairs.We also constructed a random pair sample by randomly selecting 1158 galaxy pairs from the Main galaxy sample, which has the same redshift distribution as the isolated galaxy pair sample, and in which the two components of any pair have the same redshifts. Comparative studies of luminosity and size between the members of the galaxy pairs are performed. We find and further confirm there is no tendency for paired galaxies to have similar luminosities or sizes. From the isolated pair sample we also selected a subsample with the magnitude limit of the primary raised by 2 magnitudes, so as to include pairs in which the secondary is 2 magnitudes fainter than the primary. This subsample contains 82 pairs. A random pair sample is similarly constructed.

  6. A Cosmic Void Catalog of SDSS DR12 BOSS Galaxies

    CERN Document Server

    Mao, Qingqing; Scherrer, Robert J; Scoccimarro, Roman; Tinker, Jeremy L; McBride, Cameron K; Neyrinck, Mark C; Schneider, Donald P; Pan, Kaike; Bizyaev, Dmitry; Malanushenko, Elena; Malanushenko, Viktor

    2016-01-01

    We present a cosmic void catalog using the large-scale structure galaxy catalog from the Baryon Oscillation Spectroscopic Survey (BOSS). This galaxy catalog is part of the Sloan Digital Sky Survey (SDSS) Data Release 12 and is the final catalog of SDSS-III. We take into account the survey boundaries, masks, and angular and radial selection functions, and apply the ZOBOV void finding algorithm to the galaxy catalog. After making quality cuts to ensure that the voids represent real underdense regions, we identify 1228 voids with effective radii spanning the range 20-100Mpc/h and with central densities that are, on average, 30% of the mean sample density. We discuss the basic statistics of voids, such as their size and redshift distributions, and measure the radial density profile of the voids via a stacking technique. In addition, we construct mock void catalogs from 1000 mock galaxy catalogs, and find that the properties of BOSS voids are in good agreement with those in the mock catalogs. We compare the stella...

  7. The Intrinsic Shape of Galaxies in SDSS/Galaxy Zoo

    CERN Document Server

    Rodríguez, Silvio

    2013-01-01

    By modelling the axis ratio distribution of SDSS DR8 galaxies we find the intrinsic 3D shapes of spirals and ellipticals. We use morphological information from the Galaxy Zoo project and assume a non-parametric distribution intrinsic of shapes, while taking into account dust extinction. We measure the dust extinction of the full sample of spiral galaxies and find a smaller value than previous estimations, with an edge-on extinction of $E_0 = 0.284^{+0.015}_{-0.026}$ in the SDSS r band. We also find that the distribution of minor to major axis ratio has a mean value of $ 0.267 \\pm 0.009 $, slightly larger than previous estimates mainly due to the lower extinction used; the same affects the circularity of galactic discs, which are found to be less round in shape than in previous studies, with a mean ellipticity of $0.215 \\pm 0.013$. For elliptical galaxies, we find that the minor to major axis ratio, with a mean value of $0.584 \\pm 0.006$, is larger than previous estimations due to the removal of spiral interlo...

  8. The (Double) White Dwarf Binary SDSS 1257+5428

    CERN Document Server

    Kulkarni, S R

    2010-01-01

    SDSS 1257+5428 is a white dwarf in a close orbit with a companion that has been suggested to be a neutron star. If so, it hosts the closest known neutron star, and its existence implies a great abundance of similar systems and a rate of white-dwarf neutron-star mergers similar to that of the type Ia supernova rate. Here, we present high signal-to-noise spectra of SDSS 1257+5428, which confirm an independent finding that the system is in fact composed of two white dwarfs, one relatively cool and with low mass, and the other hotter and more massive. With this, the demographics and merger rate are no longer puzzling (various factors combine to lower the latter by more than two orders of magnitude). We show that the spectra are fit well with a combination of two hydrogen model atmospheres, as long as the lines of the higher-gravity component are broadened significantly relative to what is expected from just pressure broadening. Interpreting this additional broadening as due to rotation, the inferred spin period i...

  9. Cosmological parameters from a million photometric redshifts of SDSS LRGs

    CERN Document Server

    Blake, C; Bridle, S; Lahav, O; Blake, Chris; Collister, Adrian; Bridle, Sarah; Lahav, Ofer

    2006-01-01

    We analyze MegaZ-LRG, a new photometric-redshift catalogue of Luminous Red Galaxies (LRGs) based on the imaging data of the Sloan Digital Sky Survey (SDSS) 4th Data Release. MegaZ-LRG, presented in a companion paper, contains > 10^6 photometric redshifts derived with ANNz, an Artificial Neural Network method, constrained by a spectroscopic sub-sample of ~13,000 galaxies obtained by the 2dF-SDSS LRG and Quasar (2SLAQ) survey. The catalogue spans the redshift range 0.4

  10. A Cosmic Void Catalog of SDSS DR12 BOSS Galaxies

    Science.gov (United States)

    Mao, Qingqing; Berlind, Andreas A.; Scherrer, Robert J.; Neyrinck, Mark C.; Scoccimarro, Román; Tinker, Jeremy L.; McBride, Cameron K.; Schneider, Donald P.; Pan, Kaike; Bizyaev, Dmitry; Malanushenko, Elena; Malanushenko, Viktor

    2017-02-01

    We present a cosmic void catalog using the large-scale structure galaxy catalog from the Baryon Oscillation Spectroscopic Survey (BOSS). This galaxy catalog is part of the Sloan Digital Sky Survey (SDSS) Data Release 12 and is the final catalog of SDSS-III. We take into account the survey boundaries, masks, and angular and radial selection functions, and apply the ZOBOV void finding algorithm to the Galaxy catalog. We identify a total of 10,643 voids. After making quality cuts to ensure that the voids represent real underdense regions, we obtain 1,228 voids with effective radii spanning the range 20–100 {h}-1 {Mpc} and with central densities that are, on average, 30% of the mean sample density. We release versions of the catalogs both with and without quality cuts. We discuss the basic statistics of voids, such as their size and redshift distributions, and measure the radial density profile of the voids via a stacking technique. In addition, we construct mock void catalogs from 1000 mock galaxy catalogs, and find that the properties of BOSS voids are in good agreement with those in the mock catalogs. We compare the stellar mass distribution of galaxies living inside and outside of the voids, and find no large difference. These BOSS and mock void catalogs are useful for a number of cosmological and galaxy environment studies.

  11. Absence of significant cross-correlation between WMAP and SDSS

    CERN Document Server

    Lopez-Corredoira, M; Betancort-Rijo, J

    2010-01-01

    AIMS. Recently, several authors have claimed to detect a significant cross-correlation between microwave WMAP anisotropies and the SDSS galaxy distribution. We repeat these analyses determining different cross-correlation errors: re-sampling errors, and field-to-field fluctuations. The first type of errors make use of overlapping sky regions, while the second type use non-overlapping sky regions. METHODS. For the re-sampling errors we use bootstrap and jack-knife techniques. For the field-to-field fluctuations we use three methods: 1) evaluating the dispersion of the cross-correlation when correlating separated regions of WMAP with the original region of SDSS; 2) using mock Monte Carlo WMAP maps; 3) a new method (developed herein) which gives the error as an integral of the product of the self-correlations of each map. RESULTS. The average cross-correlation for b>30 deg. is significantly larger than the re-sampling errors--both jack-knife and bootstrap give similar results--but it is of the order of the field...

  12. CENSUS OF BLUE STARS IN SDSS DR8

    Energy Technology Data Exchange (ETDEWEB)

    Scibelli, Samantha [Burnt Hills-Ballston Lake High School, 88 Lake Hill Road, Ballston, NY 12027 (United States); Newberg, Heidi Jo; Carlin, Jeffrey L. [Department of Physics, Applied Physics and Astronomy, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY 12180 (United States); Yanny, Brian, E-mail: heidi@rpi.edu [Experimental Astrophysics Group, Fermi National Accelerator Laboratory, P.O. Box 500, Batavia, IL 60510 (United States)

    2015-01-01

    We present a census of the 12,060 spectra of blue objects ((g – r){sub 0} < –0.25) in the Sloan Digital Sky Survey (SDSS) Data Release 8 (DR8). As part of the data release, all of the spectra were cross-correlated with 48 template spectra of stars, galaxies, and QSOs to determine the best match. We compared the blue spectra by eye to the templates assigned in SDSS DR8. 10,856 of the objects matched their assigned template, 170 could not be classified due to low signal-to-noise ratio, and 1034 were given new classifications. We identify 7458 DA white dwarfs, 1145 DB white dwarfs, 273 rarer white dwarfs (including carbon, DZ, DQ, and magnetic), 294 subdwarf O stars, 648 subdwarf B stars, 679 blue horizontal branch stars, 1026 blue stragglers, 13 cataclysmic variables, 129 white dwarf-M dwarf binaries, 36 objects with spectra similar to DO white dwarfs, 179, quasi-stellar objects (QSOs), and 10 galaxies. We provide two tables of these objects, sample spectra that match the templates, figures showing all of the spectra that were grouped by eye, and diagnostic plots that show the positions, colors, apparent magnitudes, proper motions, etc., for each classification. Future surveys will be able to use templates similar to stars in each of the classes we identify to automatically classify blue stars, including rare types.

  13. The Total Galactic Extinction from SDSS BHB Stars

    CERN Document Server

    Tian, Hai-Jun; Hu, Jing-Yao; Xu, Yang; Chen, Xue-Lei

    2013-01-01

    Aims: We use 12,530 photometrically-selected BHB stars} from Sloan Digital Sky Survey to estimate, the total extinction of the Milky Way in high Galactic latitude, $R_V$ and $A_V$ in each line of sight. Methods: A Bayesian method is developed to estimate the reddening values in the given lines of sight. Based on the most likely values of reddening in multiple colors, we are able to derive the values of $R_V$ and $A_V$. . Results: We select 94 zero-reddened BHB stars from 7 globular cluster as the template. The reddening in the 4 SDSS colors for the northern Galactic cap are estimated by comparing the field BHB stars with the template stars. The accuracy of this estimation is around 0.01\\,mag for the most line of sights. We also obtain $$ to be around 2.40$\\pm1.05$ and $A_V$ map within uncertainty of 0.1\\,mag. The results, including reddening values in the 4 SDSS colors, $A_V$, and $R_V$ in each line of sight, are released on line. In this work, we employ an up-to-date parallel technique on GPU card to overcom...

  14. Outflows and complex stellar kinematics in SDSS star forming galaxies

    CERN Document Server

    Cicone, Claudia; Marconi, Alessandro

    2016-01-01

    We investigate the properties of star formation-driven outflows by using a large spectroscopic sample of ~160,000 local "normal" star forming galaxies, drawn from the SDSS, spanning a wide range of star formation rates and stellar masses. The galaxy sample is divided into a fine grid of bins in the M_*-SFR parameter space, for each of which we produce a composite spectrum by stacking together the SDSS spectra of the galaxies contained in that bin. We exploit the high signal-to-noise of the stacked spectra to study the emergence of faint features of optical emission lines that may trace galactic outflows and would otherwise be too faint to detect in individual galaxy spectra. We adopt a novel approach that relies on the comparison between the line-of-sight velocity distribution (LoSVD) of the ionised gas (as traced by the [OIII]5007 and Halpha+[NII]6548,6583 emission lines) and the LoSVD of the stars, which are used as a reference tracing virial motions. Significant deviations of the gas kinematics from the st...

  15. A Statistical Survey of Peculiar L and T Dwarfs in SDSS, 2MASS, and WISE

    Science.gov (United States)

    Kellogg, Kendra; Metchev, Stanimir; Miles-Páez, Paulo A.; Tannock, Megan E.

    2017-09-01

    We present the final results from a targeted search for brown dwarfs with unusual near-infrared colors. From a positional cross-match of the Sloan Digital Sky Survey (SDSS), 2-Micron All-Sky Survey (2MASS), and Wide-Field Infrared Survey Explorer (WISE) catalogs, we have identified 144 candidate peculiar L and T dwarfs. Spectroscopy confirms that 20 of the objects are peculiar or are candidate binaries. Of the 420 objects in our full sample 9 are young (≲ 200 {Myr}; 2.1%) and another 8 (1.9%) are unusually red, with no signatures of youth. With a spectroscopic J-{K}s color of 2.58 ± 0.11 mag, one of the new objects, the L6 dwarf 2MASS J03530419+0418193, is among the reddest field dwarfs currently known and is one of the reddest objects with no signatures of youth known to date. We have also discovered another potentially very-low-gravity object, the L1 dwarf 2MASS J00133470+1109403, and independently identified the young L7 dwarf 2MASS J00440332+0228112, which was first reported by Schneider and collaborators. Our results confirm that signatures of low gravity are no longer discernible in low to moderate resolution spectra of objects older than ∼200 Myr. The 1.9% of unusually red L dwarfs that do not show other signatures of youth could be slightly older, up to ∼400 Myr. In this case a red J-{K}s color may be more diagnostic of moderate youth than individual spectral features. However, its is also possible that these objects are relatively metal-rich, and thus have enhanced atmospheric dust content.

  16. The Rewards of Patience: An 822 Day Time Delay in the Gravitational Lens SDSS J1004+4112

    CERN Document Server

    Fohlmeister, J; Falco, E E; Morgan, C W; Wambsganss, J

    2007-01-01

    We present 107 new epochs of optical monitoring data for the four brightest images of the gravitational lens SDSS J1004+4112 observed between October 2006 and June 2007. Combining this data with the previously obtained light curves, we determine the time delays between images A, B and C. We confirm our previous measurement finding that A leads B by dt_BA=40.6+-1.8 days, and find that image C leads image A by dt_CA=821.6+-2.1 days. The lower limit on the remaining delay is that image D lags image A by dt_AD>1250 days. Based on the microlensing of images A and B we estimate that the accretion disk size at a rest wavelength of 2300 angstrom is 10^{14.8+-0.3} cm for a disk inclination of cos{i}=1/2, which is consistent with the microlensing disk size-black hole mass correlation function given our estimate of the black hole mass from the MgII line width of logM_BH/M_sun=8.44+-0.14. The long delays allow us to fill in the seasonal gaps and assemble a continuous, densely sampled light curve spanning 5.7 years whose ...

  17. Black Holes at the Centers of Nearby Dwarf Galaxies

    CERN Document Server

    Moran, Edward C; Sugarman, Hannah R; Velez, Darik O; Eracleous, Michael

    2014-01-01

    Using a distance-limited portion of the Sloan Digital Sky Survey (SDSS) Data Release 7, we have identified 28 active galactic nuclei (AGNs) in nearby (d < 80 Mpc) low-mass, low-luminosity dwarf galaxies. The accreting objects at the galaxy centers are expected to be intermediate-mass black holes (IMBHs) with M_BH < 1e6 M_sun. The AGNs were selected using several optical emission-line diagnostics after careful modeling of the continuum present in the spectra. We have limited our survey to objects with spectral characteristics similar to those of Seyfert nuclei, excluding emission-line galaxies with ambiguous spectra that could be powered by stellar processes. The host galaxies in our sample are thus the least massive objects in the very local universe certain to contain central black holes. Given our focus on the nearest objects included in the SDSS, our survey is more sensitive to low-luminosity emission than previous optical searches for AGNs in low-mass galaxies. The [O III] lambda5007 luminosities of...

  18. Deburring small intersecting holes

    Energy Technology Data Exchange (ETDEWEB)

    Gillespie, L.K.

    1980-08-01

    Deburring intersecting holes is one of the most difficult deburring tasks faced by many industries. Only 14 of the 37 major deburring processes are applicable to most intersecting hole applications. Only five of these are normally applicable to small or miniature holes. Basic process capabilities and techniques used as a function of hole sizes and intersection depths are summarized.

  19. Supermassive Black Holes with High Accretion Rates in Active Galactic Nuclei. V. A New Size-Luminosity Scaling Relation for the Broad-Line Region

    CERN Document Server

    Du, Pu; Zhang, Zhi-Xiang; Huang, Ying-Ke; Wang, Kai; Hu, Chen; Qiu, Jie; Li, Yan-Rong; Fan, Xu-Liang; Fang, Xiang-Er; Bai, Jin-Ming; Bian, Wei-Hao; Yuan, Ye-Fei; Ho, Luis C; Wang, Jian-Min

    2016-01-01

    This paper reports results of the third-year campaign of monitoring super-Eddington accreting massive black holes (SEAMBHs) in active galactic nuclei (AGNs) between 2014-2015. Ten new targets were selected from quasar sample of Sloan Digital Sky Survey (SDSS), which are generally more luminous than the SEAMBH candidates in last two years. H$\\beta$ lags ($\\tau_{_{\\rm H\\beta}}$) in five of the 10 quasars have been successfully measured in this monitoring season. We find that the lags are generally shorter, by large factors, than those of objects with same optical luminosity, in light of the well-known $R_{_{\\rm H\\beta}}-L_{5100}$ relation. The five quasars have dimensionless accretion rates of $\\dot{\\mathscr{M}}=10-10^3$. Combining measurements of the previous SEAMBHs, we find that the reduction of H$\\beta$ lags tightly depends on accretion rates, $\\tau_{_{\\rm H\\beta}}/\\tau_{_{R-L}}\\propto\\dot{\\mathscr{M}}^{-0.42}$, where $\\tau_{_{R-L}}$ is the H$\\beta$ lag from the normal $R_{_{\\rm H\\beta}}-L_{5100}$ relation....

  20. Life inside black holes

    CERN Document Server

    Dokuchaev, V I

    2012-01-01

    We consider test planet and photon orbits of the third kind inside a black hole, which are stable, periodic and neither come out of the black hole nor terminate at the singularity. Interiors of supermassive black holes may be inhabited by advanced civilizations living on planets with the third-kind orbits. In principle, one can get information from the interiors of black holes by observing their white hole counterparts.

  1. Hypervelocity Star Candidates in the SEGUE G & K Dwarf Sample

    CERN Document Server

    Palladino, Lauren E; Holley-Bockelmann, Kelly; Prieto, Carlos Allende; Beers, Timothy C; Lee, Young Sun; Schneider, Donald P

    2013-01-01

    We identify 13 candidate hypervelocity stars from the Sloan Extension for Galactic Understanding and Exploration (SEGUE) G and K dwarf samples. Previous searches for hypervelocity stars have only focused on large radial velocities; in this study we also use proper motions to select the candidates. We determine the hypervelocity likelihood of each candidate, considering the significant errors often associated with high proper motion stars via Monte Carlo simulations. We find that more than half of the candidates exceed their escape velocities with at least 90% probability. All of our candidates also have less than a 60% chance of being a high velocity fluke within the SEGUE sample. Based on orbits calculated using the observed 6-d positions and velocities, few, if any, of these candidates originate from the Galactic Center. If these candidates are truly hypervelocity stars, they were not ejected by interactions with the Milky Way's supermassive black hole. This calls for a more serious examination of alternati...

  2. Supermassive Black Holes in the Early Universe

    CERN Document Server

    Melia, Fulvio

    2015-01-01

    The recent discovery of the ultraluminous quasar SDSS J010013.02+280225.8 at redshift 6.3 has exacerbated the time compression problem implied by the appearance of supermassive black holes only ~900 Myr after the big bang, and only ~500 Myr beyond the formation of Pop II and III stars. Aside from heralding the onset of cosmic reionization, these first and second generation stars could have reasonably produced the ~5-20 solar-mass seeds that eventually grew into z~6-7 quasars. But this process would have taken ~900 Myr, a timeline that appears to be at odds with the predictions of LCDM without an anomalously high accretion rate, or some exotic creation of ~10^5 solar-mass seeds. There is no evidence of either of these happening in the local universe. In this paper, we show that a much simpler, more elegant solution to the supermassive black hole anomaly is instead to view this process using the age-redshift relation predicted by the R_h=ct Universe, an FRW cosmology with zero active mass. In this context, cosm...

  3. Deriving the Age of an Individual WD: SDSS, Bok, USNO, and Bayes

    Science.gov (United States)

    2010-11-01

    Deriving the Age of an Individual WD: SDSS , Bok, USNO, and Bayes Ted von Hippel∗,†, Mukremin Kilic∗∗, Jeff Munn‡, Kurtis Williams†, Hugh Harris...m + 5 log µ + 5, has long been used as a proxy for absolute magnitude for samples with similar kinematics. Munn et al. (2004) used the SDSS and USNO...NOV 2010 2. REPORT TYPE 3. DATES COVERED 00-00-2010 to 00-00-2010 4. TITLE AND SUBTITLE Deriving the Age of an Individual WD: SDSS , Bok, USNO

  4. The Eighth Data Release of the Sloan Digital Sky Survey: First Data from SDSS-III

    OpenAIRE

    Aihara, Hiroaki; Allende Prieto, Carlos; An, Deokkeun; Anderson, Scott F.; Aubourg, Éric; Balbinot, Eduardo; Beers, Timothy C.; Berlind, Andreas A.; Bickerton, Steven J.; Bizyaev, Dmitry; Blanton, Michael R.; Bochanski, John J.; Bolton, Adam S; Bovy, Jo; Brandt, W.N.

    2011-01-01

    The Sloan Digital Sky Survey (SDSS) started a new phase in 2008 August, with new instrumentation and new surveys focused on Galactic structure and chemical evolution, measurements of the baryon oscillation feature in the clustering of galaxies and the quasar Lyα forest, and a radial velocity search for planets around ~8000 stars. This paper describes the first data release of SDSS-III (and the eighth counting from the beginning of the SDSS). The release includes five-band imaging of roughly 5...

  5. AGN Variability: Probing Black Hole Accretion

    Science.gov (United States)

    Moreno, Jackeline; O'Brien, Jack; Vogeley, Michael S.; Richards, Gordon T.; Kasliwal, Vishal P.

    2017-01-01

    We combine the long temporal baseline of Sloan Digital Sky Survey (SDSS) for quasars in Stripe 82 with the high precision photometry of the Kepler/K2 Satellite to study the physics of optical variability in the accretion disk and supermassive black hole engine. We model the lightcurves directly as Continuous-time Auto Regressive Moving Average processes (C-ARMA) with the Kali analysis package (Kasliwal et al. 2016). These models are extremely robust to irregular sampling and can capture aperiodic variability structure on various timescales. We also estimate the power spectral density and structure function of both the model family and the data. A Green's function kernel may also be estimated for the resulting C-ARMA parameter fit, which may be interpreted as the response to driving impulses such as hotspots in the accretion disk. We also examine available spectra for our AGN sample to relate observed and modelled behavior to spectral properties. The objective of this work is twofold: to explore the proper physical interpretation of different families of C-ARMA models applied to AGN optical flux variability and to relate empirical characteristic timescales of our AGN sample to physical theory or to properties estimated from spectra or simulations like the disk viscosity and temperature. We find that AGN with strong variability features on timescales resolved by K2 are well modelled by a low order C-ARMA family while K2 lightcurves with weak amplitude variability are dominated by outliers and measurement errors which force higher order model fits. This work explores a novel approach to combining SDSS and K2 data sets and presents recovered characteristic timescales of AGN variability.

  6. Massive Black Hole Binaries: Dynamical Evolution and Observational Signatures

    Directory of Open Access Journals (Sweden)

    M. Dotti

    2012-01-01

    Full Text Available The study of the dynamical evolution of massive black hole pairs in mergers is crucial in the context of a hierarchical galaxy formation scenario. The timescales for the formation and the coalescence of black hole binaries are still poorly constrained, resulting in large uncertainties in the expected rate of massive black hole binaries detectable in the electromagnetic and gravitational wave spectra. Here, we review the current theoretical understanding of the black hole pairing in galaxy mergers, with a particular attention to recent developments and open issues. We conclude with a review of the expected observational signatures of massive binaries and of the candidates discussed in literature to date.

  7. Anomaly detection for machine learning redshifts applied to SDSS galaxies

    CERN Document Server

    Hoyle, Ben; Paech, Kerstin; Bonnett, Christopher; Seitz, Stella; Weller, Jochen

    2015-01-01

    We present an analysis of anomaly detection for machine learning redshift estimation. Anomaly detection allows the removal of poor training examples, which can adversely influence redshift estimates. Anomalous training examples may be photometric galaxies with incorrect spectroscopic redshifts, or galaxies with one or more poorly measured photometric quantity. We select 2.5 million 'clean' SDSS DR12 galaxies with reliable spectroscopic redshifts, and 6730 'anomalous' galaxies with spectroscopic redshift measurements which are flagged as unreliable. We contaminate the clean base galaxy sample with galaxies with unreliable redshifts and attempt to recover the contaminating galaxies using the Elliptical Envelope technique. We then train four machine learning architectures for redshift analysis on both the contaminated sample and on the preprocessed 'anomaly-removed' sample and measure redshift statistics on a clean validation sample generated without any preprocessing. We find an improvement on all measured stat...

  8. Feature importance for machine learning redshifts applied to SDSS galaxies

    CERN Document Server

    Hoyle, Ben; Zitlau, Roman; Steiz, Stella; Weller, Jochen

    2014-01-01

    We present an analysis of importance feature selection applied to photometric redshift estimation using the machine learning architecture Random Decision Forests (RDF) with the ensemble learning routine Adaboost. We select a list of 85 easily measured (or derived) photometric quantities (or 'features') and spectroscopic redshifts for almost two million galaxies from the Sloan Digital Sky Survey Data Release 10. After identifying which features have the most predictive power, we use standard artificial Neural Networks (aNN) to show that the addition of these features, in combination with the standard magnitudes and colours, improves the machine learning redshift estimate by 18% and decreases the catastrophic outlier rate by 32%. We further compare the redshift estimate from RDF using the ensemble learning routine Adaboost with those from two different aNNs, and with photometric redshifts available from the SDSS. We find that the RDF requires orders of magnitude less computation time than the aNNs to obtain a m...

  9. Education with SDSS Data: Activities and Lessons Learned

    Science.gov (United States)

    Raddick, M. J.

    2006-12-01

    We have been developing and maintaining the SkyServer web site (http://skyserver.sdss.org), which offers the complete dataset of the Sloan Digital Sky Survey to educators, for the past five years. We have developed tools for displaying and searching the data, both as images and measured parameters. We have also developed a set of exercises that use these data to teach science at levels from elementary school through introductory college. In this talk, we will demonstrate the resources we have made available, and we will discuss the lessons we have learned from developing and maintaining these resources. We hope that these lessons will be useful for other education and public outreach programs, and for teachers who want to use data from large astronomy surveys with their students.

  10. Return of Pulsations in SDSS 0745+4538

    Science.gov (United States)

    Mukadam, Anjum S.; Townsley, D. M.; Szkody, P.; Gänsicke, B. T.; Winget, D. E.; Hermes, J. J.; Howell, Steve B.; Teske, J.; Patterson, Joseph; Kemp, Jonathan; Armstrong, Eve

    2010-11-01

    Nonradial pulsations had ceased in the accreting white dwarf SDSS J074531.92+453829.6 subsequent to its October 2006 outburst. We recently acquired optical high-speed time-series photometry on this cataclysmic variable more than three years after its outburst to find that pulsations have now returned to the primary white dwarf. Moreover, the observed pulsation periods agree with pre-outburst periods within the uncertainties of 1-2 s. This discovery is both remarkable and significant because it indicates that the outburst did not affect the interior stellar structure, which dictates the observed pulsation frequencies. Using this discovery in addition to an HST ultra-violet temperature measurement obtained one year after outburst, we have also been able to constrain the matter accreted during the 2006 outburst.

  11. Cataclysmic Variables from SDSS III. The Third Year

    CERN Document Server

    Szkody, P; Fraser, O J; Silvestri, N M; Bochanski, J J; Wolfe, M A; Agüeros, M A; Warner, B; Woudt, P; Tramposch, J; Homer, L; Schmidt, G; Knapp, G R; Anderson, S F; Covey, K; Harris, H; Hawley, S; Schneider, D P; Voges, W; Brinkmann, J; Szkody, Paula; Henden, Arne; Fraser, Oliver; Silvestri, Nicole; Bochanski, John; Wolfe, Michael A.; Ag\\"ueros, Marcel; Warner, Brian; Woudt, Patrick; Tramposch, Jonica; Homer, Lee; Schmidt, Gary; Knapp, Gillian R.; Anderson, Scott F.; Covey, Kevin; Harris, Hugh; Hawley, Suzanne; Schneider, Donald P.; Voges, Wolfgang

    2004-01-01

    This paper continues the series that identifies new cataclysmic variables found in the Sloan Digital Sky Survey. We present 36 cataclysmic variables and one possible symbiotic star from Sloan spectra obtained during 2002, of which 34 are new discoveries, 2 are known dwarf novae (BC UMa, KS UMa) and one is a known CV identified from the 2dF survey. The positions, colors and spectra of all 37 systems are presented, along with follow-up spectroscopic/photometric observations of 10 systems. As in the past 2 years of data, the new SDSS systems show a large variety of characteristics based on their inclination and magnetic fields, including 3 eclipsing systems, 4 with prominent He II emission, and 15 systems showing features of the underlying stars.

  12. Photometric Redshifts for the SDSS Early Data Release

    CERN Document Server

    Csabai, I; Connolly, A J; Szalay, A S; Györy, Z; Benítez, N; Annis, J; Brinkmann, J; Eisenstein, D J; Fukugita, M; Gunn, J; Kent, S; Lupton, R; Nichol, R C; Stoughton, C; Csabai, Istvan; Budavari, Tamas; Connolly, Andrew J.; Szalay, Alexander S.; Gyory, Zsuzsanna; Benitez, Narciso; Annis, Jim; Brinkmann, Jon; Eisenstein, Daniel; Fukugita, Masataka; Gunn, Jim; Kent, Stephen; Lupton, Robert; Nichol, Robert C.; Stoughton, Chris

    2003-01-01

    The Early Data Release from the Sloan Digital Sky survey provides one of the largest multicolor photometric catalogs currently available to the astronomical community. In this paper we present the first application of photometric redshifts to the $\\sim 6$ million extended sources within these data (with 1.8 million sources having $r' < 21$). Utilizing a range of photometric redshift techniques, from empirical to template and hybrid techniques, we investigate the statistical and systematic uncertainties present within the redshift estimates for the EDR data. For $r'<21$ we find that the redshift estimates provide realistic redshift histograms with an rms uncertainty in the photometric redshift relation of 0.035 at $r'<18$ and rising to 0.1 at $r'<21$. We conclude by describing how these photometric redshifts and derived quantities, such as spectral type, restframe colors and absolute magnitudes, are stored within the SDSS database. We provide sample queries for searching on photometric redshifts an...

  13. Lensing clusters of galaxies in the SDSS-Ⅲ

    Institute of Scientific and Technical Information of China (English)

    Zhong-Lue Wen; Jin-Lin Han; Yun-Ying Jiang

    2011-01-01

    We identify new strong lensing clusters of galaxies from the Sloan Digital Sky Survey Ⅲ (SDSS DR8) by visually inspecting color images of a large sample of clusters of galaxies.We find 68 new clusters showing giant arcs in addition to 30 known lensing systems.Among 68 cases,13 clusters are "almost certain" lensing systems with tangential giant arcs,22 clusters are "probable" and 31 clusters are "possible" lensing systems.We also find two exotic systems with blue rings.The giant arcs have angular separations of 2.0" - 25.7" from the bright central galaxies.We note that the rich clusters are more likely to be lensing systems and the separations between the arcs and the central galaxies increase with cluster richness.

  14. Seyfert 1 Composite Spectrum using SDSS Legacy Survey Data

    CERN Document Server

    Pol, Nihan

    2016-01-01

    We present a rest-frame composite spectrum for Seyfert 1 galaxies using spectra obtained from the DR12 release of the Sloan Digital Sky Survey (SDSS). The spectrum is constructed by combining data from a total of 10,112 galaxies, spanning a redshift range of 0 to 0.793. We produce an electronic table of the median and geometric mean composite Seyfert 1 spectrum. We measure the spectral index of the composite spec- trum, and compare it with that of the composite quasar spectrum. We also measure the flux and width of the strong emission lines present in the composite spectrum. We compare the entire spectrum with the quasar spectrum in the context of the AGN unification model. The two composite spectra match extremely well in the blue part of the spectrum, while there is an offset in flux in the red portion of the spectrum.

  15. Oxygen Abundance Methods in SDSS: View from Modern Statistics

    Indian Academy of Sciences (India)

    Fei Shi; Gang Zhao; James Wicker

    2010-09-01

    Our purpose is to find which is the most reliable one among various oxygen abundance determination methods. We will test the validity of several different oxygen abundance determination methods using methods of modern statistics. These methods include Bayesian analysis and information scoring. We will analyze a sample of ∼ 6000 HII galaxies from the Sloan Digital Sky Survey (SDSS) spectroscopic observations data release four. All methods that we used drew the same conclusion that the method is a more reliable oxygen abundance determination method than the Bayesian metallicity method under the existing telescope ability. The ratios of the likelihoods between the different kinds of methods tell us that the , , and 32 methods are consistent with each other because the and 32 methods are calibrated by method. The Bayesian and 23 methods are consistent with each other because both are calibrated by a galaxy model. In either case, the 2 method is an unreliable method.

  16. Cosmological Constraints from the SDSS Luminous Red Galaxies

    CERN Document Server

    Tegmark, M; Strauss, M; Weinberg, D; Blanton, M; Frieman, J A; Fukugita, M; Gunn, J; Hamilton, A; Knapp, G; Nichol, R; Ostriker, J; Padmanabhan, N; Percival, W; Schlegel, D J; Schneider, D; Scoccimarro, R; Seljak, U; Seo, H; Swanson, M; Szalay, A S; Vogeley, M; Yoo, J; Zehavi, I; Abazajian, Kevork N; Anderson, S; Annis, J; Bahcall, Neta A; Bassett, B; Berlind, A; Brinkmann, J; Budavari, T; Castander, F; Connolly, A; Csabai, I; Doi, M; Finkbeiner, D; Gillespie, B; Glazebrook, K; Hennessy, G; Hogg, D; Ivezic, Z; Jain, B; Johnston, D; Kent, S; Lamb, D; Lee, B; Lin, H; Loveday, J; Lupton, R; Munn, J A; Pan, K; Park, C; Peoples, John; Pier, J; Pope, A; Richmond, M; Rockosi, C M; Scranton, R; Sheth, R; Stebbins, A; Stoughton, C; Szapudi, I; Tucker, D; Vanden Berk, Daniel E; Yanny, B; York, D

    2006-01-01

    We measure the large-scale real-space power spectrum P(k) using luminous red galaxies (LRGs) in the Sloan Digital Sky Survey (SDSS) and use this measurement to sharpen constraints on cosmological parameters from the Wilkinson Microwave Anisotropy Probe (WMAP). We employ a matrix-based power spectrum estimation method using Pseudo-Karhunen-Loeve eigenmodes, producing uncorrelated minimum-variance measurements in 20 k-bands of both the clustering power and its anisotropy due to redshift-space distortions, with narrow and well-behaved window functions in the range 0.01h/Mpc 0.1h/Mpc and associated nonlinear complications, yet agree well with more aggressive published analyses where nonlinear modeling is crucial.

  17. Photometric Supernova Cosmology with BEAMS and SDSS-II

    CERN Document Server

    Hlozek, Renée; Bassett, Bruce; Smith, Mat; Newling, James; Varughese, Melvin; Kessler, Rick; Bernstein, Joe; Campbell, Heather; Dilday, Ben; Falck, Bridget; Frieman, Joshua; Kulhmann, Steve; Lampeitl, Hubert; Marriner, John; Nichol, Robert C; Riess, Adam G; Sako, Masao; Schneider, Donald P

    2011-01-01

    Supernova cosmology without spectroscopic confirmation is an exciting new frontier which we address here with the Bayesian Estimation Applied to Multiple Species (BEAMS) algorithm and the full three years of data from the Sloan Digital Sky Survey II Supernova Survey (SDSS-II SN). BEAMS is a Bayesian framework for using data from multiple species in statistical inference when one has the probability that each data point belongs to a given species, corresponding in this context to different types of supernovae with their probabilities derived from their multi-band lightcurves. We run the BEAMS algorithm on both Gaussian and more realistic SNANA simulations with of order 10^4 supernovae, testing the algorithm against various pitfalls one might expect in the new and somewhat uncharted territory of photometric supernova cosmology. We compare the performance of BEAMS to that of both mock spectroscopic surveys and photometric samples which have been cut using typical selection criteria. The latter typically are eith...

  18. Distribution of Doppler Redshifts of Associated Absorbers of SDSS Quasars

    Indian Academy of Sciences (India)

    Cai-Juan Pan; Zhi-Fu Chen

    2013-12-01

    Doppler redshifts of a sample of Mg II associated absorbers of SDSS DR7 quasars are analysed. We find that there might be three Gaussian components in the distribution of the Doppler redshift. The first Gaussian component, with the peak being located at Dopp = -0.0074, probably arises from absorbers with outflow histories observed in the direction close to jets of quasars. The second Gaussian component, with the peak being located at Dopp = -0.0017, possibly arises from absorbers with outflow histories observed in the direction far away from jets of quasars. Whereas, the third Gaussian component, with the peak being located at Dopp = -0.0004, might arise from the random motion of absorbers with respect to quasars.

  19. Universal void density profiles from simulation and SDSS

    CERN Document Server

    Nadathur, S; Diego, J M; Iliev, I T; Gottlöber, S; Watson, W A; Yepes, G

    2014-01-01

    We discuss the universality and self-similarity of void density profiles, for voids in realistic mock luminous red galaxy (LRG) catalogues from the Jubilee simulation, as well as in void catalogues constructed from the SDSS LRG and Main Galaxy samples. Voids are identified using a modified version of the ZOBOV watershed transform algorithm, with additional selection cuts. We find that voids in simulation are self-similar, meaning that their average rescaled profile does not depend on the void size, or -- within the range of the simulated catalogue -- on the redshift. Comparison of the profiles obtained from simulated and real voids shows an excellent match. The profiles of real voids also show a universal behaviour over a wide range of galaxy luminosities, number densities and redshifts. This points to a fundamental property of the voids found by the watershed algorithm, which can be exploited in future studies of voids.

  20. Universal void density profiles from simulation and SDSS

    Science.gov (United States)

    Nadathur, S.; Hotchkiss, S.; Diego, J. M.; Iliev, I. T.; Gottlöber, S.; Watson, W. A.; Yepes, G.

    2016-10-01

    We discuss the universality and self-similarity of void density profiles, for voids in realistic mock luminous red galaxy (LRG) catalogues from the Jubilee simulation, as well as in void catalogues constructed from the SDSS LRG and Main Galaxy samples. Voids are identified using a modified version of the ZOBOV watershed transform algorithm, with additional selection cuts. We find that voids in simulation are self-similar, meaning that their average rescaled profile does not depend on the void size, or - within the range of the simulated catalogue - on the redshift. Comparison of the profiles obtained from simulated and real voids shows an excellent match. The profiles of real voids also show a universal behaviour over a wide range of galaxy luminosities, number densities and redshifts. This points to a fundamental property of the voids found by the watershed algorithm, which can be exploited in future studies of voids.

  1. On the level of cluster assembly bias in SDSS

    Science.gov (United States)

    Zu, Ying; Mandelbaum, Rachel; Simet, Melanie; Rozo, Eduardo; Rykoff, Eli S.

    2017-09-01

    Recently, several studies have discovered a strong discrepancy between the large-scale clustering biases of two subsamples of galaxy clusters at the same halo mass, split by their average projected membership distances 〈Rmem〉. The level of this discrepancy significantly exceeds the maximum halo assembly bias predicted by Λ cold dark matter (ΛCDM). We explore whether some of the large-scale bias differences could be caused by projection effects in 〈Rmem〉 due to other systems along the line of sight. We thoroughly investigate the assembly bias of the redMaPPer clusters in Sloan Digital Sky Survey (SDSS), by defining a new variant of the average membership distance estimator \\tilde{R}_{mem} that is robust against projection effects in the cluster membership identification. Using the angular mark correlation functions, we show that the large-scale bias differences when splitting by 〈Rmem〉 can be mostly attributed to projection effects. After splitting by \\tilde{R}_{mem}, the anomalously large signal is reduced, giving a ratio of 1.02 ± 0.14 between the two clustering biases as measured from weak lensing. Using a realistic mock cluster catalogue, we predict that the bias ratio between two \\tilde{R}_{mem}-split subsamples should be ≃1.10, which is >60 per cent weaker than the maximum halo assembly bias (1.24) when split by halo concentration. Therefore, our results demonstrate that the level of halo assembly bias exhibited by clusters in SDSS is consistent with the ΛCDM prediction. With a 10-fold increase in cluster numbers, deeper ongoing surveys will enable a more robust detection of halo assembly bias. Our findings also have important implications for quantifying the impact of projection effects on cosmological constraints using photometrically selected clusters.

  2. The Milky Way Tomography with SDSS. 2. Stellar Metallicity

    Energy Technology Data Exchange (ETDEWEB)

    Ivezic, Zeljko; /Washington U., Seattle; Sesar, Branimir; /Washington U., Seattle; Juric, Mario; /Princeton, Inst. Advanced Study; Bond, Nicholas; /Princeton U.; Dalcanton, Julianne; /Washington U., Seattle; Rockosi, Constance M.; /UC, Santa Cruz; Yanny, Brian; /Fermilab; Newberg, Heidi J.; /Rensselaer Poly.; Beers, Timothy C.; /Michigan State U.; Prieto, Carlos Allende; /Texas U.; Wilhelm, Ron; /Texas Tech. /Michigan State U.

    2008-04-01

    In addition to optical photometry of unprecedented quality, the Sloan Digital Sky Survey (SDSS) is producing a massive spectroscopic database which already contains over 280,000 stellar spectra. Using effective temperature and metallicity derived from SDSS spectra for {approx}60,000 F and G type main sequence stars (0.2 < g-r < 0.6), we develop polynomial models, reminiscent of traditional methods based on the UBV photometry, for estimating these parameters from the SDSS u-g and g-r colors. These estimators reproduce SDSS spectroscopic parameters with a root-mean-square scatter of 100 K for effective temperature, and 0.2 dex for metallicity (limited by photometric errors), which are similar to random and systematic uncertainties in spectroscopic determinations. We apply this method to a photometric catalog of coadded SDSS observations and study the photometric metallicity distribution of {approx}200,000 F and G type stars observed in 300 deg{sup 2} of high Galactic latitude sky. These deeper (g < 20.5) and photometrically precise ({approx}0.01 mag) coadded data enable an accurate measurement of the unbiased metallicity distribution for a complete volume-limited sample of stars at distances between 500 pc and 8 kpc. The metallicity distribution can be exquisitely modeled using two components with a spatially varying number ratio, that correspond to disk and halo. The best-fit number ratio of the two components is consistent with that implied by the decomposition of stellar counts profiles into exponential disk and power-law halo components by Juric et al. (2008). The two components also possess the kinematics expected for disk and halo stars. The metallicity of the halo component can be modeled as a spatially invariant Gaussian distribution with a mean of [Fe/H] = -1.46 and a standard deviation of {approx}0.3 dex. The disk metallicity distribution is non-Gaussian, with a remarkably small scatter (rms {approx}0.16 dex) and the median smoothly decreasing with distance

  3. The Faint Stellar Object SDSS J1257+3419 is a Dark Matter Dominated System

    CERN Document Server

    Kamaya, Hideyuki

    2007-01-01

    A recent study has revealed SDSS J1257+3419 is either a faint and small dwarf galaxy or a faint and widely extended globular cluster. In this Letter, the author suggests this stellar system is a dwarf spheroidal (dSph). Adopting an observational relation between binding energy and mass of old stellar systems, we derive a relation between mass and size of dSphs by assuming that they are dark matter dominated and virialized objects. Letting half-light radius represent size of SDSS J1257+3419, we find that its mass is $\\sim 7\\times 10^6$ solar mass. This indicates mass-to-light ratio ($M/L$) of SDSS J1257+3419 is about 1000 in the solar unit. This large $M/L$ is expected from a Mateo plot of dSphs. Thus, we insist SDSS J1257+3419 is a dSph.

  4. Magnetic fields threading black holes: restrictions from general relativity and implications for astrophysical black holes

    Science.gov (United States)

    Garofalo, David

    2017-07-01

    The idea that black hole spin is instrumental in the generation of powerful jets in active galactic nuclei and X-ray binaries is arguably the most contentious claim in black hole astrophysics. Because jets are thought to originate in the context of electromagnetism, and the modeling of Maxwell fields in curved spacetime around black holes is challenging, various approximations are made in numerical simulations that fall under the guise of `ideal magnetohydrodynamics'. But the simplifications of this framework may struggle to capture relevant details of real astrophysical environments near black holes. In this work, we highlight tension between analytic and numerical results, specifically between the analytically derived conserved Noether currents for rotating black hole spacetimes and the results of general relativistic numerical simulations (GRMHD). While we cannot definitively attribute the issue to any specific approximation used in the numerical schemes, there seem to be natural candidates, which we explore. GRMHD notwithstanding, if electromagnetic fields around rotating black holes are brought to the hole by accretion, we show from first principles that prograde accreting disks likely experience weaker large-scale black hole-threading fields, implying weaker jets than in retrograde configurations.

  5. Size of the accretion disk in the gravitationally lensed quasar SDSS J1004+4112 from the statistics of microlensing magnifications

    CERN Document Server

    Fian, C; Hanslmeier, A; Oscoz, A; Serra-Ricart, M; Muñoz, J A; Jiménez-Vicente, J

    2016-01-01

    We present eight monitoring seasons of the four brightest images of the gravitational lens SDSS J1004+4112 observed between December 2003 and October 2010. Using measured time delays for the images A, B and C and the model predicted time delay for image D we have removed the intrinsic quasar variability, finding microlensing events of about 0.5 and 0.7 mag of amplitude in the images C and D. From the statistics of microlensing amplitudes in images A, C, and D, we have inferred the half-light radius (at {\\lambda} rest = 2407 {\\AA}) for the accretion disk using two different methods, $R_{1/2}=8.7^{+18.5}_{-5.5} \\sqrt{M/0.3 M_\\odot}$ (histograms product) and $R_{1/2} = 4.2^{+3.2}_{-2.2} \\sqrt{M/0.3 M_\\odot}$ light-days ($\\chi^2$). The results are in agreement within uncertainties with the size predicted from the black hole mass in SDSS J1004+4112 using the thin disk theory.

  6. New Constraints on Quasar Variability based on 8,000 SDSS Stripe 82 Quasars with both SDSS and CRTS Lightcurve Data

    Science.gov (United States)

    Suberlak, Krzysztof; Ivezic, Zeljko; Sesar, Branimir; MacLeod, Chelsea Louise

    2015-01-01

    We present improved constraints for the Damped Random Walk (DRW) quasar variability model based on synergistic analysis of optical lightcurves obtained by SDSS and CRTS (Catalina Real-Time Transient Survey) for a sample of 8,000 SDSS quasars from the MacLeod et al. (2010) Stripe 82 catalog. We fit observed lightcurves with a number of varying stochastic Gaussian Processes, specified by different covariance matrices. Apart from using the DRW (Ornstein-Uhlenbeck process) exponential covariance matrix, we use modified covariance functions developed by Zu et al. (2012), as well as their fitting software (Javelin). We also compare the sampling properties of the unified SDSS+CRTS dataset to anticipated cadence properties of the main LSST survey.

  7. The SDSS SkyServer Public Access to the Sloan Digital Sky Server Data

    CERN Document Server

    Szalay, A S; Thakar, A R; Kunszt, Zoltán; Malik, T; Raddick, J; Stoughton, C; Van den Berg, J

    2002-01-01

    The SkyServer provides Internet access to the public Sloan Digi-tal Sky Survey (SDSS) data for both astronomers and for science education. This paper describes the SkyServer goals and archi-tecture. It also describes our experience operating the SkyServer on the Internet. The SDSS data is public and well-documented so it makes a good test platform for research on database algorithms and performance.

  8. VizieR Online Data Catalog: SDSS damped Ly{alpha} survey: DR1 (Prochaska+, 2004)

    Science.gov (United States)

    Prochaska, J. X.; Herbert-Fort, S.

    2005-11-01

    We present the results from an automated search for damped Ly{alpha} (DLA) systems in the quasar spectra of Data Release 1 from the Sloan Digital Sky Survey (SDSS-DR1). At z~2.5, this homogeneous data set has greater statistical significance than the previous two decades of research. We derive a statistical sample of 71 DLA systems (>50 previously unpublished) at z>2.1 and measure HI column densities directly from the SDSS spectra. (1 data file).

  9. A Monte Carlo Method for Making the SDSS u-Band Magnitude More Accurate

    Science.gov (United States)

    Gu, Jiayin; Du, Cuihua; Zuo, Wenbo; Jing, Yingjie; Wu, Zhenyu; Ma, Jun; Zhou, Xu

    2016-10-01

    We develop a new Monte Carlo-based method to convert the Sloan Digital Sky Survey (SDSS) u-band magnitude to the south Galactic Cap of the u-band Sky Survey (SCUSS) u-band magnitude. Due to the increased accuracy of SCUSS u-band measurements, the converted u-band magnitude becomes more accurate compared with the original SDSS u-band magnitude, in particular at the faint end. The average u-magnitude error (for both SDSS and SCUSS) of numerous main-sequence stars with 0.2\\lt g-r\\lt 0.8 increases as the g-band magnitude becomes fainter. When g = 19.5, the average magnitude error of the SDSS u is 0.11. When g = 20.5, the average SDSS u error rises to 0.22. However, at this magnitude, the average magnitude error of the SCUSS u is just half as much as that of the SDSS u. The SDSS u-band magnitudes of main-sequence stars with 0.2\\lt g-r\\lt 0.8 and 18.5\\lt g\\lt 20.5 are converted, therefore the maximum average error of the converted u-band magnitudes is 0.11. The potential application of this conversion is to derive a more accurate photometric metallicity calibration from SDSS observations, especially for the more distant stars. Thus, we can explore stellar metallicity distributions either in the Galactic halo or some stream stars.

  10. Surfing a Black Hole

    Science.gov (United States)

    2002-10-01

    Star Orbiting Massive Milky Way Centre Approaches to within 17 Light-Hours [1] Summary An international team of astronomers [2], lead by researchers at the Max-Planck Institute for Extraterrestrial Physics (MPE) , has directly observed an otherwise normal star orbiting the supermassive black hole at the center of the Milky Way Galaxy. Ten years of painstaking measurements have been crowned by a series of unique images obtained by the Adaptive Optics (AO) NAOS-CONICA (NACO) instrument [3] on the 8.2-m VLT YEPUN telescope at the ESO Paranal Observatory. It turns out that earlier this year the star approached the central Black Hole to within 17 light-hours - only three times the distance between the Sun and planet Pluto - while travelling at no less than 5000 km/sec . Previous measurements of the velocities of stars near the center of the Milky Way and variable X-ray emission from this area have provided the strongest evidence so far of the existence of a central Black Hole in our home galaxy and, implicitly, that the dark mass concentrations seen in many nuclei of other galaxies probably are also supermassive black holes. However, it has not yet been possible to exclude several alternative configurations. In a break-through paper appearing in the research journal Nature on October 17th, 2002, the present team reports their exciting results, including high-resolution images that allow tracing two-thirds of the orbit of a star designated "S2" . It is currently the closest observable star to the compact radio source and massive black hole candidate "SgrA*" ("Sagittarius A") at the very center of the Milky Way. The orbital period is just over 15 years. The new measurements exclude with high confidence that the central dark mass consists of a cluster of unusual stars or elementary particles, and leave little doubt of the presence of a supermassive black hole at the centre of the galaxy in which we live . PR Photo 23a/02 : NACO image of the central region of the Milky Way

  11. Variable Faint Optical Sources Discovered by Comparing POSS and SDSS Catalogs

    CERN Document Server

    Sesar, B; Ivezic, Z; Lupton, R H; Munn, J A; Finkbeiner, D; Steinhardt, W; Siverd, R J; Johnston, D E; Knapp, G R; Gunn, J E; Rockosi, C M; Schlegel, D J; Vanden Berk, Daniel E; Hall, P; Schneider, D P; Brunner, R J

    2004-01-01

    We present a study of variable faint optical sources discovered by comparing the Sloan Digital Sky Survey (SDSS) and the Palomar Observatory Sky Survey (POSS) catalogs. We use SDSS measurements to photometrically recalibrate several publicly available POSS catalogs; a piecewise recalibration in 100 arcmin2 patches generally results in an improvement of photometric accuracy (rms) by nearly a factor of two, compared to the original data. The POSS I magnitudes can be improved to ~0.15 mag accuracy, and POSS II magnitudes to \\~0.10 mag accuracy. We use the recalibrated catalogs for the ~2,000 deg2 of sky in the SDSS Data Release 1 to construct a catalog of ~60,000 sources variable on time scales 10-50 years. A series of statistical tests based on the morphology of SDSS color-color diagrams, as well as visual comparison of images and comparison with repeated SDSS observations, demonstrate the robustness of the selection methods. We quantify the distribution of variable sources in the SDSS color-color diagrams, and...

  12. The alignment of SDSS satellites with the VPOS: effects of the survey footprint shape

    CERN Document Server

    Pawlowski, Marcel S

    2015-01-01

    It is sometimes argued that the uneven sky coverage of the Sloan Digital Sky Survey (SDSS) biases the distribution of satellite galaxies discovered by it to align with the polar plane defined by the 11 brighter, classical Milky Way (MW) satellites. This might prevent the SDSS satellites from adding significance to the MW's Vast Polar Structure (VPOS). We investigate whether this argument is valid by comparing the observed situation with model satellite distributions confined to the exact SDSS footprint area. We find that the SDSS satellites indeed add to the significance of the VPOS and that the survey footprint rather biases away from a close alignment between the plane fitted to the SDSS satellites and the plane fitted to the 11 classical satellites. Finding the observed satellite phase-space alignments of both the classical and SDSS satellites is a ~5{\\sigma} event with respect to an isotropic distribution. This constitutes a robust discovery of the VPOS and makes it more significant than the Great Plane o...

  13. Improved Photometric Calibrations for Red Stars Observed with the SDSS Photometric Telescope

    CERN Document Server

    Davenport, James R A; Covey, Kevin R; Hawley, Suzanne L; West, Andrew A; Schneider, Donald P

    2007-01-01

    We present a new set of photometric transformations for red stars observed with the Sloan Digital Sky Survey (SDSS) 0.5-m Photometric Telescope (PT) and the SDSS 2.5-m telescope at the Apache Point Observatory in New Mexico. Nightly PT observations of US Naval Observatory standards are used to determine extinction corrections and calibration terms for SDSS 2.5-m photometry. Systematic differences between the PT and native SDSS 2.5-m {\\it ugriz} photometry require conversions between the two systems which have previously been undefined for the reddest stars. By matching $\\sim 43,000$ stars observed with both the PT and SDSS 2.5-m, we extend the present relations to include low-mass stars with colors $0.6 \\le r-i \\le 1.7$. These corrections will allow us to place photometry of bright, low-mass trigonometric parallax stars previously observed with the PT on the 2.5-m system. We present new transformation equations and discuss applications of these data to future low-mass star studies using the SDSS.

  14. A survey of luminous high-redshift quasars with SDSS and WISE. I. target selection and optical spectroscopy

    CERN Document Server

    Wang, Feige; Fan, Xiaohui; Yang, Jinyi; Yi, Weimin; Bian, Fuyan; McGreer, Ian D; Yang, Qian; Ai, Yanli; Dong, Xiaoyi; Zuo, Wenwen; Jiang, Linhua; Green, Richard; Wang, Shu; Cai, Zheng; Wang, Ran; Yue, Minghao

    2016-01-01

    High-redshift quasars are important tracers of structure and evolution in the early universe. However, they are very rare and difficult to find when using color selection because of contamination from late-type dwarfs. High-redshift quasar surveys based on only optical colors suffer from incompleteness and low identification efficiency, especially at $z\\gtrsim4.5$. We have developed a new method to select $4.7\\lesssim z \\lesssim 5.4$ quasars with both high efficiency and completeness by combining optical and mid-IR Wide-field Infrared Survey Explorer (WISE) photometric data, and are conducting a luminous $z\\sim5$ quasar survey in the whole Sloan Digital Sky Survey (SDSS) footprint. We have spectroscopically observed 99 out of 110 candidates with $z$-band magnitudes brighter than 19.5 and 64 (64.6\\%) of them are quasars with redshifts of $4.4\\lesssim z \\lesssim 5.5$ and absolute magnitudes of $-29\\lesssim M_{1450} \\lesssim -26.4$. In addition, we also observed 14 fainter candidates selected with the same crite...

  15. Higher spin black holes

    National Research Council Canada - National Science Library

    Gutperle, Michael; Kraus, Per

    2011-01-01

    .... We find solutions that generalize the BTZ black hole and carry spin-3 charge. The black hole entropy formula yields a result for the asymptotic growth of the partition function at finite spin-3 chemical potential...

  16. Black hole hair removal

    Science.gov (United States)

    Banerjee, Nabamita; Mandal, Ipsita; Sen, Ashoke

    2009-07-01

    Macroscopic entropy of an extremal black hole is expected to be determined completely by its near horizon geometry. Thus two black holes with identical near horizon geometries should have identical macroscopic entropy, and the expected equality between macroscopic and microscopic entropies will then imply that they have identical degeneracies of microstates. An apparent counterexample is provided by the 4D-5D lift relating BMPV black hole to a four dimensional black hole. The two black holes have identical near horizon geometries but different microscopic spectrum. We suggest that this discrepancy can be accounted for by black hole hair — degrees of freedom living outside the horizon and contributing to the degeneracies. We identify these degrees of freedom for both the four and the five dimensional black holes and show that after their contributions are removed from the microscopic degeneracies of the respective systems, the result for the four and five dimensional black holes match exactly.

  17. Black Hole Hair Removal

    CERN Document Server

    Banerjee, Nabamita; Sen, Ashoke

    2009-01-01

    Macroscopic entropy of an extremal black hole is expected to be determined completely by its near horizon geometry. Thus two black holes with identical near horizon geometries should have identical macroscopic entropy, and the expected equality between macroscopic and microscopic entropies will then imply that they have identical degeneracies of microstates. An apparent counterexample is provided by the 4D-5D lift relating BMPV black hole to a four dimensional black hole. The two black holes have identical near horizon geometries but different microscopic spectrum. We suggest that this discrepancy can be accounted for by black hole hair, -- degrees of freedom living outside the horizon and contributing to the degeneracies. We identify these degrees of freedom for both the four and the five dimensional black holes and show that after their contributions are removed from the microscopic degeneracies of the respective systems, the result for the four and five dimensional black holes match exactly.

  18. Independent candidates in Mexico

    OpenAIRE

    Campos, Gonzalo Santiago

    2014-01-01

    In this paper we discuss the issue of independent candidates in Mexico, because through the so-called political reform of 2012 was incorporated in the Political Constitution of the Mexican United States the right of citizens to be registered as independent candidates. Also, in September 2013 was carried out a reform of Article 116 of the Political Constitution of the Mexican United States in order to allow independent candidates in each state of the Republic. However, prior to the constitutio...

  19. Finding Free-Floating Black Holes using Astrometric Microlensing

    Science.gov (United States)

    Lu, Jessica R.; Ofek, Eran Oded; Sinukoff, Evan; Udalski, Andrzej; Kozlowski, Szymon

    2017-01-01

    Our Galaxy most likely hosts 10-100 million stellar mass black holes. The exact number and mass function of these black holes contains important information regarding our Galaxy's star formation history, stellar mass function, and the fate of very massive stars. However, isolated stellar black holes have yet to be detected. To date, stellar mass black holes have only been definitively detected in binary systems with accreting companions or merging to produce gravitational waves. In principle, the presence of isolated black holes can be inferred from astrometric and photometric signatures produced when they lens light from a background star. We attempt to detect the astrometric lensing signatures of several photometrically identified microlensing events, toward the Galactic Bulge. Long-duration events (t_Einstein > 100 days) were selected as the most likely black hole candidates and were observed using several years of laser-guided adaptive optics observations from the W. M. Keck telescopes. We present results from this search.

  20. Quasi-evaporating black holes and cold dark matter

    CERN Document Server

    Larena, Julien

    2009-01-01

    Vilkovisky has claimed to have solved the black hole back reaction problem and finds that black holes lose only ten percent of their mass to Hawking radiation before evaporation ceases. We examine the implications of this scenario for cold dark matter, assuming that primordial black holes are created from a scale- invariant perturbation spectrum during the reheating period after inflation. The mass spectrum is expected to be dominated by 10-gram black holes. We find that nucleosynthesis constraints and the requirement that the earth presently exist do not come close to ruling out such black holes as dark matter candidates. They also evade the demand that the photon density produced by evaporating primordial black holes does not exceed the present cosmic radiation background by a factor of about one thousand.

  1. Noncommutative black holes

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-DomInguez, J C [Instituto de Fisica de la Universidad de Guanajuato PO Box E-143, 37150 Leoen Gto. (Mexico); Obregon, O [Instituto de Fisica de la Universidad de Guanajuato PO Box E-143, 37150 Leoen Gto. (Mexico); RamIrez, C [Facultad de Ciencias FIsico Matematicas, Universidad Autonoma de Puebla, PO Box 1364, 72000 Puebla (Mexico); Sabido, M [Instituto de Fisica de la Universidad de Guanajuato PO Box E-143, 37150 Leoen Gto. (Mexico)

    2007-11-15

    We study noncommutative black holes, by using a diffeomorphism between the Schwarzschild black hole and the Kantowski-Sachs cosmological model, which is generalized to noncommutative minisuperspace. Through the use of the Feynman-Hibbs procedure we are able to study the thermodynamics of the black hole, in particular, we calculate Hawking's temperature and entropy for the 'noncommutative' Schwarzschild black hole.

  2. Black Hole Thermodynamics

    Science.gov (United States)

    Israel, Werner

    This chapter reviews the conceptual developments on black hole thermodynamics and the attempts to determine the origin of black hole entropy in terms of their horizon area. The brick wall model and an operational approach are discussed. An attempt to understand at the microlevel how the quantum black hole acquires its thermal properties is included. The chapter concludes with some remarks on the extension of these techniques to describing the dynamical process of black hole evaporation.

  3. SHIELD: Observations of Three Candidate Interacting Systems

    Science.gov (United States)

    Ruvolo, Elizabeth; Miazzo, Masao; Cannon, John M.; McNichols, Andrew; Teich, Yaron; Adams, Elizabeth A.; Giovanelli, Riccardo; Haynes, Martha P.; McQuinn, Kristen B.; Salzer, John Joseph; Skillman, Evan D.; Dolphin, Andrew E.; Elson, Edward C.; Haurberg, Nathalie C.; Huang, Shan; Janowiecki, Steven; Jozsa, Gyula; Leisman, Luke; Ott, Juergen; Papastergis, Emmanouil; Rhode, Katherine L.; Saintonge, Amelie; Van Sistine, Angela; Warren, Steven R.

    2017-01-01

    Abstract:The “Survey of HI in Extremely Low-mass Dwarfs” (SHIELD) is a multiwavelength study of local volume low-mass galaxies. Using the now-complete Arecibo Legacy Fast ALFA (ALFALFA) source catalog, 82 systems are identified that meet distance, line width, and HI flux criteria for being gas-rich, low-mass galaxies. These systems harbor neutral gas reservoirs smaller than 3x10^7 M_sun, thus populating the faint end of the HI mass function with statistical confidence for the first time. In a companion poster, we present new Karl G. Jansky Very Large Array D-configuration HI spectral line observations of 32 previously unobserved galaxies. Three galaxies in that study have been discovered to lie in close angular proximity to more massive galaxies. Here we present VLA HI imaging of these candidate interacting systems. We compare the neutral gas morphology and kinematics with optical images from SDSS. We discuss the frequency of low-mass galaxies undergoing tidal interaction in the complete SHIELD sample.Support for this work was provided by NSF grant 1211683 to JMC at Macalester College.

  4. Monopole black hole skyrmions

    OpenAIRE

    Moss, I. G.; Shiiki, N.; Winstanley, E.

    2000-01-01

    Charged black hole solutions with pion hair are discussed. These can be\\ud used to study monopole black hole catalysis of proton decay.\\ud There also exist\\ud multi-black hole skyrmion solutions with BPS monopole behaviour.

  5. Monopole Black Hole Skyrmions

    OpenAIRE

    Moss, I. G.; Shiiki, N.; Winstanley, E.

    2000-01-01

    Charged black hole solutions with pion hair are discussed. These can be\\ud used to study monopole black hole catalysis of proton decay.\\ud There also exist\\ud multi-black hole skyrmion solutions with BPS monopole behaviour.

  6. Ballistic hole magnetic microscopy

    NARCIS (Netherlands)

    Haq, E.; Banerjee, T.; Siekman, M.H.; Lodder, J.C.; Jansen, R.

    2005-01-01

    A technique to study nanoscale spin transport of holes is presented: ballistic hole magnetic microscopy. The tip of a scanning tunneling microscope is used to inject hot electrons into a ferromagnetic heterostructure, where inelastic decay creates a distribution of electron-hole pairs. Spin-dependen

  7. Ballistic hole magnetic microscopy

    NARCIS (Netherlands)

    Haq, E.; Banerjee, T.; Siekman, M.H.; Lodder, J.C.; Jansen, R.

    2005-01-01

    A technique to study nanoscale spin transport of holes is presented: ballistic hole magnetic microscopy. The tip of a scanning tunneling microscope is used to inject hot electrons into a ferromagnetic heterostructure, where inelastic decay creates a distribution of electron-hole pairs.

  8. Optically Selected BL Lacertae Candidates from the Sloan Digital Sky Survey Data Release Seven

    CERN Document Server

    Plotkin, Richard M; Brandt, W N; Diamond-Stanic, A M; Fan, X; Hall, P B; Kimball, A E; Richmond, M W; Schneider, D P; Shemmer, O; Voges, W; York, D G; Bahcall, N A; Snedden, S; Bizyaev, D; Brewington, H; Malanushenko, V; Malanushenko, E; Oravetz, D; Pan, K; Simmonds, A

    2009-01-01

    We present a sample of 723 optically selected BL Lac candidates from the SDSS DR7 spectroscopic database encompassing 8250 deg^2 of sky; our sample constitutes one of the largest uniform BL Lac samples yet derived. Each BL Lac candidate has a high-quality SDSS spectrum from which we determine spectroscopic redshifts for ~60% of the objects. Redshift lower limits are estimated for the remaining objects utilizing the lack of host galaxy flux contamination in their optical spectra; we find that objects lacking spectroscopic redshifts are likely at systematically higher redshifts. Approximately 80% of our BL Lac candidates match to a radio source in FIRST/NVSS, and ~40% match to a ROSAT X-ray source. The homogeneous multiwavelength coverage allows subdivision of the sample into 637 radio-loud BL Lac candidates and 86 weak-featured radio-quiet objects. The radio-loud objects broadly support the standard paradigm unifying BL Lac objects with beamed radio galaxies. We propose that the majority of the radio-quiet obj...

  9. Follow-up of MARVELS Brown Dwarf Candidates using EXPERT

    Science.gov (United States)

    Ma, Bo; Ge, Jian; Li, Rui; Sithajan, Sirinrat; Thomas, Neil; Wang, Ji; De Lee, Nathan

    2013-02-01

    The SDSS-III MARVELS survey is a comprehensive radial velocity survey of 3,300 nearby F-K stars, between 7.6 < V < 12.0 in 2008-2012. All of the survey data for 2580 FGK stars from the first two and half years have been processed with the latest data pipeline. A total of 26 new brown dwarfs (BD) candidates have been identified in the processed RV data. We expect to have 8 more BD candidates from the ~800 stars currently under processing, which will make a total of 34 BD candidates. This proposal requests KPNO 2.1m telescope time with the EXPERT instrument, to follow up all of these BD candidates to confirm the detections and characterize the orbits. The results will be used to (1) reveal the overall distribution of the new BDs in the parameter space; (2) measure the occurrence rate of BD around FGK type stars; (3) measure dryness of the brown dwarf desert around stars with different mass and metallicity; (4) constrain theoretical models regarding the formation of brown dwarfs; (5) confirm the discovery of `desert in the brown dwarf desert'; (6) identify additional companions associated with the detected systems.

  10. Clustering Property of Wolf-Rayet Galaxies in the SDSS

    Institute of Scientific and Technical Information of China (English)

    Wei Zhang; Xu Kong; Fu-Zhen Cheng

    2008-01-01

    We have analysed, for the first time, the clustering properties of Wolf-Rayet (W-R) galaxies, using a large sample of 846 W-R galaxies selected from the Data Release 4 (DR4) of the Sloan Digital Sky Survey (SDSS). We compute the cross-correlation function between W- R galaxies and a reference sample of galaxies drawn from the DR4. We compare the function to the results for control samples of non-W-R star-forming galaxies that are matched closely in redshift, luminosity, concentration, 4000-A break strength and specific star formation rate (SSFR). On scales larger than a few Mpc, W-R galaxies have almost the same clustering amplitude as the control samples, indicating that W-R galaxies and non-W-R control galax- ies populate dark matter haloes of similar masses. On scales between 0.1-1 h-1 Mpc, W-R galaxies are less clustered than the control samples, and the size of the difference depends on the SSFR. Based on both observational and theoretical considerations, we speculate that this negative bias can be interpreted by W-R galaxies residing preferentially at the centers of their dark matter haloes. We examine the distribution of W-R galaxies more closely using the SDSS galaxy group catalogue of Yang et al., and find that ~82% of our W-R galaxies are the central galaxies of groups, compared to ~74% for the corresponding control galaxies. We find that W-R galaxies are hosted, on average, by dark matter haloes of masses of 1012,3 M☉, compared to 1012,1 M? For centrally-located W-R galaxies and 1012,7 M☉ For satellite ones. We would like to point out that this finding, which provides a direct observational support to our conjecture, is really very crude due to the small number of W-R galaxies and the incom- pleteness of the group catalogue, and needs more work in future with larger samples.

  11. Spectroscopic Confirmation of the Fifth Image of SDSS J1004+4112 and Implications for the M_BH-sigma_* Relation at z=0.68

    Energy Technology Data Exchange (ETDEWEB)

    Inada, Naohisa; Oguri, Masamune; Falco, Emilio E.; Broadhurst, Tom J.; Ofek, Eran O.; Kochanek, Christopher S.; Sharon, Keren; Smith, Graham P.

    2008-08-15

    We present the results of deep spectroscopy for the central region of the cluster lens SDSS J1004+4112 with the Subaru telescope. A secure detection of an emission line of the faint blue stellar object (component E) near the center of the brightest cluster galaxy (G1) confirms that it is the central fifth image of the lensed quasar system. In addition, we measure the stellar velocity dispersion of G1 to be {sigma}{sub *} = 352 {+-} 13 km s{sup -1}. We combine these results to obtain constraints on the mass M{sub BH} of the putative black hole (BH) at the center of the inactive galaxy G1, and hence on the M{sub BH}-{sigma}{sub *} relation at the lens redshift z{sub l} = 0.68. From detailed mass modeling, we place an upper limit on the black hole mass, M{sub BH} < 2.1 x 10{sup 10} M{sub {circle_dot}} at 1{sigma} level (< 3.1 x 10{sup 10}M{sub {circle_dot}} at 3{sigma}), which is consistent with black hole masses expected from the local and redshift-evolved M{sub BH}-{sigma}{sub *} relations, M{sub BH} {approx} 10{sup 9}-10{sup 10} M{sub {circle_dot}}.

  12. Sound Hole Sound

    CERN Document Server

    Politzer, David

    2015-01-01

    The volume of air that goes in and out of a musical instrument's sound hole is related to the sound hole's contribution to the volume of the sound. Helmholtz's result for the simplest case of steady flow through an elliptical hole is reviewed. Measurements on multiple holes in sound box geometries and scales relevant to real musical instruments demonstrate the importance of a variety of effects. Electric capacitance of single flat plates is a mathematically identical problem, offering an alternate way to understand the most important of those effects. The measurements also confirm and illuminate aspects of Helmholtz's "bottle" resonator model as applied to musical instrument sound boxes and sound holes.

  13. Black holes in binary stars

    NARCIS (Netherlands)

    Wijers, R.A.M.J.

    1996-01-01

    Introduction Distinguishing neutron stars and black holes Optical companions and dynamical masses X-ray signatures of the nature of a compact object Structure and evolution of black-hole binaries High-mass black-hole binaries Low-mass black-hole binaries Low-mass black holes Formation of black holes

  14. On Accelerated Black Holes

    CERN Document Server

    Letelier, P S; Letelier, Patricio S.; Oliveira, Samuel R.

    1998-01-01

    The C-metric is revisited and global interpretation of some associated spacetimes are studied in some detail. Specially those with two event horizons, one for the black hole and another for the acceleration. We found that the spacetime fo an accelerated Schwarzschild black hole is plagued by either conical singularities or lack of smoothness and compactness of the black hole horizon. By using standard black hole thermodynamics we show that accelerated black holes have higher Hawking temperature than Unruh temperature. We also show that the usual upper bound on the product of the mass and acceleration parameters (<1/sqrt(27)) is just a coordinate artifact. The main results are extended to accelerated Kerr black holes. We found that they are not changed by the black hole rotation.

  15. X-ray spectroscopy of a recoiling SMBH candidate

    Science.gov (United States)

    Predehl, Peter

    2008-09-01

    Recent numerical relativity simulations of coalescencing supermassive black hole (SMBH) binaries predict that SMBHs can receive kicks with velocities up to several thousand km/s due to anisotropic emission of gravitational waves. We have recently found the best candidate todate for such a recoiling SMBH (Komossa et al. 2008). We apply for a 25 ks ACIS-S exposure of this exceptional source.

  16. Mining the SDSS SkyServer SQL queries log

    Science.gov (United States)

    Hirota, Vitor M.; Santos, Rafael; Raddick, Jordan; Thakar, Ani

    2016-05-01

    SkyServer, the Internet portal for the Sloan Digital Sky Survey (SDSS) astronomic catalog, provides a set of tools that allows data access for astronomers and scientific education. One of SkyServer data access interfaces allows users to enter ad-hoc SQL statements to query the catalog. SkyServer also presents some template queries that can be used as basis for more complex queries. This interface has logged over 330 million queries submitted since 2001. It is expected that analysis of this data can be used to investigate usage patterns, identify potential new classes of queries, find similar queries, etc. and to shed some light on how users interact with the Sloan Digital Sky Survey data and how scientists have adopted the new paradigm of e-Science, which could in turn lead to enhancements on the user interfaces and experience in general. In this paper we review some approaches to SQL query mining, apply the traditional techniques used in the literature and present lessons learned, namely, that the general text mining approach for feature extraction and clustering does not seem to be adequate for this type of data, and, most importantly, we find that this type of analysis can result in very different queries being clustered together.

  17. Gravitational redshift of galaxies in clusters from SDSS and BOSS

    CERN Document Server

    Sadeh, Iftach; Lahav, Ofer

    2014-01-01

    The gravitational redshift effect allows one to directly probe the gravitational potential in clusters of galaxies. As such, it provides a fundamental test of general relativity (GR), and may help to constrain alternative theories of gravity. Following up on Wojtak, Hansen & Hjorth (2011), we present a new measurement. We take advantage of new data from the tenth data release of SDSS and BOSS, covering a range of redshift between 0.05 and 0.6. After selection, our dataset includes 60k galaxies, matched to 12k clusters, with an average cluster mass of $10^{14} M_{\\odot}$. The analysis is focused on optimizing the selection method of clusters and of galaxies, taking into account possible systematic biases. We compare the light originating from the brightest cluster galaxies (BCGs), to that of galaxies at the outskirts of clusters. We find that BCGs have an average relative redshift of 11 km/s, with a standard deviation of +7 and -5 km/s. The result is consistent with the measurement of Wojtak et al. and is ...

  18. Mg II Absorption Systems in SDSS QSO Spectra

    CERN Document Server

    Nestor, D B; Rao, S M

    2004-01-01

    We present the results of a MgII absorption-line survey using QSO spectra from the SDSS EDR. Over 1,300 doublets with rest equivalent widths greater than 0.3\\AA and redshifts $0.366 \\le z \\le 2.269$ were identified and measured. We find that the $\\lambda2796$ rest equivalent width ($W_0^{\\lambda2796}$) distribution is described very well by an exponential function $\\partial N/\\partial W_0^{\\lambda2796} = \\frac{N^*}{W^*} e^{-\\frac{W_0}{W^*}}$, with $N^*=1.187\\pm0.052$ and $W^*=0.702\\pm0.017$\\AA. Previously reported power law fits drastically over-predict the number of strong lines. Extrapolating our exponential fit under-predicts the number of $W_0 \\le 0.3$\\AA systems, indicating a transition in $dN/dW_0$ near $W_0 \\simeq 0.3$\\AA. A combination of two exponentials reproduces the observed distribution well, suggesting that MgII absorbers are the superposition of at least two physically distinct populations of absorbing clouds. We also derive a new redshift parameterization for the number density of $W_0^{\\lambd...

  19. NIBLES: an HI census of local SDSS galaxies

    CERN Document Server

    Van Driel, W; Lehnert, M; Consortium, the NIBLES

    2007-01-01

    NIBLES is a Key Project proposed for the 100m-class Nancay Radio Telescope (NRT) in France. Its aim is a census of the HI gas content and dynamics of 4,000 Sloan Digital Sky Survey galaxies in the Local Volume (900SDSS galaxies (-10 to -24 mag, for H0=70 km/s/Mpc). A pilot survey is being made of over 600 galaxies. NIBLES will be complementary to the ALFALFA and EBHIS blind HI surveys, which will detect a different ensemble of local galaxies, and which our pilot survey results indicate will detect about 40-45% of the NIBLES sample. NIBLES is an open collaboration and anyone interested in the science and willing to contribute to the project is welcome to join the score of NIBLErS.

  20. The Alignment Effect of Brightest Cluster Galaxies in the SDSS

    CERN Document Server

    Kim, R S J; Strauss, M A; Lupton, R H; Bahcall, Neta A; Gunn, J E; Kepner, J V; Postman, M; Kim, Rita S. J.; Annis, Jim; Strauss, Michael A.; Lupton, Robert H.; Bahcall, Neta A.; Gunn, James E.; Kepner, Jeremy V.; Postman, Marc

    2002-01-01

    One of the most vital observational clues for unraveling the origin of Brightest Cluster Galaxies (BCG) is the observed alignment of the BCGs with their host cluster and its surroundings. We have examined the BCG-cluster alignment effect, using clusters of galaxies detected from the Sloan Digital Sky Survey (SDSS). We find that the BCGs are preferentially aligned with the principal axis of their hosts, to a much higher redshift (z >~ 0.3) than probed by previous studies (z <~ 0.1). The alignment effect strongly depends on the magnitude difference of the BCG and the second and third brightest cluster members: we find a strong alignment effect for the dominant BCGs, while less dominant BCGs do not show any departure from random alignment with respect to the cluster. We therefore claim that the alignment process originates from the same process that makes the BCG grow dominant, be it direct mergers in the early stage of cluster formation, or a later process that resembles the galactic cannibalism scenario. We...

  1. SDSS-IV/MaNGA: Spectrophotometric Calibration Technique

    CERN Document Server

    Yan, Renbin; Bershady, Matthew A; Law, David R; Schlegel, David J; Bundy, Kevin; Drory, Niv; MacDonald, Nicholas; Bizyaev, Dmitry; Blanc, Guillermo A; Blanton, Michael R; Cherinka, Brian; Eigenbrot, Arthur; Gunn, James E; Harding, Paul; Hogg, David W; Sánchez-Gallego, José R; Sánchez, Sebastian F; Wake, David A; Weijmans, Anne-Marie; Xiao, Ting; Zhang, Kai

    2015-01-01

    Mapping Nearby Galaxies at Apache Point Observatory (MaNGA), one of three core programs in the Sloan Digital Sky Survey-IV (SDSS-IV), is an integral-field spectroscopic (IFS) survey of roughly 10,000 nearby galaxies. It employs dithered observations using 17 hexagonal bundles of 2 arcsec fibers to obtain resolved spectroscopy over a wide wavelength range of 3,600-10,300A. To map the internal variations within each galaxy, we need to perform accurate {\\it spectral surface photometry}, which is to calibrate the specific intensity at every spatial location sampled by each individual aperture element of the integral field unit. The calibration must correct only for the flux loss due to atmospheric throughput and the instrument response, but not for losses due to the finite geometry of the fiber aperture. This requires the use of standard star measurements to strictly separate these two flux loss factors (throughput versus geometry), a difficult challenge with standard single-fiber spectroscopy techniques due to v...

  2. Data augmentation for machine learning redshifts applied to SDSS galaxies

    CERN Document Server

    Hoyle, Ben; Bonnett, Christopher; Seitz, Stella; Weller, Jochen

    2015-01-01

    We present analyses of data augmentation for machine learning redshift estimation. Data augmentation makes a training sample more closely resemble a test sample, if the two base samples differ, in order to improve measured statistics of the test sample. We perform two sets of analyses by selecting 800k (1.7M) SDSS DR8 (DR10) galaxies with spectroscopic redshifts. We construct a base training set by imposing an artificial r band apparent magnitude cut to select only bright galaxies and then augment this base training set by using simulations and by applying the K-correct package to artificially place training set galaxies at a higher redshift. We obtain redshift estimates for the remaining faint galaxy sample, which are not used during training. We find that data augmentation reduces the error on the recovered redshifts by 40% in both sets of analyses, when compared to the difference in error between the ideal case and the non augmented case. The outlier fraction is also reduced by at least 10% and up to 80% u...

  3. Machine Learning Classification of SDSS Transient Survey Images

    CERN Document Server

    Buisson, L du; Bassett, B A; Smith, M

    2014-01-01

    We show that multiple machine learning algorithms can match human performance in classifying transient imaging data from the SDSS supernova survey into real objects and artefacts. This is the first step in any transient science pipeline and is currently still done by humans, but future surveys such as LSST will necessitate fully machine-enabled solutions. Using features trained from eigenimage analysis (PCA) of single-epoch g, r, i-difference images we can reach a completeness (recall) of 95%, while only incorrectly classifying 18% of artefacts as real objects, corresponding to a precision (purity) of 85%. In general the k-nearest neighbour and the SkyNet artificial neural net algorithms performed most robustly compared to other methods such as naive Bayes and kernel SVM. Our results show that PCA-based machine learning can match human success levels and can naturally be extended by including multiple epochs of data, transient colours and host galaxy information which should allow for significant further impr...

  4. The clustering of SDSS galaxy groups: mass and color dependence

    CERN Document Server

    Wang, Yu; Mo, H J; Bosch, Frank C van den; Weinmann, Simone W; Chu, Yaoquan

    2007-01-01

    We use a sample of galaxy groups selected from the SDSS DR 4 with an adaptive halo-based group finder to probe how the clustering strength of groups depends on their masses and colors. In particular, we determine the relative biases of groups of different masses, as well as that of groups with the same mass but with different colors. In agreement with previous studies, we find that more massive groups are more strongly clustered, and the inferred mass dependence of the halo bias is in good agreement with predictions for the $\\Lambda$CDM cosmology. Regarding the color dependence, we find that groups with red centrals are more strongly clustered than groups of the same mass but with blue centrals. Similar results are obtained when the color of a group is defined to be the total color of its member galaxies. The color dependence is more prominent in less massive groups and becomes insignificant in groups with masses $\\gta 10^{14}\\msunh$. We construct a mock galaxy redshift survey constructed from the large Mille...

  5. On the Level of Cluster Assembly Bias in SDSS

    CERN Document Server

    Zu, Ying; Simet, Melanie; Rozo, Eduardo; Rykoff, Eli S

    2016-01-01

    Recently, several studies have discovered a strong discrepancy between the large-scale clustering biases of two subsamples of galaxy clusters at the same halo mass, split by their average projected membership distances $R_{\\mathrm{mem}}$. The level of this discrepancy significantly exceeds the maximum halo assembly bias signal predicted by LCDM. In this study, we explore whether some of the clustering bias differences could be caused by biases in $R_{\\mathrm{mem}}$ due to projection effects from other systems along the line-of-sight. We thoroughly investigate the halo assembly bias of the photometrically-detected redMaPPer clusters in SDSS, by defining a new variant of the average membership distance estimator $\\tilde{R}_{\\mathrm{mem}}$ that is more robust against projection effects in the cluster membership identification. Using the angular mark correlation functions of clusters, we show that the large-scale bias differences when splitting by $R_{\\mathrm{mem}}$ can be largely attributed to such projection ef...

  6. Practical Spectro-Perfectionism in SDSS-III

    Science.gov (United States)

    Bailey, Stephen J.; Bolton, A.; Brownstein, J.; Kisner, T.; Pandey, P.; Schlegel, D.

    2012-01-01

    As extragalactic spectroscopic surveys push to higher redshifts, the targeted objects are fainter and fainter, yet the night-sky foreground remains as bright as ever. This requires spectral extraction algorithms to push to new limits of signal-to-noise. The "spectro-perfectionism" algorithm of Bolton & Schlegel 2010 provides a framework to achieve poisson-limited sky subtraction through the forward modeling of photons onto the spectrograph CCDs using a two dimensional point spread function. This method produces uncorrelated errors in the extracted spectra while fully preserving the input spectrum likelihood function given the raw CCD pixel data. A brute-force implementation of this algorithm would be computationally prohibitive. We present a practical implementation of this algorithm for the Baryon Oscillation Spectroscopic Survey (BOSS) of the Sloan Digital Sky Survey III (SDSS-III). This implementation handles the full complexity of real data while being computationally tractable on current-generation hardware. The gains from this implementation will increase the science reach of BOSS and will be critical for future redshift surveys such as the proposed BigBOSS project.

  7. NUV signatures of environment driven galaxy quenching in SDSS groups

    CERN Document Server

    Crossett, Jacob P; Jones, D Heath; Brown, Michael J I; Stott, John P

    2016-01-01

    We have investigated the effect of group environment on residual star formation in galaxies, using Galex NUV galaxy photometry with the SDSS group catalogue of Yang et al. (2007). We compared the (NUV $- r$) colours of grouped and non-grouped galaxies, and find a significant increase in the fraction of red sequence galaxies with blue (NUV $- r$) colours outside of groups. When comparing galaxies in mass matched samples of satellite (non-central), and non-grouped galaxies, we found a > 4{\\sigma} difference in the distribution of (NUV $- r$) colours, and an (NUV $- r$) blue fraction $> 3{\\sigma}$ higher outside groups. A comparison of satellite and non-grouped samples has found the NUV fraction is a factor of $\\sim2$ lower for satellite galaxies between $10^{10.5}M_{\\bigodot}$ and $10^{10.7}M_{\\bigodot}$, showing that higher mass galaxies are more able to form stars when not influenced by a group potential. There was a higher (NUV $- r$) blue fraction of galaxies with lower Sersic indices (n < 3) outside of ...

  8. Large Scale Structure in the SDSS Galaxy Survey

    CERN Document Server

    Doroshkevich, A G; Tucker, D L

    2004-01-01

    The Large Scale Structure (LSS) in the galaxy distribution is investigated using the Sloan Digital Sky Survey Early Data Release (SDSS EDR). Using the Minimal Spanning Tree technique we have extracted sets of filaments, of wall-like structures, of galaxy groups, and of rich clusters from this unique sample. The physical properties of these structures were then measured and compared with the expectations from Zel'dovich' theory. The measured characteristics of galaxy walls were found to be consistent with those for a spatially flat $\\Lambda$CDM cosmological model with $\\Omega_m\\approx$ 0.3 and $\\Omega_\\Lambda \\approx$ 0.7, and for Gaussian initial perturbations with a Harrison -- Zel'dovich power spectrum. Furthermore, we found that the mass functions of groups and of unrelaxed structure elements generally fit well with the expectations from Zel'dovich' theory, although there was some discrepancy for lower mass groups which may be due to incompleteness in the selected sample of groups. We also note that both g...

  9. Intrinsic alignments of SDSS-III BOSS LOWZ sample galaxies

    CERN Document Server

    Singh, Sukhdeep; More, Surhud

    2014-01-01

    Intrinsic alignments (IA) of galaxies, i.e. correlations of galaxy shapes with each other or with the density field, are a major astrophysical source of contamination for weak lensing surveys. We present the results of IA measurements of galaxies on 0.1- 200 Mpc/h scales using the SDSS-III BOSS LOWZ sample, in the redshift range 0.16

  10. Photometric redshifts of galaxies from SDSS and 2MASS

    Institute of Scientific and Technical Information of China (English)

    Tao Wang; Jia-Sheng Huang; Qiu-Sheng Gu

    2009-01-01

    In order to find the physical parameters which determine the accuracy of pho- tometric redshifts, we compare the spectroscopic and photometric redshifts (photo-z's) for a large sample of ~ 80 000 SDSS-2MASS galaxies. Photo-z's in this paper are es- timated by using the artificial neural network photometric redshift method (ANNz). For a subset of~40000 randomly selected galaxies, we find that the photometric redshift recovers the spectroscopic redshifi distribution very well with rms of 0.016. Our main results are as follows: (1) Using magnitudes directly as input parameters produces more accurate photo-z's than using colors; (2) The inclusion of 2MASS (3, H, Ks) bands does not improve photo-z's significantly, which indicates that near infrared data might not be important for the low-redshift sample; (3) Adding the concentration index (essentially the steepness of the galaxy brightness profile) as an extra input can improve the photo-z's estimation up to~10 percent; (4) Dividing the sample into early- and late-type galaxies by using the concentration index, normal and abnormal galaxies by using the emission line flux ratios, and red and blue galaxies by using color index (g - r), we can improve the accuracy of photo-z's significantly; (5) Our analysis shows that the outliers (where there is a big difference between the spectroscopic and photometric redshifts) are mainly correlated with galaxy types, e.g., most outliers are late-type (blue) galaxies.

  11. Cosmological Constraints from the SDSS maxBCG Cluster Catalog

    Energy Technology Data Exchange (ETDEWEB)

    Rozo, Eduardo; /CCAPP; Wechsler, Risa H.; /KIPAC, Menlo Park /SLAC; Rykoff, Eli S.; /UC, Santa Barbara; Annis, James T.; /Fermilab; Becker, Matthew R.; /Chicago U. /KICP, Chicago; Evrard, August E.; /Michigan U. /Michigan U., MCTP; Frieman, Joshua A.; /Fermilab /KICP, Chicago /Chicago U.; Hansen, Sarah M.; /UC, Santa Cruz; Hao, Jia; /Michigan U.; Johnston, David E.; /Northwestern U.; Koester, Benjamin P.; /KICP, Chicago /Chicago U.; McKay, Timothy A.; /Michigan U. /Michigan U., MCTP; Sheldon, Erin S.; /Brookhaven; Weinberg, David H.; /CCAPP /Ohio State U.

    2009-08-03

    We use the abundance and weak lensing mass measurements of the SDSS maxBCG cluster catalog to simultaneously constrain cosmology and the richness-mass relation of the clusters. Assuming a flat {Lambda}CDM cosmology, we find {sigma}{sub 8}({Omega}{sub m}/0.25){sup 0.41} = 0.832 {+-} 0.033 after marginalization over all systematics. In common with previous studies, our error budget is dominated by systematic uncertainties, the primary two being the absolute mass scale of the weak lensing masses of the maxBCG clusters, and uncertainty in the scatter of the richness-mass relation. Our constraints are fully consistent with the WMAP five-year data, and in a joint analysis we find {sigma}{sub 8} = 0.807 {+-} 0.020 and {Omega}{sub m} = 0.265 {+-} 0.016, an improvement of nearly a factor of two relative to WMAP5 alone. Our results are also in excellent agreement with and comparable in precision to the latest cosmological constraints from X-ray cluster abundances. The remarkable consistency among these results demonstrates that cluster abundance constraints are not only tight but also robust, and highlight the power of optically-selected cluster samples to produce precision constraints on cosmological parameters.

  12. The Demographics of galactic bulges in the SDSS database

    CERN Document Server

    Kim, Keunho; Jeong, Hyunjin; Aragon-Salamanca, Alfonso; Smith, Rory; Yi, Sukyoung K

    2016-01-01

    We present a new database of our two-dimensional bulge-disk decompositions for 14,233 galaxies drawn from SDSS DR12 in order to examine the properties of bulges residing in the local universe ($0.005 < z < 0.05$). We performed decompositions in $g$ and $r$ bands by utilizing the {\\sc{galfit}} software. The bulge colors and bulge-to-total ratios are found to be sensitive to the details in the decomposition technique, and hence we hereby provide full details of our method. The $g-r$ colors of bulges derived are almost constantly red regardless of bulge size except for the bulges in the low bulge-to-total ratio galaxies ($B/T_{\\rm r} \\lesssim 0.3$). Bulges exhibit similar scaling relations to those followed by elliptical galaxies, but the bulges in galaxies with lower bulge-to-total ratios clearly show a gradually larger departure in slope from the elliptical galaxy sequence. The scatters around the scaling relations are also larger for the bulges in galaxies with lower bulge-to-total ratios. Both the depa...

  13. The Angular Power Spectra of Photometric SDSS LRGs

    CERN Document Server

    Thomas, Shaun A; Lahav, Ofer

    2010-01-01

    We construct new galaxy angular power spectra based on the extended, updated and final SDSS II Luminous Red Galaxy (LRG) photometric redshift survey: MegaZ DR7. Encapsulating 7746 deg^{2} we utilise 723,556 photometrically determined LRGs between 0.45 < z < 0.65 in a 3.3 (Gpc h^{-1})^3 spherical harmonic analysis of the galaxy distribution. By combining four photometric redshift bins we find preliminary parameter constraints of f_{b} = \\Omega_{b}/\\Omega_{m} = 0.173 +/- 0.046 and \\Omega_{m} = 0.260 +/- 0.035 assuming H_{0} = 75 km s^{-1} Mpc^{-1}, n_{s}=1 and \\Omega_{k} = 0. These limits are consistent with the CMB and the previous data release (DR4). The C_{\\ell} are sensitive to redshift space distortions and therefore we also recast our constraints into a measurement of \\beta ~ \\Omega_{m}^{0.55}/b in different redshift shells. The robustness of these power spectra with respect to a number of potential systematics such as extinction, photometric redshift and ANNz training set extrapolation are examined...

  14. Supersymmetry versus black holes at the LHC

    CERN Document Server

    Roy, Arunava

    2007-01-01

    Supersymmetry and extra dimensions are the two most promising candidates for new physics at the TeV scale. Supersymmetric particles or extra-dimensional effects could soon be observed at the Large Hadron Collider. We propose a simple but powerful method to discriminate the two models: the analysis of isolated leptons with high transverse momentum. Black hole events are simulated with the CATFISH black hole generator. Supersymmetry simulations use a combination of PYTHIA and ISAJET, the latter providing the mass spectrum. Our results show the measure of the dilepton invariant mass provides a strong signature to differentiate supersymmetry and black hole events at the Large Hadron Collider. Analysis of event-shape variables and multilepton events complement and strengthen this conclusion.

  15. Supersymmetry Versus Black Holes at the Lhc

    Science.gov (United States)

    Roy, Arunava; Cavaglià, Marco

    Supersymmetry and extra dimensions are the two most promising candidates for new physics at the TeV scale. Supersymmetric particles or extra-dimensional effects could soon be observed at the Large Hadron Collider. We propose a simple but effective method to discriminate the two models: the analysis of isolated leptons with high transverse momentum. Black hole events are simulated with the CATFISH black hole generator. Supersymmetry simulations use a combination of PYTHIA and ISAJET, the latter providing the mass spectrum. Our results show that the measure of the dilepton invariant mass provides a promising signature to differentiate supersymmetry and black hole events at the Large Hadron Collider. Analysis of event-shape variables and multilepton events complement and strengthen this conclusion.

  16. Black hole unitarity and antipodal entanglement

    CERN Document Server

    Hooft, Gerard t

    2016-01-01

    Hawking particles emitted by a black hole are usually found to have thermal spectra, if not exactly, then by a very good approximation. Here, we argue differently. Locally, Hawking particles are thermal, but globally not: the Hawking particles emerging from one hemisphere of a black hole are 100 % entangled with the Hawking particles emerging from the other hemisphere. Consequently, their thermal fluctuations are identical, so if a rare event takes place on one hemisphere, the same event will be seen at the antipodal point on the other hemisphere. We explain why such bizarre behaviour is demanded by the requirement that black hole evaporation is described by a unitary scattering matrix. Region I and the diametrically opposite region II of the Penrose diagram represent antipodal points in a CPT relation, as was suggested before. On the horizon itself, antipodal points are identified, as long as there is no matter falling in. A candidate instanton is proposed to describe the formation and evaporation of virtual...

  17. The Tenth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the SDSS-III Apache Point Observatory Galactic Evolution Experiment

    CERN Document Server

    Ahn, Christopher P; Prieto, Carlos Allende; Anders, Friedrich; Anderson, Scott F; Anderton, Timothy; Andrews, Brett H; Aubourg, Éric; Bailey, Stephen; Bastien, Fabienne A; Bautista, Julian E; Beers, Timothy C; Beifiori, Alessandra; Bender, Chad F; Berlind, Andreas A; Beutler, Florian; Bhardwaj, Vaishali; Bird, Jonathan C; Bizyaev, Dmitry; Blake, Cullen H; Blanton, Michael R; Blomqvist, Michael; Bochanski, John J; Bolton, Adam S; Borde, Arnaud; Bovy, Jo; Bradley, Alaina Shelden; Brandt, W N; Brauer, Dorothée; Brinkmann, J; Brownstein, Joel R; Busca, Nicolás G; Carithers, William; Carlberg, Joleen K; Carnero, Aurelio R; Carr, Michael A; Chiappini, Cristina; Chojnowski, S Drew; Chuang, Chia-Hsun; Comparat, Johan; Crepp, Justin R; Cristiani, Stefano; Croft, Rupert A C; Cuesta, Antonio J; Cunha, Katia; da Costa, Luiz N; Dawson, Kyle S; De Lee, Nathan; Dean, Janice D R; Delubac, Timothée; Deshpande, Rohit; Dhital, Saurav; Ealet, Anne; Ebelke, Garrett L; Edmondson, Edward M; Eisenstein, Daniel J; Epstein, Courtney R; Escoffier, Stephanie; Esposito, Massimiliano; Evans, Michael L; Fabbian, D; Fan, Xiaohui; Favole, Ginevra; Castellá, Bruno Femen\\'\\ia; Alvar, Emma Fernández; Feuillet, Diane; Ak, Nurten Filiz; Finley, Hayley; Fleming, Scott W; Font-Ribera, Andreu; Frinchaboy, Peter M; Galbraith-Frew, J G; Garc\\'\\ia-Hernández, D A; Pérez, Ana E Garc\\'\\ia; Ge, Jian; Génova-Santos, R; Gillespie, Bruce A; Girardi, Léo; Hernández, Jonay I González; Gott, J Richard; Gunn, James E; Guo, Hong; Halverson, Samuel; Harding, Paul; Harris, David W; Hasselquist, Sten; Hawley, Suzanne L; Hayden, Michael; Hearty, Frederick R; Ho, Shirley; Hogg, David W; Holtzman, Jon A; Honscheid, Klaus; Huehnerhoff, Joseph; Ivans, Inese I; Jackson, Kelly M; Jiang, Peng; Johnson, Jennifer A; Kirkby, David; Kinemuchi, K; Klaene, Mark A; Kneib, Jean-Paul; Koesterke, Lars; Lan, Ting-Wen; Lang, Dustin; Goff, Jean-Marc Le; Lee, Khee-Gan; Lee, Young Sun; Long, Daniel C; Loomis, Craig P; Lucatello, Sara; Lupton, Robert H; Ma, Bo; Mahadevan, Suvrath; Maia, Marcio A G; Majewski, Steven R; Malanushenko, Elena; Malanushenko, Viktor; Manchado, A; Manera, Marc; Maraston, Claudia; Margala, Daniel; Martell, Sarah L; Masters, Karen L; McBride, Cameron K; McGreer, Ian D; McMahon, Richard G; Ménard, Brice; Mészáros, Sz; Miralda-Escudé, Jordi; Miyatake, Hironao; Montero-Dorta, Antonio D; Montesano, Francesco; More, Surhud; Morrison, Heather L; Muna, Demitri; Munn, Jeffrey A; Myers, Adam D; Nguyen, Duy Cuong; Nichol, Robert C; Nidever, David L; Noterdaeme, Pasquier; Nuza, Sebastián E; O'Connell, Julia E; O'Connell, Robert W; O'Connell, Ross; Olmstead, Matthew D; Oravetz, Daniel J; Owen, Russell; Padmanabhan, Nikhil; Palanque-Delabrouille, Nathalie; Pan, Kaike; Parejko, John K; Pâris, Isabelle; Pepper, Joshua; Percival, Will J; Pérez-Ràfols, Ignasi; Perottoni, Hélio Dotto; Petitjean, Patrick; Pieri, Matthew M; Pinsonneault, M H; Prada, Francisco; Price-Whelan, Adrian M; Raddick, M Jordan; Rahman, Mubdi; Rebolo, Rafael; Reid, Beth A; Richards, Jonathan C; Riffel, Rogério; Robin, Annie C; Rocha-Pinto, H J; Rockosi, Constance M; Roe, Natalie A; Ross, Ashley J; Ross, Nicholas P; Rossi, Graziano; Roy, Arpita; Rubiño-Martin, J A; Sabiu, Cristiano G; Sánchez, Ariel G; Santiago, Basílio; Sayres, Conor; Schiavon, Ricardo P; Schlegel, David J; Schlesinger, Katharine J; Schmidt, Sarah J; Schneider, Donald P; Schultheis, Mathias; Sellgren, Kris; Shen, Yue; Shetrone, Matthew; Shu, Yiping; Simmons, Audrey E; Skrutskie, M F; Slosar, Anže; Smith, Verne V; Snedden, Stephanie A; Sobeck, Jennifer S; Sobreira, Flavia; Stassun, Keivan G; Steinmetz, Matthias; Strauss, Michael A; Streblyanska, Alina; Suzuki, Nao; Swanson, Molly E C; Terrien, Ryan C; Thakar, Aniruddha R; Thomas, Daniel; Thompson, Benjamin A; Tinker, Jeremy L; Tojeiro, Rita; Troup, Nicholas W; Vandenberg, Jan; Magaña, Mariana Vargas; Viel, Matteo; Vogt, Nicole P; Wake, David A; Weaver, Benjamin A; Weinberg, David H; Weiner, Benjamin J; White, Martin; White, Simon D M; Wilson, John C; Wisniewski, John P; Wood-Vasey, W M; Yèche, Christophe; York, Donald G; Zamora, O; Zasowski, Gail; Zehavi, Idit; Zheng, Zheng; Zhu, Guangtun

    2013-01-01

    The Sloan Digital Sky Survey (SDSS) has been in operation since 2000 April. This paper presents the tenth public data release (DR10) from its current incarnation, SDSS-III. This data release includes the first spectroscopic data from the Apache Point Observatory Galaxy Evolution Experiment (APOGEE), along with spectroscopic data from the Baryon Oscillation Spectroscopic Survey (BOSS) taken through 2012 July. The APOGEE instrument is a near-infrared R~22,500 300-fiber spectrograph covering 1.514--1.696 microns. The APOGEE survey is studying the chemical abundances and radial velocities of roughly 100,000 red giant star candidates in the bulge, bar, disk, and halo of the Milky Way. DR10 includes 178,397 spectra of 57,454 stars, each typically observed three or more times, from APOGEE. Derived quantities from these spectra (radial velocities, effective temperatures, surface gravities, and metallicities) are also included.DR10 also roughly doubles the number of BOSS spectra over those included in the ninth data r...

  18. THE TENTH DATA RELEASE OF THE SLOAN DIGITAL SKY SURVEY: FIRST SPECTROSCOPIC DATA FROM THE SDSS-III APACHE POINT OBSERVATORY GALACTIC EVOLUTION EXPERIMENT

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Christopher P.; Anderton, Timothy [Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112 (United States); Alexandroff, Rachael [Center for Astrophysical Sciences, Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); Allende Prieto, Carlos [Instituto de Astrofísica de Canarias (IAC), C/Vía Láctea, s/n, E-38200, La Laguna, Tenerife (Spain); Anders, Friedrich [Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, D-14482 Potsdam (Germany); Anderson, Scott F.; Bhardwaj, Vaishali [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Andrews, Brett H. [Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States); Aubourg, Éric; Bautista, Julian E. [APC, University of Paris Diderot, CNRS/IN2P3, CEA/IRFU, Observatoire de Paris, Sorbonne Paris Cité, F-75205 Paris (France); Bailey, Stephen; Beutler, Florian [Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, CA 94720 (United States); Bastien, Fabienne A.; Berlind, Andreas A.; Bird, Jonathan C. [Department of Physics and Astronomy, Vanderbilt University, VU Station 1807, Nashville, TN 37235 (United States); Beers, Timothy C. [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States); Beifiori, Alessandra [Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstraße, D-85748 Garching (Germany); Bender, Chad F. [Department of Astronomy and Astrophysics, 525 Davey Laboratory, The Pennsylvania State University, University Park, PA 16802 (United States); Bizyaev, Dmitry [Apache Point Observatory, P.O. Box 59, Sunspot, NM 88349 (United States); Blake, Cullen H. [Department of Physics and Astronomy, University of Pennsylvania, 219 S. 33rd St., Philadelphia, PA 19104 (United States); and others

    2014-04-01

    The Sloan Digital Sky Survey (SDSS) has been in operation since 2000 April. This paper presents the Tenth Public Data Release (DR10) from its current incarnation, SDSS-III. This data release includes the first spectroscopic data from the Apache Point Observatory Galaxy Evolution Experiment (APOGEE), along with spectroscopic data from the Baryon Oscillation Spectroscopic Survey (BOSS) taken through 2012 July. The APOGEE instrument is a near-infrared R ∼ 22,500 300 fiber spectrograph covering 1.514-1.696 μm. The APOGEE survey is studying the chemical abundances and radial velocities of roughly 100,000 red giant star candidates in the bulge, bar, disk, and halo of the Milky Way. DR10 includes 178,397 spectra of 57,454 stars, each typically observed three or more times, from APOGEE. Derived quantities from these spectra (radial velocities, effective temperatures, surface gravities, and metallicities) are also included. DR10 also roughly doubles the number of BOSS spectra over those included in the Ninth Data Release. DR10 includes a total of 1,507,954 BOSS spectra comprising 927,844 galaxy spectra, 182,009 quasar spectra, and 159,327 stellar spectra selected over 6373.2 deg{sup 2}.

  19. The SDSS-III DR12 MARVELS radial velocity data release: the first data release from the multiple object Doppler exoplanet survey

    Science.gov (United States)

    Ge, Jian; Thomas, Neil B.; Li, Rui; Senan Seieroe Grieves, Nolan; Ma, Bo; de Lee, Nathan M.; Lee, Brian C.; Liu, Jian; Bolton, Adam S.; Thakar, Aniruddha R.; Weaver, Benjamin; SDSS-Iii Marvels Team

    2015-01-01

    We present the first data release from the SDSS-III Multi-object APO Radial Velocity Exoplanet Large-area Survey (MARVELS) through the SDSS-III DR12. The data include 181,198 radial velocity (RV) measurements for a total of 5520 different FGK stars with V~7.6-12, of which more than 80% are dwarfs and subdwarfs while remainders are GK giants, among a total of 92 fields nearly randomly spread out over the entire northern sky taken with a 60-object MARVELS dispersed fixed-delay interferometer instrument over four years (2008-2012). There were 55 fields with a total of 3300 FGK stars which had 14 or more observations over about 2-year survey window. The median number of observations for these plates is 27 RV measurements. This represents the largest homogeneous sample of precision RV measurements of relatively bright stars. In this first released data, a total of 18 giant planet candidates, 16 brown dwarfs, and over 500 binaries with additional 96 targets having RV variability indicative of a giant planet companion are reported. The released data were produced by the MARVELS finalized 1D pipeline. We will also report preliminary statistical results from the MARVELS 2D data pipeline which has produced a median RV precision of ~30 m/s for stable stars.

  20. Microlensing Signature of Binary Black Holes

    Science.gov (United States)

    Schnittman, Jeremy; Sahu, Kailash; Littenberg, Tyson

    2012-01-01

    We calculate the light curves of galactic bulge stars magnified via microlensing by stellar-mass binary black holes along the line-of-sight. We show the sensitivity to measuring various lens parameters for a range of survey cadences and photometric precision. Using public data from the OGLE collaboration, we identify two candidates for massive binary systems, and discuss implications for theories of star formation and binary evolution.

  1. Black hole mass estimate for a sample of radio-loud narrow-line Seyfert 1 galaxies

    CERN Document Server

    Calderone, G; Colpi, M; Dotti, M

    2012-01-01

    We discuss the relationship between a standard Shakura & Sunyaev (1973) accretion disk model and the Big Blue Bump (BBB) observed in Type 1 AGN, and propose a new method to estimate black hole masses. We apply this method to a sample of 23 radio-loud narrow-line Seyfert 1 (RL-NLS1) galaxies, using data from WISE (Wide-field Infrared Survey Explorer), SDSS (Sloan Digital Sky Survey) and GALEX. Our black hole mass estimates are at least a factor $\\sim$6 above previous results based on single epoch virial methods, while the Eddington ratios are correspondingly lower. Hence, the black hole masses of RL-NLS1 galaxies are typically above $10^8 M_{\\sun}$, in agreement with the typical black hole mass of blazars.

  2. Effect of observational holes and borders on lacunarity and fractality measurements in a galaxy catalogue

    CERN Document Server

    García-Farieta, Jorge E

    2016-01-01

    Cosmological observations reveal that the Universe contains a hierarchy of galaxy clustering with a transition to homogeneity on large scales according to the $\\Lambda$CDM model. Some observational estimates suggest that the Universe behaves as a multifractal object, where galactic clustering is based on generalisation of the dimension in metric spaces. From this point of view, we study the spatial distribution of points by simulating galaxies on large scales in the Universe with samples from the Sloan Digital Sky Survey (SDSS), including observational holes in the masks. We build homogeneous samples following the radial selection function using the "shuffle" method for a main sample of $3,273,548$ points limited to the redshift range $0.0020$ and percentages of holes near $40\\%$, $r_H$ is displaced on scales on the order of $120~Mpc/h$. Hole percentages between $10\\%$ and $30\\%$ show an $r_H$ of $70-90~Mpc/h$, and for percentages below $10\\%$, $r_H$ decreases to become equal to the $r_H$ value of the SDSS-BO...

  3. The Eighth Data Release of the Sloan Digital Sky Survey: First Data from SDSS-III

    Energy Technology Data Exchange (ETDEWEB)

    Aihara, Hiroaki; /Tokyo U.; Prieto, Carlos Allende; /Laguna U., Tenerife; An, Deokkeun; /Ewha Women' s U., Seoul; Anderson, Scott F.; /Washington U., Seattle, Astron. Dept.; Aubourg, Eric; /APC, Paris /DAPNIA, Saclay; Balbinot, Eduardo; /Rio Grande do Sul U. /Rio de Janeiro Observ.; Beers, Timothy C.; /Michigan State U.; Berlind, Andreas A.; /Vanderbilt U.; Bickerton, Steven J.; /Princeton U.; Bizyaev, Dmitry; /Apache Point Observ.; Blanton, Michael R.; /New York U., CCPP /Penn State U.

    2011-01-01

    The Sloan Digital Sky Survey (SDSS) started a new phase in August 2008, with new instrumentation and new surveys focused on Galactic structure and chemical evolution, measurements of the baryon oscillation feature in the clustering of galaxies and the quasar Ly{alpha} forest, and a radial velocity search for planets around {approx}8000 stars. This paper describes the first data release of SDSS-III (and the eighth counting from the beginning of the SDSS). The release includes 5-band imaging of roughly 5200 deg{sup 2} in the Southern Galactic Cap, bringing the total footprint of the SDSS imaging to 14,555 deg{sup 2}, or over a third of the Celestial Sphere. All the imaging data have been reprocessed with an improved sky-subtraction algorithm and a final, self-consistent recalibration and flat-field determination. This release also includes all data from the second phase of the Sloan Extension for Galactic Understanding and Evolution (SEGUE-2), consisting of spectroscopy of approximately 118,000 stars at both high and low Galactic latitudes. All the more than half a million stellar spectra obtained with the SDSS spectrograph have been reprocessed through an improved stellar parameters pipeline, which has better determination of metallicity for high metallicity stars.

  4. Galaxy-Galaxy Weak Lensing Measurements from SDSS: I. Image Processing and Lensing signals

    CERN Document Server

    Luo, Wentao; Zhang, Jun; Tweed, Dylan; Fu, Liping; Mo, H J; Bosch, Frank C van den; Shu, Chenggang; Li, Ran; Li, Nan; Liu, Xiangkun; Pan, Chuzhong; Wang, Yiran; Radovich, Mario

    2016-01-01

    As the first paper in a series on the study of the galaxy-galaxy lensing from Sloan Digital Sky Survey Data Release 7 (SDSS DR7), we present our image processing pipeline that corrects the systematics primarily introduced by the Point Spread Function (PSF). Using this pipeline, we processed SDSS DR7 imaging data in $r$ band and generated a background galaxy catalog containing the shape information of each galaxy. Based on our own shape measurements of the galaxy images from SDSS DR7, we extract the galaxy-galaxy (GG) lensing signals around foreground spectroscopic galaxies binned in different luminosity and stellar mass. The overall signals are in good agreement with those obtained by \\citet{Mandelbaum2005, Mandelbaum2006} from the SDSS DR4. The results in this paper with higher signal to noise ratio is due to the larger survey area than SDSS DR4, confirm that more luminous/massive galaxies bear stronger GG lensing signal. We also divide the foreground galaxies into red/blue and star forming/quenched subsampl...

  5. Photometric Covariance in Multi-Band Surveys: Understanding the Photometric Error in the SDSS

    CERN Document Server

    Scranton, R; Szalay, A S; Lupton, R H; Johnston, D; Budavari, T; Brinkmann, J; Fukugita, M; Scranton, Ryan; Connolly, Andrew J.; Szalay, Alexander S.; Lupton, Robert H.; Johnston, David; Budavari, Tamas; Brinkman, John; Fukugita, Masatake

    2005-01-01

    In this paper we describe a detailed analysis of the photometric uncertainties present within the Sloan Digital Sky Survey (SDSS) imaging survey based on repeat observations of approximately 200 square degrees of the sky. We show that, for the standard SDSS aperture systems (petrocounts, counts_model, psfcounts and cmodel_counts), the errors generated by the SDSS photometric pipeline under-estimate the observed scatter in the individual bands. The degree of disagreement is a strong function of aperture and magnitude (ranging from 20% to more than a factor of 2). We also find that the photometry in the five optical bands can be highly correlated for both point sources and galaxies, although the correlation for point sources is almost entirely due to variable objects. Without correcting for this covariance the SDSS color errors could be in over-estimated by a factor of two to three. Combining these opposing effects, the SDSS errors on the colors differ from the observed color variation by approximately 10-20% f...

  6. The Final SDSS High-Redshift Quasar Sample of 52 Quasars at z>5.7

    CERN Document Server

    Jiang, Linhua; Fan, Xiaohui; Strauss, Michael A; Banados, Eduardo; Becker, Robert H; Bian, Fuyan; Farnsworth, Kara; Shen, Yue; Wang, Feige; Wang, Ran; Wang, Shu; White, Richard L; Wu, Jin; Wu, Xue-Bing; Yang, Jinyi; Yang, Qian

    2016-01-01

    We present the discovery of nine quasars at $z\\sim6$ identified in the Sloan Digital Sky Survey (SDSS) imaging data. This completes our survey of $z\\sim6$ quasars in the SDSS footprint. Our final sample consists of 52 quasars at $5.7SDSS single-epoch imaging survey (the main survey), 10 quasars with $20\\le z_{\\rm AB}\\le20.5$ selected from 4223 deg$^2$ of the SDSS overlap regions (regions with two or more imaging scans), and 13 quasars down to $z_{\\rm AB}\\approx22$ mag from the 277 deg$^2$ in Stripe 82. They span a wide luminosity range of $-29.0\\le M_{1450}\\le-24.5$. This well-defined sample is used to derive the quasar luminosity function (QLF) at $z\\sim6$. After combining our SDSS sample with two faint ($M_{1450}\\ge-23$ mag) quasars from the literature, we obtain the parameters for a double power-law fit to the QLF. The bright-end slope $\\beta$ of the QLF is well constrained to be $\\beta=-2.8\\pm0.2$. Due to the...

  7. Testing black holes via X-ray reflection spectroscopy

    Science.gov (United States)

    Bambi, Cosimo; Nampalliwar, Sourabh; Cardenas-Avendano, Alejandro

    2016-07-01

    Astrophysical black hole candidates are thought to be the Kerr black holes of general relativity. However, a direct observational evidence is still lacking. The study of the properties of the radiation emitted by gas in the inner part of the accretion disk can provide useful information on the spacetime geometry around these compact objects and test the Kerr black hole hypothesis. The iron line method is the most promising techniques to test black hole candidates. In this talk, we present a new reflection model for testing the Kerr black hole hypothesis. We use the formalism of the transfer function and we split the calculations into two blocks. One is the calculation of the transfer function, which takes into account all the relativistic effects and only depends on the background metric. The second block is the calculation of the intrinsic spectrum in the rest frame of the gas. We have developed a code to compute transfer functions in arbitrary stationary and axisymmetric spacetimes. The transfer functions are tabulated in FITS files and combined with XILLVER, which is the best reflection code available today. The result is best model to test black hole candidates via X-ray reflection spectroscopy.

  8. Astrophysical black holes

    CERN Document Server

    Gorini, Vittorio; Moschella, Ugo; Treves, Aldo; Colpi, Monica

    2016-01-01

    Based on graduate school lectures in contemporary relativity and gravitational physics, this book gives a complete and unified picture of the present status of theoretical and observational properties of astrophysical black holes. The chapters are written by internationally recognized specialists. They cover general theoretical aspects of black hole astrophysics, the theory of accretion and ejection of gas and jets, stellar-sized black holes observed in the Milky Way, the formation and evolution of supermassive black holes in galactic centers and quasars as well as their influence on the dynamics in galactic nuclei. The final chapter addresses analytical relativity of black holes supporting theoretical understanding of the coalescence of black holes as well as being of great relevance in identifying gravitational wave signals. With its introductory chapters the book is aimed at advanced graduate and post-graduate students, but it will also be useful for specialists.

  9. Extremal Hairy Black Holes

    CERN Document Server

    Gonzalez, P A; Saavedra, Joel; Vasquez, Yerko

    2014-01-01

    We consider a gravitating system consisting of a scalar field minimally coupled to gravity with a self-interacting potential and an U(1) electromagnetic field. Solving the coupled Einstein-Maxwell-scalar system we find exact hairy charged black hole solutions with the scalar field regular everywhere. We go to the zero temperature limit and we study the effect of the scalar field on the near horizon geometry of an extremal black hole. We find that except a critical value of the charge of the black hole there is also a critical value of the charge of the scalar field beyond of which the extremal black hole is destabilized. We study the thermodynamics of these solutions and we find that if the space is flat then at low temperature the Reissner-Nordstr\\"om black hole is thermodynamically preferred, while if the space is AdS the hairy charged black hole is thermodynamically preferred at low temperature.

  10. Charged Lifshitz Black Holes

    OpenAIRE

    Dehghani, M. H.; Pourhasan, R.; Mann, R. B.

    2011-01-01

    We investigate modifications of the Lifshitz black hole solutions due to the presence of Maxwell charge in higher dimensions for arbitrary $z$ and any topology. We find that the behaviour of large black holes is insensitive to the topology of the solutions, whereas for small black holes significant differences emerge. We generalize a relation previously obtained for neutral Lifshitz black branes, and study more generally the thermodynamic relationship between energy, entropy, and chemical pot...

  11. Perturbations around black holes

    CERN Document Server

    Wang, B

    2005-01-01

    Perturbations around black holes have been an intriguing topic in the last few decades. They are particularly important today, since they relate to the gravitational wave observations which may provide the unique fingerprint of black holes' existence. Besides the astrophysical interest, theoretically perturbations around black holes can be used as testing grounds to examine the proposed AdS/CFT and dS/CFT correspondence.

  12. Physics of black holes

    OpenAIRE

    Thorne, Kip S.

    1982-01-01

    The activity at the galactic center might be fuelled by energy release near a large black hole. In this talk I describe some relativistic effects which may be relevant to this process. I use Newtonian language so far as possible and illustrate the effects with simple  analogies. Specifically, I describe the gravitational field near a black hole, Lens‐Thirring and geodetic precession, electro‐magnetic energy extraction of the spin energy of a black hole and the structure of accretion tori arou...

  13. SDSS-IV MaNGA: Survey Design and Progress

    Science.gov (United States)

    Yan, Renbin; MaNGA Team

    2016-01-01

    The ongoing SDSS-IV/MaNGA Survey will obtain integral field spectroscopy at a resolution of R~2000 with a wavelength coverage from 3,600A to 10,300A for 10,000 nearby galaxies. Within each 3 degree diameter pointing of the 2.5m Sloan Telescope, we deploy 17 hexagonal fiber bundles with sizes ranging from 12 to 32 arcsec in diameter. The bundles are build with 2 arcsec fibers and have a 56% fill factor. During observations, we obtained sets of exposures at 3 different dither positions to achieve near-critical sampling of the effective point spread function, which has a FWHM about 2.5 arcsec, corresponding to 1-2 kpc for the majority of the galaxies targeted. The flux calibration is done using 12 additional mini-fiber-bundles targeting standard stars simultaneously with science targets, achieving a calibration accuracy better than 5% over 90% of the wavelength range. The target galaxies are selected to ensure uniform spatial coverage in units of effective radii for the majority of the galaxies while maximizing spatial resolution. About 2/3 of the sample is covered out to 1.5Re (primary sample) and 1/3 of the sample covered to 2.5Re (secondary sample). The sample is designed to have approximately equal representation from high and low mass galaxies while maintaining volume-limited selection at fixed absolute magnitudes. We obtain an average S/N of 4 per Angstrom in r-band continuum at a surface brightness of 23 AB arcsec-2. With spectral stacking in an elliptical annulus covering 1-1.5Re, our primary sample galaxies have a median S/N of ~60 per Angstrom in r-band.

  14. Identification of Outflows and Candidate Dual Active Galactic Nuclei in SDSS Quasars at z=0.8-1.6

    CERN Document Server

    Barrows, R Scott; Kennefick, Julia; Comerford, Julia M; Kennefick, Daniel; Berrier, Joel C

    2013-01-01

    We present a sample of 131 quasars from the Sloan Digital Sky Survey at redshifts 0.8

  15. Strong Candidate for AGN Feedback: VLT/X-shooter Observations of BALQSO SDSS J0831+0354

    CERN Document Server

    Chamberlain, Carter; Benn, Chris

    2015-01-01

    We measure the location and energetics of a SIV BALQSO outflow. This ouflow has a velocity of 10,800 km s$^{-1}$ and a kinetic luminosity of $10^{45.7}$ erg s$^{-1}$, which is 5.2% of the Eddington luminosity of the quasar. From collisional excitation models of the observed SIV$/$SIV* absorption troughs, we measure a hydrogen number density of $n_\\mathrm{\\scriptscriptstyle H}=10^{4.3}$ cm$^{-3}$, which allows us to determine that the outflow is located 110 pc from the quasar. Since SIV is formed in the same ionization phase as CIV, our results can be generalized to the ubiquitous CIV BALs. Our accumulated distance measurements suggest that observed BAL outflows are located much farther away from the central source than is generally assumed (0.01-0.1 pc).

  16. Asymptotic black holes

    Science.gov (United States)

    Ho, Pei-Ming

    2017-04-01

    Following earlier works on the KMY model of black-hole formation and evaporation, we construct the metric for a matter sphere in gravitational collapse, with the back-reaction of pre-Hawking radiation taken into consideration. The mass distribution and collapsing velocity of the matter sphere are allowed to have an arbitrary radial dependence. We find that a generic gravitational collapse asymptote to a universal configuration which resembles a black hole but without horizon. This approach clarifies several misunderstandings about black-hole formation and evaporation, and provides a new model for black-hole-like objects in the universe.

  17. Asymptotic Black Holes

    CERN Document Server

    Ho, Pei-Ming

    2016-01-01

    Following earlier works on the KMY model of black-hole formation and evaporation, we construct the metric for a matter sphere in gravitational collapse, with the back-reaction of pre-Hawking radiation taken into consideration. The mass distribution and collapsing velocity of the matter sphere are allowed to have an arbitrary radial dependence. We find that a generic gravitational collapse asymptote to a universal configuration which resembles a black hole but without horizon. This approach clarifies several misunderstandings about black-hole formation and evaporation, and provides a new model for black-hole-like objects in the universe.

  18. Candidate Disk Wide Binaries in the Sloan Digital Sky Survey

    CERN Document Server

    Sesar, Branimir; Juric, Mario

    2008-01-01

    Using SDSS Data Release 6, we construct two independent samples of candidate stellar wide binaries selected as i) pairs of unresolved sources with angular separation in the range 3'' - 16'', ii) common proper motion pairs with 5'' - 30'' angular separation, and make them publicly available. These samples are dominated by disk stars, and we use them to constrain the shape of the main-sequence photometric parallax relation M_r(r-i) and to study the properties of wide binary systems. We estimate M_r(r-i) by searching for a relation that minimizes the difference between distance moduli of primary and secondary components of wide binary candidates. We model M_r(r-i) by a fourth degree polynomial and determine the coefficients using Markov Chain Monte Carlo fitting, independently for each sample. Aided by the derived photometric parallax relation, we construct a series of high-quality catalogs of candidate main-sequence binary stars. Using these catalogs, we study the distribution of semi-major axes of wide binarie...

  19. Measuring the Innermost Stable Circular Orbits of Supermassive Black Holes

    Science.gov (United States)

    Chartas, G.; Krawczynski, H.; Zalesky, L.; Kochanek, C. S.; Dai, X.; Morgan, C. W.; Mosquera, A.

    2017-03-01

    We present a promising new technique, the g-distribution method, for measuring the inclination angle (i), the innermost stable circular orbit (ISCO), and the spin of a supermassive black hole. The g-distribution method uses measurements of the energy shifts in the relativistic iron line emitted by the accretion disk of a supermassive black hole due to microlensing by stars in a foreground galaxy relative to the g-distribution shifts predicted from microlensing caustic calculations. We apply the method to the gravitationally lensed quasars RX J1131–1231 (z s = 0.658, z l = 0.295), QJ 0158–4325 (z s = 1.294, z l = 0.317), and SDSS 1004+4112 (z s = 1.734, z l = 0.68). For RX J1131‑1231, our initial results indicate that r ISCO ≲ 8.5 gravitational radii (r g) and i ≳ 55° (99% confidence level). We detect two shifted Fe lines in several observations, as predicted in our numerical simulations of caustic crossings. The current ΔE distribution of RX J1131–1231 is sparsely sampled, but further X-ray monitoring of RX J1131–1231 and other lensed quasars will provide improved constraints on the inclination angles, ISCO radii, and spins of the black holes of distant quasars.

  20. Light-hole exciton in a nanowire quantum dot

    Science.gov (United States)

    Jeannin, Mathieu; Artioli, Alberto; Rueda-Fonseca, Pamela; Bellet-Amalric, Edith; Kheng, Kuntheak; André, Régis; Tatarenko, Serge; Cibert, Joël; Ferrand, David; Nogues, Gilles

    2017-01-01

    Quantum dots inserted inside semiconductor nanowires are extremely promising candidates as building blocks for solid-state-based quantum computation and communication. They provide very high crystalline and optical properties and offer a convenient geometry for electrical contacting. Having a complete determination and full control of their emission properties is one of the key goals of nanoscience researchers. Here we use strain as a tool to create in a single magnetic nanowire quantum dot a light-hole exciton, an optically active quasiparticle formed from a single electron bound to a single light hole. In this frame, we provide a general description of the mixing within the hole quadruplet induced by strain or confinement. A multi-instrumental combination of cathodoluminescence, polarization-resolved Fourier imaging, and magneto-optical spectroscopy, allows us to fully characterize the hole ground state, including its valence band mixing with heavy-hole states.

  1. Quantum Gravity Effects On Charged Micro Black Holes Thermodynamics

    CERN Document Server

    Abbasvandi, N; Radiman, Shahidan; Abdullah, W A T Wan

    2016-01-01

    The charged black hole thermodynamics is corrected in terms of the quantum gravity effects. Most of the quantum gravity theories support the idea that near the Planck scale, the standard Heisenberg uncertainty principle should be reformulated by the so-called Generalized Uncertainty Principle (GUP) which provides a perturbation framework to perform required modifications of the black hole quantities. In this paper, we consider the effects of the minimal length and maximal momentum as GUP type I and the minimal length, minimal momentum, and maximal momentum as GUP type II on thermodynamics of the charged TeV-scale black holes. We also generalized our study to the universe with the extra dimensions based on the ADD model. In this framework, the effect of the electrical charge on thermodynamics of the black hole and existence of the charged black hole remnants as a potential candidate for the dark matter particles are discussed.

  2. Robust automatic photometry of local galaxies from SDSS Dissecting the color magnitude relation with color profiles

    CERN Document Server

    Consolandi, Guido; Fumagalli, Michele; Dotti, Massimo; Fossati, Matteo

    2016-01-01

    We present an automatic procedure to perform reliable photometry of galaxies on SDSS images. We selected a sample of 5853 galaxies in the Coma and Virgo superclusters. For each galaxy, we derive Petrosian g and i magnitudes, surface brightness profiles and color profiles. Unlike the SDSS pipeline, our procedure is not affected by the well known shredding problem and efficiently extracts Petrosian magnitudes for all galaxies. Hence we derived magnitudes even from the population of galaxies missed by the SDSS that represents 25% of all Local supercluster galaxies and ~95% of galaxies with g =0.35R{Pet})) zone, and (ii), we compute template color profiles, discussing the dependences of the templates on the galaxy masses and on their morphological type. The two analyses consistently lead to a picture where elliptical galaxies show no color gradients, irrespective of their masses. Spirals, instead, display a steeper gradient in their color profiles with increasing mass, consistently with the growing relevance of a...

  3. The Milky Way Tomography with SDSS. V. Mapping the Dark Matter Halo

    CERN Document Server

    Loebman, Sarah R; Quinn, Thomas R; Bovy, Jo; Christensen, Charlotte R; Juric, Mario; Roskar, Rok; Brooks, Alyson M; Governato, Fabio

    2014-01-01

    We present robust constraints from the Sloan Digital Sky Survey (SDSS) on the shape and distribution of the dark matter halo within the Milky Way (MW). Using the number density distribution and kinematics of SDSS halo stars, we probe the dark matter distribution to heliocentric distances exceeding 10 kpc and galactocentric distances exceeding 20 kpc. Our analysis utilizes Jeans equations to generate two-dimensional acceleration maps throughout the volume; this approach is thoroughly tested on a cosmologically derived N-body+SPH simulation of a MW-like galaxy. We show that the known accelerations (gradients of the gravitational potential) can be successfully recovered in such a realistic system. Leveraging the baryonic gravitational potential derived by Bovy & Rix (2013), we show that the gravitational potential implied by the SDSS observations cannot be explained, assuming Newtonian gravity, by visible matter alone: the gravitational force experienced by stars at galactocentric distances of 20 kpc is as m...

  4. Post common envelope binaries from SDSS. XII: The orbital period distribution

    CERN Document Server

    Gómez-Morán, A Nebot; Schreiber, M R; Rebassa-Mansergas, A; Schwope, A D; Southworth, J; Aungwerojwit, A; Bothe, M; Davis, P J; Kolb, U; Müller, M; Papadaki, C; Pyrzas, S; Rabitz, A; Rodríguez-Gil, P; Schmidtobreick, L; Schwarz, R; Tappert, C; Toloza, O; Vogel, J; Zorotovic, M

    2011-01-01

    The complexity of the common envelope phase and of magnetic stellar wind braking currently limits our understanding of close binary evolution. Because of their intrinsically simple structure, observational population studies of white dwarf plus main sequence (WDMS) binaries hold the potential to test theoretical models and constrain their parameters. The Sloan Digital Sky Survey (SDSS) has provided a large and homogeneously selected sample of WDMS binaries, which we are characterising in terms of orbital and stellar parameters. We have obtained radial velocity information for 385 WDMS binaries from follow-up spectroscopy, and for an additional 861 systems from the SDSS sub-spectra. Radial velocity variations identify 191 of these WDMS binaries as post common envelope binaries (PCEBs). Orbital periods of 58 PCEBs were subsequently measured, predominantly from time-resolved spectroscopy, bringing the total number of SDSS PCEBs with orbital parameters to 79. Observational biases inherent to this PCEB sample were...

  5. SDSS-RM: A Multi-Object AGN Reverberation Mapping Project

    Science.gov (United States)

    Shen, Y.; SDSS-RM Collaboration

    2016-10-01

    The Sloan Digital Sky Survey Reverberation Mapping (SDSS-RM) project is a dedicated multi-object RM program that simultaneously monitors ˜ 850 quasars at 0.1measure RM lags for a homogeneous AGN sample. The combination of multi-year, high-cadence photometric light curves since 2010 (hundreds of epochs) and dedicated SDSS spectroscopy (32 epochs completed in 2014 with more epochs in 2015 and beyond) will enable important studies on the structure of the broad-line region (BLR), RM lags and BH mass measurements, as well as ancillary science such as quasar variability, host galaxy properties, and quasar absorption lines. I will summarize the current status of the program and present some early science results based on the year-1 SDSS-RM data.

  6. Hole transport in pure and doped hematite

    Science.gov (United States)

    Liao, Peilin; Carter, Emily A.

    2012-07-01

    Hematite (α-Fe2O3) is a promising candidate for use in photovoltaic (PV) and photoelectrochemical devices. Its poor conductivity is one major drawback. Doping hematite either p-type or n-type greatly enhances its measured conductivity and is required for potential p-n junctions in PVs. Here, we study hole transport in pure and doped hematite using an electrostatically embedded cluster model with ab initio quantum mechanics (unrestricted Hartree-Fock theory). Consistent with previous work, the model suggests that hole hopping is via oxygen anions for pure hematite. The activation energy for hole mobility is predicted to be at least 0.1 eV higher than the activation energy for electron mobility, consistent with the trend observed in experiments. We examine four dopants—magnesium(II), nickel(II), copper(II), and manganese(II/III) in direct cation substitution sites—to gain insight into the mechanism by which conductivity is improved. The activation energies are used to assess qualitative effects of different dopants. The hole carriers are predicted to be attracted to O anions near the dopants. The magnitude of the trapping effect is similar among the four dopants in their +2 oxidation states. The multivalent character of Mn doping facilitates local hole transport around Mn centers via a low-barrier O-Mn-O pathway, which suggests that higher hole mobility can be achieved with increasing Mn doping concentration, especially when a network of these low-barrier pathways is produced. Our results suggest that the experimentally observed conductivity increase in Mg-, Ni-, and Cu-doped p-type hematite is mostly due to an increase in hole carriers rather than improved mobility, and that Mg-, Ni-, and Cu-doping perform similarly, while the conductivity of Mn-doped hematite might be significantly improved in the high doping concentration limit.

  7. Comparing PyMorph and SDSS photometry. I. Background sky and model fitting effects

    Science.gov (United States)

    Fischer, J.-L.; Bernardi, M.; Meert, A.

    2017-01-01

    A number of recent estimates of the total luminosities of galaxies in the SDSS are significantly larger than those reported by the SDSS pipeline. This is because of a combination of three effects: one is simply a matter of defining the scale out to which one integrates the fit when defining the total luminosity, and amounts on average to ≤0.1 mags even for the most luminous galaxies. The other two are less trivial and tend to be larger; they are due to differences in how the background sky is estimated and what model is fit to the surface brightness profile. We show that PyMorph sky estimates are fainter than those of the SDSS DR7 or DR9 pipelines, but are in excellent agreement with the estimates of Blanton et al. (2011). Using the SDSS sky biases luminosities by more than a few tenths of a magnitude for objects with half-light radii ≥7 arcseconds. In the SDSS main galaxy sample these are typically luminous galaxies, so they are not necessarily nearby. This bias becomes worse when allowing the model more freedom to fit the surface brightness profile. When PyMorph sky values are used, then two component Sersic-Exponential fits to E+S0s return more light than single component deVaucouleurs fits (up to ˜0.2 mag), but less light than single Sersic fits (0.1 mag). Finally, we show that PyMorph fits of Meert et al. (2015) to DR7 data remain valid for DR9 images. Our findings show that, especially at large luminosities, these PyMorph estimates should be preferred to the SDSS pipeline values.

  8. Comprehensive assessment of toxic metals in urban and suburban street deposited sediments (SDSs) in the biggest metropolitan area of China.

    Science.gov (United States)

    Shi, G; Chen, Z; Bi, C; Li, Y; Teng, J; Wang, L; Xu, S

    2010-03-01

    A set of toxic metals, i.e. As, Hg, Pb, Cd, Cu, Zn, Ni and Cr, in urban and suburban SDSs were investigated comparatively in the biggest metropolitan area of China, Shanghai. Results showed that all of the metals except As were accumulated greatly, much higher than background values. Geo-accumulation index indicated that metal contamination in urban SDSs was generally heavier than that in suburban SDSs. Potential ecological risk index demonstrated that overall risks caused by metals were considerable. Cd contributed 52% to the overall risk. Multivariate statistical analysis revealed that in urban SDSs, Zn, Ni, Cd, Pb, Cu and Cr were related to traffic and industry; coal combustion led to elevated levels of Hg; soil parent materials controlled As contents. In suburban SDSs, Pb, Cu, As and Cd largely originated from traffic pollution; Zn, Ni and Cr were associated with industrial contaminants; Hg was mainly from domestic solid waste.

  9. Evidence of Primordial Clustering around the QSO SDSS J1030+0524 at z=6.28

    Science.gov (United States)

    Stiavelli, M.; Djorgovski, S. G.; Pavlovsky, C.; Scarlata, C.; Stern, D.; Mahabal, A.; Thompson, D.; Dickinson, M.; Panagia, N.; Meylan, G.

    2005-03-01

    We present tentative evidence of primordial clustering, manifested as an excess of color-selected objects in the field of the QSO SDSS J1030+0524 at redshift z=6.28. We have selected objects red in i775-z850 on the basis of Hubble Space Telescope Advanced Camera for Surveys imaging of a field centered on the QSO. Compared to data at comparable depth obtained by the Great Observatories Origins Deep Survey, we find an excess of objects with i775-z850>=1.5 in the QSO field. The significance of the detection is estimated to be ~97% on the basis of the counts alone and increases to 99.4% if one takes into account the color distribution. If confirmed, this would represent the highest redshift example of galaxy clustering and would have implications on models for the growth of structure. Bias-driven clustering of first luminous objects forming in the highest peaks of the primordial density field is expected in most models of early structure formation. The redshift of one of the candidates has been found to be z=5.970 by our spectroscopy with the Keck I Low Resolution Imaging Spectrometer, confirming the validity of our color selection. Based, in part, on data obtained at the W. M. Keck Observatory, which is operated as a scientific partnership between the California Institute of Technology, the University of California, and NASA, and was made possible by the generous financial support of the W. M. Keck Foundation.

  10. Attenuation Laws for Galaxies with Different Star Formation Histories, Based on the SDSS Images

    Directory of Open Access Journals (Sweden)

    Vince, O.

    2009-06-01

    Full Text Available Attenuation curves (laws in the optical part of thespectrum (from about 3500 AA~to 9000 AA are determined for galaxieswith different star formation histories (SFHs using images in five photometrical bands from the Sloan Digital Sky Survey (SDSS. Owing to large surveys like SDSS, it is possible to defineseveral subgroups of galaxies with similar SFHs using two spectralindices that trace SFH. Attenuation curves are analyzed in termsof SFH and compared to the curves that are often used for dustcorrection of the observed data.

  11. VizieR Online Data Catalog: Predicted LIR for SDSS galaxies (Ellison+, 2016)

    Science.gov (United States)

    Ellison, S. L.; Teimoorinia, H.; Rosario, D. J.; Trevor Mendel, J.

    2016-07-01

    In this work we will make use of data from three separate spacecraft that collected data in the FIR: the Infrared Astronomical Satellite (IRAS; Neugebauer et al., 1984ApJ...278L...1N), AKARI (Murakami et al., 2007PASJ...59S.369M) and Herschel (Pilbratt et al., 2010A&A...518L...1P). Based on a sample of 1136 galaxies identified in a cross-match between the SDSS and Herschel Stripe 82 Survey, we have trained an ANN to predict IR luminosities based on 23 input parameters measured from SDSS imaging and spectroscopy. (1 data file).

  12. Empirical extinction coefficients for the GALEX, SDSS, 2MASS and WISE passbands

    OpenAIRE

    2013-01-01

    Using the "standard pair" technique of paring stars of almost nil and high extinction but otherwise of almost identical stellar parameters from the SDSS, and combing the SDSS, GALEX, 2MASS and WISE photometry ranging from the far UV to the mid-IR, we have measured dust reddening in the FUV-NUV, NUV-u, u-g, g-r, r-i, i-z, z-J, J-H, H-Ks, Ks-W1 and W1-W2 colors for thousands of Galactic stars. The measurements, together with the E(B-V) values given by Schlegel et al. (1998), allow us to derive ...

  13. Applying the Support Vector Machine Method to Matching IRAS and SDSS Catalogues

    Directory of Open Access Journals (Sweden)

    Chen Cao

    2007-10-01

    Full Text Available This paper presents results of applying a machine learning technique, the Support Vector Machine (SVM, to the astronomical problem of matching the Infra-Red Astronomical Satellite (IRAS and Sloan Digital Sky Survey (SDSS object catalogues. In this study, the IRAS catalogue has much larger positional uncertainties than those of the SDSS. A model was constructed by applying the supervised learning algorithm (SVM to a set of training data. Validation of the model shows a good identification performance (∼ 90% correct, better than that derived from classical cross-matching algorithms, such as the likelihood-ratio method used in previous studies.

  14. A Trio of Metal-Rich Dust and Gas Disks Found Orbiting Candidate White Dwarfs with K-Band Excess

    CERN Document Server

    Farihi, J; Steele, P R; Girven, J; Burleigh, M R; Breedt, E; Koester, D

    2011-01-01

    This paper reports follow-up photometric and spectroscopic observations, including warm Spitzer IRAC photometry of seven white dwarfs from the SDSS with apparent excess flux in UKIDSS K-band observations. Six of the science targets were selected from 16,785 DA star candidates identified either spectroscopically or photometrically within SDSS DR7, spatially cross-correlated with HK detections in UKIDSS DR8. Thus the selection criteria are completely independent of stellar mass, effective temperature above 8000 K, and the presence (or absence) of atmospheric metals. The infrared fluxes of one target are compatible with a spatially-unresolved late M or early L-type companion, while three stars exhibit excess emissions consistent with warm circumstellar dust. These latter targets have spectral energy distributions similar to known dusty white dwarfs with high fractional infrared luminosities (thus the K-band excesses). Optical spectroscopy reveals the stars with disk-like excesses are polluted with heavy elements...

  15. Eddington-limited accretion and the black hole mass function at redshift 6

    CERN Document Server

    Willott, Chris J; Arzoumanian, Doris; Bergeron, Jacqueline; Crampton, David; Delorme, Philippe; Hutchings, John B; Omont, Alain; Reyle, Celine; Schade, David

    2010-01-01

    We present discovery observations of a quasar in the Canada-France High-z Quasar Survey (CFHQS) at redshift z=6.44. We also use near-IR spectroscopy of nine CFHQS quasars at z~6 to determine black hole masses. These are compared with similar estimates for more luminous Sloan Digital Sky Survey (SDSS) quasars to investigate the relationship between black hole mass and quasar luminosity. We find a strong correlation between MgII FWHM and UV luminosity and that most quasars at this early epoch are accreting close to the Eddington limit. Thus these quasars appear to be in an early stage of their life cycle where they are building up their black hole mass exponentially. Combining these results with the quasar luminosity function, we derive the black hole mass function at z=6. Our black hole mass function is ~10^4 times lower than at z=0 and substantially below estimates from previous studies. The main uncertainties which could increase the black hole mass function are a larger population of obscured quasars at hig...

  16. SDSS-III: Massive Spectroscopic Surveys of the Distant Universe, the Milky Way, and Extra-Solar Planetary Systems

    Science.gov (United States)

    Eisenstein, Daniel J.; Weinberg, David H.; Agol, Eric; Aihara, Hiroaki; Allende Prieto, Carlos; Anderson, Scott F.; Arns, James A.; Aubourg, Éric; Bailey, Stephen; Balbinot, Eduardo; Barkhouser, Robert; Beers, Timothy C.; Berlind, Andreas A.; Bickerton, Steven J.; Bizyaev, Dmitry; Blanton, Michael R.; Bochanski, John J.; Bolton, Adam S.; Bosman, Casey T.; Bovy, Jo; Brandt, W. N.; Breslauer, Ben; Brewington, Howard J.; Brinkmann, J.; Brown, Peter J.; Brownstein, Joel R.; Burger, Dan; Busca, Nicolas G.; Campbell, Heather; Cargile, Phillip A.; Carithers, William C.; Carlberg, Joleen K.; Carr, Michael A.; Chang, Liang; Chen, Yanmei; Chiappini, Cristina; Comparat, Johan; Connolly, Natalia; Cortes, Marina; Croft, Rupert A. C.; Cunha, Katia; da Costa, Luiz N.; Davenport, James R. A.; Dawson, Kyle; De Lee, Nathan; Porto de Mello, Gustavo F.; de Simoni, Fernando; Dean, Janice; Dhital, Saurav; Ealet, Anne; Ebelke, Garrett L.; Edmondson, Edward M.; Eiting, Jacob M.; Escoffier, Stephanie; Esposito, Massimiliano; Evans, Michael L.; Fan, Xiaohui; Femenía Castellá, Bruno; Dutra Ferreira, Leticia; Fitzgerald, Greg; Fleming, Scott W.; Font-Ribera, Andreu; Ford, Eric B.; Frinchaboy, Peter M.; García Pérez, Ana Elia; Gaudi, B. Scott; Ge, Jian; Ghezzi, Luan; Gillespie, Bruce A.; Gilmore, G.; Girardi, Léo; Gott, J. Richard; Gould, Andrew; Grebel, Eva K.; Gunn, James E.; Hamilton, Jean-Christophe; Harding, Paul; Harris, David W.; Hawley, Suzanne L.; Hearty, Frederick R.; Hennawi, Joseph F.; González Hernández, Jonay I.; Ho, Shirley; Hogg, David W.; Holtzman, Jon A.; Honscheid, Klaus; Inada, Naohisa; Ivans, Inese I.; Jiang, Linhua; Jiang, Peng; Johnson, Jennifer A.; Jordan, Cathy; Jordan, Wendell P.; Kauffmann, Guinevere; Kazin, Eyal; Kirkby, David; Klaene, Mark A.; Knapp, G. R.; Kneib, Jean-Paul; Kochanek, C. S.; Koesterke, Lars; Kollmeier, Juna A.; Kron, Richard G.; Lampeitl, Hubert; Lang, Dustin; Lawler, James E.; Le Goff, Jean-Marc; Lee, Brian L.; Lee, Young Sun; Leisenring, Jarron M.; Lin, Yen-Ting; Liu, Jian; Long, Daniel C.; Loomis, Craig P.; Lucatello, Sara; Lundgren, Britt; Lupton, Robert H.; Ma, Bo; Ma, Zhibo; MacDonald, Nicholas; Mack, Claude; Mahadevan, Suvrath; Maia, Marcio A. G.; Majewski, Steven R.; Makler, Martin; Malanushenko, Elena; Malanushenko, Viktor; Mandelbaum, Rachel; Maraston, Claudia; Margala, Daniel; Maseman, Paul; Masters, Karen L.; McBride, Cameron K.; McDonald, Patrick; McGreer, Ian D.; McMahon, Richard G.; Mena Requejo, Olga; Ménard, Brice; Miralda-Escudé, Jordi; Morrison, Heather L.; Mullally, Fergal; Muna, Demitri; Murayama, Hitoshi; Myers, Adam D.; Naugle, Tracy; Neto, Angelo Fausti; Nguyen, Duy Cuong; Nichol, Robert C.; Nidever, David L.; O'Connell, Robert W.; Ogando, Ricardo L. C.; Olmstead, Matthew D.; Oravetz, Daniel J.; Padmanabhan, Nikhil; Paegert, Martin; Palanque-Delabrouille, Nathalie; Pan, Kaike; Pandey, Parul; Parejko, John K.; Pâris, Isabelle; Pellegrini, Paulo; Pepper, Joshua; Percival, Will J.; Petitjean, Patrick; Pfaffenberger, Robert; Pforr, Janine; Phleps, Stefanie; Pichon, Christophe; Pieri, Matthew M.; Prada, Francisco; Price-Whelan, Adrian M.; Raddick, M. Jordan; Ramos, Beatriz H. F.; Reid, I. Neill; Reyle, Celine; Rich, James; Richards, Gordon T.; Rieke, George H.; Rieke, Marcia J.; Rix, Hans-Walter; Robin, Annie C.; Rocha-Pinto, Helio J.; Rockosi, Constance M.; Roe, Natalie A.; Rollinde, Emmanuel; Ross, Ashley J.; Ross, Nicholas P.; Rossetto, Bruno; Sánchez, Ariel G.; Santiago, Basilio; Sayres, Conor; Schiavon, Ricardo; Schlegel, David J.; Schlesinger, Katharine J.; Schmidt, Sarah J.; Schneider, Donald P.; Sellgren, Kris; Shelden, Alaina; Sheldon, Erin; Shetrone, Matthew; Shu, Yiping; Silverman, John D.; Simmerer, Jennifer; Simmons, Audrey E.; Sivarani, Thirupathi; Skrutskie, M. F.; Slosar, Anže; Smee, Stephen; Smith, Verne V.; Snedden, Stephanie A.; Stassun, Keivan G.; Steele, Oliver; Steinmetz, Matthias; Stockett, Mark H.; Stollberg, Todd; Strauss, Michael A.; Szalay, Alexander S.; Tanaka, Masayuki; Thakar, Aniruddha R.; Thomas, Daniel; Tinker, Jeremy L.; Tofflemire, Benjamin M.; Tojeiro, Rita; Tremonti, Christy A.; Vargas Magaña, Mariana; Verde, Licia; Vogt, Nicole P.; Wake, David A.; Wan, Xiaoke; Wang, Ji; Weaver, Benjamin A.; White, Martin; White, Simon D. M.; Wilson, John C.; Wisniewski, John P.; Wood-Vasey, W. Michael; Yanny, Brian; Yasuda, Naoki; Yèche, Christophe; York, Donald G.; Young, Erick; Zasowski, Gail; Zehavi, Idit; Zhao, Bo

    2011-09-01

    Building on the legacy of the Sloan Digital Sky Survey (SDSS-I and II), SDSS-III is a program of four spectroscopic surveys on three scientific themes: dark energy and cosmological parameters, the history and structure of the Milky Way, and the population of giant planets around other stars. In keeping with SDSS tradition, SDSS-III will provide regular public releases of all its data, beginning with SDSS Data Release 8 (DR8), which was made public in 2011 January and includes SDSS-I and SDSS-II images and spectra reprocessed with the latest pipelines and calibrations produced for the SDSS-III investigations. This paper presents an overview of the four surveys that comprise SDSS-III. The Baryon Oscillation Spectroscopic Survey will measure redshifts of 1.5 million massive galaxies and Lyα forest spectra of 150,000 quasars, using the baryon acoustic oscillation feature of large-scale structure to obtain percent-level determinations of the distance scale and Hubble expansion rate at z = 100 per resolution element), H-band (1.51 μm MARVELS) will monitor radial velocities of more than 8000 FGK stars with the sensitivity and cadence (10-40 m s-1, ~24 visits per star) needed to detect giant planets with periods up to two years, providing an unprecedented data set for understanding the formation and dynamical evolution of giant planet systems. As of 2011 January, SDSS-III has obtained spectra of more than 240,000 galaxies, 29,000 z >= 2.2 quasars, and 140,000 stars, including 74,000 velocity measurements of 2580 stars for MARVELS.

  17. Chandra Finds Well-Established Black Holes In Distant Quasars

    Science.gov (United States)

    2002-03-01

    University of Arizona and her colleagues disagree. In addition to the three distant Sloan quasars, they observed 14 other quasars with distances between 12 and 12.5 billion light years. Bechtold's group looked at their larger sample to determine that the younger, more distant quasars were radiating a lower percentage of their energy in X-rays. "The X-ray data are consistent with predictions of some theories that a hot gas atmosphere is associated with the accretion disk swirling around a central supermassive black hole," said Bechtold, provided the distant quasars have more massive black holes than nearby ones. "These theories predict that large supermassive black holes should be relatively weaker X-ray emittters than smaller ones, which is what we observed with Chandra." All groups agreed that the masses of the black holes producing the X-rays are huge, given their relative youth. By various estimates, the three quasars each weighed in at between one and 10 billion times the mass of the Sun. By comparison, the black hole at the center of the Milky Way is believed to contain the mass equivalent to only about 3 million Suns. Daniel Schwartz of the Harvard-Smithsonian Center for Astrophysics took a different approach to the same data. In addition to looking at the quasars themselves, he examined the space around them. His search paid off with the discovery of a new X-ray source, which may be only about half a million light years away from the quasar SDSS 1306+0356 "It's not clear what the source is," said Schwartz. "One plausible explanation is that it is due to a high-energy jet of material ejected by the quasar over at least several hundred thousand years." Chandra has detected a number of such jets, which could be generated by the extraction of energy from the rotation of a supermassive black hole. In addition to SDSS 1306+0356, which has a cosmological redshift z = 5.99, the other distant Sloan Digital Sky Survey quasars observed in this study are SDSS 0836+0054 (redshift

  18. Black Hole Dynamic Potentials

    Indian Academy of Sciences (India)

    Koustubh Ajit Kabe

    2012-09-01

    In the following paper, certain black hole dynamic potentials have been developed definitively on the lines of classical thermodynamics. These potentials have been refined in view of the small differences in the equations of the laws of black hole dynamics as given by Bekenstein and those of thermodynamics. Nine fundamental black hole dynamical relations have been developed akin to the four fundamental thermodynamic relations of Maxwell. The specific heats , and , have been defined. For a black hole, these quantities are negative. The d equation has been obtained as an application of these fundamental relations. Time reversible processes observing constancy of surface gravity are considered and an equation connecting the internal energy of the black hole , the additional available energy defined as the first free energy function , and the surface gravity , has been obtained. Finally as a further application of the fundamental relations, it has been proved for a homogeneous gravitational field in black hole space times or a de Sitter black hole that $C_{\\Omega,\\Phi}-C_{J,Q}=\\kappa \\left[\\left(\\dfrac{\\partial J}{\\partial \\kappa}\\right)_{\\Omega,\\Phi}\\left(\\dfrac{\\partial \\Omega}{\\partial \\kappa}\\right)_{J,Q}+\\left(\\dfrac{\\partial Q}{\\partial \\kappa}\\right)_{\\Omega,\\Phi}\\left(\\dfrac{\\partial\\Phi}{\\partial \\kappa}\\right)_{J,Q}\\right]$. This is dubbed as the homogeneous fluid approximation in context of the black holes.

  19. Black holes matter

    DEFF Research Database (Denmark)

    Kragh, Helge Stjernholm

    2016-01-01

    Review essay, Marcia Bartusiak, Black Hole: How an Idea Abandoned by Newtonians, Hated by Einstein, and Gambled On by Hawking Became Loved (New Haven: Yale University Press, 2015).......Review essay, Marcia Bartusiak, Black Hole: How an Idea Abandoned by Newtonians, Hated by Einstein, and Gambled On by Hawking Became Loved (New Haven: Yale University Press, 2015)....

  20. Perturbing supersymmetric black hole

    CERN Document Server

    Onozawa, H; Mishima, T; Ishihara, H; Onozawa, Hisashi; Okamura, Takashi; Mishima, Takashi; Ishihara, Hideki

    1996-01-01

    An investigation of the perturbations of the Reissner-Nordstr\\"{o}m black hole in the N=2 supergravity is presented. In the extreme case, the black hole responds to the perturbation of each field in the same manner. This is possibly because we can match the modes of the graviton, gravitino, and photon using supersymmetry transformations.

  1. Black hole levitron

    NARCIS (Netherlands)

    Arsiwalla, X.D.; Verlinde, E.P.

    2010-01-01

    We study the problem of spatially stabilizing four dimensional extremal black holes in background electric/magnetic fields. Whilst looking for stationary stable solutions describing black holes placed in external fields we find that taking a continuum limit of Denef et al.’s multicenter

  2. Newborn Black Holes

    Science.gov (United States)

    Science Teacher, 2005

    2005-01-01

    Scientists using NASA's Swift satellite say they have found newborn black holes, just seconds old, in a confused state of existence. The holes are consuming material falling into them while somehow propelling other material away at great speeds. "First comes a blast of gamma rays followed by intense pulses of x-rays. The energies involved are much…

  3. Scattering by Black Holes

    CERN Document Server

    Andersson, N

    2000-01-01

    This is a chapter on Black-hole Scattering that was commissioned for an Encyclopaedia on Scattering edited by Pike and Sabatier, to be published by Academic Press. The chapter surveys wave propagation in black-hole spacetimes, diffraction effects in wave scattering, resonances, quasinormal modes and related topics.

  4. Disregarding the 'Hole Argument'

    CERN Document Server

    Roberts, Bryan W

    2014-01-01

    Jim Weatherall has suggested that Einstein's hole argument, as presented by Earman and Norton (1987), is based on a misleading use of mathematics. I argue on the contrary that Weatherall demands an implausible restriction on how mathematics is used. The hole argument, on the other hand, is in no new danger at all.

  5. Lifshitz Topological Black Holes

    CERN Document Server

    Mann, R B

    2009-01-01

    I find a class of black hole solutions to a (3+1) dimensional theory gravity coupled to abelian gauge fields with negative cosmological constant that has been proposed as the dual theory to a Lifshitz theory describing critical phenomena in (2+1) dimensions. These black holes are all asymptotic to a Lifshitz fixed point geometry and depend on a single parameter that determines both their area (or size) and their charge. Most of the solutions are obtained numerically, but an exact solution is also obtained for a particular value of this parameter. The thermodynamic behaviour of large black holes is almost the same regardless of genus, but differs considerably for small black holes. Screening behaviour is exhibited in the dual theory for any genus, but the critical length at which it sets in is genus-dependent for small black holes.

  6. Cosmological Black Holes

    CERN Document Server

    Stornaiolo, C

    2002-01-01

    In this letter we propose the existence of low density black holes and discuss its compatibility with the cosmological observations. The origin of these black holes can be traced back to the collapse of long wavelength cosmological perturbations during the matter dominated era, when the densities are low enough to neglect any internal and thermal pressure. By introducing a threshold density $\\hat{\\rho}$ above which pressure and non-gravitational interactions become effective, we find the highest wavelength for the perturbations that can reach an equilibrium state instead of collapsing to a black hole. The low density black holes introduced here, if they exist, can be observed through weak and strong gravitational lensing effects. Finally we observe that we obtained here a cosmological model which is capable to explain in a qualitative way the void formation together with the value $\\Omega=1$. But we remark that it needs to be improved by considering non spherical symmetric black holes.

  7. Primordial Black Hole Baryogenesis

    CERN Document Server

    Baumann, D; Turok, N G; Baumann, Daniel; Steinhardt, Paul J.; Turok, Neil

    2007-01-01

    We reconsider the possibility that the observed baryon asymmetry was generated by the evaporation of primordial black holes that dominated the early universe. We present a simple derivation showing that the baryon asymmetry is insensitive to the initial black hole density and the cosmological model but is sensitive to the temperature-dependence of the CP and baryon-violating (or lepton-violating) interactions. We also consider the possibility that black holes stop evaporating and form Planck-mass remnants that act as dark matter. We show that primordial black holes cannot simultaneously account for both the observed baryon asymmetry and the (remnant) dark matter density unless the magnitude of CP violation is much greater than expected from most particle physics models. Finally, we apply these results to ekpyrotic/cyclic models, in which primordial black holes may form when branes collide. We find that obtaining the observed baryon asymmetry is compatible with the other known constraints on parameters.

  8. Black Hole Critical Phenomena Without Black Holes

    CERN Document Server

    Liebling, S L

    2000-01-01

    Studying the threshold of black hole formation via numerical evolution has led to the discovery of fascinating nonlinear phenomena. Power-law mass scaling, aspects of universality, and self-similarity have now been found for a large variety of models. However, questions remain. Here I briefly review critical phenomena, discuss some recent results, and describe a model which demonstrates similar phenomena without gravity.

  9. Primary and Presidential Candidates

    DEFF Research Database (Denmark)

    Goddard, Joseph

    2012-01-01

    This article looks at primary and presidential candidates in 2008 and 2012. Evidence suggests that voters are less influenced by candidates’ color, gender, or religious observation than previously. Conversely, markers of difference remain salient in the imaginations of pollsters and journalists...

  10. Fundamental Plane of FSRQs from SDSS DR5 Quasar Catalogue

    Indian Academy of Sciences (India)

    Ting-Ting Wang; C.-Y. Su; Z.-F. Chen; Y.-P. Qin; G.-A. Wang

    2011-03-01

    In this work, we explore a sample of 362 flat-spectrum radio quasars (FSRQs) to investigate the jet formation. We find that the fundamental plane for our FSRQs can be expressed as 5\\;GHz ∝ $^{-0.19}_{\\text{bh}}$ $^{1.08}_{\\text{2\\; keV}}$. We also find that the 5 GHz luminosities are tightly related to both black hole mass and Eddington ratio, which is established as 5\\;GHz ∝ $^{0.67}_{\\text{bh}}$ (bol/EDD)1.32.

  11. Quantifying dwarf satellites through gravitational imaging : The case of SDSS J120602.09+514229.5

    NARCIS (Netherlands)

    Vegetti, Simona; Czoske, Oliver; Koopmans, Léon V. E.

    2010-01-01

    SDSS J120602.09+514229.5 is a gravitational lens system formed by a group of galaxies at redshift z(FG) = 0.422 lensing a bright background galaxy at redshift z(BG) = 2.001. The main peculiarity of this system is the presence of a luminous satellite near the Einstein radius, which slightly deforms t

  12. Identification of Metal Absorption Lines on Quasar Spectra of SDSS DR9

    Indian Academy of Sciences (India)

    Cai-Juan Pan; Cheng-Yu Su; Mu-Sheng Li; Wei-Rong Huang

    2014-09-01

    Absorption lines are an important tool for probing the gas in the Universe. Our group aim to identify the metal absorption lines imprinted on the quasar spectra of the BOSS. In this work, we show the metal absorption lines identified in the spectrum of SDSS J160032.95+323638.7.

  13. Spectroscopic classification of CSS150213:100134+453359 in SDSS J100134.51+453339.9

    Science.gov (United States)

    Elias-Rosa, Nancy; Benetti, Stefano; Dennefeld, Michel; De Cicco, Demetra; Sowicka, Paulina; Ordovas-Pascual, Ignacio; Lam, Marco Cheuk-Yin

    2015-02-01

    We report the spectroscopic observation of CSS150213:100134+453359 in SDSS J100134.51+453339.9. The observation was performed with the Asiago 1.82m Copernico Telescope (+AFOSC; range 340-820 nm; resolution 1.4 nm), equipped with the CCD Andor IKON L936.

  14. Galaxy-galaxy and galaxy-cluster lensing with the SDSS and the FIRST surveys

    CERN Document Server

    Demetroullas, Constantinos

    2016-01-01

    We perform a galaxy-galaxy lensing study by correlating the shapes of $\\sim$2.7 $\\times$ 10$^5$ galaxies selected from the VLA FIRST radio survey with the positions of $\\sim$38.5 million SDSS galaxies, $\\sim$132000 BCGs and $\\sim$78000 SDSS galaxies that are also detected in the VLA FIRST survey. The measurements are conducted on angular scales ${\\theta}$ $\\lesssim$ 1200 arcsec. On scales ${\\theta}$ $\\lesssim$ 200 arcsec we find that the measurements are corrupted by residual systematic effects associated with the instrumental beam of the VLA data. Using simulations we show that we can successfully apply a correction for these effects. Using the three lens samples (the SDSS DR10 sample, the BCG sample and the SDSS-FIRST matched object sample) we measure a tangential shear signal that is inconsistent with zero at the 10${\\sigma}$, 3.8${\\sigma}$ and 9${\\sigma}$ level respectively. Fitting an NFW model to the detected signals we find that the ensemble mass profile of the BCG sample agrees with the values in the ...

  15. Structural analysis of the SDSS Cosmic Web - I. Non-linear density field reconstructions

    NARCIS (Netherlands)

    Platen, Erwin; van de Weygaert, Rien; Jones, Bernard J. T.; Vegter, Gert; Calvo, Miguel A. Aragón

    2011-01-01

    This study is the first in a series in which we analyse the structure and topology of the Cosmic Web as traced by the Sloan Digital Sky Survey (SDSS). The main issue addressed in the present study is the translation of the irregularly distributed discrete spatial data in the galaxy redshift survey i

  16. Structural analysis of the SDSS Cosmic Web : I. Non-linear density field reconstructions

    NARCIS (Netherlands)

    Platen, Erwin; Weygaert, Rien van de; Jones, Bernard J.T.; Vegter, Gert; Aragón Calvo, Miguel A.

    2011-01-01

    This study is the first in a series in which we analyse the structure and topology of the Cosmic Web as traced by the Sloan Digital Sky Survey (SDSS). The main issue addressed in the present study is the translation of the irregularly distributed discrete spatial data in the galaxy redshift survey i

  17. The many scales to cosmic homogeneity: Use of multiple tracers from the SDSS

    CERN Document Server

    Sarkar, Prakash; Pandey, Biswajit; Kedia, Atul; Sarkar, Suman

    2016-01-01

    We carry out multifractal analyses of multiple tracers namely the main galaxy sample, the LRG sample and the quasar sample from the SDSS to test the assumption of cosmic homogeneity and identify the scale of transition to homogeneity, if any. We consider the behaviour of the scaled number counts and the scaling relations of different moments of the galaxy number counts in spheres of varying radius $R$ to calculate the spectrum of the Minkowski-Bouligand general dimension $D_{q} (R)$ for $-4 \\leq q \\leq 4$. The present analysis provides us the opportunity to study the spectrum of the generalized dimension $D_{q}(R)$ for multiple tracers of the cosmic density field over a wide range of length scales and allows us to confidently test the validity of the assumption of cosmic homogeneity. Our analysis indicates that the SDSS main galaxy sample is homogeneous on a length scales of $80\\, h^{-1}\\, {\\rm Mpc} $ and beyond whereas the SDSS quasar sample and the SDSS LRG sample show transition to homogeneity on an even l...

  18. VizieR Online Data Catalog: SDSS quasars balmer emission lines (Liu+, 2014)

    Science.gov (United States)

    Liu, X.; Shen, Y.; Bian, F.; Loeb, A.; Tremaine, S.

    2017-03-01

    We start with the SDSS DR7 quasar catalog (Schneider et al. 2010AJ....139.2360S, Cat. VII/260), adopting the spectral measurements of Shen et al. (2011, J/ApJS/194/45). Among the SDSS DR7 quasars, 20,774 are at z examination. Here and throughout, we refer to the 399 objects as the "offset" sample. Using the spectral models, we measure the offset of the broad emission lines relative to the systemic velocity. The systemic redshift is estimated from the core component of [O III], which may be different (by a median offset of 32 km/s with a standard deviation of 125 km/s) from the nominal redshift listed by the DR7 catalog based on the SDSS spectroscopic pipeline (Stoughton et al. 2002AJ....123..485S). Our adopted systemic redshift agrees with the improved redshift for SDSS quasars from Hewett & Wild (2010, J/MNRAS/405/2302) within uncertainties. (1 data file).

  19. On the Observed W_MgII--L_[OII] Correlation in SDSS QSO Spectra

    CERN Document Server

    López, Gilberto

    2011-01-01

    This paper investigates the effect of differential aperture loss with SDSS fibers and examines whether such selection bias would result in the observed correlation between rest-frame absorption equivalent width of MgII absorbers, Wr(2796), and mean associated [OII] luminosity, L_[OII], in SDSS QSO spectra. We demonstrate based on a Monte Carlo simulation that the observed Wr(2796) vs. L_[OII] correlation of MgII absorbers can be well-reproduced, if all galaxies found in deep surveys possess extended MgII halos and if the extent of MgII halos scales proportionally with galaxy mass as shown in previous studies. The observed correlation can be explained by a combination of (1) the known Wr(2796) vs. rho anti-correlation in galaxy and MgII absorber pairs and (2) an increasing aperture loss in the 3" diameter SDSS fiber for galaxies at larger rho. Galaxies at larger projected distances produce on average weaker MgII absorbers and weaker (or zero) L_[OII] in SDSS QSO spectra. We show that such correlation diminishe...

  20. The SDSS-IV extended Baryonic Oscillation Spectroscopic Survey: Luminous Red Galaxy Target Selection

    CERN Document Server

    Prakash, Abhishek; Newman, Jeffrey A; Ross, Ashley J; Myers, Adam D; Dawson, Kyle S; Kneib, Jean-Paul; Percival, Will J; Bautista, Julian E; Comparat, Johan; Tinker, Jeremy L; Schlegel, David J; Tojeiro, Rita; Ho, Shirley; Lang, Dustin; Rao, Sandhya M; McBride, Cameron K; Zhu, Guangtun Ben; Brownstein, Joel R; Bailey, Stephen; Bolton, Adam S; Delubac, Timothee; Mariappan, Vivek; Blanton, Michael R; Reid, Beth; Schneider, Donald P; Seo, Hee-Jong; Rosell, Aurelio Carnero; Prada, Francisco

    2015-01-01

    We describe the algorithm used to select the Luminous Red Galaxy (LRG) sample for the extended Baryon Oscillation Spectroscopic Survey (eBOSS) of the Sloan Digital Sky Survey IV (SDSS-IV) using photometric data from both the SDSS and the Wide-Field Infrared Survey Explorer (WISE). LRG targets are required to meet a set of color selection criteria and have z-band and i-band MODEL magnitudes z < 19.95 and 19.9 < i < 21.8, respectively. Our algorithm selects roughly 50 LRG targets per square degree, the great majority of which lie in the redshift range 0.6 < z < 1.0 (median redshift 0.71). We demonstrate that our methods are highly effective at eliminating stellar contamination and lower-redshift galaxies. We perform a number of tests using spectroscopic data from SDSS-III/BOSS to determine the redshift reliability of our target selection and its ability to meet the science requirements of eBOSS. The SDSS spectra are of high enough signal-to-noise ratio that at least 89% of the target sample yield...