HOW TO FIND GRAVITATIONALLY LENSED TYPE Ia SUPERNOVAE

International Nuclear Information System (INIS)

Goldstein, Daniel A.; Nugent, Peter E.

2017-01-01

Type Ia supernovae (SNe Ia) that are multiply imaged by gravitational lensing can extend the SN Ia Hubble diagram to very high redshifts ( z ≳ 2), probe potential SN Ia evolution, and deliver high-precision constraints on H _0, w , and Ω_m via time delays. However, only one, iPTF16geu, has been found to date, and many more are needed to achieve these goals. To increase the multiply imaged SN Ia discovery rate, we present a simple algorithm for identifying gravitationally lensed SN Ia candidates in cadenced, wide-field optical imaging surveys. The technique is to look for supernovae that appear to be hosted by elliptical galaxies, but that have absolute magnitudes implied by the apparent hosts’ photometric redshifts that are far brighter than the absolute magnitudes of normal SNe Ia (the brightest type of supernovae found in elliptical galaxies). Importantly, this purely photometric method does not require the ability to resolve the lensed images for discovery. Active galactic nuclei, the primary sources of contamination that affect the method, can be controlled using catalog cross-matches and color cuts. Highly magnified core-collapse SNe will also be discovered as a byproduct of the method. Using a Monte Carlo simulation, we forecast that the Large Synoptic Survey Telescope can discover up to 500 multiply imaged SNe Ia using this technique in a 10 year z -band search, more than an order of magnitude improvement over previous estimates. We also predict that the Zwicky Transient Facility should find up to 10 multiply imaged SNe Ia using this technique in a 3 year R -band search—despite the fact that this survey will not resolve a single system.

HOW TO FIND GRAVITATIONALLY LENSED TYPE Ia SUPERNOVAE

Energy Technology Data Exchange (ETDEWEB)

Goldstein, Daniel A.; Nugent, Peter E. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States)

2017-01-01

Type Ia supernovae (SNe Ia) that are multiply imaged by gravitational lensing can extend the SN Ia Hubble diagram to very high redshifts ( z ≳ 2), probe potential SN Ia evolution, and deliver high-precision constraints on H {sub 0}, w , and Ω{sub m} via time delays. However, only one, iPTF16geu, has been found to date, and many more are needed to achieve these goals. To increase the multiply imaged SN Ia discovery rate, we present a simple algorithm for identifying gravitationally lensed SN Ia candidates in cadenced, wide-field optical imaging surveys. The technique is to look for supernovae that appear to be hosted by elliptical galaxies, but that have absolute magnitudes implied by the apparent hosts’ photometric redshifts that are far brighter than the absolute magnitudes of normal SNe Ia (the brightest type of supernovae found in elliptical galaxies). Importantly, this purely photometric method does not require the ability to resolve the lensed images for discovery. Active galactic nuclei, the primary sources of contamination that affect the method, can be controlled using catalog cross-matches and color cuts. Highly magnified core-collapse SNe will also be discovered as a byproduct of the method. Using a Monte Carlo simulation, we forecast that the Large Synoptic Survey Telescope can discover up to 500 multiply imaged SNe Ia using this technique in a 10 year z -band search, more than an order of magnitude improvement over previous estimates. We also predict that the Zwicky Transient Facility should find up to 10 multiply imaged SNe Ia using this technique in a 3 year R -band search—despite the fact that this survey will not resolve a single system.

UTILIZING TYPE Ia SUPERNOVAE IN A LARGE, FAST, IMAGING SURVEY TO CONSTRAIN DARK ENERGY

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Zentner, Andrew R.; Bhattacharya, Suman

2009-01-01

We study the utility of a large sample of Type Ia supernovae (SNe Ia) that might be observed in an imaging survey that rapidly scans a large fraction of the sky for constraining dark energy. We consider both the information contained in the traditional luminosity distance test as well as the spread in Ia SN fluxes at fixed redshift induced by gravitational lensing. As would be required from an imaging survey, we include a treatment of photometric redshift uncertainties in our analysis. Our primary result is that the information contained in the mean distance moduli of SNe Ia and the dispersion of SN Ia distance moduli complement each other, breaking a degeneracy between the present dark energy equation of state and its time variation without the need for a high-redshift (z ∼> 0.8) SN sample. Including lensing information also allows for some internal calibration of photometric redshifts. To address photometric redshift uncertainties, we present dark energy constraints as a function of the size of an external set of spectroscopically observed SNe that may be used for redshift calibration, N spec . Depending upon the details of potentially available, external SN data sets, we find that an imaging survey can constrain the dark energy equation of state at the epoch where it is best constrained w p , with a 1σ error of σ(w p ) ∼ 0.03-0.09. In addition, the marginal improvement in the error σ(w p ) from an increase in the spectroscopic calibration sample drops once N spec ∼ a few x 10 3 . This result is important because it is of the order of the size of calibration samples likely to be compiled in the coming decade and because, for samples of this size, the spectroscopic and imaging surveys individually place comparable constraints on the dark energy equation of state. In all cases, it is best to calibrate photometric redshifts with a set of spectroscopically observed SNe with relatively more objects at high redshift (z ∼> 0.5) than the parent sample of

THE CARNEGIE SUPERNOVA PROJECT: SECOND PHOTOMETRY DATA RELEASE OF LOW-REDSHIFT TYPE Ia SUPERNOVAE

International Nuclear Information System (INIS)

Stritzinger, Maximilian D.; Phillips, M. M.; Campillay, Abdo; Morrell, Nidia; Krzeminski, Wojtek; Roth, Miguel; Boldt, Luis N.; Burns, Chris; Freedman, Wendy L.; Madore, Barry F.; Persson, Sven E.; Contreras, Carlos; Gonzalez, Sergio; Folatelli, Gaston; Salgado, Francisco; DePoy, D. L.; Marshall, J. L.; Rheault, Jean-Philippe; Suntzeff, Nicholas B.; Hamuy, Mario

2011-01-01

The Carnegie Supernova Project (CSP) was a five-year observational survey conducted at Las Campanas Observatory that obtained, among other things, high-quality light curves of ∼100 low-redshift Type Ia supernovae (SNe Ia). Presented here is the second data release of nearby SN Ia photometry consisting of 50 objects, with a subset of 45 having near-infrared follow-up observations. Thirty-three objects have optical pre-maximum coverage with a subset of 15 beginning at least five days before maximum light. In the near-infrared, 27 objects have coverage beginning before the epoch of B-band maximum, with a subset of 13 beginning at least five days before maximum. In addition, we present results of a photometric calibration program to measure the CSP optical (uBgVri) bandpasses with an accuracy of ∼1%. Finally, we report the discovery of a second SN Ia, SN 2006ot, similar in its characteristics to the peculiar SN 2006bt.

THE MEAN TYPE IA SUPERNOVA SPECTRUM OVER THE PAST NINE GIGAYEARS

International Nuclear Information System (INIS)

Sullivan, M.; Ellis, R. S.; Howell, D. A.; Riess, A.; Nugent, P. E.; Gal-Yam, A.

2009-01-01

We examine the possibility of evolution with redshift in the mean rest-frame ultraviolet (UV; λ ∼ H and Kand Mg II blends, indicating lower IME abundances in the higher redshift SNe. A larger fraction of luminous, wider light-curve width (higher s tretch ) SNe Ia are expected at higher redshift than locally, so we compare our observed spectral evolution with that predicted by a redshift-evolving stretch distribution coupled with a stretch-dependent SN Ia spectrum. We show that the sense of the spectral evolution can be reproduced by this simple model, though the highest redshift events seem additionally deficient in Si and Ca. We also examine the mean SN Ia UV-optical colors as a function of redshift, thought to be sensitive to variations in progenitor composition. We find that the expected stretch variations are sufficient to explain the differences, although improved data at z ∼ 0 will enable more precise tests. Thus, to the extent possible with the available data sets, our results support the continued use of SNe Ia as standardized candles.

Spectral Sequences of Type Ia Supernovae. I. Connecting Normal and Subluminous SNe Ia and the Presence of Unburned Carbon

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Heringer, E.; Kerkwijk, M. H. van [Department of Astronomy and Astrophysics, University of Toronto, 50 Saint George Street, Toronto, ON M5S 3H4 (Canada); Sim, S. A. [Astrophysics Research Centre, School of Mathematics and Physics, Queens University Belfast, Belfast BT7 1NN (United Kingdom); Kerzendorf, W. E. [European Southern Observatory (ESO), Karl-Schwarzschild-Straße 2, D-85748 Garching (Germany)

2017-09-01

Type Ia supernovae (SNe Ia) are generally agreed to arise from thermonuclear explosions of carbon–oxygen white dwarfs. The actual path to explosion, however, remains elusive, with numerous plausible parent systems and explosion mechanisms suggested. Observationally, SNe Ia have multiple subclasses, distinguished by their light curves and spectra. This raises the question of whether these indicate that multiple mechanisms occur in nature or that explosions have a large but continuous range of physical properties. We revisit the idea that normal and 91bg-like SNe can be understood as part of a spectral sequence in which changes in temperature dominate. Specifically, we find that a single ejecta structure is sufficient to provide reasonable fits of both the normal SN Ia SN 2011fe and the 91bg-like SN 2005bl, provided that the luminosity and thus temperature of the ejecta are adjusted appropriately. This suggests that the outer layers of the ejecta are similar, thus providing some support for a common explosion mechanism. Our spectral sequence also helps to shed light on the conditions under which carbon can be detected in premaximum SN Ia spectra—we find that emission from iron can “fill in” the carbon trough in cool SNe Ia. This may indicate that the outer layers of the ejecta of events in which carbon is detected are relatively metal-poor compared to events in which carbon is not detected.

THE LOCAL HOSTS OF TYPE Ia SUPERNOVAE

International Nuclear Information System (INIS)

Neill, James D.; Martin, D. Christopher; Barlow, Tom A.; Foster, Karl; Friedman, Peter G.; Morrissey, Patrick; Wyder, Ted K.; Sullivan, Mark; Howell, D. Andrew; Conley, Alex; Seibert, Mark; Madore, Barry F.; Neff, Susan G.; Schiminovich, David; Bianchi, Luciana; Donas, Jose; Milliard, Bruno; Heckman, Timothy M.; Lee, Young-Wook; Rich, R. Michael

2009-01-01

We use multi-wavelength, matched aperture, integrated photometry from the Galaxy Evolution Explorer (GALEX), the Sloan Digital Sky Survey, and the RC3 to estimate the physical properties of 166 nearby galaxies hosting 168 well-observed Type Ia supernovae (SNe Ia). The ultraviolet (UV) imaging of local SN Ia hosts from GALEX allows a direct comparison with higher-redshift hosts measured at optical wavelengths that correspond to the rest-frame UV. Our data corroborate well-known features that have been seen in other SN Ia samples. Specifically, hosts with active star formation produce brighter and slower SNe Ia on average, and hosts with luminosity-weighted ages older than 1 Gyr produce on average more faint, fast, and fewer bright, slow SNe Ia than younger hosts. New results include that in our sample, the faintest and fastest SNe Ia occur only in galaxies exceeding a stellar mass threshold of ∼10 10 M sun , leading us to conclude that their progenitors must arise in populations that are older and/or more metal rich than the general SN Ia population. A low host extinction subsample hints at a residual trend in peak luminosity with host age, after correcting for light-curve shape, giving the appearance that older hosts produce less-extincted SNe Ia on average. This has implications for cosmological fitting of SNe Ia, and suggests that host age could be useful as a parameter in the fitting. Converting host mass to metallicity and computing 56 Ni mass from the supernova light curves, we find that our local sample is consistent with a model that predicts a shallow trend between stellar metallicity and the 56 Ni mass that powers the explosion, but we cannot rule out the absence of a trend. We measure a correlation between 56 Ni mass and host age in the local universe that is shallower and not as significant as that seen at higher redshifts. The details of the age- 56 Ni mass correlations at low and higher redshift imply a luminosity-weighted age threshold of ∼3 Gyr

THE CARNEGIE SUPERNOVA PROJECT: ANALYSIS OF THE FIRST SAMPLE OF LOW-REDSHIFT TYPE-Ia SUPERNOVAE

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Folatelli, Gaston; Phillips, M. M.; Contreras, Carlos; Stritzinger, Maximilian; Boldt, Luis; Gonzalez, Sergio; Krzeminski, Wojtek; Morrell, Nidia; Roth, Miguel; Salgado, Francisco; Burns, Christopher R.; Freedman, W. L.; Persson, S. E.; Madore, Barry F.; Murphy, David; Hamuy, Mario; Suntzeff, Nicholas B.; Krisciunas, Kevin; Wyatt, Pamela; Li Weidong

2010-01-01

An analysis of the first set of low-redshift (z s ) light curves in a well-understood photometric system. Methods are described for deriving light-curve parameters, and for building template light curves which are used to fit SN Ia data in the ugriBVYJH bands. The intrinsic colors at maximum light are calibrated using a subsample of supernovae (SNe) assumed to have suffered little or no reddening, enabling color excesses to be estimated for the full sample. The optical-NIR color excesses allow the properties of the reddening law in the host galaxies to be studied. A low average value of the total-to-selective absorption coefficient, R V ∼ 1.7, is derived when using the entire sample of SNe. However, when the two highly reddened SNe (SN 2005A and SN 2006X) in the sample are excluded, a value R V ∼ 3.2 is obtained, similar to the standard value for the Galaxy. The red colors of these two events are well matched by a model where multiple scattering of photons by circumstellar dust steepens the effective extinction law. The absolute peak magnitudes of the SNe are studied in all bands using a two-parameter linear fit to the decline rates and the colors at maximum light, or alternatively, the color excesses. In both cases, similar results are obtained with dispersions in absolute magnitudes of 0.12-0.16 mag, depending on the specific filter-color combination. In contrast to the results obtained from the comparison of the color excesses, these fits of absolute magnitude give R V ∼ 1-2 when the dispersion is minimized, even when the two highly reddened SNe are excluded. This discrepancy suggests that, beyond the 'normal' interstellar reddening produced in the host galaxies, there is an intrinsic dispersion in the colors of SNe Ia which is correlated with luminosity but independent of the decline rate. Finally, a Hubble diagram for the best-observed subsample of SNe is produced by combining the results of the fits of absolute magnitude versus decline rate and color

Superluminous supernovae as standardizable candles and high-redshift distance probes

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Inserra, C.; Smartt, S. J., E-mail: c.inserra@qub.ac.uk [Astrophysics Research Centre, School of Mathematics and Physics, Queens University Belfast, Belfast BT7 1NN (United Kingdom)

2014-12-01

We investigate the use of type Ic superluminous supernovae (SLSN Ic) as standardizable candles and distance indicators. Their appeal as cosmological probes stems from their remarkable peak luminosities, hot blackbody temperatures, and bright rest-frame ultraviolet emission. We present a sample of 16 published SLSN, from redshifts 0.1 to 1.2, and calculate accurate K corrections to determine uniform magnitudes in 2 synthetic rest-frame filter bandpasses with central wavelengths at 400 nm and 520 nm. At 400 nm, we find an encouragingly low scatter in their uncorrected, raw mean magnitudes with M(400) = –21.86 ± 0.35 mag for the full sample of 16 objects. We investigate the correlation between their decline rates and peak magnitude and find that the brighter events appear to decline more slowly. In a manner similar to the Phillips relation for type Ia SNe (SNe Ia), we define a ΔM {sub 20} decline relation. This correlates peak magnitude and decline over 20 days and can reduce the scatter in standardized peak magnitudes to ±0.22 mag. We further show that M(400) appears to have a strong color dependence. Redder objects are fainter and also become redder faster. Using this peak magnitudecolor evolution relation, a surprisingly low scatter of between ±0.08 mag and ±0.13 mag can be found in peak magnitudes, depending on sample selection. However, we caution that only 8 to 10 objects currently have enough data to test this peak magnitudecolor evolution relation. We conclude that SLSN Ic are promising distance indicators in the high-redshift universe in regimes beyond those possible with SNe Ia. Although the empirical relationships are encouraging, the unknown progenitor systems, how they may evolve with redshift, and the uncertain explosion physics are of some concern. The two major measurement uncertainties are the limited numbers of low-redshift, well-studied objects available to test these relationships and internal dust extinction in the host galaxies.

LINKING TYPE Ia SUPERNOVA PROGENITORS AND THEIR RESULTING EXPLOSIONS

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Foley, Ryan J.; Kirshner, Robert P.; Simon, Joshua D.; Burns, Christopher R.; Gal-Yam, Avishay; Hamuy, Mario; Morrell, Nidia I.; Phillips, Mark M.; Shields, Gregory A.; Sternberg, Assaf

2012-01-01

Comparing the ejecta velocities at maximum brightness and narrow circumstellar/interstellar Na D absorption line profiles of a sample of 23 Type Ia supernovae (SNe Ia), we determine that the properties of SN Ia progenitor systems and explosions are intimately connected. As demonstrated by Sternberg et al., half of all SNe Ia with detectable Na D absorption at the host-galaxy redshift in high-resolution spectroscopy have Na D line profiles with significant blueshifted absorption relative to the strongest absorption component, which indicates that a large fraction of SN Ia progenitor systems have strong outflows. In this study, we find that SNe Ia with blueshifted circumstellar/interstellar absorption systematically have higher ejecta velocities and redder colors at maximum brightness relative to the rest of the SN Ia population. This result is robust at a 98.9%-99.8% confidence level, providing the first link between the progenitor systems and properties of the explosion. This finding is further evidence that the outflow scenario is the correct interpretation of the blueshifted Na D absorption, adding additional confirmation that some SNe Ia are produced from a single-degenerate progenitor channel. An additional implication is that either SN Ia progenitor systems have highly asymmetric outflows that are also aligned with the SN explosion or SNe Ia come from a variety of progenitor systems where SNe Ia from systems with strong outflows tend to have more kinetic energy per unit mass than those from systems with weak or no outflows.

Type-Ia supernova rates to redshift 2.4 from clash: The cluster lensing and supernova survey with Hubble

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Graur, O.; Rodney, S. A.; Riess, A. G.; Medezinski, E.; Maoz, D.; Jha, S. W.; Holoien, T. W.-S.; McCully, C.; Patel, B.; Postman, M.; Dahlen, T.; Strolger, L.-G.; Coe, D.; Bradley, L.; Koekemoer, A.; Benítez, N.; Molino, A.; Jouvel, S.; Nonino, M.; Balestra, I.

2014-01-01

We present the supernova (SN) sample and Type-Ia SN (SN Ia) rates from the Cluster Lensing And Supernova survey with Hubble (CLASH). Using the Advanced Camera for Surveys and the Wide Field Camera 3 on the Hubble Space Telescope (HST), we have imaged 25 galaxy-cluster fields and parallel fields of non-cluster galaxies. We report a sample of 27 SNe discovered in the parallel fields. Of these SNe, ∼13 are classified as SN Ia candidates, including four SN Ia candidates at redshifts z > 1.2. We measure volumetric SN Ia rates to redshift 1.8 and add the first upper limit on the SN Ia rate in the range 1.8 < z < 2.4. The results are consistent with the rates measured by the HST/GOODS and Subaru Deep Field SN surveys. We model these results together with previous measurements at z < 1 from the literature. The best-fitting SN Ia delay-time distribution (DTD; the distribution of times that elapse between a short burst of star formation and subsequent SN Ia explosions) is a power law with an index of −1.00 −0.06(0.10) +0.06(0.09) (statistical) −0.08 +0.12 (systematic), where the statistical uncertainty is a result of the 68% and 95% (in parentheses) statistical uncertainties reported for the various SN Ia rates (from this work and from the literature), and the systematic uncertainty reflects the range of possible cosmic star-formation histories. We also test DTD models produced by an assortment of published binary population synthesis (BPS) simulations. The shapes of all BPS double-degenerate DTDs are consistent with the volumetric SN Ia measurements, when the DTD models are scaled up by factors of 3-9. In contrast, all BPS single-degenerate DTDs are ruled out by the measurements at >99% significance level.

A blinded determination of H0 from low-redshift Type Ia supernovae, calibrated by Cepheid variables

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Zhang, Bonnie R.; Childress, Michael J.; Davis, Tamara M.; Karpenka, Natallia V.; Lidman, Chris; Schmidt, Brian P.; Smith, Mathew

2017-10-01

Presently, a >3σ tension exists between values of the Hubble constant H0 derived from analysis of fluctuations in the cosmic microwave background by Planck, and local measurements of the expansion using calibrators of Type Ia supernovae (SNe Ia). We perform a blinded re-analysis of Riess et al. (2011) to measure H0 from low-redshift SNe Ia, calibrated by Cepheid variables and geometric distances including to NGC 4258. This paper is a demonstration of techniques to be applied to the Riess et al. (2016) data. Our end-to-end analysis starts from available Harvard -Smithsonian Center for Astrophysics (CfA3) and Lick Observatory Supernova Search (LOSS) photometries, providing an independent validation of Riess et al. (2011). We obscure the value of H0 throughout our analysis and the first stage of the referee process, because calibration of SNe Ia requires a series of often subtle choices, and the potential for results to be affected by human bias is significant. Our analysis departs from that of Riess et al. (2011) by incorporating the covariance matrix method adopted in Supernova Legacy Survey and Joint Lightcurve Analysis to quantify SN Ia systematics, and by including a simultaneous fit of all SN Ia and Cepheid data. We find H_0 = 72.5 ± 3.1 ({stat}) ± 0.77 ({sys}) km s-1 Mpc-1with a three-galaxy (NGC 4258+LMC+MW) anchor. The relative uncertainties are 4.3 per cent statistical, 1.1 per cent systematic, and 4.4 per cent total, larger than in Riess et al. (2011) (3.3 per cent total) and the Efstathiou (2014) re-analysis (3.4 per cent total). Our error budget for H0 is dominated by statistical errors due to the small size of the SN sample, whilst the systematic contribution is dominated by variation in the Cepheid fits, and for the SNe Ia, uncertainties in the host galaxy mass dependence and Malmquist bias.

ON THE DEPENDENCE OF TYPE Ia SNe LUMINOSITIES ON THE METALLICITY OF THEIR HOST GALAXIES

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Moreno-Raya, Manuel E.; Mollá, Mercedes; López-Sánchez, Ángel R.; Galbany, Lluís; Vílchez, José Manuel; Rosell, Aurelio Carnero; Domínguez, Inmaculada

2016-01-01

The metallicity of the progenitor system producing a type Ia supernova (SN Ia) could play a role in its maximum luminosity, as suggested by theoretical predictions. We present an observational study to investigate if such a relationship exists. Using the 4.2 m William Herschel Telescope (WHT) we have obtained intermediate-resolution spectroscopy data of a sample of 28 local galaxies hosting SNe Ia, for which distances have been derived using methods independent of those based on SN Ia parameters. From the emission lines observed in their optical spectra, we derived the gas-phase oxygen abundance in the region where each SN Ia exploded. Our data show a trend, with an 80% of chance not being due to random fluctuation, between SNe Ia absolute magnitudes and the oxygen abundances of the host galaxies, in the sense that luminosities tend to be higher for galaxies with lower metallicities. This result seems likely to be in agreement with both the theoretically expected behavior and with other observational results. This dependence M B –Z might induce systematic errors when it is not considered when deriving SNe Ia luminosities and then using them to derive cosmological distances

The Influence of Host Galaxies in Type Ia Supernova Cosmology

Energy Technology Data Exchange (ETDEWEB)

Uddin, Syed A. [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing, Jiangshu (China); Mould, Jeremy [Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Melbourne, VIC (Australia); Lidman, Chris; Zhang, Bonnie R. [Australian Research Council Centre of Excellence for All-sky Astrophysics (CAASTRO) (Australia); Ruhlmann-Kleider, Vanina, E-mail: saushuvo@gmail.com [CEA, Centre de Saclay, Irfu/SPP, F-91191 Gif-sur-Yvette, Paris (France)

2017-10-10

We use a sample of 1338 spectroscopically confirmed and photometrically classified Type Ia supernovae (SNe Ia) sourced from Carnegie Supernova Project, Center for Astrophysics Supernova Survey, Sloan Digital Sky Survey-II, and SuperNova Legacy Survey SN samples to examine the relationships between SNe Ia and the galaxies that host them. Our results provide confirmation with improved statistical significance that SNe Ia, after standardization, are on average more luminous in massive hosts (significance >5 σ ), and decline more rapidly in massive hosts (significance >9 σ ) and in hosts with low specific star formation rates (significance >8 σ ). We study the variation of these relationships with redshift and detect no evolution. We split SNe Ia into pairs of subsets that are based on the properties of the hosts and fit cosmological models to each subset. Including both systematic and statistical uncertainties, we do not find any significant shift in the best-fit cosmological parameters between the subsets. Among different SN Ia subsets, we find that SNe Ia in hosts with high specific star formation rates have the least intrinsic scatter ( σ {sub int} = 0.08 ± 0.01) in luminosity after standardization.

Two populations of progenitors for Type Ia supernovae?

Science.gov (United States)

Mannucci, F.; Della Valle, M.; Panagia, N.

2006-08-01

We use recent observations of the evolution of the Type Ia supernova (SN Ia) rate with redshift, the dependence of the SN Ia rate on the colours of the parent galaxies, and the enhancement of the SN Ia rate in radio-loud early-type galaxies to derive on robust empirical grounds, the delay time distribution (DTD) between the formation of the progenitor star and its explosion as an SN. Our analysis finds: (i) delay times as long as 3-4 Gyr, derived from observations of SNe Ia at high redshift, cannot reproduce the dependence of the SN Ia rate on the colours and on the radio-luminosity of the parent galaxies, as observed in the local Universe; (ii) the comparison between observed SN rates and a grid of theoretical `single-population' DTDs shows that only a few of them are possibly consistent with observations. The most successful models are all predicting a peak of SN explosions soon after star formation and an extended tail in the DTD, and can reproduce the data but only at a modest statistical confidence level; (iii) present data are best matched by a bimodal DTD, in which about 50 per cent of SNe Ia (dubbed `prompt' SNe Ia) explode soon after their stellar birth, in a time of the order of 108 yr, while the remaining 50 per cent (`tardy' SNe Ia) have a much wider distribution, well described by an exponential function with a decay time of about 3 Gyr. The presence in the DTD of both a strong peak at early times and a prolonged exponential tail, coupled with the well-established bimodal distribution of the decay rate (Δm15) and the systematic difference observed in the expansion velocities of the ejecta of SNe Ia in ellipticals and spirals, suggests the existence of two classes of progenitors. We discuss the cosmological implications of this result and make simple predictions, which are testable with future instrumentation.

Type-Ia Supernova Rates to Redshift 2.4 from Clash: The Cluster Lensing and Supernova Survey with Hubble

Science.gov (United States)

Graur, O.; Rodney, S. A.; Maoz, D.; Riess, A. G.; Jha, S. W.; Postman, M.; Dahlen, T.; Holoien, T. W.-S.; McCully, C.; Patel, B.;

Testing ΛCDM at the lowest redshifts with SN Ia and galaxy velocities

Energy Technology Data Exchange (ETDEWEB)

Huterer, Dragan; Shafer, Daniel L. [Department of Physics, University of Michigan, 450 Church Street, Ann Arbor, MI 48109 (United States); Scolnic, Daniel M. [University of Chicago, Kavli Institute for Cosmological Physics, 5640 South Ellis Avenue, Chicago, IL 60637 (United States); Schmidt, Fabian, E-mail: huterer@umich.edu, E-mail: dshafer2@jhu.edu, E-mail: dscolnic@kicp.uchicago.edu, E-mail: fabians@mpa-garching.mpg.de [Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, 85748 Garching (Germany)

2017-05-01

Peculiar velocities of objects in the nearby universe are correlated due to the gravitational pull of large-scale structure. By measuring these velocities, we have a unique opportunity to test the cosmological model at the lowest redshifts. We perform this test, using current data to constrain the amplitude of the ''signal'' covariance matrix describing the velocities and their correlations. We consider a new, well-calibrated ''Supercal'' set of low-redshift SNe Ia as well as a set of distances derived from the fundamental plane relation of 6dFGS galaxies. Analyzing the SN and galaxy data separately, both results are consistent with the peculiar velocity signal of our fiducial ΛCDM model, ruling out the noise-only model with zero peculiar velocities at greater than 7σ (SNe) and 8σ (galaxies). When the two data sets are combined appropriately, the precision of the test increases slightly, resulting in a constraint on the signal amplitude of A = 1.05{sub −0.21}{sup +0.25}, where A = 1 corresponds to our fiducial model. Equivalently, we report an 11% measurement of the product of the growth rate and amplitude of mass fluctuations evaluated at z {sub eff} = 0.02, f σ{sub 8} = 0.428{sub −0.045}{sup +0.048}, valid for our fiducial ΛCDM model. We explore the robustness of the results to a number of conceivable variations in the analysis and find that individual variations shift the preferred signal amplitude by less than ∼0.5σ. We briefly discuss our Supercal SN Ia results in comparison with our previous results using the JLA compilation.

The Host Galaxies of Type Ia Supernovae Discovered by the Palomar Transient Factory

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Pan, Y.-C.; Sullivan, M.; McGuire, K.; Hook, I. M.; Nugent, P. E.; Howell, D. A.; Arcavi, I.; Botyanszki, J.; Cenko, Stephen Bradley; DeRose, J.

2013-01-01

We present spectroscopic observations of the host galaxies of 82 low-redshift type Ia supernovae (SNe Ia) discovered by the Palomar Transient Factory (PTF). We determine star-formation rates, gas-phase stellar metallicities, and stellar masses and ages of these objects. As expected, strong correlations between the SN Ia light-curve width (stretch) and the host age mass metallicity are found: fainter, faster-declining events tend to be hosted by older massive metal-rich galaxies. There is some evidence that redder SNe Ia explode in higher metallicity galaxies, but we found no relation between the SN colour and host galaxy extinction based on the Balmer decrement, suggesting that the colour variation of these SNe does not primarily arise from this source. SNe Ia in higher-mass metallicity galaxies also appear brighter after stretch colour corrections than their counterparts in lower mass hosts, and the stronger correlation is with gas-phase metallicity suggesting this may be the more important variable. We also compared the host stellar mass distribution to that in galaxy targeted SN surveys and the high-redshift untargeted Supernova Legacy Survey (SNLS). SNLS has many more low mass galaxies, while the targeted searches have fewer. This can be explained by an evolution in the galaxy stellar mass function, coupled with a SN delay-time distribution proportional to t1. Finally, we found no significant difference in the mass--metallicity relation of our SN Ia hosts compared to field galaxies, suggesting any metallicity effect on the SN Ia rate is small.

Photometry of High-Redshift Gravitationally Lensed Type Ia Supernovae

Science.gov (United States)

Haynie, Annastasia

2018-01-01

Out of more than 1100 well-identified Type Ia Supernovae, only roughly 10 of them are at z> 1.5. High redshift supernovae are hard to detect but this is made easier by taking advantage of the effects of gravitational lensing, which magnifies objects in the background field of massive galaxy clusters. Supernova Nebra (z= ~1.8), among others, was discovered during observations taken as part of the RELICS survey, which focused on fields of view that experience strong gravitational lensing effects. SN Nebra, which sits behind galaxy cluster Abell 1763, is magnified and therefore appears closer and easier to see than with HST alone. Studying high-redshift supernovae like SN Nebra is an important step towards creating cosmological models that accurately describe the behavior of dark energy in the early Universe. Recent efforts have been focused on improving photometry and the building and fitting of preliminary light curves.

REVEALING TYPE Ia SUPERNOVA PHYSICS WITH COSMIC RATES AND NUCLEAR GAMMA RAYS

International Nuclear Information System (INIS)

Horiuchi, Shunsaku; Beacom, John F.

2010-01-01

Type Ia supernovae (SNe Ia) remain mysterious despite their central importance in cosmology and their rapidly increasing discovery rate. The progenitors of SNe Ia can be probed by the delay time between progenitor birth and explosion as SNe Ia. The explosions and progenitors of SNe Ia can be probed by MeV nuclear gamma rays emitted in the decays of radioactive nickel and cobalt into iron. We compare the cosmic star formation and SN Ia rates, finding that their different redshift evolution requires a large fraction of SNe Ia to have large delay times. A delay-time distribution of the form t -α with α = 1.0 ± 0.3 provides a good fit, implying that 50% of SNe Ia explode more than ∼1 Gyr after progenitor birth. The extrapolation of the cosmic SN Ia rate to z = 0 agrees with the rate we deduce from catalogs of local SNe Ia. We investigate prospects for gamma-ray telescopes to exploit the facts that escaping gamma rays directly reveal the power source of SNe Ia and uniquely provide tomography of the expanding ejecta. We find large improvements relative to earlier studies by Gehrels et al. in 1987 and Timmes and Woosley in 1997 due to larger and more certain SN Ia rates and advances in gamma-ray detectors. The proposed Advanced Compton Telescope, with a narrow-line sensitivity ∼60 times better than that of current satellites, would, on an annual basis, detect up to ∼100 SNe Ia (3σ) and provide revolutionary model discrimination for SNe Ia within 20 Mpc, with gamma-ray light curves measured with ∼10σ significance daily for ∼100 days. Even more modest improvements in detector sensitivity would open a new and invaluable astronomy with frequent SN Ia gamma-ray detections.

A Second Ladder: Testing for Bias in the Type Ia Distance Scale with SBF

Science.gov (United States)

Milne, Peter

2016-10-01

We propose obtaining Surface Brightness Fluctuation (SBF) distances to the hosts galaxies of 20 nearby type Ia supernovae (SNe Ia), resulting in a sample of 29 SNe Ia in 27 galaxies when combined with HST-SBF distances from the literature. This sample can then be compared with the existing 18 SN Ia distances from Cepheids. Through these comparisons, we will determine if there are any discrepancies between the SBF distance scale, which is extended into the Hubble flow using early-type galaxies, and the SNIa distance scale, for which local calibrators are scarce and host galaxy types and SN environments are heterogenous. Since recent measurements of UV-optical colors suggest that SN Ia properties do depend on galaxy type and environment, it is essential that SNe Ia in all galaxy types are included when extending SN Ia distances to the distant Hubble flow. Since the conclusion that universal expansion is accelerating was originally based on SNe Ia distances, and because recent measurements of UV-optical colors suggest that SN Ia properties do depend on galaxy type and environment, it is essential to measure the same types of SNe in the same types of galaxies. To meet this goal, we propose to measure high-precision SBF distances to all early-type galaxies that have hosted SNIa within 80 Mpc. We will therefore be able to distinguish between systematic offsets in the derived Hubble constant between galaxies and/or SNe of different types and correct for them. SBF is the only distance measurement technique with statistical uncertainties comparable to SN Ia that can be applied to the early-type of galaxies in which the majority of the high-redshift SNIa occur.

Fitting and Phenomenology in Type IA Supernova Cosmology: Generalized Likelihood Analyses for Multiple Evolving Populations and Observations of Near-Infrared Lightcurves Including Host Galaxy Properties

Science.gov (United States)

Ponder, Kara A.

In the late 1990s, Type Ia supernovae (SNeIa) led to the discovery that the Universe is expanding at an accelerating rate due to dark energy. Since then, many different tracers of acceleration have been used to characterize dark energy, but the source of cosmic acceleration has remained a mystery. To better understand dark energy, future surveys such as the ground-based Large Synoptic Survey Telescope and the space-based Wide-Field Infrared Survey Telescope will collect thousands of SNeIa to use as a primary dark energy probe. These large surveys will be systematics limited, which makes it imperative for our insight regarding systematics to dramatically increase over the next decade for SNeIa to continue to contribute to precision cosmology. I approach this problem by improving statistical methods in the likelihood analysis and collecting near infrared (NIR) SNeIa with their host galaxies to improve the nearby data set and search for additional systematics. Using more statistically robust methods to account for systematics within the likelihood function can increase accuracy in cosmological parameters with a minimal precision loss. Though a sample of at least 10,000 SNeIa is necessary to confirm multiple populations of SNeIa, the bias in cosmology is ˜ 2 sigma with only 2,500 SNeIa. This work focused on an example systematic (host galaxy correlations), but it can be generalized for any systematic that can be represented by a distribution of multiple Gaussians. The SweetSpot survey gathered 114 low-redshift, NIR SNeIa that will act as a crucial anchor sample for the future high redshift surveys. NIR observations are not as affected by dust contamination, which may lead to increased understanding of systematics seen in optical wavelengths. We obtained spatially resolved spectra for 32 SweetSpot host galaxies to test for local host galaxy correlations. For the first time, we probe global host galaxy correlations with NIR brightnesses from the current literature

The type Ia supernova SNLS-03D3bb from a super-Chandrasekhar-masswhite dwarf star

Energy Technology Data Exchange (ETDEWEB)

Howell, D.Andrew; Sullivan, Mark; Nugent, Peter E.; Ellis,Richard S.; Conley, Alexander J.; Le Borgne, Damien; Carlberg, RaymondG.; Guy, Julien; Balam, David; Basa, Stephane; Fouchez, Dominique; Hook,Isobel M.; Hsiao, Eric Y.; Neill, James D.; Pain, Reynald; Perrett,Kathryn M.; Pritchet, Christopher J.

2006-02-01

The acceleration of the expansion of the universe, and theneed for Dark Energy, were inferred from the observations of Type Iasupernovae (SNe Ia) 1;2. There is consensus that SNeIa are thermonuclearexplosions that destroy carbon-oxygen white dwarf stars that accretematter from a companion star3, although the nature of this companionremains uncertain. SNe Ia are thought to be reliable distance indicatorsbecause they have a standard amount of fuel and a uniform trigger theyare predicted to explode when the mass of the white dwarf nears theChandrasekhar mass 4 - 1.4 solar masses. Here we show that the highredshift supernova SNLS-03D3bb has an exceptionally high luminosity andlow kinetic energy that both imply a super-Chandrasekhar mass progenitor.Super-Chandrasekhar mass SNeIa shouldpreferentially occur in a youngstellar population, so this may provide an explanation for the observedtrend that overluminous SNe Ia only occur in young environments5;6. Sincethis supernova does not obey the relations that allow them to becalibrated as standard candles, and since no counterparts have been foundat low redshift, future cosmology studies will have to considercontamination from such events.

Photometric classification and redshift estimation of LSST Supernovae

Science.gov (United States)

Dai, Mi; Kuhlmann, Steve; Wang, Yun; Kovacs, Eve

2018-04-01

Supernova (SN) classification and redshift estimation using photometric data only have become very important for the Large Synoptic Survey Telescope (LSST), given the large number of SNe that LSST will observe and the impossibility of spectroscopically following up all the SNe. We investigate the performance of a SN classifier that uses SN colors to classify LSST SNe with the Random Forest classification algorithm. Our classifier results in an AUC of 0.98 which represents excellent classification. We are able to obtain a photometric SN sample containing 99% SNe Ia by choosing a probability threshold. We estimate the photometric redshifts (photo-z) of SNe in our sample by fitting the SN light curves using the SALT2 model with nested sampling. We obtain a mean bias () of 0.012 with σ ( z_phot-z_spec/1+z_spec) = 0.0294 without using a host-galaxy photo-z prior, and a mean bias () of 0.0017 with σ ( z_phot-z_spec/1+z_spec) = 0.0116 using a host-galaxy photo-z prior. Assuming a flat ΛCDM model with Ωm = 0.3, we obtain Ωm of 0.305 ± 0.008 (statistical errors only), using the simulated LSST sample of photometric SNe Ia (with intrinsic scatter σint = 0.11) derived using our methodology without using host-galaxy photo-z prior. Our method will help boost the power of SNe from the LSST as cosmological probes.

Conformal cosmological model and SNe Ia data

International Nuclear Information System (INIS)

Zakharov, A. F.; Pervushin, V. N.

2012-01-01

Now there is a huge scientific activity in astrophysical studies and cosmological ones in particular. Cosmology transforms from a pure theoretical branch of science into an observational one. All the cosmological models have to pass observational tests. The supernovae type Ia (SNe Ia) test is among the most important ones. If one applies the test to determine parameters of the standard Friedmann-Robertson-Walker cosmological model one can conclude that observations lead to the discovery of the dominance of the Λ term and as a result to an acceleration of the Universe. However, there are big mysteries connected with an origin and an essence of dark matter (DM) and the Λ term or dark energy (DE). Alternative theories of gravitation are treated as a possible solution of DM and DE puzzles. The conformal cosmological approach is one of possible alternatives to the standard ΛCDM model. As it was noted several years ago, in the framework of the conformal cosmological approach an introduction of a rigid matter can explain observational data without Λ term (or dark energy). We confirm the claim with much larger set of observational data.

HUBBLE RESIDUALS OF NEARBY TYPE Ia SUPERNOVAE ARE CORRELATED WITH HOST GALAXY MASSES

International Nuclear Information System (INIS)

Kelly, Patrick L.; Burke, David L.; Hicken, Malcolm; Mandel, Kaisey S.; Kirshner, Robert P.

2010-01-01

From Sloan Digital Sky Survey u'g'r'i'z' imaging, we estimate the stellar masses of the host galaxies of 70 low-redshift Type Ia supernovae (SNe Ia, 0.015 10.8 M sun in a cosmology fit yields 1 + w = 0.22 +0.152 -0.108 , while a combination where the 30 nearby SNe instead have host masses greater than 10 10.8 M sun yields 1 + w = -0.03 +0.217 -0.143 . Progenitor metallicity, stellar population age, and dust extinction correlate with galaxy mass and may be responsible for these systematic effects. Host galaxy measurements will yield improved distances to SNe Ia.

LUMINOSITY FUNCTIONS OF TYPE Ia SUPERNOVAE AND THEIR HOST GALAXIES FROM THE SLOAN DIGITAL SKY SURVEY

International Nuclear Information System (INIS)

Yasuda, Naoki; Fukugita, Masataka

2010-01-01

The sample of 137 low-redshift type Ia supernovae (SNe Ia) with 0.05 ≤ z ≤ 0.3 obtained from the Sloan Digital Sky Survey (SDSS)-II supernova survey for the southern equatorial stripe of 300 deg 2 is used to derive the luminosity functions (LFs) of SNe Ia and of their host galaxies in the g, r, i passbands. We show that the LF of SNe Ia host galaxies matches well with that of galaxies in the general field, suggesting that the occurrence of SNe Ia does not favor a particular type of galaxy but is predominantly proportional to the luminosity of galaxies. The evidence is weak that the SNe rate varies with the color of host galaxies. The only evidence that points to possible correlation between the SN rate and star formation activity is that the SN rate in late-type galaxies is higher than that in early-type galaxies by 31% ± 35%. In our low-redshift sample, the component of type Ia SN rate that is proportional to star formation activity is not evident in the integrated SN rate, while our observation is compatible with the current two-component models. The sample contains eight SNe Ia whose host galaxies were not identified, but it is shown that their occurrence is consistent with them occurring in low-luminous galaxies beyond the survey. The LF of SNe Ia is approximately Gaussian with the full width at half-maximum being a factor of σ = 0.24 mag or 1.67 in luminosity. The Gaussian distribution becomes tighter if the ratio of extinction to reddening, R V , is lower than the characteristic value for the Milky Way and if luminosity is corrected for the light-curve shape. The average color excess is ∼0.07 mag, which is significantly smaller than reddening expected for field galaxies. This color excess does not vary with the distance of the SNe from the center of the host galaxy to 15 kpc. This suggests that the major part of the color excess appears to be either intrinsic or reddening that arises in the immediate environment of SNe, rather than interstellar

EVOLUTION IN THE VOLUMETRIC TYPE Ia SUPERNOVA RATE FROM THE SUPERNOVA LEGACY SURVEY

Energy Technology Data Exchange (ETDEWEB)

Perrett, K.; Gonzalez-Gaitan, S.; Carlberg, R. [Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON, M5S 3H4 (Canada); Sullivan, M.; Hook, I. M. [Department of Physics (Astrophysics), University of Oxford, DWB, Keble Road, Oxford OX1 3RH (United Kingdom); Conley, A. [Center for Astrophysics and Space Astronomy, University of Colorado, 593 UCB, Boulder, CO 80309-0593 (United States); Fouchez, D. [CPPM, CNRS-IN2P3 and University Aix Marseille II, Case 907, 13288 Marseille cedex 9 (France); Ripoche, P. [Lawrence Berkeley National Laboratory, Mail Stop 50-232, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Neill, J. D. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, 1200 East California Blvd., Pasadena, CA 91125 (United States); Astier, P.; Balland, C.; Guy, J.; Hardin, D.; Pain, R.; Regnault, N. [LPNHE, Universite Pierre et Marie Curie Paris 6, Universite Paris Diderot Paris 7, CNRS-IN2P3, 4 place Jussieu, 75005 Paris (France); Balam, D. [Dominion Astrophysical Observatory, Herzberg Institute of Astrophysics, 5071 West Saanich Road, Victoria, BC, V9E 2E7 (Canada); Basa, S. [Laboratoire d' Astrophysique de Marseille, Pole de l' Etoile Site de Chateau-Gombert, 38, rue Frederic Joliot-Curie, 13388 Marseille cedex 13 (France); Howell, D. A. [Las Cumbres Observatory Global Telescope Network, 6740 Cortona Dr., Suite 102, Goleta, CA 93117 (United States); Palanque-Delabrouille, N. [DSM/IRFU/SPP, CEA-Saclay, F-91191 Gif-sur-Yvette (France); Pritchet, C., E-mail: perrett@astro.utoronto.ca, E-mail: sullivan@astro.ox.ac.uk [Department of Physics and Astronomy, University of Victoria, P.O. Box 3055, Stn CSC, Victoria, BC, V8W 3P6 (Canada); and others

2012-08-15

We present a measurement of the volumetric Type Ia supernova (SN Ia) rate (SNR{sub Ia}) as a function of redshift for the first four years of data from the Canada-France-Hawaii Telescope Supernova Legacy Survey (SNLS). This analysis includes 286 spectroscopically confirmed and more than 400 additional photometrically identified SNe Ia within the redshift range 0.1 {<=} z {<=} 1.1. The volumetric SNR{sub Ia} evolution is consistent with a rise to z {approx} 1.0 that follows a power law of the form (1+z){sup {alpha}}, with {alpha} = 2.11 {+-} 0.28. This evolutionary trend in the SNLS rates is slightly shallower than that of the cosmic star formation history (SFH) over the same redshift range. We combine the SNLS rate measurements with those from other surveys that complement the SNLS redshift range, and fit various simple SN Ia delay-time distribution (DTD) models to the combined data. A simple power-law model for the DTD (i.e., {proportional_to}t{sup -{beta}}) yields values from {beta} = 0.98 {+-} 0.05 to {beta} = 1.15 {+-} 0.08 depending on the parameterization of the cosmic SFH. A two-component model, where SNR{sub Ia} is dependent on stellar mass (M{sub stellar}) and star formation rate (SFR) as SNR{sub Ia}(z) = A Multiplication-Sign M{sub stellar}(z) + B Multiplication-Sign SFR(z), yields the coefficients A = (1.9 {+-} 0.1) Multiplication-Sign 10{sup -14} SNe yr{sup -1} M{sup -1}{sub Sun} and B = (3.3 {+-} 0.2) Multiplication-Sign 10{sup -4} SNe yr{sup -1} (M{sub Sun} yr{sup -1}){sup -1}. More general two-component models also fit the data well, but single Gaussian or exponential DTDs provide significantly poorer matches. Finally, we split the SNLS sample into two populations by the light-curve width (stretch), and show that the general behavior in the rates of faster-declining SNe Ia (0.8 {<=} s < 1.0) is similar, within our measurement errors, to that of the slower objects (1.0 {<=} s < 1.3) out to z {approx} 0.8.

Pre-nebular Light Curves of SNe I

Energy Technology Data Exchange (ETDEWEB)

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

2017-09-01

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

Discovering the Nature of Dark Energy: Towards Better Distances from Type Ia Supernovae -- Final Technical Report

Energy Technology Data Exchange (ETDEWEB)

Filippenko, Alexei Vladimir [Univ. of California, Berkeley, CA (United States)

2014-05-09

Type Ia supernovae (SNe Ia; exploding white-dwarf stars) were the key to the Nobel-worthy 1998 discovery and subsequent verification that the expansion of the Universe is accelerating, driven by the effects of dark energy. Understanding the nature of this mysterious, yet dominant, component of the Universe is at the forefront of research in cosmology and fundamental physics. SNe Ia will continue to play a leading role in this enterprise, providing precise cosmological distances that improve constraints on the nature of dark energy. However, for this effort to succeed, we need to more thoroughly understand relatively nearby SNe Ia, because our conclusions come only from comparisons between them and distant (high-redshift) SNe Ia. Thus, detailed studies of relatively nearby SNe Ia are the focus of this research program. Many interesting results were obtained during the course of this project; these were published in 32 refereed research papers that acknowledged the grant. A major accomplishment was the publication of supernova (SN) rates derived from about a decade of operation of the Lick Observatory Supernova Search (LOSS) with the 0.76-meter Katzman Automatic Imaging Telescope (KAIT). We have determined the most accurate rates for SNe of different types in large, nearby galaxies in the present-day Universe, and these can be compared with SN rates far away (and hence long ago in the past) to set constraints on the types of stars that explode. Another major accomplishment was the publication of the light curves (brightness vs. time) of 165 SNe Ia, along with optical spectroscopy of many of these SNe as well as other SNe Ia, providing an extensive, homogeneous database for detailed studies. We have conducted intensive investigations of a number of individual SNe Ia, including quite unusual examples that allow us to probe the entire range of SN explosions and provide unique insights into these objects and the stars before they explode. My team's studies have also

Type Ia supernovae, standardizable candles, and gravity

Science.gov (United States)

Wright, Bill S.; Li, Baojiu

2018-04-01

Type Ia supernovae (SNe Ia) are generally accepted to act as standardizable candles, and their use in cosmology led to the first confirmation of the as yet unexplained accelerated cosmic expansion. Many of the theoretical models to explain the cosmic acceleration assume modifications to Einsteinian general relativity which accelerate the expansion, but the question of whether such modifications also affect the ability of SNe Ia to be standardizable candles has rarely been addressed. This paper is an attempt to answer this question. For this we adopt a semianalytical model to calculate SNe Ia light curves in non-standard gravity. We use this model to show that the average rescaled intrinsic peak luminosity—a quantity that is assumed to be constant with redshift in standard analyses of Type Ia supernova (SN Ia) cosmology data—depends on the strength of gravity in the supernova's local environment because the latter determines the Chandrasekhar mass—the mass of the SN Ia's white dwarf progenitor right before the explosion. This means that SNe Ia are no longer standardizable candles in scenarios where the strength of gravity evolves over time, and therefore the cosmology implied by the existing SN Ia data will be different when analysed in the context of such models. As an example, we show that the observational SN Ia cosmology data can be fitted with both a model where (ΩM,ΩΛ)=(0.62 ,0.38 ) and Newton's constant G varies as G (z )=G0(1 +z )-1/4 and the standard model where (ΩM,ΩΛ)=(0.3 ,0.7 ) and G is constant, when the Universe is assumed to be flat.

Photometric classification of type Ia supernovae in the SuperNova Legacy Survey with supervised learning

Energy Technology Data Exchange (ETDEWEB)

Möller, A. [Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611 (Australia); Ruhlmann-Kleider, V.; Leloup, C.; Neveu, J.; Palanque-Delabrouille, N.; Rich, J. [Irfu, SPP, CEA Saclay, F-91191 Gif sur Yvette Cedex (France); Carlberg, R. [Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H8 (Canada); Lidman, C. [Australian Astronomical Observatory, North Ryde, NSW 2113 (Australia); Pritchet, C., E-mail: anais.moller@anu.edu.au, E-mail: vanina.ruhlmann-kleider@cea.fr, E-mail: clement.leloup@cea.fr, E-mail: jneveu@lal.in2p3.fr, E-mail: nathalie.palanque-delabrouille@cea.fr, E-mail: james.rich@cea.fr, E-mail: raymond.carlberg@utoronto.ca, E-mail: chris.lidman@aao.gov.au, E-mail: pritchet@uvic.ca [Department of Physics and Astronomy, University of Victoria, P.O. Box 3055, Victoria, BC V8W 3P6 (Canada)

2016-12-01

In the era of large astronomical surveys, photometric classification of supernovae (SNe) has become an important research field due to limited spectroscopic resources for candidate follow-up and classification. In this work, we present a method to photometrically classify type Ia supernovae based on machine learning with redshifts that are derived from the SN light-curves. This method is implemented on real data from the SNLS deferred pipeline, a purely photometric pipeline that identifies SNe Ia at high-redshifts (0.2 < z < 1.1). Our method consists of two stages: feature extraction (obtaining the SN redshift from photometry and estimating light-curve shape parameters) and machine learning classification. We study the performance of different algorithms such as Random Forest and Boosted Decision Trees. We evaluate the performance using SN simulations and real data from the first 3 years of the Supernova Legacy Survey (SNLS), which contains large spectroscopically and photometrically classified type Ia samples. Using the Area Under the Curve (AUC) metric, where perfect classification is given by 1, we find that our best-performing classifier (Extreme Gradient Boosting Decision Tree) has an AUC of 0.98.We show that it is possible to obtain a large photometrically selected type Ia SN sample with an estimated contamination of less than 5%. When applied to data from the first three years of SNLS, we obtain 529 events. We investigate the differences between classifying simulated SNe, and real SN survey data. In particular, we find that applying a thorough set of selection cuts to the SN sample is essential for good classification. This work demonstrates for the first time the feasibility of machine learning classification in a high- z SN survey with application to real SN data.

Photometric classification of type Ia supernovae in the SuperNova Legacy Survey with supervised learning

International Nuclear Information System (INIS)

Möller, A.; Ruhlmann-Kleider, V.; Leloup, C.; Neveu, J.; Palanque-Delabrouille, N.; Rich, J.; Carlberg, R.; Lidman, C.; Pritchet, C.

2016-01-01

In the era of large astronomical surveys, photometric classification of supernovae (SNe) has become an important research field due to limited spectroscopic resources for candidate follow-up and classification. In this work, we present a method to photometrically classify type Ia supernovae based on machine learning with redshifts that are derived from the SN light-curves. This method is implemented on real data from the SNLS deferred pipeline, a purely photometric pipeline that identifies SNe Ia at high-redshifts (0.2 < z < 1.1). Our method consists of two stages: feature extraction (obtaining the SN redshift from photometry and estimating light-curve shape parameters) and machine learning classification. We study the performance of different algorithms such as Random Forest and Boosted Decision Trees. We evaluate the performance using SN simulations and real data from the first 3 years of the Supernova Legacy Survey (SNLS), which contains large spectroscopically and photometrically classified type Ia samples. Using the Area Under the Curve (AUC) metric, where perfect classification is given by 1, we find that our best-performing classifier (Extreme Gradient Boosting Decision Tree) has an AUC of 0.98.We show that it is possible to obtain a large photometrically selected type Ia SN sample with an estimated contamination of less than 5%. When applied to data from the first three years of SNLS, we obtain 529 events. We investigate the differences between classifying simulated SNe, and real SN survey data. In particular, we find that applying a thorough set of selection cuts to the SN sample is essential for good classification. This work demonstrates for the first time the feasibility of machine learning classification in a high- z SN survey with application to real SN data.

Type-Ia Supernova Rates and the Progenitor Problem: A Review

Science.gov (United States)

Maoz, D.; Mannucci, F.

2012-01-01

The identity of the progenitor systems of type-Ia supernovae (SNe Ia) is a major unsolved problem in astrophysics. SN Ia rates are providing some striking clues. We review the basics of SN rate measurement, preach about some sins of SN rate measurement and analysis, and illustrate one of these sins with an analogy about Martian scientists. We review the recent progress in measuring SN Ia rates in various environments and redshifts, and their use to reconstruct the SN Ia delay-time distribution (DTD) - the SN rate versus time that would follow a hypothetical brief burst of star formation. A good number of DTD measurements, using a variety of methods, appear to be converging. At delays 1measurements show a similar, ~t-1, power-law shape. The DTD peaks at the shortest delays probed. This result supports the idea of a double-degenerate progenitor origin for SNe Ia. Single-degenerate progenitors may still play a role in producing short-delay SNe Ia, or perhaps all SNe Ia, if the red-giant donor channel is more efficient than is found by most theoretical models. The DTD normalization enjoys fairly good agreement (though perhaps some tension), among the various measurements, with a Hubble time-integrated DTD value of about 2+/-1 SNe Ia per 1000Msolar (stellar mass formed with a low-mass turnover initial mass function). The local WD binary population suggests that the WD merger rate can explain the Galactic SN Ia rate, but only if sub-Chandra mergers lead to SN Ia events. We point to some future directions that should lead to progress in the field, including measurement of the bivariate (delay and stretch) SN Ia response function.

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

International Nuclear Information System (INIS)

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

2011-01-01

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

Constraining cosmological parameter with SN Ia

International Nuclear Information System (INIS)

Putri, A N Indra; Wulandari, H R Tri

2016-01-01

A type I supemovae (SN Ia) is an exploding white dwarf, whose mass exceeds Chandrasekar limit (1.44 solar mass). If a white dwarf is in a binary system, it may accrete matter from the companion, resulting in an excess mass that cannot be balanced by the pressure of degenerated electrons in the core. SNe Ia are highly luminous objects, that they are visible from very high distances. After some corrections (stretch (s), colour (c), K-corrections, etc.), the variations in the light curves of SNe Ia can be suppressed to be no more than 10%. Their high luminosity and almost uniform intrinsic brightness at the peak light, i.e. M B ∼ -19, make SNe Ia ideal standard candle. Because of their visibility from large distances, SNe Ia can be employed as a cosmological measuring tool. It was analysis of SNe Ia data that indicated for the first time, that the universe is not only expanding, but also accelerating. This work analyzed a compilation of SNe Ia data to determine several cosmological parameters (H 0 , Ω m , Ω a , and w ). It can be concluded from the analysis, that our universe is a flat, dark energy dominated universe, and that the cosmological constant A is a suitable candidate for dark energy. (paper)

SPECTROSCOPY OF TYPE Ia SUPERNOVAE BY THE CARNEGIE SUPERNOVA PROJECT

International Nuclear Information System (INIS)

Folatelli, Gastón; Morrell, Nidia; Phillips, Mark M.; Hsiao, Eric; Campillay, Abdo; Contreras, Carlos; Castellón, Sergio; Roth, Miguel; Hamuy, Mario; Anderson, Joseph P.; Krzeminski, Wojtek; Stritzinger, Maximilian; Burns, Christopher R.; Freedman, Wendy L.; Madore, Barry F.; Murphy, David; Persson, S. E.; Prieto, José L.; Suntzeff, Nicholas B.; Krisciunas, Kevin

2013-01-01

This is the first release of optical spectroscopic data of low-redshift Type Ia supernovae (SNe Ia) by the Carnegie Supernova Project including 604 previously unpublished spectra of 93 SNe Ia. The observations cover a range of phases from 12 days before to over 150 days after the time of B-band maximum light. With the addition of 228 near-maximum spectra from the literature, we study the diversity among SNe Ia in a quantitative manner. For that purpose, spectroscopic parameters are employed such as expansion velocities from spectral line blueshifts and pseudo-equivalent widths (pW). The values of those parameters at maximum light are obtained for 78 objects, thus providing a characterization of SNe Ia that may help to improve our understanding of the properties of the exploding systems and the thermonuclear flame propagation. Two objects, namely, SNe 2005M and 2006is, stand out from the sample by showing peculiar Si II and S II velocities but otherwise standard velocities for the rest of the ions. We further study the correlations between spectroscopic and photometric parameters such as light-curve decline rate and color. In agreement with previous studies, we find that the pW of Si II absorption features are very good indicators of light-curve decline rate. Furthermore, we demonstrate that parameters such as pW2 (Si II 4130) and pW6 (Si II 5972) provide precise calibrations of the peak B-band luminosity with dispersions of ≈0.15 mag. In the search for a secondary parameter in the calibration of peak luminosity for SNe Ia, we find a ≈2σ-3σ correlation between B-band Hubble residuals and the velocity at maximum light of S II and Si II lines

SPECTROSCOPY OF TYPE Ia SUPERNOVAE BY THE CARNEGIE SUPERNOVA PROJECT

Energy Technology Data Exchange (ETDEWEB)

Folatelli, Gaston [Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU, WPI), Todai Institutes for Advanced Study, the University of Tokyo, 277-8583 Kashiwa (Japan); Morrell, Nidia; Phillips, Mark M.; Hsiao, Eric; Campillay, Abdo; Contreras, Carlos; Castellon, Sergio; Roth, Miguel [Las Campanas Observatory, Carnegie Observatories, Casilla 601, La Serena (Chile); Hamuy, Mario; Anderson, Joseph P. [Departamento de Astronomia, Universidad de Chile, Casilla 36-D, Santiago (Chile); Krzeminski, Wojtek [N. Copernicus Astronomical Center, ul. Bartycka 18, 00-716 Warszawa (Poland); Stritzinger, Maximilian [Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C (Denmark); Burns, Christopher R.; Freedman, Wendy L.; Madore, Barry F.; Murphy, David; Persson, S. E. [Observatories of the Carnegie Institution of Washington, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Prieto, Jose L. [Department of Astrophysical Sciences, Princeton University, 4 Ivy Ln., Princeton, NJ 08544 (United States); Suntzeff, Nicholas B.; Krisciunas, Kevin, E-mail: gaston.folatelli@ipmu.jp [George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics and Astronomy, Texas A and M University, College Station, TX 77843 (United States); and others

2013-08-10

This is the first release of optical spectroscopic data of low-redshift Type Ia supernovae (SNe Ia) by the Carnegie Supernova Project including 604 previously unpublished spectra of 93 SNe Ia. The observations cover a range of phases from 12 days before to over 150 days after the time of B-band maximum light. With the addition of 228 near-maximum spectra from the literature, we study the diversity among SNe Ia in a quantitative manner. For that purpose, spectroscopic parameters are employed such as expansion velocities from spectral line blueshifts and pseudo-equivalent widths (pW). The values of those parameters at maximum light are obtained for 78 objects, thus providing a characterization of SNe Ia that may help to improve our understanding of the properties of the exploding systems and the thermonuclear flame propagation. Two objects, namely, SNe 2005M and 2006is, stand out from the sample by showing peculiar Si II and S II velocities but otherwise standard velocities for the rest of the ions. We further study the correlations between spectroscopic and photometric parameters such as light-curve decline rate and color. In agreement with previous studies, we find that the pW of Si II absorption features are very good indicators of light-curve decline rate. Furthermore, we demonstrate that parameters such as pW2 (Si II 4130) and pW6 (Si II 5972) provide precise calibrations of the peak B-band luminosity with dispersions of Almost-Equal-To 0.15 mag. In the search for a secondary parameter in the calibration of peak luminosity for SNe Ia, we find a Almost-Equal-To 2{sigma}-3{sigma} correlation between B-band Hubble residuals and the velocity at maximum light of S II and Si II lines.

The cosmic transparency measured with Type Ia supernovae: implications for intergalactic dust

Science.gov (United States)

Goobar, Ariel; Dhawan, Suhail; Scolnic, Daniel

2018-04-01

Observations of high-redshift Type Ia supernovae (SNe Ia) are used to study the cosmic transparency at optical wavelengths. Assuming a flat ΛCDM cosmological model based on BAO and CMB results, redshift dependent deviations of SN Ia distances are used to constrain mechanisms that would dim light. The analysis is based on the most recent Pantheon SN compilation, for which there is a 0.03± 0.01 {(stat)} mag discrepancy in the distant supernova distance moduli relative to the ΛCDM model anchored by supernovae at z measurements can be modeled with a cosmic dust density Ω _IGM^dust = 8 \\cdot 10^{-5} (1+z)^{-1}, corresponding to an average attenuation of 2 . 10-5 mag Mpc-1 in V-band. Forthcoming SN Ia studies may provide a definitive measurement of the IGM dust properties, while still providing an unbiased estimate of cosmological parameters by introducing additional parameters in the global fits to the observations.

EVIDENCE FOR A CORRELATION BETWEEN THE Si II λ4000 WIDTH AND TYPE Ia SUPERNOVA COLOR

International Nuclear Information System (INIS)

Nordin, J.; Oestman, L.; Goobar, A.; Balland, C.; Lampeitl, H.; Nichol, R. C.; Sako, M.; Schneider, D. P.; Smith, M.; Sollerman, J.; Wheeler, J. C.

2011-01-01

We study the pseudo-equivalent width of the Si II λ4000 feature of Type Ia supernovae (SNe Ia) in the redshift range 0.0024 ≤ z ≤ 0.634. We find that this spectral indicator correlates with the light curve color excess (SALT2c) as well as previously defined spectroscopic subclasses (Branch types) and the evolution of the Si II λ6150 velocity, i.e., the so-called velocity gradient. Based on our study of 55 objects from different surveys, we find indications that the Si II λ4000 spectral indicator could provide important information to improve cosmological distance measurements with SNe Ia.

A TYPE Ia SUPERNOVA AT REDSHIFT 1.55 IN HUBBLE SPACE TELESCOPE INFRARED OBSERVATIONS FROM CANDELS

International Nuclear Information System (INIS)

Rodney, Steven A.; Riess, Adam G.; Jones, David O.; Dahlen, Tomas; Ferguson, Henry C.; Casertano, Stefano; Grogin, Norman A.; Strolger, Louis-Gregory; Hjorth, Jens; Frederiksen, Teddy F.; Weiner, Benjamin J.; Mobasher, Bahram; Challis, Peter; Kirshner, Robert P.; Faber, S. M.; Filippenko, Alexei V.; Garnavich, Peter; Hayden, Brian; Graur, Or; Jha, Saurabh W.

2012-01-01

We report the discovery of a Type Ia supernova (SN Ia) at redshift z = 1.55 with the infrared detector of the Wide Field Camera 3 (WFC3-IR) on the Hubble Space Telescope (HST). This object was discovered in CANDELS imaging data of the Hubble Ultra Deep Field and followed as part of the CANDELS+CLASH Supernova project, comprising the SN search components from those two HST multi-cycle treasury programs. This is the highest redshift SN Ia with direct spectroscopic evidence for classification. It is also the first SN Ia at z > 1 found and followed in the infrared, providing a full light curve in rest-frame optical bands. The classification and redshift are securely defined from a combination of multi-band and multi-epoch photometry of the SN, ground-based spectroscopy of the host galaxy, and WFC3-IR grism spectroscopy of both the SN and host. This object is the first of a projected sample at z > 1.5 that will be discovered by the CANDELS and CLASH programs. The full CANDELS+CLASH SN Ia sample will enable unique tests for evolutionary effects that could arise due to differences in SN Ia progenitor systems as a function of redshift. This high-z sample will also allow measurement of the SN Ia rate out to z ≈ 2, providing a complementary constraint on SN Ia progenitor models.

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

International Nuclear Information System (INIS)

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

2014-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2014-08-29

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

THE TYPE Ia SUPERNOVA RATE IN RADIO AND INFRARED GALAXIES FROM THE CANADA-FRANCE-HAWAII TELESCOPE SUPERNOVA LEGACY SURVEY

International Nuclear Information System (INIS)

Graham, M. L.; Pritchet, C. J.; Balam, D.; Fabbro, S.; Sullivan, M.; Hook, I. M.; Howell, D. A.; Gwyn, S. D. J.; Astier, P.; Balland, C.; Guy, J.; Hardin, D.; Pain, R.; Regnault, N.; Basa, S.; Carlberg, R. G.; Perrett, K.; Conley, A.; Fouchez, D.; Rich, J.

2010-01-01

We have combined the large SN Ia database of the Canada-France-Hawaii Telescope Supernova Legacy Survey and catalogs of galaxies with photometric redshifts, Very Large Array 1.4 GHz radio sources, and Spitzer infrared sources. We present eight SNe Ia in early-type host galaxies which have counterparts in the radio and infrared source catalogs. We find the SN Ia rate in subsets of radio and infrared early-type galaxies is ∼1-5 times the rate in all early-type galaxies, and that any enhancement is always ∼<2σ. Rates in these subsets are consistent with predictions of the two-component 'A+B' SN Ia rate model. Since infrared properties of radio SN Ia hosts indicate dust-obscured star formation, we incorporate infrared star formation rates into the 'A+B' model. We also show the properties of SNe Ia in radio and infrared galaxies suggest the hosts contain dust and support a continuum of delay time distributions (DTDs) for SNe Ia, although other DTDs cannot be ruled out based on our data.

Understanding type Ia supernovae through their U-band spectra

Science.gov (United States)

Nordin, J.; Aldering, G.; Antilogus, P.; Aragon, C.; Bailey, S.; Baltay, C.; Barbary, K.; Bongard, S.; Boone, K.; Brinnel, V.; Buton, C.; Childress, M.; Chotard, N.; Copin, Y.; Dixon, S.; Fagrelius, P.; Feindt, U.; Fouchez, D.; Gangler, E.; Hayden, B.; Hillebrandt, W.; Kim, A.; Kowalski, M.; Kuesters, D.; Leget, P.-F.; Lombardo, S.; Lin, Q.; Pain, R.; Pecontal, E.; Pereira, R.; Perlmutter, S.; Rabinowitz, D.; Rigault, M.; Runge, K.; Rubin, D.; Saunders, C.; Smadja, G.; Sofiatti, C.; Suzuki, N.; Taubenberger, S.; Tao, C.; Thomas, R. C.; Nearby Supernova Factory

2018-06-01

Context. Observations of type Ia supernovae (SNe Ia) can be used to derive accurate cosmological distances through empirical standardization techniques. Despite this success neither the progenitors of SNe Ia nor the explosion process are fully understood. The U-band region has been less well observed for nearby SNe, due to technical challenges, but is the most readily accessible band for high-redshift SNe. Aims: Using spectrophotometry from the Nearby Supernova Factory, we study the origin and extent of U-band spectroscopic variations in SNe Ia and explore consequences for their standardization and the potential for providing new insights into the explosion process. Methods: We divide the U-band spectrum into four wavelength regions λ(uNi), λ(uTi), λ(uSi) and λ(uCa). Two of these span the Ca H&K λλ 3934, 3969 complex. We employ spectral synthesis using SYNAPPS to associate the two bluer regions with Ni/Co and Ti. Results: The flux of the uTi feature is an extremely sensitive temperature/luminosity indicator, standardizing the SN peak luminosity to 0.116 ± 0.011 mag root mean square (RMS). A traditional SALT2.4 fit on the same sample yields a 0.135 mag RMS. Standardization using uTi also reduces the difference in corrected magnitude between SNe originating from different host galaxy environments. Early U-band spectra can be used to probe the Ni+Co distribution in the ejecta, thus offering a rare window into the source of light curve power. The uCa flux further improves standardization, yielding a 0.086 ± 0.010 mag RMS without the need to include an additional intrinsic dispersion to reach χ2/dof 1. This reduction in RMS is partially driven by an improved standardization of Shallow Silicon and 91T-like SNe. All tables are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/614/A71. Individual SN spectra shown are available at http://snfactory.lbl.gov/snf/data

Defining photometric peculiar type Ia supernovae

Energy Technology Data Exchange (ETDEWEB)

González-Gaitán, S.; Pignata, G.; Förster, F.; Gutiérrez, C. P.; Bufano, F.; Galbany, L.; Hamuy, M.; De Jaeger, T. [Millennium Institute of Astrophysics, Casilla 36-D, Santiago (Chile); Hsiao, E. Y.; Phillips, M. M. [Carnegie Observatories, Las Campanas Observatory, Casilla 601, La Serena (Chile); Folatelli, G. [Kavli Institute for the Physics and Mathematics of the Universe, the University of Tokyo, Kashiwa 277-8583 (Kavli IPMU, WPI) (Japan); Anderson, J. P., E-mail: sgonzale@das.uchile.cl [European Southern Observatory, Alonso de Córdova 3107, Casilla 19, Santiago (Chile)

2014-11-10

We present a new photometric identification technique for SN 1991bg-like type Ia supernovae (SNe Ia), i.e., objects with light curve characteristics such as later primary maxima and the absence of a secondary peak in redder filters. This method is capable of selecting this sub-group from the normal type Ia population. Furthermore, we find that recently identified peculiar sub-types such as SNe Iax and super-Chandrasekhar SNe Ia have photometric characteristics similar to 91bg-like SNe Ia, namely, the absence of secondary maxima and shoulders at longer wavelengths, and can also be classified with our technique. The similarity of these different SN Ia sub-groups perhaps suggests common physical conditions. This typing methodology permits the photometric identification of peculiar SNe Ia in large upcoming wide-field surveys either to study them further or to obtain a pure sample of normal SNe Ia for cosmological studies.

ON THE RATES OF TYPE Ia SUPERNOVAE IN DWARF AND GIANT HOSTS WITH ROTSE-IIIb

International Nuclear Information System (INIS)

Quimby, Robert M.; Yuan Fang; Akerlof, Carl; Wheeler, J. Craig; Warren, Michael S.

2012-01-01

We present a sample of 23 spectroscopically confirmed Type Ia supernovae (SNe Ia) that were discovered in the background of galaxy clusters targeted by ROTSE-IIIb and use up to 18 of these to determine the local (z-bar 0.05) volumetric rate. Since our survey is flux limited and thus biased against fainter objects, the pseudo-absolute magnitude distribution (pAMD) of SNe Ia in a given volume is an important concern, especially the relative frequency of high- to low-luminosity SNe Ia. We find that the pAMD derived from the volume-limited Lick Observatory Supernova Search (LOSS) sample is incompatible with the distribution of SNe Ia in a volume-limited (z B > –16) galaxies, whereas only 1 out of 79 nearby SDSS-II SNe Ia have such faint hosts. It is possible that previous works have undercounted either low-luminosity SNe Ia, SNe Ia in low-luminosity hosts, or peculiar SNe Ia (sometimes explicitly), and the total SNe Ia rate may be higher than the canonical value.

THE ULTRAVIOLET BRIGHTEST TYPE Ia SUPERNOVA 2011de

International Nuclear Information System (INIS)

Brown, Peter J.

2014-01-01

We present and discuss the ultraviolet (UV)/optical photometric light curves and absolute magnitudes of the Type Ia supernova (SN Ia) 2011de from the Swift Ultraviolet/Optical Telescope. We find it to be the UV brightest SN Ia yet observed—more than a factor of 10 brighter than normal SNe Ia in the mid-ultraviolet. We find that the UV/optical brightness and broad light curve evolution can be modeled with additional flux from the shock of the ejecta hitting a relatively large red giant companion separated by 6 × 10 13 cm. However, the post-maximum behavior of other UV-bright SNe Ia can also be modeled in a similar manner, including objects with UV spectroscopy or pre-maximum photometry which is inconsistent with this model. This suggests that similar UV luminosities can be intrinsic or caused by other forms of shock interaction. The high velocities reported for SN 2011de make it distinct from the UV-bright ''super-Chandrasekhar'' SNe Ia and the NUV-blue group of normal SNe Ia. SN 2011de is an extreme example of the UV variations in SNe Ia

THE SUPERNOVA DELAY TIME DISTRIBUTION IN GALAXY CLUSTERS AND IMPLICATIONS FOR TYPE-Ia PROGENITORS AND METAL ENRICHMENT

International Nuclear Information System (INIS)

Maoz, Dan; Sharon, Keren; Avishay Gal-Yam

2010-01-01

Knowledge of the supernova (SN) delay time distribution (DTD)-the SN rate versus time that would follow a hypothetical brief burst of star formation-can shed light on SN progenitors and physics, as well as on the timescales of chemical enrichment in different environments. We compile recent measurements of the Type-Ia SN (SN Ia) rate in galaxy clusters at redshifts from z = 0 out to z = 1.45, just 2 Gyr after cluster star formation at z ∼ 3. We review the plausible range for the observed total iron-to-stellar mass ratio in clusters, based on the latest data and analyses, and use it to constrain the time-integrated number of SN Ia events in clusters. With these data, we recover the DTD of SNe Ia in cluster environments. The DTD is sharply peaked at the shortest time-delay interval we probe, 0Gyr -1.2±0.3 from t = 400 Myr to a Hubble time can satisfy both constraints. Shallower power laws such as t -1/2 cannot, assuming a single DTD, and a single star formation burst (either brief or extended) at high z. This implies that 50%-85% of SNe Ia explode within 1 Gyr of star formation. DTDs from double-degenerate (DD) models, which generically have ∼t -1 shapes over a wide range of timescales, match the data, but only if their predictions are scaled up by factors of 5-10. Single-degenerate (SD) DTDs always give poor fits to the data, due to a lack of delayed SNe and overall low numbers of SNe. The observations can also be reproduced with a combination of two SN Ia populations-a prompt SD population of SNe Ia that explodes within a few Gyr of star formation, and produces about 60% of the iron mass in clusters, and a DD population that contributes the events seen at z < 1.5. An alternative scenario of a single, prompt, SN Ia population, but a composite star formation history in clusters, consisting of a burst at high z, followed by a constant star formation rate, can reproduce the SN rates, but is at odds with direct measurements of star formation in clusters at 0 < z

The discovery of the most distant known type Ia supernova at redshift 1.914

DEFF Research Database (Denmark)

Jones, Dennis; Rodney, S.A.; Riess, A.G.

2013-01-01

We present the discovery of a Type Ia supernova (SN) at redshift z = 1.914 from the CANDELS multi-cycle treasury program on the Hubble Space Telescope (HST). This SN was discovered in the infrared using the Wide-Field Camera 3, and it is the highest-redshift Type Ia SN yet observed. We classify t...

PROMPT Ia SUPERNOVAE ARE SIGNIFICANTLY DELAYED

International Nuclear Information System (INIS)

Raskin, Cody; Scannapieco, Evan; Rhoads, James; Della Valle, Massimo

2009-01-01

The time delay between the formation of a population of stars and the onset of type Ia supernovae (SNe Ia) sets important limits on the masses and nature of SN Ia progenitors. Here, we use a new observational technique to measure this time delay by comparing the spatial distributions of SNe Ia to their local environments. Previous work attempted such analyses encompassing the entire host of each SN Ia, yielding inconclusive results. Our approach confines the analysis only to the relevant portions of the hosts, allowing us to show that even so-called prompt SNe Ia that trace star formation on cosmic timescales exhibit a significant delay time of 200-500 million years. This implies that either the majority of Ia companion stars have main-sequence masses less than 3 M sun , or that most SNe Ia arise from double white dwarf binaries. Our results are also consistent with a SNe Ia rate that traces the white dwarf formation rate, scaled by a fixed efficiency factor.

The Evolution of the Type Ia Supernova Luminosity Function

NARCIS (Netherlands)

Shen, K.J.; Toonen, S.; Graur, O.

2017-01-01

Type Ia supernovae (SNe Ia) exhibit a wide diversity of peak luminosities and light curve shapes: the faintest SNe Ia are 10 times less luminous and evolve more rapidly than the brightest SNe Ia. Their differing characteristics also extend to their stellar age distributions, with fainter SNe Ia

Physics of type Ia supernovae

International Nuclear Information System (INIS)

Hoeflich, Peter

2006-01-01

The last decade has witnessed an explosive growth of high-quality data for thermonuclear explosions of a white dwarf star, the type Ia supernovae (SNe Ia). Advances in computational methods provide new insights into the physics of the phenomenon and a direct, quantitative link between observables and explosion physics. Both trends combined provided spectacular results, allowed to address, to identify specific problems and to narrow down the range of scenarios. Current topics include the relation between SNe Ia and their progenitors, the influence of the metallicities and accretion on the explosion, and details of the burning front. How can we understand the apparent homogeneity and probe for the diversity of SNe Ia? Here, we want give an overview of the current status of our understanding of supernovae physics in light of recent results

Impact of cosmic inhomogeneities on SNe observations

Science.gov (United States)

Kainulainen, Kimmo; Marra, Valerio

2010-06-01

We study the impact of cosmic inhomogeneities on the interpretation of SNe observations. We build an inhomogeneous universe model that can confront supernova data and yet is reasonably well compatible with the Copernican Principle. Our model combines a relatively small local void, that gives apparent acceleration at low redshifts, with a meatball model that gives sizeable lensing (dimming) at high redshifts. Together these two elements, which focus on different effects of voids on the data, allow the model to mimic the concordance model.

Forecast and analysis of the cosmological redshift drift

Energy Technology Data Exchange (ETDEWEB)

Lazkoz, Ruth; Leanizbarrutia, Iker [University of the Basque Country UPV/EHU, Department of Theoretical Physics, Bilbao (Spain); Salzano, Vincenzo [University of Szczecin, Institute of Physics, Sczcecin (Poland)

2018-01-15

The cosmological redshift drift could lead to the next step in high-precision cosmic geometric observations, becoming a direct and irrefutable test for cosmic acceleration. In order to test the viability and possible properties of this effect, also called Sandage-Loeb (SL) test, we generate a model-independent mock data set in order to compare its constraining power with that of the future mock data sets of Type Ia Supernovae (SNe) and Baryon Acoustic Oscillations (BAO). The performance of those data sets is analyzed by testing several cosmological models with the Markov chain Monte Carlo (MCMC) method, both independently as well as combining all data sets. Final results show that, in general, SL data sets allow for remarkable constraints on the matter density parameter today Ω{sub m} on every tested model, showing also a great complementarity with SNe and BAO data regarding dark energy parameters. (orig.)

Forecast and analysis of the cosmological redshift drift.

Science.gov (United States)

Lazkoz, Ruth; Leanizbarrutia, Iker; Salzano, Vincenzo

2018-01-01

The cosmological redshift drift could lead to the next step in high-precision cosmic geometric observations, becoming a direct and irrefutable test for cosmic acceleration. In order to test the viability and possible properties of this effect, also called Sandage-Loeb (SL) test, we generate a model-independent mock data set in order to compare its constraining power with that of the future mock data sets of Type Ia Supernovae (SNe) and Baryon Acoustic Oscillations (BAO). The performance of those data sets is analyzed by testing several cosmological models with the Markov chain Monte Carlo (MCMC) method, both independently as well as combining all data sets. Final results show that, in general, SL data sets allow for remarkable constraints on the matter density parameter today [Formula: see text] on every tested model, showing also a great complementarity with SNe and BAO data regarding dark energy parameters.

MEASURING EJECTA VELOCITY IMPROVES TYPE Ia SUPERNOVA DISTANCES

International Nuclear Information System (INIS)

Foley, Ryan J.; Kasen, Daniel

2011-01-01

We use a sample of 121 spectroscopically normal Type Ia supernovae (SNe Ia) to show that their intrinsic color is correlated with their ejecta velocity, as measured from the blueshift of the Si II λ6355 feature near maximum brightness, v SiII . The SN Ia sample was originally used by Wang et al. to show that the relationship between color excess and peak magnitude, which in the absence of intrinsic color differences describes a reddening law, was different for two subsamples split by v SiII (defined as 'Normal' and 'High Velocity'). We verify this result, but find that the two subsamples have the same reddening law when extremely reddened events (E(B - V)>0.35 mag) are excluded. We also show that (1) the High-Velocity subsample is offset by ∼0.06 mag to the red from the Normal subsample in the (B max - V max )-M V plane, (2) the B max - V max cumulative distribution functions of the two subsamples have nearly identical shapes, but the High-Velocity subsample is offset by ∼0.07 mag to the red in B max - V max , and (3) the bluest High-Velocity SNe Ia are ∼0.10 mag redder than the bluest Normal SNe Ia. Together, this evidence indicates a difference in intrinsic color for the subsamples. Accounting for this intrinsic color difference reduces the scatter in Hubble residuals from 0.190 mag to 0.130 mag for SNe Ia with A V ∼ V found in large SN Ia samples. We explain the correlation between ejecta velocity and color as increased line blanketing in the High-Velocity SNe Ia, causing them to become redder. We discuss some implications of this result, and stress the importance of spectroscopy for future SN Ia cosmology surveys, with particular focus on the design of WFIRST.

An exploration of heterogeneity in supernova type Ia samples

Energy Technology Data Exchange (ETDEWEB)

Alam, Ujjaini [Physics and Applied Mathematics Unit, Indian Statistical Institute, Kolkata (India); Lasue, Jeremie, E-mail: ujjaini.alam@gmail.com, E-mail: jeremie.lasue@irap.omp.eu [IRAP, Université de Toulouse, CNRS, UPS, CNES, Toulouse (France)

2017-06-01

We examine three SNe Type Ia datasets: Union2.1, JLA and Panstarrs to check their consistency using cosmology blind statistical analyses as well as cosmological parameter fitting. We find that the Panstarrs dataset is the most stable of the three to changes in the data, although it does not, at the moment, go to high enough redshifts to tightly constrain the equation of state of dark energy, w . The Union2.1, drawn from several different sources, appears to be somewhat susceptible to changes within the dataset. The JLA reconstructs well for a smaller number of cosmological parameters. At higher degrees of freedom, the dependence of its errors on redshift can lead to varying results between subsets. Panstarrs is inconsistent with the other two datasets at about 2σ confidence level, and JLA and Union2.1 are about 1σ away from each other. For the Ω{sub 0} {sub m} − w cosmological reconstruction, with no additional data, the 1σ range of values in w for selected subsets of each dataset is two times larger for JLA and Union2.1 as compared to Panstarrs. The range in Ω{sub 0} {sub m} for the same subsets remains approximately similar for all three datasets. We find that although there are differences in the fitting and correction techniques used in the different samples, the most important criterion is the selection of the SNe, a slightly different SNe selection can lead to noticeably different results both in the purely statistical analysis and in cosmological reconstruction. We note that a single, high quality low redshift sample could help decrease the uncertainties in the result. We also note that lack of homogeneity in the magnitude errors may bias the results and should either be modeled, or its effect neutralized by using other, complementary datasets. A supernova sample with high quality data at both high and low redshifts, constructed from a few surveys to avoid heterogeneity in the sample, and with homogeneous errors, would result in a more robust

Mass-accreting white dwarfs and type Ia supernovae

Science.gov (United States)

Wang, Bo

2018-05-01

Type Ia supernovae (SNe Ia) play a prominent role in understanding the evolution of the Universe. They are thought to be thermonuclear explosions of mass-accreting carbon-oxygen white dwarfs (CO WDs) in binaries, although the mass donors of the accreting WDs are still not well determined. In this article, I review recent studies on mass-accreting WDs, including H- and He-accreting WDs. I also review currently most studied progenitor models of SNe Ia, i.e., the single-degenerate model (including the WD+MS channel, the WD+RG channel and the WD+He star channel), the double-degenerate model (including the violent merger scenario) and the sub-Chandrasekhar mass model. Recent progress on these progenitor models is discussed, including the initial parameter space for producing SNe Ia, the binary evolutionary paths to SNe Ia, the progenitor candidates for SNe Ia, the possible surviving companion stars of SNe Ia, some observational constraints, etc. Some other potential progenitor models of SNe Ia are also summarized, including the hybrid CONe WD model, the core-degenerate model, the double WD collision model, the spin-up/spin-down model and the model of WDs near black holes. To date, it seems that two or more progenitor models are needed to explain the observed diversity among SNe Ia.

TYPE Ia SUPERNOVA CARBON FOOTPRINTS

International Nuclear Information System (INIS)

Thomas, R. C.; Nugent, P.; Aldering, G.; Aragon, C.; Bailey, S.; Childress, M.; Fakhouri, H. K.; Hsiao, E. Y.; Loken, S.; Antilogus, P.; Bongard, S.; Canto, A.; Baltay, C.; Buton, C.; Kerschhaggl, M.; Kowalski, M.; Paech, K.; Chotard, N.; Copin, Y.; Gangler, E.

2011-01-01

We present convincing evidence of unburned carbon at photospheric velocities in new observations of five Type Ia supernovae (SNe Ia) obtained by the Nearby Supernova Factory. These SNe are identified by examining 346 spectra from 124 SNe obtained before +2.5 days relative to maximum. Detections are based on the presence of relatively strong C II λ6580 absorption 'notches' in multiple spectra of each SN, aided by automated fitting with the SYNAPPS code. Four of the five SNe in question are otherwise spectroscopically unremarkable, with ions and ejection velocities typical of SNe Ia, but spectra of the fifth exhibit high-velocity (v > 20, 000 km s –1 ) Si II and Ca II features. On the other hand, the light curve properties are preferentially grouped, strongly suggesting a connection between carbon-positivity and broadband light curve/color behavior: three of the five have relatively narrow light curves but also blue colors and a fourth may be a dust-reddened member of this family. Accounting for signal to noise and phase, we estimate that 22 +10 –6% of SNe Ia exhibit spectroscopic C II signatures as late as –5 days with respect to maximum. We place these new objects in the context of previously recognized carbon-positive SNe Ia and consider reasonable scenarios seeking to explain a physical connection between light curve properties and the presence of photospheric carbon. We also examine the detailed evolution of the detected carbon signatures and the surrounding wavelength regions to shed light on the distribution of carbon in the ejecta. Our ability to reconstruct the C II λ6580 feature in detail under the assumption of purely spherical symmetry casts doubt on a 'carbon blobs' hypothesis, but does not rule out all asymmetric models. A low volume filling factor for carbon, combined with line-of-sight effects, seems unlikely to explain the scarcity of detected carbon in SNe Ia by itself.

The Type Ia Supernova Rate in Radio and Infrared Galaxies from the CFHT Supernova Legacy Survey

OpenAIRE

Graham, M. L.; Pritchet, C. J.; Sullivan, M.; Howell, D. A.; Gwyn, S. D. J.; Astier, P.; Balland, C.; Basa, S.; Carlberg, R. G.; Conley, A.; Fouchez, D.; Guy, J.; Hardin, D.; Hook, I. M.; Pain, R.

2009-01-01

We have combined the large SN Ia database of the Canada-France-Hawaii Telescope Supernova Legacy Survey and catalogs of galaxies with photometric redshifts, VLA 1.4 GHz radio sources, and Spitzer infrared sources. We present eight SNe Ia in early-type host galaxies which have counterparts in the radio and infrared source catalogs. We find the SN Ia rate in subsets of radio and infrared early-type galaxies is ~1-5 times the rate in all early-type galaxies, and that any enhancement is always

Rates and progenitors of type Ia supernovae

Energy Technology Data Exchange (ETDEWEB)

Wood-Vasey, William Michael [Univ. of California, Berkeley, CA (United States)

2004-01-01

The remarkable uniformity of Type Ia supernovae has allowed astronomers to use them as distance indicators to measure the properties and expansion history of the Universe. However, Type Ia supernovae exhibit intrinsic variation in both their spectra and observed brightness. The brightness variations have been approximately corrected by various methods, but there remain intrinsic variations that limit the statistical power of current and future observations of distant supernovae for cosmological purposes. There may be systematic effects in this residual variation that evolve with redshift and thus limit the cosmological power of SN Ia luminosity-distance experiments. To reduce these systematic uncertainties, we need a deeper understanding of the observed variations in Type Ia supernovae. Toward this end, the Nearby Supernova Factory has been designed to discover hundreds of Type Ia supernovae in a systematic and automated fashion and study them in detail. This project will observe these supernovae spectrophotometrically to provide the homogeneous high-quality data set necessary to improve the understanding and calibration of these vital cosmological yardsticks. From 1998 to 2003, in collaboration with the Near-Earth Asteroid Tracking group at the Jet Propulsion Laboratory, a systematic and automated searching program was conceived and executed using the computing facilities at Lawrence Berkeley National Laboratory and the National Energy Research Supercomputing Center. An automated search had never been attempted on this scale. A number of planned future large supernovae projects are predicated on the ability to find supernovae quickly, reliably, and efficiently in large datasets. A prototype run of the SNfactory search pipeline conducted from 2002 to 2003 discovered 83 SNe at a final rate of 12 SNe/month. A large, homogeneous search of this scale offers an excellent opportunity to measure the rate of Type Ia supernovae. This thesis presents a new method for

Rates and progenitors of type Ia supernovae

International Nuclear Information System (INIS)

Wood-Vasey, William Michael

2004-01-01

The remarkable uniformity of Type Ia supernovae has allowed astronomers to use them as distance indicators to measure the properties and expansion history of the Universe. However, Type Ia supernovae exhibit intrinsic variation in both their spectra and observed brightness. The brightness variations have been approximately corrected by various methods, but there remain intrinsic variations that limit the statistical power of current and future observations of distant supernovae for cosmological purposes. There may be systematic effects in this residual variation that evolve with redshift and thus limit the cosmological power of SN Ia luminosity-distance experiments. To reduce these systematic uncertainties, we need a deeper understanding of the observed variations in Type Ia supernovae. Toward this end, the Nearby Supernova Factory has been designed to discover hundreds of Type Ia supernovae in a systematic and automated fashion and study them in detail. This project will observe these supernovae spectrophotometrically to provide the homogeneous high-quality data set necessary to improve the understanding and calibration of these vital cosmological yardsticks. From 1998 to 2003, in collaboration with the Near-Earth Asteroid Tracking group at the Jet Propulsion Laboratory, a systematic and automated searching program was conceived and executed using the computing facilities at Lawrence Berkeley National Laboratory and the National Energy Research Supercomputing Center. An automated search had never been attempted on this scale. A number of planned future large supernovae projects are predicated on the ability to find supernovae quickly, reliably, and efficiently in large datasets. A prototype run of the SNfactory search pipeline conducted from 2002 to 2003 discovered 83 SNe at a final rate of 12 SNe/month. A large, homogeneous search of this scale offers an excellent opportunity to measure the rate of Type Ia supernovae. This thesis presents a new method for

An Empirical Fitting Method to Type Ia Supernova Light Curves. III. A Three-parameter Relationship: Peak Magnitude, Rise Time, and Photospheric Velocity

Science.gov (United States)

Zheng, WeiKang; Kelly, Patrick L.; Filippenko, Alexei V.

2018-05-01

We examine the relationship between three parameters of Type Ia supernovae (SNe Ia): peak magnitude, rise time, and photospheric velocity at the time of peak brightness. The peak magnitude is corrected for extinction using an estimate determined from MLCS2k2 fitting. The rise time is measured from the well-observed B-band light curve with the first detection at least 1 mag fainter than the peak magnitude, and the photospheric velocity is measured from the strong absorption feature of Si II λ6355 at the time of peak brightness. We model the relationship among these three parameters using an expanding fireball with two assumptions: (a) the optical emission is approximately that of a blackbody, and (b) the photospheric temperatures of all SNe Ia are the same at the time of peak brightness. We compare the precision of the distance residuals inferred using this physically motivated model against those from the empirical Phillips relation and the MLCS2k2 method for 47 low-redshift SNe Ia (0.005 Ia in our sample with higher velocities are inferred to be intrinsically fainter. Eliminating the high-velocity SNe and applying a more stringent extinction cut to obtain a “low-v golden sample” of 22 SNe, we obtain significantly reduced scatter of 0.108 ± 0.018 mag in the new relation, better than those of the Phillips relation and the MLCS2k2 method. For 250 km s‑1 of residual peculiar motions, we find 68% and 95% upper limits on the intrinsic scatter of 0.07 and 0.10 mag, respectively.

Interacting scalar tensor cosmology in light of SNeIa, CMB, BAO and OHD observational data sets

International Nuclear Information System (INIS)

Rabiei, Sayed Wrya; Saaidi, Khaled; Sheikhahmadi, Haidar; Aghamohammadi, Ali

2016-01-01

In this work, an interacting chameleon-like scalar field scenario, by considering SNeIa, CMB, BAO, and OHD data sets, is investigated. In fact, the investigation is realized by introducing an ansatz for the effective dark energy equation of state, which mimics the behavior of chameleon-like models. Based on this assumption, some cosmological parameters, including the Hubble, deceleration, and coincidence parameters, in such a mechanism are analyzed. It is realized that, to estimate the free parameters of a theoretical model, by regarding the systematic errors it is better that the whole of the above observational data sets would be considered. In fact, if one considers SNeIa, CMB, and BAO, but disregards OHD, it maybe leads to different results. Also, to get a better overlap between the contours with the constraint χ m 2 ≤ 1, the χ T 2 function could be re-weighted. The relative probability functions are plotted for marginalized likelihood L(Ω m0 , ω 1 , β) according to the two dimensional confidence levels 68.3, 90, and 95.4%. Meanwhile, the value of the free parameters which maximize the marginalized likelihoods using the above confidence levels are obtained. In addition, based on these calculations the minimum value of χ 2 based on the free parameters of the ansatz for the effective dark energy equation of state is achieved. (orig.)

The Carnegie Supernova Project. I. Third Photometry Data Release of Low-redshift Type Ia Supernovae and Other White Dwarf Explosions

DEFF Research Database (Denmark)

Krisciunas, Kevin; Contreras, Carlos; Burns, Christopher R.

2017-01-01

We present final natural-system optical (ugriBV) and near-infrared (YJH) photometry of 134 supernovae (SNe) with probable white dwarf progenitors that were observed in 2004-2009 as part of the first stage of the Carnegie Supernova Project (CSP-I). The sample consists of 123 Type. Ia SNe, 5 Type...

Utilizing the Updated Gamma-Ray Bursts and Type Ia Supernovae to Constrain the Cardassian Expansion Model and Dark Energy

Directory of Open Access Journals (Sweden)

Jun-Jie Wei

2015-01-01

Full Text Available We update gamma-ray burst (GRB luminosity relations among certain spectral and light-curve features with 139 GRBs. The distance modulus of 82 GRBs at z>1.4 can be calibrated with the sample at z≤1.4 by using the cubic spline interpolation method from the Union2.1 Type Ia supernovae (SNe Ia set. We investigate the joint constraints on the Cardassian expansion model and dark energy with 580 Union2.1 SNe Ia sample (z<1.4 and 82 calibrated GRBs’ data (1.4high-z GRBs to 580 SNe Ia significantly improves the constraint on Ωm-ΩΛ plane. In the Cardassian expansion model, the best fit is Ωm=0.24-0.15+0.15 and n=0.16-0.52+0.30  (1σ, which is consistent with the ΛCDM cosmology (n=0 in the 1σ confidence region. We also discuss two dark energy models in which the equation of state w(z is parameterized as w(z=w0 and w(z=w0+w1z/(1+z, respectively. Based on our analysis, we see that our universe at higher redshift up to z=8.2 is consistent with the concordance model within 1σ confidence level.

SHOCK BREAKOUT IN TYPE II PLATEAU SUPERNOVAE: PROSPECTS FOR HIGH-REDSHIFT SUPERNOVA SURVEYS

International Nuclear Information System (INIS)

Tominaga, N.; Morokuma, T.; Blinnikov, S. I.; Nomoto, K.; Baklanov, P.; Sorokina, E. I.

2011-01-01

Shock breakout is the brightest radiative phenomenon in a supernova (SN) but is difficult to be observed owing to the short duration and X-ray/ultraviolet (UV)-peaked spectra. After the first observation from the rising phase reported in 2008, its observability at high redshift is attracting enormous attention. We perform multigroup radiation hydrodynamics calculations of explosions for evolutionary presupernova models with various main-sequence masses M MS , metallicities Z, and explosion energies E. We present multicolor light curves of shock breakouts in Type II plateau SNe, being the most frequent core-collapse SNe, and predict apparent multicolor light curves of shock breakout at various redshifts z. We derive the observable SN rate and reachable redshift as functions of filter x and limiting magnitude m x,lim by taking into account an initial mass function, cosmic star formation history, intergalactic absorption, and host galaxy extinction. We propose a realistic survey strategy optimized for shock breakout. For example, the g'-band observable SN rate for m g',lim = 27.5 mag is 3.3 SNe deg -2 day -1 and half of them are located at z ≥ 1.2. It is clear that the shock breakout is a beneficial clue for probing high-z core-collapse SNe. We also establish ways to identify shock breakout and constrain SN properties from the observations of shock breakout, brightness, timescale, and color. We emphasize that the multicolor observations in blue optical bands with ∼hour intervals, preferably over ≥2 continuous nights, are essential to efficiently detect, identify, and interpret shock breakout.

Observational properties of SNe Ia progenitors close to the explosion

Science.gov (United States)

Tornambé, A.; Piersanti, L.; Raimondo, G.; Delgrande, R.

2018-04-01

We determine the expected signal in various observational bands of supernovae Ia progenitors just before the explosion by assuming the rotating double-degenerate scenario. Our results are valid also for all the evolutionary scenarios invoking rotation as the driving mechanism of the accretion process as well as the evolution up to the explosion. We find that the observational properties depend mainly on the mass of the exploding object, even if the angular momentum evolution after the end of the mass accretion phase and before the onset of C-burning plays a non-negligible role. Just before the explosion, the magnitude MV ranges between 9 and 11 mag, while the colour (F225W - F555W) is about -1.64 mag. The photometric properties remain constant for a few decades before the explosion. During the last few months, the luminosity decreases very rapidly. The corresponding decline in the optical bands varies from a few hundredths up to one magnitude, the exact value depending on both the white dwarf total mass and the braking efficiency at the end of the mass transfer. This feature is related to the exponentially increasing energy production, which drives the formation of a convective core rapidly extending over a large part of the exploding object. Also, a drop in the angular velocity occurs. We find that observations in the soft X band (0.5-2 keV) may be used to check if the evolution of the SNe Ia progenitors up to the explosion is driven by rotation and, hence, to discriminate among different progenitor scenarios.

Spectroscopy of High-Redshift Supernovae from the ESSENCE Project: The First 2 Years

Science.gov (United States)

Matheson, Thomas; Blondin, Stéphane; Foley, Ryan J.; Chornock, Ryan; Filippenko, Alexei V.; Leibundgut, Bruno; Smith, R. Chris; Sollerman, Jesper; Spyromilio, Jason; Kirshner, Robert P.; Clocchiatti, Alejandro; Aguilera, Claudio; Barris, Brian; Becker, Andrew C.; Challis, Peter; Covarrubias, Ricardo; Garnavich, Peter; Hicken, Malcolm; Jha, Saurabh; Krisciunas, Kevin; Li, Weidong; Miceli, Anthony; Miknaitis, Gajus; Prieto, Jose Luis; Rest, Armin; Riess, Adam G.; Salvo, Maria Elena; Schmidt, Brian P.; Stubbs, Christopher W.; Suntzeff, Nicholas B.; Tonry, John L.

2005-05-01

We present the results of spectroscopic observations of targets discovered during the first 2 years of the ESSENCE project. The goal of ESSENCE is to use a sample of ~200 Type Ia supernovae (SNe Ia) at moderate redshifts (0.2Canada], CONICYT [Chile], the Australian Research Council [Australia], CNPq [Brazil], and CONICET [Argentina] [programs GN-2002B-Q-14, GN-2003B-Q-14, and GS-2003B-Q-11]) the Magellan Telescopes at Las Campanas Observatory; the MMT Observatory, a joint facility of the Smithsonian Institution and the University of Arizona; and the F. L. Whipple Observatory, which is operated by the Smithsonian Astrophysical Observatory. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration; the Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

Interacting scalar tensor cosmology in light of SNeIa, CMB, BAO and OHD observational data sets

Energy Technology Data Exchange (ETDEWEB)

Rabiei, Sayed Wrya; Saaidi, Khaled [Faculty of Science University of Kurdistan, Department of Physics, Sanandaj (Iran, Islamic Republic of); Sheikhahmadi, Haidar [Faculty of Science University of Kurdistan, Department of Physics, Sanandaj (Iran, Islamic Republic of); Institute for Advance Studies in Basic Sciences (IASBS) Gava Zang, Zanjan (Iran, Islamic Republic of); Aghamohammadi, Ali [Sanandaj Branch Islamic Azad University, Sanandaj (Iran, Islamic Republic of)

2016-02-15

In this work, an interacting chameleon-like scalar field scenario, by considering SNeIa, CMB, BAO, and OHD data sets, is investigated. In fact, the investigation is realized by introducing an ansatz for the effective dark energy equation of state, which mimics the behavior of chameleon-like models. Based on this assumption, some cosmological parameters, including the Hubble, deceleration, and coincidence parameters, in such a mechanism are analyzed. It is realized that, to estimate the free parameters of a theoretical model, by regarding the systematic errors it is better that the whole of the above observational data sets would be considered. In fact, if one considers SNeIa, CMB, and BAO, but disregards OHD, it maybe leads to different results. Also, to get a better overlap between the contours with the constraint χ{sub m}{sup 2} ≤ 1, the χ{sub T}{sup 2} function could be re-weighted. The relative probability functions are plotted for marginalized likelihood L(Ω{sub m0}, ω{sub 1}, β) according to the two dimensional confidence levels 68.3, 90, and 95.4%. Meanwhile, the value of the free parameters which maximize the marginalized likelihoods using the above confidence levels are obtained. In addition, based on these calculations the minimum value of χ{sup 2} based on the free parameters of the ansatz for the effective dark energy equation of state is achieved. (orig.)

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.

HOST GALAXIES OF TYPE Ia SUPERNOVAE FROM THE NEARBY SUPERNOVA FACTORY

International Nuclear Information System (INIS)

Childress, M.; Aldering, G.; Aragon, C.; Bailey, S.; Fakhouri, H. K.; Hsiao, E. Y.; Kim, A. G.; Loken, S.; Antilogus, P.; Bongard, S.; Canto, A.; Cellier-Holzem, F.; Guy, J.; Baltay, C.; Buton, C.; Kerschhaggl, M.; Kowalski, M.; Chotard, N.; Copin, Y.; Gangler, E.

2013-01-01

We present photometric and spectroscopic observations of galaxies hosting Type Ia supernovae (SNe Ia) observed by the Nearby Supernova Factory. Combining Galaxy Evolution Explorer (GALEX) UV data with optical and near-infrared photometry, we employ stellar population synthesis techniques to measure SN Ia host galaxy stellar masses, star formation rates (SFRs), and reddening due to dust. We reinforce the key role of GALEX UV data in deriving accurate estimates of galaxy SFRs and dust extinction. Optical spectra of SN Ia host galaxies are fitted simultaneously for their stellar continua and emission lines fluxes, from which we derive high-precision redshifts, gas-phase metallicities, and Hα-based SFRs. With these data we show that SN Ia host galaxies present tight agreement with the fiducial galaxy mass-metallicity relation from Sloan Digital Sky Survey (SDSS) for stellar masses log(M * /M ☉ ) > 8.5 where the relation is well defined. The star formation activity of SN Ia host galaxies is consistent with a sample of comparable SDSS field galaxies, though this comparison is limited by systematic uncertainties in SFR measurements. Our analysis indicates that SN Ia host galaxies are, on average, typical representatives of normal field galaxies.

THE IMPACT OF METALLICITY ON THE RATE OF TYPE Ia SUPERNOVAE

International Nuclear Information System (INIS)

Kistler, Matthew D.; Stanek, K. Z.; Kochanek, Christopher S.; Thompson, Todd A.; Prieto, José L.

2013-01-01

The metallicity of a star strongly affects both its evolution and the properties of the stellar remnant that results from its demise. It is generally accepted that stars with initial masses below ∼8 M ☉ leave behind white dwarfs and that some sub-population of these lead to Type Ia supernovae (SNe Ia). However, it is often tacitly assumed that metallicity has no effect on the rate of SNe Ia. We propose that a consequence of the effects of metallicity is to significantly increase the SN Ia rate in lower-metallicity galaxies, in contrast to previous expectations. This is because lower-metallicity stars leave behind higher-mass white dwarfs, which should be easier to bring to explosion. We first model SN Ia rates in relation to galaxy masses and ages alone, finding that the elevation in the rate of SNe Ia in lower-mass galaxies measured by Lick Observatory SN Search is readily explained. However, we then see that models incorporating this effect of metallicity agree just as well. Using the same parameters to estimate the cosmic SN Ia rate, we again find good agreement with data up to z ≈ 2. We suggest that this degeneracy warrants more detailed examination of host galaxy metallicities. We discuss additional implications, including for hosts of high-z SNe Ia, the SN Ia delay time distribution, super-Chandrasekhar SNe, and cosmology.

LOWER BOUNDS ON PHOTOMETRIC REDSHIFT ERRORS FROM TYPE Ia SUPERNOVA TEMPLATES

International Nuclear Information System (INIS)

Asztalos, S.; Nikolaev, S.; De Vries, W.; Olivier, S.; Cook, K.; Wang, L.

2010-01-01

Cosmology with Type Ia supernova heretofore has required extensive spectroscopic follow-up to establish an accurate redshift. Though this resource-intensive approach is tolerable at the present discovery rate, the next generation of ground-based all-sky survey instruments will render it unsustainable. Photometry-based redshift determination may be a viable alternative, though the technique introduces non-negligible errors that ultimately degrade the ability to discriminate between competing cosmologies. We present a strictly template-based photometric redshift estimator and compute redshift reconstruction errors in the presence of statistical errors. Under highly degraded photometric conditions corresponding to a statistical error σ of 0.5, the residual redshift error is found to be 0.236 when assuming a nightly observing cadence and a single Large Synoptic Science Telescope (LSST) u-band filter. Utilizing all six LSST bandpass filters reduces the residual redshift error to 9.1 x 10 -3 . Assuming a more optimistic statistical error σ of 0.05, we derive residual redshift errors of 4.2 x 10 -4 , 5.2 x 10 -4 , 9.2 x 10 -4 , and 1.8 x 10 -3 for observations occuring nightly, every 5th, 20th and 45th night, respectively, in each of the six LSST bandpass filters. Adopting an observing cadence in which photometry is acquired with all six filters every 5th night and a realistic supernova distribution, binned redshift errors are combined with photometric errors with a σ of 0.17 and systematic errors with a σ∼ 0.003 to derive joint errors (σ w , σ w ' ) of (0.012, 0.066), respectively, in (w,w') with 68% confidence using Fisher matrix formalism. Though highly idealized in the present context, the methodology is nonetheless quite relevant for the next generation of ground-based all-sky surveys.

Type Ia Supernova Properties as a Function of the Distance to the Host Galaxy in the SDSS-II SN Survey

Energy Technology Data Exchange (ETDEWEB)

Galbany, Lluis [Institut de Fisica d' Altes Energies (IFAE), Barcelona (Spain); et al.

2012-08-20

We use type-Ia supernovae (SNe Ia) discovered by the SDSS-II SN Survey to search for dependencies between SN Ia properties and the projected distance to the host galaxy center, using the distance as a proxy for local galaxy properties (local star-formation rate, local metallicity, etc.). The sample consists of almost 200 spectroscopically or photometrically confirmed SNe Ia at redshifts below 0.25. The sample is split into two groups depending on the morphology of the host galaxy. We fit light-curves using both MLCS2k2 and SALT2, and determine color (AV, c) and light-curve shape (delta, x1) parameters for each SN Ia, as well as its residual in the Hubble diagram. We then correlate these parameters with both the physical and the normalized distances to the center of the host galaxy and look for trends in the mean values and scatters of these parameters with increasing distance. The most significant (at the 4-sigma level) finding is that the average fitted AV from MLCS2k2 and c from SALT2 decrease with the projected distance for SNe Ia in spiral galaxies. We also find indications that SNe in elliptical galaxies tend to have narrower light-curves if they explode at larger distances, although this may be due to selection effects in our sample. We do not find strong correlations between the residuals of the distance moduli with respect to the Hubble flow and the galactocentric distances, which indicates a limited correlation between SN magnitudes after standardization and local host metallicity.

SINGLE-DEGENERATE TYPE Ia SUPERNOVAE ARE PREFERENTIALLY OVERLUMINOUS

International Nuclear Information System (INIS)

Fisher, Robert; Jumper, Kevin

2015-01-01

Recent observational and theoretical progress has favored merging and helium-accreting sub-Chandrasekhar mass white dwarfs (WDs) in the double-degenerate and the double-detonation channels, respectively, as the most promising progenitors of normal Type Ia supernovae (SNe Ia). Thus the fate of rapidly accreting Chandrasekhar mass WDs in the single-degenerate channel remains more mysterious then ever. In this paper, we clarify the nature of ignition in Chandrasekhar-mass single-degenerate SNe Ia by analytically deriving the existence of a characteristic length scale which establishes a transition from central ignitions to buoyancy-driven ignitions. Using this criterion, combined with data from three-dimensional simulations of convection and ignition, we demonstrate that the overwhelming majority of ignition events within Chandrasekhar-mass WDs in the single-degenerate channel are buoyancy-driven, and consequently lack a vigorous deflagration phase. We thus infer that single-degenerate SNe Ia are generally expected to lead to overluminous 1991T-like SNe Ia events. We establish that the rates predicted from both the population of supersoft X-ray sources (SSSs) and binary population synthesis models of the single-degenerate channel are broadly consistent with the observed rates of overluminous SNe Ia, and suggest that the population of SSSs are the dominant stellar progenitors of SNe 1991T-like events. We further demonstrate that the single-degenerate channel contribution to the normal and failed 2002cx-like rates is not likely to exceed 1% of the total SNe Ia rate. We conclude with a range of observational tests of overluminous SNe Ia which will either support or strongly constrain the single-degenerate scenario

First-Year Spectroscopy for the SDSS-II Supernova Survey

Energy Technology Data Exchange (ETDEWEB)

Zheng, Chen; Romani, Roger W.; Sako, Masao; Marriner, John; Bassett, Bruce; Becker, Andrew; Choi, Changsu; Cinabro, David; DeJongh, Fritz; Depoy, Darren L.; Dilday, Ben; Doi, Mamoru; Frieman, Joshua A.; Garnavich, Peter M.; Hogan, Craig J.; Holtzman, Jon; Im, Myungshin; Jha, Saurabh; Kessler, Richard; Konishi, Kohki; Lampeitl, Hubert

2008-03-25

This paper presents spectroscopy of supernovae discovered in the first season of the Sloan Digital Sky Survey-II Supernova Survey. This program searches for and measures multi-band light curves of supernovae in the redshift range z = 0.05-0.4, complementing existing surveys at lower and higher redshifts. Our goal is to better characterize the supernova population, with a particular focus on SNe Ia, improving their utility as cosmological distance indicators and as probes of dark energy. Our supernova spectroscopy program features rapid-response observations using telescopes of a range of apertures, and provides confirmation of the supernova and host-galaxy types as well as precise redshifts. We describe here the target identification and prioritization, data reduction, redshift measurement, and classification of 129 SNe Ia, 16 spectroscopically probable SNe Ia, 7 SNe Ib/c, and 11 SNe II from the first season. We also describe our efforts to measure and remove the substantial host galaxy contamination existing in the majority of our SN spectra.

SPECTROSCOPIC OBSERVATIONS OF SN 2012fr: A LUMINOUS, NORMAL TYPE Ia SUPERNOVA WITH EARLY HIGH-VELOCITY FEATURES AND A LATE VELOCITY PLATEAU

International Nuclear Information System (INIS)

Childress, M. J.; Scalzo, R. A.; Sim, S. A.; Tucker, B. E.; Yuan, F.; Schmidt, B. P.; Cenko, S. B.; Filippenko, A. V.; Silverman, J. M.; Contreras, C.; Hsiao, E. Y.; Phillips, M.; Morrell, N.; Jha, S. W.; McCully, C.; Anderson, J. P.; De Jaeger, T.; Forster, F.; Benetti, S.; Bufano, F.

2013-01-01

We present 65 optical spectra of the Type Ia SN 2012fr, 33 of which were obtained before maximum light. At early times, SN 2012fr shows clear evidence of a high-velocity feature (HVF) in the Si II λ6355 line that can be cleanly decoupled from the lower velocity ''photospheric'' component. This Si II λ6355 HVF fades by phase –5; subsequently, the photospheric component exhibits a very narrow velocity width and remains at a nearly constant velocity of ∼12,000 km s –1 until at least five weeks after maximum brightness. The Ca II infrared triplet exhibits similar evidence for both a photospheric component at v ≈ 12,000 km s –1 with narrow line width and long velocity plateau, as well as an HVF beginning at v ≈ 31,000 km s –1 two weeks before maximum. SN 2012fr resides on the border between the ''shallow silicon'' and ''core-normal'' subclasses in the Branch et al. classification scheme, and on the border between normal and high-velocity Type Ia supernovae (SNe Ia) in the Wang et al. system. Though it is a clear member of the ''low velocity gradient'' group of SNe Ia and exhibits a very slow light-curve decline, it shows key dissimilarities with the overluminous SN 1991T or SN 1999aa subclasses of SNe Ia. SN 2012fr represents a well-observed SN Ia at the luminous end of the normal SN Ia distribution and a key transitional event between nominal spectroscopic subclasses of SNe Ia.

THE IMPACT OF METALLICITY ON THE RATE OF TYPE Ia SUPERNOVAE

Energy Technology Data Exchange (ETDEWEB)

Kistler, Matthew D. [California Institute of Technology, Mail Code 350-17, Pasadena, CA 91125 (United States); Stanek, K. Z.; Kochanek, Christopher S.; Thompson, Todd A. [Center for Cosmology and Astro-Particle Physics, Ohio State University, Columbus, OH 43210 (United States); Prieto, Jose L. [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States)

2013-06-20

The metallicity of a star strongly affects both its evolution and the properties of the stellar remnant that results from its demise. It is generally accepted that stars with initial masses below {approx}8 M{sub Sun} leave behind white dwarfs and that some sub-population of these lead to Type Ia supernovae (SNe Ia). However, it is often tacitly assumed that metallicity has no effect on the rate of SNe Ia. We propose that a consequence of the effects of metallicity is to significantly increase the SN Ia rate in lower-metallicity galaxies, in contrast to previous expectations. This is because lower-metallicity stars leave behind higher-mass white dwarfs, which should be easier to bring to explosion. We first model SN Ia rates in relation to galaxy masses and ages alone, finding that the elevation in the rate of SNe Ia in lower-mass galaxies measured by Lick Observatory SN Search is readily explained. However, we then see that models incorporating this effect of metallicity agree just as well. Using the same parameters to estimate the cosmic SN Ia rate, we again find good agreement with data up to z Almost-Equal-To 2. We suggest that this degeneracy warrants more detailed examination of host galaxy metallicities. We discuss additional implications, including for hosts of high-z SNe Ia, the SN Ia delay time distribution, super-Chandrasekhar SNe, and cosmology.

Type Ia supernovae as speed sensors at intermediate redshifts

International Nuclear Information System (INIS)

Zhang Pengjie; Chen Xuelei

2008-01-01

Large scale peculiar velocity (LSPV) is a crucial probe of dark matter, dark energy, and gravity at cosmological scales. However, its application is severely limited by measurement obstacles. We show that fluctuations in type Ia supernovae fluxes induced by LSPV offer a promising approach to measure LSPV at intermediate redshifts. In the 3D Fourier space, gravitational lensing, the dominant systematical error, is well suppressed, localized, and can be further corrected effectively. Advances in supernova observations can further significantly reduce shot noise induced by supernova intrinsic fluctuations, which is the dominant statistical error. Robust mapping on the motion of the dark universe through type Ia supernovae is thus feasible to z∼0.5.

The Foundation Supernova Survey: motivation, design, implementation, and first data release

Science.gov (United States)

Foley, Ryan J.; Scolnic, Daniel; Rest, Armin; Jha, S. W.; Pan, Y.-C.; Riess, A. G.; Challis, P.; Chambers, K. C.; Coulter, D. A.; Dettman, K. G.; Foley, M. M.; Fox, O. D.; Huber, M. E.; Jones, D. O.; Kilpatrick, C. D.; Kirshner, R. P.; Schultz, A. S. B.; Siebert, M. R.; Flewelling, H. A.; Gibson, B.; Magnier, E. A.; Miller, J. A.; Primak, N.; Smartt, S. J.; Smith, K. W.; Wainscoat, R. J.; Waters, C.; Willman, M.

2018-03-01

The Foundation Supernova Survey aims to provide a large, high-fidelity, homogeneous, and precisely calibrated low-redshift Type Ia supernova (SN Ia) sample for cosmology. The calibration of the current low-redshift SN sample is the largest component of systematic uncertainties for SN cosmology, and new data are necessary to make progress. We present the motivation, survey design, observation strategy, implementation, and first results for the Foundation Supernova Survey. We are using the Pan-STARRS telescope to obtain photometry for up to 800 SNe Ia at z ≲ 0.1. This strategy has several unique advantages: (1) the Pan-STARRS system is a superbly calibrated telescopic system, (2) Pan-STARRS has observed 3/4 of the sky in grizyP1 making future template observations unnecessary, (3) we have a well-tested data-reduction pipeline, and (4) we have observed ˜3000 high-redshift SNe Ia on this system. Here, we present our initial sample of 225 SN Ia grizP1 light curves, of which 180 pass all criteria for inclusion in a cosmological sample. The Foundation Supernova Survey already contains more cosmologically useful SNe Ia than all other published low-redshift SN Ia samples combined. We expect that the systematic uncertainties for the Foundation Supernova Sample will be two to three times smaller than other low-redshift samples. We find that our cosmologically useful sample has an intrinsic scatter of 0.111 mag, smaller than other low-redshift samples. We perform detailed simulations showing that simply replacing the current low-redshift SN Ia sample with an equally sized Foundation sample will improve the precision on the dark energy equation-of-state parameter by 35 per cent, and the dark energy figure of merit by 72 per cent.

Progenitor's Signatures in Type Ia Supernova Remnants

NARCIS (Netherlands)

Chiotellis, A.; Kosenko, D.; Schure, K.M.; Vink, J.

2013-01-01

The remnants of Type Ia supernovae (SNe Ia) can provide important clues about their progenitor histories. We discuss two well-observed supernova remnants (SNRs) that are believed to have resulted from SNe Ia, and use various tools to shed light on the possible progenitor histories. We find that

Host galaxies of type ia supernovae from the nearby supernova factory

Science.gov (United States)

Childress, Michael Joseph

Type Ia Supernovae (SNe Ia) are excellent distance indicators, yet the full details of the underlying physical mechanism giving rise to these dramatic stellar deaths remain unclear. As large samples of cosmological SNe Ia continue to be collected, the scatter in brightnesses of these events is equally affected by systematic errors as statistical. Thus we need to understand the physics of SNe Ia better, and in particular we must know more about the progenitors of these SNe so that we can derive better estimates for their true intrinsic brightnesses. The host galaxies of SNe Ia provide important indirect clues as to the nature of SN Ia progenitors. In this Thesis we utilize the host galaxies of SNe Ia discovered by the Nearby Supernova Factory (SNfactory) to pursue several key investigations into the nature of SN Ia progenitors and their effects on SN Ia brightnesses. We first examine the host galaxy of SN 2007if, an important member of the subclass of SNe Ia whose extreme brightnesses indicate a progenitor that exceeded the canonical Chandrasekhar-mass value presumed for normal SNe Ia, and show that the host galaxy of this SN is composed of very young stars and has extremely low metallicity, providing important constraints on progenitor scenarios for this SN. We then utilize the full sample of SNfactory host galaxy masses (measured from photometry) and metallicities (derived from optical spectroscopy) to examine several global properties of SN Ia progenitors: (i) we show that SN Ia hosts show tight agreement with the normal galaxy mass-metallicity relation; (ii) comparing the observed distribution of SN Ia host galaxy masses to a theoretical model that couples galaxy physics to the SN Ia delay time distribution (DTD), we show the power of the SN Ia host mass distribution in constraining the SN Ia DTD; and (iii) we show that the lack of ultra-low metallicities in the SNfactory SN Ia host sample gives provisional support for the theorized low-metallicity inhibition of

THE ABSOLUTE MAGNITUDES OF TYPE Ia SUPERNOVAE IN THE ULTRAVIOLET

International Nuclear Information System (INIS)

Brown, Peter J.; Roming, Peter W. A.; Ciardullo, Robin; Gronwall, Caryl; Hoversten, Erik A.; Pritchard, Tyler; Milne, Peter; Bufano, Filomena; Mazzali, Paolo; Elias-Rosa, Nancy; Filippenko, Alexei V.; Li Weidong; Foley, Ryan J.; Hicken, Malcolm; Kirshner, Robert P.; Gehrels, Neil; Holland, Stephen T.; Immler, Stefan; Phillips, Mark M.; Still, Martin

2010-01-01

We examine the absolute magnitudes and light-curve shapes of 14 nearby (redshift z = 0.004-0.027) Type Ia supernovae (SNe Ia) observed in the ultraviolet (UV) with the Swift Ultraviolet/Optical Telescope. Colors and absolute magnitudes are calculated using both a standard Milky Way extinction law and one for the Large Magellanic Cloud that has been modified by circumstellar scattering. We find very different behavior in the near-UV filters (uvw1 rc covering ∼2600-3300 A after removing optical light, and u ∼ 3000-4000 A) compared to a mid-UV filter (uvm2 ∼2000-2400 A). The uvw1 rc - b colors show a scatter of ∼0.3 mag while uvm2-b scatters by nearly 0.9 mag. Similarly, while the scatter in colors between neighboring filters is small in the optical and somewhat larger in the near-UV, the large scatter in the uvm2 - uvw1 colors implies significantly larger spectral variability below 2600 A. We find that in the near-UV the absolute magnitudes at peak brightness of normal SNe Ia in our sample are correlated with the optical decay rate with a scatter of 0.4 mag, comparable to that found for the optical in our sample. However, in the mid-UV the scatter is larger, ∼1 mag, possibly indicating differences in metallicity. We find no strong correlation between either the UV light-curve shapes or the UV colors and the UV absolute magnitudes. With larger samples, the UV luminosity might be useful as an additional constraint to help determine distance, extinction, and metallicity in order to improve the utility of SNe Ia as standardized candles.

Manganese in Dwarf Galaxies as a Probe of Type Ia Supernovae

Science.gov (United States)

De Los Reyes, Mithi; Kirby, Evan N.

2018-06-01

Despite the importance of thermonuclear or Type Ia supernovae (SNe) as standard candles in astrophysics, the physical mechanisms behind Type Ia SNe are still poorly constrained. Theoretically, the nucleosynthetic yields from Type Ia SNe can distinguish among different models of Type Ia explosions. For example, neutron-rich elements such as manganese (Mn) are sensitive probes of the physics of Type Ia SNe because their abundances are correlated to the density of the progenitor white dwarf. Since dwarf galaxies' chemical evolution is dominated by Type Ia SNe at late times, Type Ia nucleosynthetic yields can be indirectly inferred from stellar abundances in dwarf galaxies. However, previous measurements of Mn in dwarf galaxies are too incomplete to draw definitive conclusions on the Type Ia explosion mechanism. In this work, we therefore use medium-resolution stellar spectroscopy from Keck/DEIMOS to measure Mn abundances in red giants in several Milky Way satellite galaxies. We report average Type Ia Mn yields computed from these abundances, and we discuss the implications for Type Ia supernova physics.

Probing the distance-duality relation with high- z data

Energy Technology Data Exchange (ETDEWEB)

Holanda, R.F.L. [Departamento de Física, Universidade Estadual da Paraíba, 58429-500, Campina Grande—PB (Brazil); Busti, V.C. [Departamento de Física Matemática, Instituto de Física, Universidade de São Paulo, CEP 05508-090, São Paulo—SP (Brazil); Lima, F.S. [Departamento de Física, Universidade Federal de Campina Grande, 58429-900, Campina Grande—PB (Brazil); Alcaniz, J.S., E-mail: holanda@uepb.edu.br, E-mail: viniciusbusti@gmail.com, E-mail: limasdl@bol.com.br, E-mail: alcaniz@on.br [Departamento de Astronomia, Observatório Nacional, 20921-400, Rio de Janeiro—RJ (Brazil)

2017-09-01

Measurements of strong gravitational lensing jointly with type Ia supernovae (SNe Ia) observations have been used to test the validity of the cosmic distance duality relation (CDDR), D{sub L}( z )/[(1+ z ){sup 2D{sub A}}( z )]=η=1, where D{sub L}(z) and D{sub A}(z) are the luminosity and the angular diameter distances to a given redshift z , respectively. However, several lensing systems lie in the interval 1.4 ≤ z ≤ 3.6 i.e., beyond the redshift range of current SNe Ia compilations ( z ≈ 1.50), which prevents this kind of test to be fully explored. In this paper, we circumvent this problem by testing the CDDR considering observations of strong gravitational lensing along with SNe Ia and (a subsample from) the latest gamma-ray burst distance modulus data, whose redshift range is 0.033 ≤ z ≤ 9.3. We parameterize their luminosity distances with a second degree polynomial function and search for possible deviations from the CDDR validity by using four different η( z ) functions: η( z )=1+η{sub 0z}, η( z )=1+η{sub 0z}/(1+ z ), η( z )=(1+ z ){sup η{sub 0}} and η( z )=1+η{sub 0ln}(1+ z ). Unlike previous tests done at redshifts lower than 1.50, the likelihood for η{sub 0} depends strongly on the η( z ) function considered, but we find no significant deviation from the CDDR validity (η{sub 0}=0). However, our analyses also point to the fact that caution is needed when one fits data in higher redshifts to test the CDDR as well as a better understanding of the mass distribution of lenses also is required for more accurate results.

WD+RG systems as the progenitors of type Ia supernovae

International Nuclear Information System (INIS)

Wang Bo; Han Zhanwen

2010-01-01

Type Ia supernovae (SNe Ia) play an important role in the study of cosmic evolution, especially in cosmology. There are several progenitor models for SNe Ia proposed in the past years. By considering the effect of accretion disk instability on the evolution of white dwarf (WD) binaries, we performed detailed binary evolution calculations for the WD + red-giant (RG) channel of SNe Ia, in which a carbon-oxygen WD accretes material from a RG star to increase its mass to the Chandrasekhar mass limit. According to these calculations, we mapped out the initial and final parameters for SNe Ia in the orbital period-secondary mass (log P i - M i 2 ) plane for various WD masses for this channel. We discussed the influence of the variation of the duty cycle value on the regions for producing SNe Ia. Similar to previous studies, this work also indicates that the long-period dwarf novae offer possible ways for producing SNe Ia. Meanwhile, we find that the surviving companion stars from this channel have a low mass after the SN explosion, which may provide a means for the formation of the population of single low-mass WDs ( o-dot ).

A Hubble Diagram of Distant Type IA Supernovae

Science.gov (United States)

Hamuy, M.; Phillips, M. M.; Suntzeff, N. B.; Aviles, R.; Maza, J.

1993-12-01

Due to their extreme luminosities at maximum light, type Ia supernovae (SNe Ia) have long been considered among the most attractive cosmological standard candles. Although nearly all work to date has been devoted to attempts to use these objects to determine the local rate of expansion of the universe (Ho), SNe Ia also provide one of the few direct techniques for measuring the deceleration parameter qo. However, in a recent study of nine well-observed events based largely on data obtained at CTIO, Phillips (1993, ApJ, 413, L105) found clear evidence for a significant intrinsic dispersion in SNe Ia absolute magnitudes amounting to ~ 0.8 mag in B, ~ 0.7 mag in V, and ~ 0.5 mag in I. Such a range in peak luminosity could introduce a subtantial Malmquist bias into searches for distant (z rate of the B light curve. Interestingly, the most luminous SNe in our sample all occurred in spiral galaxies, which is true for Phillips' sample of nearby SNe Ia as well. This is opposite to what one would expect if dust extinction were important. These findings are consistent with recent speculations that the progenitors of SNe Ia are white dwarfs covering a range of masses, and also suggest that the brightest events may be found in galaxies which are still actively forming stars. The implications for the use of SNe Ia to measure qo are briefly discussed. This research has been supported by Grant 92/0312 from Fondo Nacional de Ciencias y Tecnología (FONDECYT-Chile).

Confronting quintessence models with recent high-redshift supernovae data

International Nuclear Information System (INIS)

Calvo, G. Barro; Maroto, A. L.

2006-01-01

We confront the predictions of different quintessence models with recent measurements of the luminosity distance from two sets of supernovae type Ia. In particular, we consider the 157 SNe Ia in the Gold dataset with z M -α and Ω M -w φ planes for the different models and compare their predictions with dark energy models with constant equation of state

THE SPECTROSCOPIC DIVERSITY OF TYPE Ia SUPERNOVAE

International Nuclear Information System (INIS)

Blondin, S.; Matheson, T.; Kirshner, R. P.; Mandel, K. S.; Challis, P.; Berlind, P.; Calkins, M.; Garnavich, P. M.; Jha, S. W.; Modjaz, M.; Riess, A. G.; Schmidt, B. P.

2012-01-01

We present 2603 spectra of 462 nearby Type Ia supernovae (SNe Ia), including 2065 previously unpublished spectra, obtained during 1993-2008 through the Center for Astrophysics Supernova Program. There are on average eight spectra for each of the 313 SNe Ia with at least two spectra. Most of the spectra were obtained with the FAST spectrograph at the Fred Lawrence Whipple Observatory 1.5 m telescope and reduced in a consistent manner, making this data set well suited for studies of SN Ia spectroscopic diversity. Using additional data from the literature, we study the spectroscopic and photometric properties of SNe Ia as a function of spectroscopic class using the classification schemes of Branch et al. and Wang et al. The width-luminosity relation appears to be steeper for SNe Ia with broader lines, although the result is not statistically significant with the present sample. Based on the evolution of the characteristic Si II λ6355 line, we propose improved methods for measuring velocity gradients, revealing a larger range than previously suspected, from ∼0 to ∼400 km s −1 day −1 considering the instantaneous velocity decline rate at maximum light. We find a weaker and less significant correlation between Si II velocity and intrinsic B – V color at maximum light than reported by Foley et al., owing to a more comprehensive treatment of uncertainties and host galaxy dust. We study the extent of nuclear burning and the presence of unburnt carbon in the outermost layers of the ejecta and report new detections of C II λ6580 in 23 early-time SN Ia spectra. The frequency of C II detections is not higher in SNe Ia with bluer colors or narrower light curves, in conflict with the recent results of Thomas et al. Based on nebular spectra of 27 SNe Ia, we find no relation between the FWHM of the iron emission feature at ∼4700 Å and Δm 15 (B) after removing the two low-luminosity SN 1986G and SN 1991bg, suggesting that the peak luminosity is not strongly dependent

A MEASUREMENT OF THE RATE OF TYPE Ia SUPERNOVAE IN GALAXY CLUSTERS FROM THE SDSS-II SUPERNOVA SURVEY

International Nuclear Information System (INIS)

Dilday, Benjamin; Jha, Saurabh W.; Bassett, Bruce; Becker, Andrew; Bender, Ralf; Hopp, Ulrich; Castander, Francisco; Cinabro, David; Frieman, Joshua A.; Galbany, LluIs; Miquel, Ramon; Garnavich, Peter; Goobar, Ariel; Ihara, Yutaka; Kessler, Richard; Lampeitl, Hubert; Nichol, Robert C.; Marriner, John; Molla, Mercedes

2010-01-01

We present measurements of the Type Ia supernova (SN) rate in galaxy clusters based on data from the Sloan Digital Sky Survey-II (SDSS-II) Supernova Survey. The cluster SN Ia rate is determined from 9 SN events in a set of 71 C4 clusters at z ≤ 0.17 and 27 SN events in 492 maxBCG clusters at 0.1 ≤ z ≤ 0.3. We find values for the cluster SN Ia rate of (0.37 +0.17+0.01 -0.12-0.01 ) SNur h 2 and (0.55 +0.13+0.02 -0.11-0.01 ) SNur h 2 (SNux = 10 -12 L -1 xsun yr -1 ) in C4 and maxBCG clusters, respectively, where the quoted errors are statistical and systematic, respectively. The SN rate for early-type galaxies is found to be (0.31 +0.18+0.01 -0.12-0.01 ) SNur h 2 and (0.49 +0.15+0.02 -0.11-0.01 ) SNur h 2 in C4 and maxBCG clusters, respectively. The SN rate for the brightest cluster galaxies (BCG) is found to be (2.04 +1.99+0.07 -1.11-0.04 ) SNur h 2 and (0.36 +0.84+0.01 -0.30-0.01 ) SNur h 2 in C4 and maxBCG clusters, respectively. The ratio of the SN Ia rate in cluster early-type galaxies to that of the SN Ia rate in field early-type galaxies is 1.94 +1.31+0.043 -0.91-0.015 and 3.02 +1.31+0.062 -1.03-0.048 , for C4 and maxBCG clusters, respectively. The SN rate in galaxy clusters as a function of redshift, which probes the late time SN Ia delay distribution, shows only weak dependence on redshift. Combining our current measurements with previous measurements, we fit the cluster SN Ia rate data to a linear function of redshift, and find r L = [(0.49 +0.15 -0.14 )+(0.91 +0.85 -0.81 ) x z] SNuB h 2 . A comparison of the radial distribution of SNe in cluster to field early-type galaxies shows possible evidence for an enhancement of the SN rate in the cores of cluster early-type galaxies. With an observation of at most three hostless, intra-cluster SNe Ia, we estimate the fraction of cluster SNe that are hostless to be (9.4 +8.3 -5.1 )%.

New approaches for modeling type Ia supernovae

International Nuclear Information System (INIS)

Zingale, Michael; Almgren, Ann S.; Bell, John B.; Day, Marcus S.; Rendleman, Charles A.; Woosley, Stan

2007-01-01

Type Ia supernovae (SNe Ia) are the largest thermonuclear explosions in the Universe. Their light output can be seen across great distances and has led to the discovery that the expansion rate of the Universe is accelerating. Despite the significance of SNe Ia, there are still a large number of uncertainties in current theoretical models. Computational modeling offers the promise to help answer the outstanding questions. However, even with today's supercomputers, such calculations are extremely challenging because of the wide range of length and timescales. In this paper, we discuss several new algorithms for simulations of SNe Ia and demonstrate some of their successes

TESTING THE DISTANCE-DUALITY RELATION WITH GALAXY CLUSTERS AND TYPE Ia SUPERNOVAE

International Nuclear Information System (INIS)

Holanda, R. F. L.; Lima, J. A. S.; Ribeiro, M. B.

2010-01-01

In this Letter, we propose a new and model-independent cosmological test for the distance-duality (DD) relation, η = D L (z)(1 + z) -2 /D A (z) = 1, where D L and D A are, respectively, the luminosity and angular diameter distances. For D L we consider two sub-samples of Type Ia supernovae (SNe Ia) taken from Constitution data whereas D A distances are provided by two samples of galaxy clusters compiled by De Filippis et al. and Bonamente et al. by combining Sunyaev-Zeldovich effect and X-ray surface brightness. The SNe Ia redshifts of each sub-sample were carefully chosen to coincide with the ones of the associated galaxy cluster sample (Δz A (z) ape D L (z), we have tested the DD relation by assuming that η is a function of the redshift parameterized by two different expressions: η(z) = 1 + η 0 z and η(z) = 1 + η 0 z/(1 + z), where η 0 is a constant parameter quantifying a possible departure from the strict validity of the reciprocity relation (η 0 = 0). In the best scenario (linear parameterization), we obtain η 0 = -0.28 +0.44 -0.44 (2σ, statistical + systematic errors) for the De Filippis et al. sample (elliptical geometry), a result only marginally compatible with the DD relation. However, for the Bonamente et al. sample (spherical geometry) the constraint is η 0 = -0.42 +0.34 -0.34 (3σ, statistical + systematic errors), which is clearly incompatible with the duality-distance relation.

WISH: Wide-field Imaging Durvayor for High-redshift

Science.gov (United States)

Yamada, Toru

2015-08-01

We introduce the concept and current status of WISH project and discuss the science cases. WISH is a proposed space science mission for JAXA, which is dedicated for the deep and wide-field near-infrared imaging surveys. The mission contains the 1.5m cooled telescope as well as the imager with the FoV of ~850 square arcmin. The main goal of WISH is to detect and study galaxies at z=8-15 in the earliest history of structure formation in the universe. The key feature is to conduct WISH Ultra Deep Survey, which images in total of 100 square degrees in 6 broad-band filters at 0.9-4.5 micron down to 28AB magnitude. While more than 10^5 galaxies at z=8-9, 10^4 galaxies at z=11-12 will be detected, WISH-UDS is designed to constrain UV luminosity function at z=15. Depending on the models of the earliest evolution history, 1-1000 galaxies at z~15 (~100 galaxies for the moderate cases) will be detected. The UV spectral properties as well as the clustering properties of galaxies at z=8-15 can be studied as well; UV slope can be measured up to z=15, and the stellar and dark-matter-halo masses can be obtained up to z=9. WISH UDS can provide excellent opportunities for studying SNe at high redshift. Up to ~7000 type Ia SNe at z>1 can be detected and the distance modulus can be constrained with the precision of 0.9-1.5% at z>1.5. More than 100 Super Luminous SNe at z>6, and 10 SLSN at z>10 can also be detected, which allow us to study the earliest history of massive star formation in the universe. WISH imaging surveys as well as WISHSpec, which is an optional parallel-operation simple IFU spectrograph, also provide unique opportunities in various astronomical fields. WISH mission proposal was submitted to JAXA in February 2015 for the first down selection of JAXA Large Strategic Science Mission targeting the launch date in 2020-22. International collaborations including SAO (G.Fazio et al.), LAM (D. Burgarella et al.) and Canada (M.Sawicki et al.) are also actively coordinated.

Investigating the Effect of Cosmic Opacity on Standard Candles

International Nuclear Information System (INIS)

Hu, J.; Yu, H.; Wang, F. Y.

2017-01-01

Standard candles can probe the evolution of dark energy over a large redshift range. But the cosmic opacity can degrade the quality of standard candles. In this paper, we use the latest observations, including Type Ia supernovae (SNe Ia) from the “joint light-curve analysis” sample and Hubble parameters, to probe the opacity of the universe. A joint fitting of the SNe Ia light-curve parameters, cosmological parameters, and opacity is used in order to avoid the cosmological dependence of SNe Ia luminosity distances. The latest gamma-ray bursts are used in order to explore the cosmic opacity at high redshifts. The cosmic reionization process is considered at high redshifts. We find that the sample supports an almost transparent universe for flat ΛCDM and XCDM models. Meanwhile, free electrons deplete photons from standard candles through (inverse) Compton scattering, which is known as an important component of opacity. This Compton dimming may play an important role in future supernova surveys. From analysis, we find that about a few per cent of the cosmic opacity is caused by Compton dimming in the two models, which can be corrected.

CIRCUMSTELLAR SHELLS IN ABSORPTION IN TYPE Ia SUPERNOVAE

International Nuclear Information System (INIS)

Borkowski, Kazimierz J.; Blondin, John M.; Reynolds, Stephen P.

2009-01-01

Progenitors of Type Ia supernovae (SNe) have been predicted to modify their ambient circumstellar (CSM) and interstellar environments through the action of their powerful winds. While there is X-ray and optical evidence for circumstellar interaction in several remnants of Type Ia SNe, widespread evidence for such interaction in Type Ia SNe themselves has been lacking. We consider prospects for the detection of CSM shells that have been predicted to be common around Type Ia SNe. Such shells are most easily detected in Na I absorption lines. Variable (declining) absorption is expected to occur soon after the explosion, primarily during the SN rise time, for shells located within ∼1-10 pc of a SN. The distance of the shell from the SN can be determined by measuring the timescale for line variability.

Non-Local Thermodynamic Equilibrium Spectrum Synthesis of Type IA Supernovae

Science.gov (United States)

Nugent, Peter Edward

1997-09-01

Type Ia supernovae (SNe Ia) are valuable distance indicators for cosmology and the elements they eject are are important for nucleosynthesis. They appear to be thermonuclear disruptions of carbon-oxygen white dwarfs that accrete from companion stars until they approach the Chandrasekbar mass, and there is a suspicion that the propagation of the nuclear burning front involves a transition from a deflagration to a detonation. Detailed modeling of the atmospheres and spectra of SNe Ia is needed to advance our understanding of SNe Ia. Comparison of synthetic and observed spectra provides information on the temperature, density, velocity, and composition of the ejected matter and thus constrain hydrodynamical models. In addition, the expanding photosphere method yields distances to individual events that are independent of distances based on the decay of 56Ni in SNe Ia and of Cepheid variable stars in the parent galaxies. This thesis is broken down into 4 major sections, each highlighting a different way with which to use spectrum synthesis to analyze SNe Ia. Chapters 2 and 3 look at normal SNe Ia and their potential use as distance indicators using SEAM. Chapter 4 examines spectral correlations with luminosity in SNe Ia and provides a plausible explanation for these correlations via spectrum synthesis. In Chapter 5 the spectra of various hydrodynamical models are calculated in an effort to answer the question of which current progenitor/explosion model is the most plausible for a SN Ia. Finally, we look at the importance of NLTE calculations and line identifications in Chapter 6. Also included are two appendices which contain more technical information concerning γ-ray deposition and the thermalization parameter.

Clues on Type Ia Supernovae Progenitors

International Nuclear Information System (INIS)

Piersanti, Luciano; Tornambe, Amedeo

2005-01-01

We show that in the framework of canonical stellar evolution it is hard, if not impossible, to determine the growth in mass of a CO White Dwarf, up to the Chandrasekhar limit by means of mass transfer from its companion in a binary system. This is the case either if matter is accreted from a normal companion with an H-rich envelope or if direct CO accretion occurs from a CO WD companion. At variance, we show that if the effects of rotation are taken into account in modeling the accretion process, a CO WD can increase its mass at the expenses of the degenerate CO companion up and beyond 1.4 M· , so that an explosive event of the type Ia class is naturally produced. This theoretical finding revives the Double Degenerate scenario for type Ia SNe progenitors. In such a case the internal spread in the observational properties of type Ia SNe may be interpreted as a consequence of different total masses; hence differences between SNe Ia in nearby elliptical galaxies and the majority of those in spirals should be expected and the current use of type Ia SNe as cosmological distance indicators should be justified

The cosmic transparency measured with Type Ia supernovae: implications for intergalactic dust

Science.gov (United States)

Goobar, Ariel; Dhawan, Suhail; Scolnic, Daniel

2018-06-01

Observations of high-redshift Type Ia supernovae (SNe Ia) are used to study the cosmic transparency at optical wavelengths. Assuming a flat Λ cold dark matter (ΛCDM) cosmological model based on baryon acoustic oscillations and cosmic microwave background measurements, redshift dependent deviations of SN Ia distances are used to constrain mechanisms that would dim light. The analysis is based on the most recent Pantheon SN compilation, for which there is a 0.03 ± 0.01 {({stat})} mag discrepancy in the distant supernova distance moduli relative to the ΛCDM model anchored by supernovae at z < 0.05. While there are known systematic uncertainties that combined could explain the observed offset, here we entertain the possibility that the discrepancy may instead be explained by scattering of supernova light in the intergalactic medium (IGM). We focus on two effects: Compton scattering by free electrons and extinction by dust in the IGM. We find that if the discrepancy is entirely due to dimming by dust, the measurements can be modelled with a cosmic dust density Ω _IGM^dust = 8 × 10^{-5} (1+z)^{-1}, corresponding to an average attenuation of 2 × 10-5 mag Mpc-1 in V band. Forthcoming SN Ia studies may provide a definitive measurement of the IGM dust properties, while still providing an unbiased estimate of cosmological parameters by introducing additional parameters in the global fits to the observations.

A CATALOG OF NEAR-INFRARED SPECTRA FROM TYPE Ia SUPERNOVAE

International Nuclear Information System (INIS)

Marion, G. H.; Wheeler, J. C.; Robinson, E. L.; Hoeflich, P.; Gerardy, C. L.; Vacca, W. D.

2009-01-01

We present 41 near-infrared (NIR, 0.7-2.5 μm) spectra from normal Type Ia supernovae (SNe Ia) obtained at epochs ranging from 14 days before to 75 days with respect to the maximum light date in the V band. All data were obtained at the Infrared Telescope Facility using the SpeX instrument. We identify many spectral features, measure the Doppler velocities, and discuss the chemical distribution of explosion products in SNe Ia. We describe procedures for smoothing data, fitting continua, and measuring absorption features to ensure consistency for measurement and analysis. This sample provides the first opportunity to examine and compare a large number of SNe Ia in this wavelength region. NIR data are a rich source of information about explosion products whose signatures are blended or obscured in other spectral regions and NIR observations probe a greater radial depth than optical wavelengths. We analyze similarities and differences in the spectra and we show that the progressive development of spectral features for normal SNe Ia in the NIR is consistent with time. We confirm the presence of O I, Mg II, Ca II, Si II, Fe II, and Co II in these SNe. Possible identifications are made for S I, Si III, Mn II, and Fe III. There is no evidence in these data for H I, He I, C I, or C II. As the explosion products expand and cool, progressively deeper layers are revealed. Thus, a time sequence of spectra examines the chemical structure and provides direct evidence of the physical properties of SNe Ia from the outer layers to deep inside the SN. Measured Doppler velocities indicate that burning products in SNe Ia are distributed in distinct layers with no large-scale mixing. Carbon is not detected in these data, in agreement with previous results with NIR data establishing very low limits on carbon abundance in SNe Ia. Carbon burning products, O and Mg, are plentiful in the outer layers suggesting that the entire progenitor is burned in the explosion. The data provide a

STRESS Counting Supernovae

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Botticella, M. T.; Cappellaro, E.; Riello, M.; Greggio, L.; Benetti, S.; Patat, F.; Turatto, M.; Altavilla, G.; Pastorello, A.; Valenti, S.; Zampieri, L.; Harutyunyan, A.; Pignata, G.; Taubenberger, S.

2008-12-01

The rate of occurrence of supernovae (SNe) is linked to some of the basic ingredients of galaxy evolution, such as the star formation rate, the chemical enrichment and feedback processes. SN rates at intermediate redshift and their dependence on specific galaxy properties have been investigated in the Southern inTermediate Redshift ESO Supernova Search (STRESS). The rate of core collapse SNe (CC SNe) at a redshift of around 0.25 is found to be a factor two higher than the local value, whereas the SNe Ia rate remains almost constant. SN rates in red and blue galaxies were also measured and it was found that the SNe Ia rate seems to be constant in galaxies of different colour, whereas the CC SN rate seems to peak in blue galaxies, as in the local Universe.

EVOLVING TO TYPE Ia SUPERNOVAE WITH SHORT DELAY TIMES

International Nuclear Information System (INIS)

Wang Bo; Chen Xuefei; Han Zhanwen; Meng Xiangcun

2009-01-01

The single-degenerate model is currently a favorable progenitor model for Type Ia supernovae (SNe Ia). Recent investigations on the white dwarf (WD) + He star channel of the single-degenerate model imply that this channel is noteworthy for producing SNe Ia. In this paper, we studied SN Ia birthrates and delay times of this channel via a detailed binary population synthesis approach. We found that the Galactic SN Ia birthrate from the WD + He star channel is ∼0.3 x 10 -3 yr -1 according to our standard model, and that this channel can explain SNe Ia with short delay times (∼4.5 x 10 7 -1.4 x 10 8 yr). Meanwhile, these WD + He star systems may be related to the young supersoft X-ray sources prior to SN Ia explosions.

Twenty-Three High-Redshift Supernovae from the Institute for Astronomy Deep Survey: Doubling the Supernova Sample at z > 0.7

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Barris, Brian J.; Tonry, John L.; Blondin, Stéphane; Challis, Peter; Chornock, Ryan; Clocchiatti, Alejandro; Filippenko, Alexei V.; Garnavich, Peter; Holland, Stephen T.; Jha, Saurabh; Kirshner, Robert P.; Krisciunas, Kevin; Leibundgut, Bruno; Li, Weidong; Matheson, Thomas; Miknaitis, Gajus; Riess, Adam G.; Schmidt, Brian P.; Smith, R. Chris; Sollerman, Jesper; Spyromilio, Jason; Stubbs, Christopher W.; Suntzeff, Nicholas B.; Aussel, Hervé; Chambers, K. C.; Connelley, M. S.; Donovan, D.; Henry, J. Patrick; Kaiser, Nick; Liu, Michael C.; Martín, Eduardo L.; Wainscoat, Richard J.

2004-02-01

We present photometric and spectroscopic observations of 23 high-redshift supernovae (SNe) spanning a range of z=0.34-1.03, nine of which are unambiguously classified as Type Ia. These SNe were discovered during the IfA Deep Survey, which began in 2001 September and observed a total of 2.5 deg2 to a depth of approximately m~25-26 in RIZ over 9-17 visits, typically every 1-3 weeks for nearly 5 months, with additional observations continuing until 2002 April. We give a brief description of the survey motivations, observational strategy, and reduction process. This sample of 23 high-redshift SNe includes 15 at z>=0.7, doubling the published number of objects at these redshifts, and indicates that the evidence for acceleration of the universe is not due to a systematic effect proportional to redshift. In combination with the recent compilation of Tonry et al. (2003), we calculate cosmological parameter density contours that are consistent with the flat universe indicated by the cosmic microwave background (Spergel et al. 2003). Adopting the constraint that Ωtotal=1.0, we obtain best-fit values of (Ωm,ΩΛ)=(0.33,0.67) using 22 SNe from this survey augmented by the literature compilation. We show that using the empty-beam model for gravitational lensing does not eliminate the need for ΩΛ>0. Experience from this survey indicates great potential for similar large-scale surveys while also revealing the limitations of performing surveys for z>1 SNe from the ground. CFHT: Based in part on observations obtained at the Canada-France-Hawaii Telescope (CFHT), which is operated by the National Research Council of Canada, the Institut National des Science de l'Univers of the Centre National de la Recherche Scientifique of France, and the University of Hawaii. CTIO: Based in part on observations taken at the Cerro Tololo Inter-American Observatory. Keck: Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership

A Measurement of the Rate of Type Ia Supernovae in Galaxy Clusters from the SDSS-II Supernova Survey

Energy Technology Data Exchange (ETDEWEB)

Dilday, Benjamin; /Rutgers U., Piscataway /Chicago U. /KICP, Chicago; Bassett, Bruce; /Cape Town U., Dept. Math. /South African Astron. Observ.; Becker, Andrew; /Washington U., Seattle, Astron. Dept.; Bender, Ralf; /Munich, Tech. U. /Munich U. Observ.; Castander, Francisco; /Barcelona, IEEC; Cinabro, David; /Wayne State U.; Frieman, Joshua A.; /Chicago U. /Fermilab; Galbany, Lluis; /Barcelona, IFAE; Garnavich, Peter; /Notre Dame U.; Goobar, Ariel; /Stockholm U., OKC /Stockholm U.; Hopp, Ulrich; /Munich, Tech. U. /Munich U. Observ. /Tokyo U.

2010-03-01

We present measurements of the Type Ia supernova (SN) rate in galaxy clusters based on data from the Sloan Digital Sky Survey-II (SDSS-II) Supernova Survey. The cluster SN Ia rate is determined from 9 SN events in a set of 71 C4 clusters at z {le} 0.17 and 27 SN events in 492 maxBCG clusters at 0.1 {le} z {le} 0.3. We find values for the cluster SN Ia rate of (0.37{sub -0.12-0.01}{sup +0.17+0.01}) SNur h{sup 2} and (0.55{sub -0.11-0.01}{sup +0.13+0.02}) SNur h{sup 2} (SNux = 10{sup -12}L{sub x{circle_dot}}{sup -1} yr{sup -1}) in C4 and maxBCG clusters, respectively, where the quoted errors are statistical and systematic, respectively. The SN rate for early-type galaxies is found to be (0.31{sub -0.12-0.01}{sup +0.18+0.01}) SNur h{sup 2} and (0.49{sub -0.11-0.01}{sup +0.15+0.02}) SNur h{sup 2} in C4 and maxBCG clusters, respectively. The SN rate for the brightest cluster galaxies (BCG) is found to be (2.04{sub -1.11-0.04}{sup +1.99+0.07}) SNur h{sup 2} and (0.36{sub -0.30-0.01}{sup +0.84+0.01}) SNur h{sup 2} in C4 and maxBCG clusters, respectively. The ratio of the SN Ia rate in cluster early-type galaxies to that of the SN Ia rate in field early-type galaxies is 1.94{sub -0.91-0.015}{sup +1.31+0.043} and 3.02{sub -1.03-0.048}{sup +1.31+0.062}, for C4 and maxBCG clusters, respectively. The SN rate in galaxy clusters as a function of redshift, which probes the late time SN Ia delay distribution, shows only weak dependence on redshift. Combining our current measurements with previous measurements, we fit the cluster SN Ia rate data to a linear function of redshift, and find r{sub L} = [(0.49{sub -0.14}{sup +0.15}) + (0.91{sub -0.81}{sup +0.85}) x z] SNuB h{sup 2}. A comparison of the radial distribution of SNe in cluster to field early-type galaxies shows possible evidence for an enhancement of the SN rate in the cores of cluster early-type galaxies. With an observation of at most 3 hostless, intra-cluster SNe Ia, we estimate the fraction of cluster SNe that are

The curious case of SN 2011dn: A very peculiar type Ia supernova?

Science.gov (United States)

Rachubo, Alisa

Type Ia supernovae (SNe Ia) are excellent cosmological distance indicators due to the uniformity in their light curves, which led to the major discovery of the accelerated expansion of the universe. However, SNe Ia are not so uniform as one may expect, as there are many peculiar SNe Ia that exhibit differences in their photometric and spectroscopic behavior from normal SNe Ia. One of the goals of supernova cosmology today is to produce a cleaner sample of SNe Ia without these peculiar SNe Ia. Here we consider SN 2011dn, a peculiar SN Ia candidate. In 2011, Salvo, et al. carried out a preliminary analysis of a subset of the data prescribed here, and identified spectral and photometric peculiarities in this object's evolution that warranted further analysis. Here, we present a complete re-reduction and reanalysis of B, V,R, and I photometry of SN 2011dn obtained at Mount Laguna Observatory, spanning from 7 days before maximum light in B to 88 days past maximum light. In addition, we also consider total flux spectra from 9 days before maximum light to 4 days after maximum light, along with ultraviolet (UV) photometry obtained with the Swift telescope. From SN 2011dn's optical spectra, we find that SN 2011dn most closely resembles a SN 1991T-like type Ia supernova ('91T-like SN Ia). Such SNe Ia are typically more luminous than normal SNe Ia, and possess broader (i.e., they decline less rapidly than normal from maximum light) light curves. Their Deltam15(B) (drop in B magnitude 15 days after maximum light) are typically significantly less than the canonical value of 1.1, and can be as low as 0.8. In the earlier preliminary analysis, Salvo et al. measured a surprisingly high Deltam15(B) value for SN 2011dn, of ˜ 1.1. Since SN 2011dn was embedded in UGC 11501 (its host galaxy), however, it is possible that some of the light from the host galaxy was included in the photometric aperture, resulting in inaccurate photometric measurements. Here, in order to better isolate the

HIGH-VELOCITY LINE FORMING REGIONS IN THE TYPE Ia SUPERNOVA 2009ig

International Nuclear Information System (INIS)

Marion, G. H.; Foley, Ryan J.; Challis, Peter; Kirshner, Robert P.; Vinko, Jozsef; Wheeler, J. Craig; Silverman, Jeffrey M.; Hsiao, Eric Y.; Brown, Peter J.; Filippenko, Alexei V.; Garnavich, Peter; Landsman, Wayne B.; Parrent, Jerod T.; Pritchard, Tyler A.; Roming, Peter W. A.; Wang, Xiaofeng

2013-01-01

We report measurements and analysis of high-velocity (HVF) (>20,000 km s –1 ) and photospheric absorption features in a series of spectra of the Type Ia supernova (SN) 2009ig obtained between –14 days and +13 days with respect to the time of maximum B-band luminosity (B-max). We identify lines of Si II, Si III, S II, Ca II, and Fe II that produce both HVF and photospheric-velocity (PVF) absorption features. SN 2009ig is unusual for the large number of lines with detectable HVF in the spectra, but the light-curve parameters correspond to a slightly overluminous but unexceptional SN Ia (M B = –19.46 mag and Δm 15 (B) = 0.90 mag). Similarly, the Si II λ6355 velocity at the time of B-max is greater than 'normal' for an SN Ia, but it is not extreme (v Si = 13,400 km s –1 ). The –14 days and –13 days spectra clearly resolve HVF from Si II λ6355 as separate absorptions from a detached line forming region. At these very early phases, detached HVF are prevalent in all lines. From –12 days to –6 days, HVF and PVF are detected simultaneously, and the two line forming regions maintain a constant separation of about 8000 km s –1 . After –6 days all absorption features are PVF. The observations of SN 2009ig provide a complete picture of the transition from HVF to PVF. Most SNe Ia show evidence for HVF from multiple lines in spectra obtained before –10 days, and we compare the spectra of SN 2009ig to observations of other SNe. We show that each of the unusual line profiles for Si II λ6355 found in early-time spectra of SNe Ia correlate to a specific phase in a common development sequence from HVF to PVF

ON THE PROGENITORS OF SUPER-CHANDRASEKHAR MASS TYPE Ia SUPERNOVAE

International Nuclear Information System (INIS)

Chen Wencong; Li Xiangdong

2009-01-01

Type Ia supernovae (SNe Ia) can be used as the standard candle to determine the cosmological distances because they are thought to have a uniform fuel amount. Recent observations of several overluminous SNe Ia suggest that the white dwarf masses at supernova explosion may significantly exceed the canonical Chandrasekhar mass limit. These massive white dwarfs may be supported by rapid differential rotation. Based on a single-degenerate model and the assumption that the white dwarf would differentially rotate when the accretion rate M-dot>3 x 10 -7 M-odot yr -1 , we have calculated the evolutions of close binaries consisting of a white dwarf and a normal companion. To include the effect of rotation, we introduce an effective mass M eff for white dwarfs. For the donor stars with two different metallicities Z = 0.02 and 0.001, we present the distribution of the initial donor star masses and the orbital periods of the progenitors of super-Chandrasekhar mass SNe Ia. The calculation results indicate that, for an initial massive white dwarf of 1.2 M sun , a considerable fraction of SNe Ia may result from super-Chandrasekhar mass white dwarfs, but very massive (> 1.7 M sun ) white dwarfs are difficult to form, and none of them could be found in old populations. However, super-Chandrasekhar mass SNe Ia are very rare when the initial mass of white dwarfs is 1.0 M sun . Additionally, SNe Ia in low metallicity environment are more likely to be homogeneous.

Resolving Supernovae, H0, and the Equation of State with HST

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Strolger, Louis-Gregory; Rohde, A. C.; Gorski, M. J.; Riess, A. G.; Lampeitl, H.; Ferguson, H. C.; Martel, A. R.

2006-12-01

There is little understood about the nature of the dark energy component of the universe. Presently, inconsistency in the value of the Hubble constant and the limited sample of Type Ia supernovae (SNeIa) at z>1 provide the largest sources of uncertainty in the evolutionary nature of dark energy. There is also growing suspicion that SNeIa may be the result of at least two physical mechanisms, which may produce unnoticed effects in cosmological parameters. The preferred bulk mechanism for SN Ia progenitors, and more importantly the accuracy of the same empirical corrections over all redshifts, can be ascertained by studying the rate of SNeIa in the early universe. The notably few SNeIa found at z>1.4 in the deep HST surveys have suggested that most SNeIa take 3-4 Gyr to develop from a single burst of star formation. Simple tests of this conclusion would be to gather a more statistically significant sample of SNeIa in the desired redshift range, or just a few events at z>2. We present our new investigations with HST into these critical issues. Our Cycle 15 program, SHOES, continues the search for SNeIa at z>1 with ACS, but has an added component of simultaneous observations with NICMOS of Cepheids in galaxies that have hosted well studied SNeIa. These observations are expected to greatly reduce the uncertainty in H_0 (likewise reducing uncertainty in Omega_M), which along with the increased overall z>1 sample, will likely reduce dark energy constraints by approximately 40%. With the addition of the SHOES sample to those from PANS and GOODS, we will have nearly 4 times as many z>1 SNeIa to test the bulk delay of SNeIa from the cosmic star formation rate history. And by performing creative combinations of the data, we will ultimately produce an ultra deep survey for possible z>2 SNeIa.

The double-degenerate model for the progenitors of Type Ia supernovae

Science.gov (United States)

Liu, D.; Wang, B.; Han, Z.

2018-02-01

The double-degenerate (DD) model, involving the merging of massive double carbon-oxygen white dwarfs (CO WDs) driven by gravitational wave radiation, is one of the classical pathways for the formation of Type Ia supernovae (SNe Ia). Recently, it has been proposed that the WD+He subgiant channel has a significant contribution to the production of massive double WDs, in which the primary WD accumulates mass by accreting He-rich matter from an He subgiant. We evolved about 1800 CO WD+He star systems and obtained a large and dense grid for producing SNe Ia through the DD model. We then performed a series of binary population synthesis simulations for the DD model, in which the WD+He subgiant channel is calculated by interpolations in the SN Ia production grid. According to our standard model, the Galactic birth rate of SNe Ia is about 2.4 × 10- 3 yr- 1 for the WD+He subgiant channel of the DD model; the total birth rate is about 3.7 × 10- 3 yr- 1 for all channels, reproducing that of observations. Previous theoretical models still have deficit with the observed SNe Ia with delay times 8 Gyr. After considering the WD+He subgiant channel, we found that the delay time distributions are comparable with the observed results. Additionally, some recent studies proposed that the violent WD mergers are more likely to produce SNe Ia based on the DD model. We estimated that the violent mergers through the DD model may contribute to at most 16 per cent of all SNe Ia.

Cataclysmic Variables as Supernova Ia Progenitors

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Stella Kafka

2012-06-01

Full Text Available Although the identification of the progenitors of type Ia supernovae (SNeIa remains controversial, it is generally accepted that they originate from binary star systems in which at least one component is a carbon-oxygen white dwarf (WD; those systems are grouped under the wide umbrella of cataclysmic variables. Current theories for SNeIa progenitors hold that, either via Roche lobe overflow of the companion or via a wind, the WD accumulates hydrogen or helium rich material which is then burned to C and O onto the WD’s surface. However, the specifics of this scenario are far from being understood or defined, allowing for a wealth of theories fighting for attention and a dearth of observations to support them. I discuss the latest attempts to identify and study those controversial SNeIa progenitors. I also introduce the most promising progenitor in hand and I present observational diagnostics that can reveal more members of the category.

THE EFFECT OF HOST GALAXIES ON TYPE Ia SUPERNOVAE IN THE SDSS-II SUPERNOVA SURVEY

International Nuclear Information System (INIS)

Lampeitl, Hubert; Smith, Mathew; Nichol, Robert C.; Bassett, Bruce; Cinabro, David; Dilday, Benjamin; Jha, Saurabh W.; Foley, Ryan J.; Frieman, Joshua A.; Garnavich, Peter M.; Goobar, Ariel; Nordin, Jakob; Im, Myungshin; Marriner, John; Miquel, Ramon; Oestman, Linda; Riess, Adam G.; Sako, Masao; Schneider, Donald P.; Sollerman, Jesper

2010-01-01

We present an analysis of the host galaxy dependences of Type Ia Supernovae (SNe Ia) from the full three year sample of the SDSS-II Supernova Survey. We re-discover, to high significance, the strong correlation between host galaxy type and the width of the observed SN light curve, i.e., fainter, quickly declining SNe Ia favor passive host galaxies, while brighter, slowly declining Ia's favor star-forming galaxies. We also find evidence (at between 2σ and 3σ) that SNe Ia are ≅0.1 ± 0.04 mag brighter in passive host galaxies than in star-forming hosts, after the SN Ia light curves have been standardized using the light-curve shape and color variations. This difference in brightness is present in both the SALT2 and MCLS2k2 light-curve fitting methodologies. We see evidence for differences in the SN Ia color relationship between passive and star-forming host galaxies, e.g., for the MLCS2k2 technique, we see that SNe Ia in passive hosts favor a dust law of R V = 1.0 ± 0.2, while SNe Ia in star-forming hosts require R V = 1.8 +0.2 -0.4 . The significance of these trends depends on the range of SN colors considered. We demonstrate that these effects can be parameterized using the stellar mass of the host galaxy (with a confidence of >4σ) and including this extra parameter provides a better statistical fit to our data. Our results suggest that future cosmological analyses of SN Ia samples should include host galaxy information.

THE OXYGEN FEATURES IN TYPE Ia SUPERNOVAE AND IMPLICATIONS FOR THE NATURE OF THERMONUCLEAR EXPLOSIONS

International Nuclear Information System (INIS)

Zhao, Xulin; Wang, Xiaofeng; Sai, Hanna; Huang, Fang; Rui, Liming; Maeda, Keiichi; Wang, Lifan; Zhang, Jujia; Zhang, Tianmeng

2016-01-01

The absorption feature O i λ 7773 is an important spectral indicator for type Ia supernovae (SNe Ia) that can be used to trace the unburned material in outer layers of the exploding white dwarf (WD). In this work, we use a large sample of SNe Ia to examine this absorption at early phases (i.e., 13 day ≲ t ≲ 7 day) and make comparisons with the absorption features of Si ii λ 6355 and the Ca ii near-infrared triplet. We show that for a subgroup of spectroscopically normal SNe with normal photospheric velocities (i.e., v si ≲ 12,500 km s 1 at optical maximum), the line strength of the high velocity feature (HVF) of O i is inversely correlated with that of Si ii (or Ca ii), and this feature also shows a negative correlation with the luminosity of SNe Ia. This finding, together with other features we find for the O i HVF, reveal that for this subgroup of SNe Ia, explosive oxygen burning occurs in the outermost layer of the SN. Differences in the oxygen burning could lead to the observed diversity, which is in remarkable agreement with the popular delayed-detonation model of Chandrasekhar mass WDs.

THE OXYGEN FEATURES IN TYPE Ia SUPERNOVAE AND IMPLICATIONS FOR THE NATURE OF THERMONUCLEAR EXPLOSIONS

Energy Technology Data Exchange (ETDEWEB)

Zhao, Xulin; Wang, Xiaofeng; Sai, Hanna; Huang, Fang; Rui, Liming [Physics Department and Tsinghua Center for Astrophysics, Tsinghua University, Beijing, 100084 (China); Maeda, Keiichi [Department of Astronomy, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto 606-8502 (Japan); Wang, Lifan [Mitchell Institute for Fundamental Physics and Astronomy, Texas A and M University, College Station, TX 77843 (United States); Zhang, Jujia [Yunnan Observatories, Chinese Academy of Sciences, Kunming, 650216 (China); Zhang, Tianmeng, E-mail: wang_xf@mail.tsinghua.edu.cn, E-mail: zhaoxl11@mails.tsinghua.edu.cn, E-mail: keiichi.maeda@kusastro.kyoto-u.ac.jp [National Astronomical Observatory of China, Chinese Academy of Sciences, Beijing, 100012 (China)

2016-08-01

The absorption feature O i λ 7773 is an important spectral indicator for type Ia supernovae (SNe Ia) that can be used to trace the unburned material in outer layers of the exploding white dwarf (WD). In this work, we use a large sample of SNe Ia to examine this absorption at early phases (i.e., 13 day ≲ t ≲ 7 day) and make comparisons with the absorption features of Si ii λ 6355 and the Ca ii near-infrared triplet. We show that for a subgroup of spectroscopically normal SNe with normal photospheric velocities (i.e., v {sub si} ≲ 12,500 km s{sup 1} at optical maximum), the line strength of the high velocity feature (HVF) of O i is inversely correlated with that of Si ii (or Ca ii), and this feature also shows a negative correlation with the luminosity of SNe Ia. This finding, together with other features we find for the O i HVF, reveal that for this subgroup of SNe Ia, explosive oxygen burning occurs in the outermost layer of the SN. Differences in the oxygen burning could lead to the observed diversity, which is in remarkable agreement with the popular delayed-detonation model of Chandrasekhar mass WDs.

VELOCITY EVOLUTION AND THE INTRINSIC COLOR OF TYPE Ia SUPERNOVAE

International Nuclear Information System (INIS)

Foley, Ryan J.; Sanders, Nathan E.; Kirshner, Robert P.

2011-01-01

To understand how best to use observations of Type Ia supernovae (SNe Ia) to obtain precise and accurate distances, we investigate the relations between spectra of SNe Ia and their intrinsic colors. Using a sample of 1630 optical spectra of 255 SNe, based primarily on data from the CfA Supernova Program, we examine how the velocity evolution and line strengths of Si II λ6355 and Ca II H and K are related to the B – V color at peak brightness. We find that the maximum-light velocity of Si II λ6355 and Ca II H and K and the maximum-light pseudo-equivalent width of Si II λ6355 are correlated with intrinsic color, with intrinsic color having a linear relation with the Si II λ6355 measurements. Ca II H and K does not have a linear relation with intrinsic color, but lower-velocity SNe tend to be intrinsically bluer. Combining the spectroscopic measurements does not improve intrinsic color inference. The intrinsic color scatter is larger for higher-velocity SNe Ia—even after removing a linear trend with velocity—indicating that lower-velocity SNe Ia are more 'standard crayons'. Employing information derived from SN Ia spectra has the potential to improve the measurements of extragalactic distances and the cosmological properties inferred from them.

Spectroscopic Determination of the Low Redshift Type Ia Supernova Rate from the Sloan Digital Sky Survey

Energy Technology Data Exchange (ETDEWEB)

Krughoff, K.Simon; Connolly, Andrew J.; Frieman, Joshua; SubbaRao, Mark; Kilper, Gary; Schneider, Donald P.

2011-04-10

Supernova rates are directly coupled to high mass stellar birth and evolution. As such, they are one of the few direct measures of the history of cosmic stellar evolution. In this paper we describe an probabilistic technique for identifying supernovae within spectroscopic samples of galaxies. We present a study of 52 type Ia supernovae ranging in age from -14 days to +40 days extracted from a parent sample of \\simeq 50,000 spectra from the SDSS DR5. We find a Supernova Rate (SNR) of 0.472^{+0.048}_{-0.039}(Systematic)^{+0.081}_{-0.071}(Statistical)SNu at a redshift of = 0.1. This value is higher than other values at low redshift at the 1{\\sigma}, but is consistent at the 3{\\sigma} level. The 52 supernova candidates used in this study comprise the third largest sample of supernovae used in a type Ia rate determination to date. In this paper we demonstrate the potential for the described approach for detecting supernovae in future spectroscopic surveys.

Searching for supernovae in the multiply-imaged galaxies behind the gravitational telescope A370

OpenAIRE

Petrushevska, T.; Goobar, A.; Lagattuta, D. J.; Amanullah, R.; Hangard, L.; Fabbro, S.; Lidman, C.; Paech, K.; Richard, J.; Kneib, J. P.

2018-01-01

Strong lensing by massive galaxy clusters can provide magnification of the flux and even multiple images of the galaxies that lie behind them. This phenomenon facilitates observations of high-redshift supernovae (SNe), that would otherwise remain undetected. Type Ia supernovae (SNe Ia) detections are of particular interest because of their standard brightness, since they can be used to improve either cluster lensing models or cosmological parameter measurements. We present a ground-based, nea...

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

Science.gov (United States)

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

2018-06-01

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

SN 2016jhj at redshift 0.34: extending the Type II supernova Hubble diagram using the standard candle method

Science.gov (United States)

de Jaeger, T.; Galbany, L.; Filippenko, A. V.; González-Gaitán, S.; Yasuda, N.; Maeda, K.; Tanaka, M.; Morokuma, T.; Moriya, T. J.; Tominaga, N.; Nomoto, K.; Komiyama, Y.; Anderson, J. P.; Brink, T. G.; Carlberg, R. G.; Folatelli, G.; Hamuy, M.; Pignata, G.; Zheng, W.

2017-12-01

Although Type Ia supernova cosmology has now reached a mature state, it is important to develop as many independent methods as possible to understand the true nature of dark energy. Recent studies have shown that Type II supernovae (SNe II) offer such a path and could be used as alternative distance indicators. However, the majority of these studies were unable to extend the Hubble diagram above redshift z = 0.3 because of observational limitations. Here, we show that we are now ready to move beyond low redshifts and attempt high-redshift (z ≳ 0.3) SN II cosmology as a result of new-generation deep surveys such as the Subaru/Hyper Suprime-Cam survey. Applying the 'standard candle method' to SN 2016jhj (z = 0.3398 ± 0.0002; discovered by HSC) together with a low-redshift sample, we are able to construct the highest-redshift SN II Hubble diagram to date with an observed dispersion of 0.27 mag (i.e. 12-13 per cent in distance). This work demonstrates the bright future of SN II cosmology in the coming era of large, wide-field surveys like that of the Large Synoptic Survey Telescope.

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

International Nuclear Information System (INIS)

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

2011-01-01

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

The Sloan Digital Sky Survey-II Supernova Survey: Technical Summary

Energy Technology Data Exchange (ETDEWEB)

Frieman, Joshua A.; /Fermilab /KICP, Chicago /Chicago U., Astron. Astrophys. Ctr.; Bassett, Bruce; /Cape Town U. /South African Astron. Observ.; Becker, Andrew; /Washington; Choi, Changsu; /Seoul Natl. U.; Cinabro, David; /Wayne State U.; DeJongh, Don Frederic; /Fermilab; Depoy, Darren L.; /Ohio State U.; Doi, Mamoru; /Tokyo U.; Garnavich, Peter M.; /Notre Dame U.; Hogan, Craig J.; /Washington U., Seattle, Astron. Dept.; Holtzman, Jon; /New Mexico State U.; Im, Myungshin; /Seoul Natl. U.; Jha, Saurabh; /Stanford U., Phys. Dept.; Konishi, Kohki; /Tokyo U.; Lampeitl, Hubert; /Baltimore, Space Telescope Sci.; Marriner, John; /Fermilab; Marshall, Jennifer L.; /Ohio State U.; McGinnis,; /Fermilab; Miknaitis, Gajus; /Fermilab; Nichol, Robert C.; /Portsmouth U.; Prieto, Jose Luis; /Ohio State U. /Rochester Inst. Tech. /Stanford U., Phys. Dept. /Pennsylvania U.

2007-09-14

The Sloan Digital Sky Survey-II (SDSS-II) has embarked on a multi-year project to identify and measure light curves for intermediate-redshift (0.05 < z < 0.35) Type Ia supernovae (SNe Ia) using repeated five-band (ugriz) imaging over an area of 300 sq. deg. The survey region is a stripe 2.5 degrees wide centered on the celestial equator in the Southern Galactic Cap that has been imaged numerous times in earlier years, enabling construction of a deep reference image for discovery of new objects. Supernova imaging observations are being acquired between 1 September and 30 November of 2005-7. During the first two seasons, each region was imaged on average every five nights. Spectroscopic follow-up observations to determine supernova type and redshift are carried out on a large number of telescopes. In its first two three-month seasons, the survey has discovered and measured light curves for 327 spectroscopically confirmed SNe Ia, 30 probable SNe Ia, 14 confirmed SNe Ib/c, 32 confirmed SNe II, plus a large number of photometrically identified SNe Ia, 94 of which have host-galaxy spectra taken so far. This paper provides an overview of the project and briefly describes the observations completed during the first two seasons of operation.

Type Ia supernovae in elliptical and spiral galaxies - Possible differences in photometric homogeneity

International Nuclear Information System (INIS)

Filippenko, A.V.

1989-01-01

It is shown that beta, the initial postmaximum rate of SN brightness decline (in the B band) defined by Pskovskii (1977), may have a smaller dispersion among SNe Ia in elliptical galaxies than in all other types of galaxies. Contamination of the sample by SNe Ib is unlikely to be the primary cause of this difference. Although the number of objects is very small, it is also possible that the velocity of SN Ia ejecta in elliptical galaxies is lower than in spiral galaxies. If correct, these observations provide the first direct evidence for physical differences among SNe Ia in different environments; reddening variations due to gas and dust are unlikely to produce most of the observed dispersion in beta among spirals. One obvious possibility is that the SNe Ia in spiral galaxies come from intermediate-mass stars, and that differences in the metallicities, accretion rates, or other properties account for the observations. A more extreme, improbable explanation is that not all SNe Ia in spiral galaxies result from carbon deflagrations of carbon-oxygen white dwarfs. 43 refs

Host galaxy spectra and consequences for supernova typing from the SDSS SN survey

Energy Technology Data Exchange (ETDEWEB)

Olmstead, Matthew D.; Brown, Peter J.; Brownstein, Joel R.; Dawson, Kyle S. [Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112 (United States); Sako, Masao; Gupta, Ravi R. [Department of Physics and Astronomy, University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA 19104 (United States); Bassett, Bruce; Kunz, Martin [African Institute for Mathematical Sciences, 6 Melrose Road, Muizenberg, 7945 (South Africa); Bizyaev, Dmitry; Brinkmann, J.; Brewington, Howard; Ebelke, Garrett L. [Apache Point Observatory, P.O. Box 59, Sunspot, NM 88349 (United States); Campbell, Heather [Institute of Astronomy, Madingley Road, Cambridge CB4 0HA (United Kingdom); D' Andrea, Chris B.; Lampeitl, Hubert [Institute of Cosmology and Gravitation, Dennis Sciama Building, University of Portsmouth, Portsmouth, PO1 3FX (United Kingdom); Frieman, Joshua A. [Center for Particle Astrophysics, Fermi National Accelerator Laboratory, P.O. Box 500, Batavia, IL 60510 (United States); Galbany, Lluís [Institut de Física d' Altes Energies, Universitat Autònoma de Barcelona, E-08193 Bellaterra (Barcelona) (Spain); Garnavich, Peter [Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States); Hlozek, Renee [Department of Astrophysics, Peyton Hall, 4 Ivy Lane, Princeton, NJ 08544 (United States); Jha, Saurabh W., E-mail: olmstead@physics.utah.edu [Department of Physics and Astronomy, Rutgers, the State University of New Jersey, 136 Frelinghuysen Road, Piscataway, NJ 08854 (United States); and others

2014-04-01

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, this sample represents the largest systematic, unbiased, magnitude limited spectroscopic survey of 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 analysis of SN astrophysics. Finally, we investigate the differences in the interpretation of the light curve properties with and without knowledge of the redshift. Without host galaxy redshifts, we find that SALT2 light curve fits are systematically biased toward 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.

Type Ia Supernovae: Energetics, Neutronization and Nucleosynthesis

International Nuclear Information System (INIS)

Truran, James W.; Calder, Alan C.; Townsley, Dean M.; Seitenzahl, Ivo R.; Peng, Fang; Vladimirova, Natalia; Lamb, Donald Q.; Brown, Edward F.

2007-01-01

The utility of Type Ia supernovae, not simply as probes of the distance scale but also as a means of constraining the properties of dark energy, demands a significant improvement in theoretical predictions of their properties in outburst. To this end, we have given substantial effort to quantifying the energetics and nucleosynthesis properties of deflagration fronts in the interiors of the putative carbon-oxygen white dwarf progenitors of Type Ia thermonuclear supernovae. We briefly review some essential features of our flame model and its properties in this paper and discuss its implications both for our multidimensional numerical simulations of SNe Ia and for nucleosynthesis (specifically 56Ni production) in SNe Ia and Galactic chemical evolution

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

International Nuclear Information System (INIS)

Pinto, Philip A.; Eastman, Ronald G.

2000-01-01

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

Cosmological constraints from supernova data set with corrected redshift

International Nuclear Information System (INIS)

Feoli, A; Rillo, V; Grasso, M; Mancini, L

2012-01-01

Observations of distant type Ia supernovae (SNe Ia), used as standard candles, support the notion that the Cosmos is filled with a mysterious form of energy, the dark energy. The constraints on cosmological parameters derived from data of SNe Ia and the measurements of the cosmic microwave background anisotropies indicate that the dark energy amounts to≅ 70% of all the energy contained in the Universe. In the hypothesis of a flat Universe (Ω m + Ω Λ = 1), we investigate if the dark energy is really required in order to explain the SNe Ia experimental data, and, in this case, how much of such unknown energy is actually deduced from the analysis of these data and must be introduced in the ΛCDM model of cosmology. In particular we are interested in verifying if the Einstein-de Sitter model of the expanding Universe is really to be ruled out. By using a fitting procedure based on the Newton method search for a minimum, we reanalyzed the 'Union compilation' reported by Kowalski et al. (2008) formed by 307 SNe, obtaining a very different estimate of the dark energy, that is≅ 60%. Furthermore, in order to balance the correction of the apparent magnitude of SNe Ia, due to the dilation or stretching of the corresponding light curve width, we introduce a suitable modified redsfhit. Taking into account this correction, we refitted the Union compilation dataset after a selection cut. The main result that emerges from our analysis is that the values of Ω m and Ω Λ strongly depend on the fitting procedure and the selected sample. In particular, the constraint we obtain on the mass density, normalized by the critical mass density, is Ω m = 0.7 for a sample of 252, and Ω m = 1 for a sample of 242 SNe Ia respectively. The latter case does not imply the existence of any additional form of dark energy.

RATES AND DELAY TIMES OF TYPE Ia SUPERNOVAE

International Nuclear Information System (INIS)

Ruiter, Ashley J.; Belczynski, Krzysztof; Fryer, Chris

2009-01-01

We analyze the evolution of binary stars to calculate synthetic rates and delay times of the most promising Type Ia Supernovae (SNe Ia) progenitors. We present and discuss evolutionary scenarios in which a white dwarf (WD) reaches the Chandrasekhar mass and potentially explodes in a SNe Ia. We consider Double Degenerate (DDS; merger of two WDs), Single Degenerate (SDS; WD accreting from H-rich companion), and AM Canum Venaticorum (AM CVn; WD accreting from He-rich companion) scenarios. The results are presented for two different star formation histories: burst (elliptical-like galaxies) and continuous (spiral-like galaxies). It is found that delay times for the DDS in our standard model (with common envelope efficiency α CE = 1) follow a power-law distribution. For the SDS we note a wide range of delay times, while AM CVn progenitors produce a short burst of SNe Ia at early times. The DDS median delay time falls between ∼0.5 and 1 Gyr; the SDS between ∼2 and 3 Gyr; and the AM CVn between ∼0.8 and 0.6 Gyr depending on the assumed α CE . For a Milky-Way-like (MW-like) galaxy, we estimate the rates of SNe Ia arising from different progenitors as: ∼10 -4 yr -1 for the SDS and AM CVn, and ∼10 -3 yr -1 for the DDS. We point out that only the rates for two merging carbon-oxygen WDs, the only systems found in the DDS, are consistent with the observed rates for typical MW-like spirals. We also note that DDS progenitors are the dominant population in elliptical galaxies. The fact that the delay time distribution for the DDS follows a power law implies more SNe Ia (per unit mass) in young rather than in aged populations. Our results do not exclude other scenarios, but strongly indicate that the DDS is the dominant channel generating SNe Ia in spiral galaxies, at least in the framework of our adopted evolutionary models. Since it is believed that WD mergers cannot produce a thermonuclear explosion given the current understanding of accreting WDs, either the

Rotation of the accreting white dwarfs and diversity of type Ia supernovae

International Nuclear Information System (INIS)

Uenishi, Tatsuhiro; Nomoto, Kenichi; Hachisu, Izumi

2003-01-01

We consider rotation of progenitor white dwarfs for a possible source of the diversity of Type Ia supernovae (SNe Ia). Hydrostatic structure of rotating white dwarfs with different masses are calculated. Evolutionary sequences of white dwarfs are explored and the effect of 'supercritical' rotation in binary system is examined. Possible effects of rotation to cause diversity of SNe Ia are discussed

Double-detonation model of type Ia supernovae with a variable helium layer ignition mass

International Nuclear Information System (INIS)

Zhou Wei-Hong; Zhao Gang; Wang Bo

2014-01-01

Although Type Ia supernovae (SNe Ia) play an important role in the study of cosmology, their progenitors are still poorly understood. Thermonuclear explosions from the helium double-detonation sub-Chandrasekhar mass model have been considered as an alternative method for producing SNe Ia. By adopting the assumption that a double detonation occurs when a He layer with a critical ignition mass accumulates on the surface of a carbon—oxygen white dwarf (CO WD), we perform detailed binary evolution calculations for the He double-detonation model, in which a He layer from a He star accumulates on a CO WD. According to these calculations, we obtain the initial parameter spaces for SNe Ia in the orbital period and secondary mass plane for various initial WD masses. We implement these results into a detailed binary population synthesis approach to calculate SN Ia birthrates and delay times. From this model, the SN Ia birthrate in our Galaxy is ∼0.4 − 1.6 × 10 −3 yr −1 . This indicates that the double-detonation model only produces part of the SNe Ia. The delay times from this model are ∼ 70 – 710 Myr, which contribute to the young population of SNe Ia in the observations. We found that the CO WD + sdB star system CD–30 11223 could produce an SN Ia via the double-detonation model in its future evolution. (research papers)

The WD+He star binaries as the progenitors of type Ia supernovae

Directory of Open Access Journals (Sweden)

Wang Bo

2017-12-01

Full Text Available Employing the MESA stellar evolution code, we computed He accretion onto carbon-oxygen white dwarfs (CO WDs.We found two possible outcomes for models in which the WD steadily grows in mass towards the Chandrasekhar limit. For relatively low He-accretion rates carbon ignition occurs in the center, leading to a type Ia supernova (SN Ia explosion, whereas for relatively high accretion rates carbon is ignited off-center, probably leading to collapse. Thus the parameter space producing SNe Ia is reduced compared to what was assumed in earlier papers, in which the possibility of off-center ignition was ignored. We then applied these results in binary population synthesis modelling, finding a modest reduction in the expected birthrate of SNe Ia resulting from the WD+He star channel.

A Significantly off-center 56Ni Distribution for the Low-Luminosity Type Ia Supernova SN 2016brx from the 100IAS survey

Science.gov (United States)

Dong, Subo; Katz, Boaz; Kollmeier, Juna A.; Kushnir, Doron; Elias-Rosa, N.; Bose, Subhash; Morrell, Nidia; Prieto, J. L.; Chen, Ping; Kochanek, C. S.; Brandt, G. M.; Holoien, T. W.-S.; Gal-Yam, Avishay; Morales-Garoffolo, Antonia; Parker, Stuart; Phillips, M. M.; Piro, Anthony L.; Shappee, B. J.; Simon, Joshua D.; Stanek, K. Z.

2018-06-01

We present nebular-phase spectra of the Type Ia supernova (SN Ia) 2016brx, a member of the 1991bg-like subclass that lies at the faint end of the SN Ia luminosity function. Nebular spectra are available for only three other 1991bg-like SNe, and their Co line centers are all within ≲ 500 km/s of each other. In contrast, the nebular Co line center of SN 2016brx is blue-shifted by >1500 km/s compared to them and by ≈1200 km/s compared to the rest frame. This is a significant shift relative to the narrow nebular line velocity dispersion of ≲ 2000 km/s of these SNe. The large range of nebular line shifts implies that the 56Ni in the ejecta of SN 1991bg-like events is off-center by ˜1000 km/s rather than universally centrally confined as previously suggested. With the addition of SN 2016brx, the Co nebular line shapes of 1991bg-like objects appear to connect with the brighter SNe Ia that show double-peaked profiles, hinting at a continuous distribution of line profiles among SNe Ia. One class of models to produce both off-center and bi-modal 56Ni distributions is collisions of white dwarfs with unequal and equal masses.

Testing cosmic transparency with the latest baryon acoustic oscillations and type Ia supernovae data

International Nuclear Information System (INIS)

Chen Jun; Yu Hong-Wei; Li Zheng-Xiang; Wu Pu-Xun

2013-01-01

Observations show that Type Ia supernovae (SNe Ia) are dimmer than expected from a matter dominated Universe. It has been suggested that this observed phenomenon can also be explained using light absorption instead of dark energy. However, there is a serious degeneracy between the cosmic absorption parameter and the present matter density parameter Ω m when one tries to place constraints on the cosmic opacity using SNe Ia data. We combine the latest baryon acoustic oscillation (BAO) and Union2 SNe Ia data in order to break this degeneracy. Assuming a flat ΛCDM model, we find that, although an opaque Universe is favored by SNe Ia+BAO since the best fit value of the cosmic absorption parameter is larger than zero, Ω m = 1 is ruled out at the 99.7% confidence level. Thus, cosmic opacity is not sufficient to account for the present observations and dark energy or modified gravity is still required.

A Moderate Redshift Supernova Search Program

Science.gov (United States)

Adams, M. T.; Wheeler, J. C.; Ward, M.; Wren, W. R.; Schmidt, B. P.

1995-12-01

We report on a recently initiated supernova (SN) search program using the McDonald Observatory 0.76m telescope and Prime Focus Camera (PFC). This SN search program takes advantage of the PFC's 42.6 x 42.6 arcmin FOV to survey moderate redshift Abell clusters in single Kron-Cousins R-band images. Our scientific goal is to discover and provide quality BVRI photometric follow-up, to R \\ +21, for a significant SNe sample at 0.03 group (Perlmutter et al 1995, ApJ, 440, L41), and the High Redshift SN Search Team (Schmidt et al 1995, Aiguiblava NATO ASI Proceedings). The McDonald SN search program includes a sample of the Abell clusters used by Lauer and Postman (1994, ApJ, 425, 418) to analyze Local Group motion. SNe discovered in these clusters contribute to the resolution of the Local Group motion controversy. We present an overview of the McDonald Observatory supernova search program, and discuss recent results.

IMPROVED DISTANCES TO TYPE Ia SUPERNOVAE WITH TWO SPECTROSCOPIC SUBCLASSES

International Nuclear Information System (INIS)

Wang, X.; Filippenko, A. V.; Ganeshalingam, M.; Li, W.; Silverman, J. M.; Chornock, R.; Foley, R. J.; Macomber, B.; Serduke, F. J. D.; Steele, T. N.; Wong, D. S.; Wang, L.; Gates, E. L.

2009-01-01

We study the observables of 158 relatively normal Type Ia supernovae (SNe Ia) by dividing them into two groups in terms of the expansion velocity inferred from the absorption minimum of the Si II λ6355 line in their spectra near B-band maximum brightness. One group ('Normal') consists of normal SNe Ia populating a narrow strip in the Si II velocity distribution, with an average expansion velocity (v) = 10, 600 ± 400 km s -1 near B maximum; the other group ('HV') consists of objects with higher velocities, v ∼> 11, 800 km s -1 . Compared with the Normal group, the HV one shows a narrower distribution in both the peak luminosity and the luminosity decline rate Δm 15 . In particular, their B-V colors at maximum brightness are found to be on average redder by ∼ 0.1 mag, suggesting that they either are associated with dusty environments or have intrinsically red B-V colors. The HV SNe Ia are also found to prefer a lower extinction ratio R V ∼ 1.6 (versus ∼ 2.4 for the Normal ones). Applying such an absorption-correction dichotomy to SNe Ia of these two groups remarkably reduces the dispersion in their peak luminosity from 0.178 mag to only 0.125 mag.

THE RISE TIME OF NORMAL AND SUBLUMINOUS TYPE Ia SUPERNOVAE

Energy Technology Data Exchange (ETDEWEB)

Gonzalez-Gaitan, S.; Perrett, K.; Carlberg, R. [Department of Astronomy and Astrophysics, University of Toronto, 50 St. george Street, Toronto, ON M5S 3H4 (Canada); Conley, A. [Center for Astrophysics and Space Astronomy, University of Colorado, 593 UCB, Boulder, CO 80309-0593 (United States); Bianco, F. B.; Howell, D. A.; Graham, M. L. [Department of Physics, University of California, Santa Barbara, Broida Hall, Mail Code 9530, Santa Barbara, CA 93106-9530 (United States); Sullivan, M.; Hook, I. M. [Department of Physics (Astrophysics), University of Oxford, DWB, Keble Road, Oxford, OX1 3RH (United Kingdom); Astier, P.; Balland, C.; Fourmanoit, N.; Guy, J.; Hardin, D.; Pain, R. [LPNHE, Universite Pierre et Marie Curie Paris 6, Universite Paris Diderot Paris 7, CNRS-IN2P3, 4 Place Jussieu, 75252 Paris Cedex 05 (France); Balam, D. [Dominion Astrophysical Observatory, Herzberg Institute of Astrophysics, 5071 West Saanich Road, Victoria, BC V9E 2E7 (Canada); Basa, S. [Laboratoire d' Astrophysique de Marseille, Pole de l' Etoile Site de Chateau-Gombert, 38, rue Frederic Joliot-Curie, 13388 Marseille cedex 13 (France); Fouchez, D. [CPPM, CNRS-IN2P3 and University Aix Marseille II, Case 907, 13288 Marseille cedex 9 (France); Lidman, C. [Australian Astronomical Observatory, P.O. Box 296, Epping, NSW 1710 (Australia); Palanque-Delabrouille, N., E-mail: gonzalez@astro.utoronto.ca [DSM/IRFU/SPP, CEA-Saclay, F-91191 Gif-sur-Yvette (France); and others

2012-01-20

We calculate the average stretch-corrected rise time of Type Ia supernovae (SNe Ia) in the Supernova Legacy Survey. We use the aggregate light curves of spectroscopic and photometrically identified SNe Ia to fit the rising part of the light curve with a simple quadratic model. We obtain a light curve shape corrected, i.e., stretch-corrected, fiducial rise time of 17.02{sup +0.18}{sub -0.28} (stat) days. The measured rise time differs from an earlier finding by the SNLS (Conley et al.) due to the use of different SN Ia templates. We compare it to nearby samples using the same methods and find no evolution in the early part of the light curve of SNe Ia up to z = 1. We search for variations among different populations, particularly subluminous objects, by dividing the sample in stretch. Bright and slow decliners (s > 1.0) have consistent stretch-corrected rise times compared to fainter and faster decliners (0.8 < s {<=} 1.0); they are shorter by 0.57{sup +0.47}{sub -0.50} (stat) days. Subluminous SNe Ia (here defined as objects with s {<=} 0.8), although less constrained, are also consistent, with a rise time of 18.03{sup +0.81}{sub -1.37} (stat) days. We study several systematic biases and find that the use of different fiducial templates may affect the average rise time but not the intrinsic differences between populations. Based on our results, we estimate that subluminous SNe Ia are powered by 0.05-0.35 M{sub Sun} of {sup 56}Ni synthesized in the explosion. Our conclusions are the same for the single-stretch and two-stretch parameterizations of the light curve.

Binary Paths to Type Ia Supernovae Explosions: the Highlights

Science.gov (United States)

Ferrario, Lilia

2013-01-01

This symposium was focused on the hunt for the progenitors of Type Ia supernovae (SNe Ia). Is there a main channel for the production of SNe Ia? If so, are these elusive progenitors single degenerate or double degenerate systems? Although most participants seemed to favor the single degenerate channel, there was no general agreement on the type of binary system at play. An observational puzzle that was highlighted was the apparent paucity of supersoft sources in our Galaxy and also in external galaxies. The single degenerate channel (and as it was pointed out, quite possibly also the double degenerate channel) requires the binary system to pass through a phase of steady nuclear burning. However, the observed number of supersoft sources falls short by a factor of up to 100 in explaining the estimated birth rates of SNe Ia. Thus, are these supersoft sources somehow hidden away and radiating at different wavelengths, or are we missing some important pieces of this puzzle that may lead to the elimination of a certain class of progenitor? Another unanswered question concerns the dependence of SNe Ia luminosities on the age of their host galaxy. Several hypotheses were put forward, but none was singled out as the most likely explanation. It is fair to say that at the end of the symposium the definitive answer to the vexed progenitor question remained well and truly wide open.

Reconstruction of the interaction term between dark matter and dark energy using SNe Ia

Energy Technology Data Exchange (ETDEWEB)

Solano, Freddy Cueva; Nucamendi, Ulises, E-mail: freddy@ifm.umich.mx, E-mail: ulises@ifm.umich.mx [Instituto de Física y Matemáticas, Universidad Michoacana de San Nicolás de Hidalgo, Edificio C-3, Ciudad Universitaria, CP. 58040, Morelia, Michoacán (Mexico)

2012-04-01

We apply a parametric reconstruction method to a homogeneous, isotropic and spatially flat Friedmann-Robertson-Walker (FRW) cosmological model filled of a fluid of dark energy (DE) with constant equation of state (EOS) parameter interacting with dark matter (DM)\\@. The reconstruction method is based on expansions of the general interaction term and the relevant cosmological variables in terms of Chebyshev polynomials which form a complete set orthonormal functions. This interaction term describes an exchange of energy flow between the DE and DM within dark sector. To show how the method works we do the reconstruction of the interaction function expanding it in terms of only the first six Chebyshev polynomials and obtain the best estimation for the coefficients of the expansion assuming three models: (a) a DE equation of the state parameter w = −1 (an interacting cosmological Λ), (b) a DE equation of the state parameter w = constant with a dark matter density parameter fixed, (c) a DE equation of the state parameter w = constant with a free constant dark matter density parameter to be estimated, and using the Union2 SNe Ia data set from ''The Supernova Cosmology Project'' (SCP) composed by 557 type Ia supernovae. In both cases, the preliminary reconstruction shows that in the best scenario there exist the possibility of a crossing of the noninteracting line Q = 0 in the recent past within the 1σ and 2σ errors from positive values at early times to negative values at late times. This means that, in this reconstruction, there is an energy transfer from DE to DM at early times and an energy transfer from DM to DE at late times. We conclude that this fact is an indication of the possible existence of a crossing behavior in a general interaction coupling between dark components.

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.

Swift UVOT Grism Observations of Nearby Type Ia Supernovae - I. Observations and Data Reduction

Science.gov (United States)

Pan, Y.-C.; Foley, R. J.; Filippenko, A. V.; Kuin, N. P. M.

2018-05-01

Ultraviolet (UV) observations of Type Ia supernovae (SNe Ia) are useful tools for understanding progenitor systems and explosion physics. In particular, UV spectra of SNe Ia, which probe the outermost layers, are strongly affected by the progenitor metallicity. In this work, we present 120 Neil Gehrels Swift Observatory UV spectra of 39 nearby SNe Ia. This sample is the largest UV (λ Ia to date, doubling the number of UV spectra and tripling the number of SNe with UV spectra. The sample spans nearly the full range of SN Ia light-curve shapes (Δm15(B) ≈ 0.6-1.8 mag). The fast turnaround of Swift allows us to obtain UV spectra at very early times, with 13 out of 39 SNe having their first spectra observed ≳ 1 week before peak brightness and the earliest epoch being 16.5 days before peak brightness. The slitless design of the Swift UV grism complicates the data reduction, which requires separating SN light from underlying host-galaxy light and occasional overlapping stellar light. We present a new data-reduction procedure to mitigate these issues, producing spectra that are significantly improved over those of standard methods. For a subset of the spectra we have nearly simultaneous Hubble Space Telescope UV spectra; the Swift spectra are consistent with these comparison data.

THE ABSENCE OF EX-COMPANIONS IN TYPE Ia SUPERNOVA REMNANTS

Energy Technology Data Exchange (ETDEWEB)

Di Stefano, R. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Kilic, Mukremin, E-mail: rd@cfa.harvard.edu, E-mail: kilic@ou.edu [Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, 440 West Brooks Street, Norman, OK 73019 (United States)

2012-11-01

Type Ia supernovae (SNe Ia) play important roles in our study of the expansion and acceleration of the universe, but because we do not know the exact nature or natures of the progenitors, there is a systematic uncertainty that must be resolved if SNe Ia are to become more precise cosmic probes. No progenitor system has ever been identified either in the pre- or post-explosion images of a Ia event. There have been recent claims for and against the detection of ex-companion stars in several SNe Ia remnants. These studies, however, usually ignore the angular momentum gain of the progenitor white dwarf (WD), which leads to a spin-up phase and a subsequent spin-down phase before explosion. For spin-down timescales greater than 10{sup 5} years, the donor star could be too dim to detect by the time of explosion. Here we revisit the current limits on ex-companion stars to SNR 0509-67.5, a 400-year-old remnant in the Large Magellanic Cloud. If the effects of possible angular momentum gain on the WD are included, a wide range of single-degenerate progenitor models are allowed for this remnant. We demonstrate that the current absence of evidence for ex-companion stars in this remnant, as well as other SNe Ia remnants, does not necessarily provide the evidence of absence for ex-companions. We discuss potential ways to identify such ex-companion stars through deep imaging observations.

THE ABSENCE OF EX-COMPANIONS IN TYPE Ia SUPERNOVA REMNANTS

International Nuclear Information System (INIS)

Di Stefano, R.; Kilic, Mukremin

2012-01-01

Type Ia supernovae (SNe Ia) play important roles in our study of the expansion and acceleration of the universe, but because we do not know the exact nature or natures of the progenitors, there is a systematic uncertainty that must be resolved if SNe Ia are to become more precise cosmic probes. No progenitor system has ever been identified either in the pre- or post-explosion images of a Ia event. There have been recent claims for and against the detection of ex-companion stars in several SNe Ia remnants. These studies, however, usually ignore the angular momentum gain of the progenitor white dwarf (WD), which leads to a spin-up phase and a subsequent spin-down phase before explosion. For spin-down timescales greater than 10 5 years, the donor star could be too dim to detect by the time of explosion. Here we revisit the current limits on ex-companion stars to SNR 0509-67.5, a 400-year-old remnant in the Large Magellanic Cloud. If the effects of possible angular momentum gain on the WD are included, a wide range of single-degenerate progenitor models are allowed for this remnant. We demonstrate that the current absence of evidence for ex-companion stars in this remnant, as well as other SNe Ia remnants, does not necessarily provide the evidence of absence for ex-companions. We discuss potential ways to identify such ex-companion stars through deep imaging observations.

Exploring JLA supernova data with improved flux-averaging technique

Energy Technology Data Exchange (ETDEWEB)

Wang, Shuang; Wen, Sixiang; Li, Miao, E-mail: wangshuang@mail.sysu.edu.cn, E-mail: wensx@mail2.sysu.edu.cn, E-mail: limiao9@mail.sysu.edu.cn [School of Physics and Astronomy, Sun Yat-Sen University, University Road (No. 2), Zhuhai (China)

2017-03-01

In this work, we explore the cosmological consequences of the ''Joint Light-curve Analysis'' (JLA) supernova (SN) data by using an improved flux-averaging (FA) technique, in which only the type Ia supernovae (SNe Ia) at high redshift are flux-averaged. Adopting the criterion of figure of Merit (FoM) and considering six dark energy (DE) parameterizations, we search the best FA recipe that gives the tightest DE constraints in the ( z {sub cut}, Δ z ) plane, where z {sub cut} and Δ z are redshift cut-off and redshift interval of FA, respectively. Then, based on the best FA recipe obtained, we discuss the impacts of varying z {sub cut} and varying Δ z , revisit the evolution of SN color luminosity parameter β, and study the effects of adopting different FA recipe on parameter estimation. We find that: (1) The best FA recipe is ( z {sub cut} = 0.6, Δ z =0.06), which is insensitive to a specific DE parameterization. (2) Flux-averaging JLA samples at z {sub cut} ≥ 0.4 will yield tighter DE constraints than the case without using FA. (3) Using FA can significantly reduce the redshift-evolution of β. (4) The best FA recipe favors a larger fractional matter density Ω {sub m} . In summary, we present an alternative method of dealing with JLA data, which can reduce the systematic uncertainties of SNe Ia and give the tighter DE constraints at the same time. Our method will be useful in the use of SNe Ia data for precision cosmology.

TIDALLY ENHANCED STELLAR WIND: A WAY TO MAKE THE SYMBIOTIC CHANNEL TO TYPE Ia SUPERNOVA VIABLE

International Nuclear Information System (INIS)

Chen, X.; Han, Z.; Tout, C. A.

2011-01-01

In the symbiotic (or WD+RG) channel of the single-degenerate scenario for type Ia supernovae (SNe Ia), the explosions occur a relatively long time after star formation. The birthrate from this channel would be too low to account for all observed SNe Ia were it not for some mechanism to enhance the rate of accretion on to the white dwarf. A tidally enhanced stellar wind, of the type which has been postulated to explain many phenomena related to giant star evolution in binary systems, can do this. Compared to mass stripping, this model extends the space of SNe Ia progenitors to longer orbital periods and hence increases the birthrate to about 0.0069 yr -1 for the symbiotic channel. Two symbiotic stars, T CrB and RS Oph, considered to be the most likely progenitors of SNe Ia through the symbiotic channel, are well inside the period-companion mass space predicted by our models.

Could there be a hole in type Ia supernovae?

International Nuclear Information System (INIS)

Kasen, Daniel; Nugent, Peter; Thomas, R.C.; Wang, Lifan

2004-01-01

In the favored progenitor scenario, Type Ia supernovae (SNe Ia) arise from a white dwarf accreting material from a non-degenerate companion star. Soon after the white dwarf explodes, the ejected supernova material engulfs the companion star; two-dimensional hydrodynamical simulations by Marietta et al. (2001) show that, in the interaction, the companion star carves out a conical hole of opening angle 30-40 degrees in the supernova ejecta. In this paper we use multi-dimensional Monte Carlo radiative transfer calculations to explore the observable consequences of an ejecta-hole asymmetry. We calculate the variation of the spectrum, luminosity, and polarization with viewing angle for the aspherical supernova near maximum light. We find that the supernova looks normal from almost all viewing angles except when one looks almost directly down the hole. In the latter case, one sees into the deeper, hotter layers of ejecta. The supernova is relatively brighter and has a peculiar spectrum characterized by more highly ionized species, weaker absorption features, and lower absorption velocities. The spectrum viewed down the hole is comparable to the class of SN 1991T-like supernovae. We consider how the ejecta-hole asymmetry may explain the current spectropolarimetric observations of SNe Ia, and suggest a few observational signatures of the geometry. Finally, we discuss the variety currently seen in observed SNe Ia and how an ejecta-hole asymmetry may fit in as one of several possible sources of diversity

CfA3: 185 TYPE Ia SUPERNOVA LIGHT CURVES FROM THE CfA

International Nuclear Information System (INIS)

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

2009-01-01

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

THEORETICAL CLUES TO THE ULTRAVIOLET DIVERSITY OF TYPE Ia SUPERNOVAE

Energy Technology Data Exchange (ETDEWEB)

Brown, Peter J.; Wang, Lifan [George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Texas A. and M. University, Department of Physics and Astronomy, 4242 TAMU, College Station, TX 77843 (United States); Baron, E. [Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, 440 W. Brooks, Rm 100, Norman, OK 73019-2061 (United States); Milne, Peter [Steward Observatory, University of Arizona, Tucson, AZ 85719 (United States); Roming, Peter W. A., E-mail: pbrown@physics.tamu.edu [Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78238 (United States)

2015-08-10

The effect of metallicity on the observed light of Type Ia supernovae (SNe Ia) could lead to systematic errors as the absolute magnitudes of local and distant SNe Ia are compared to measure luminosity distances and determine cosmological parameters. The UV light may be especially sensitive to metallicity, though different modeling methods disagree as to the magnitude, wavelength dependence, and even the sign of the effect. The outer density structure, {sup 56}Ni, and to a lesser degree asphericity, also impact the UV. We compute synthetic photometry of various metallicity-dependent models and compare to UV/optical photometry from the Swift Ultra-Violet/Optical Telescope. We find that the scatter in the mid-UV to near-UV colors is larger than predicted by changes in metallicity alone and is not consistent with reddening. We demonstrate that a recently employed method to determine relative abundances using UV spectra can be done using UVOT photometry, but we warn that accurate results require an accurate model of the cause of the variations. The abundance of UV photometry now available should provide constraints on models that typically rely on UV spectroscopy for constraining metallicity, density, and other parameters. Nevertheless, UV spectroscopy for a variety of supernova explosions is still needed to guide the creation of accurate models. A better understanding of the influences affecting the UV is important for using SNe Ia as cosmological probes, as the UV light may test whether SNe Ia are significantly affected by evolutionary effects.

Theoretical Clues to the Ultraviolet Diversity of Type Ia Supernovae

Science.gov (United States)

Brown, Peter J.; Baron, E.; Milne, Peter; Roming, Peter W. A.; Wang, Lifan

2015-08-01

The effect of metallicity on the observed light of Type Ia supernovae (SNe Ia) could lead to systematic errors as the absolute magnitudes of local and distant SNe Ia are compared to measure luminosity distances and determine cosmological parameters. The UV light may be especially sensitive to metallicity, though different modeling methods disagree as to the magnitude, wavelength dependence, and even the sign of the effect. The outer density structure, 56Ni, and to a lesser degree asphericity, also impact the UV. We compute synthetic photometry of various metallicity-dependent models and compare to UV/optical photometry from the Swift Ultra-Violet/Optical Telescope. We find that the scatter in the mid-UV to near-UV colors is larger than predicted by changes in metallicity alone and is not consistent with reddening. We demonstrate that a recently employed method to determine relative abundances using UV spectra can be done using UVOT photometry, but we warn that accurate results require an accurate model of the cause of the variations. The abundance of UV photometry now available should provide constraints on models that typically rely on UV spectroscopy for constraining metallicity, density, and other parameters. Nevertheless, UV spectroscopy for a variety of supernova explosions is still needed to guide the creation of accurate models. A better understanding of the influences affecting the UV is important for using SNe Ia as cosmological probes, as the UV light may test whether SNe Ia are significantly affected by evolutionary effects.

THEORETICAL CLUES TO THE ULTRAVIOLET DIVERSITY OF TYPE Ia SUPERNOVAE

International Nuclear Information System (INIS)

Brown, Peter J.; Wang, Lifan; Baron, E.; Milne, Peter; Roming, Peter W. A.

2015-01-01

The effect of metallicity on the observed light of Type Ia supernovae (SNe Ia) could lead to systematic errors as the absolute magnitudes of local and distant SNe Ia are compared to measure luminosity distances and determine cosmological parameters. The UV light may be especially sensitive to metallicity, though different modeling methods disagree as to the magnitude, wavelength dependence, and even the sign of the effect. The outer density structure, 56 Ni, and to a lesser degree asphericity, also impact the UV. We compute synthetic photometry of various metallicity-dependent models and compare to UV/optical photometry from the Swift Ultra-Violet/Optical Telescope. We find that the scatter in the mid-UV to near-UV colors is larger than predicted by changes in metallicity alone and is not consistent with reddening. We demonstrate that a recently employed method to determine relative abundances using UV spectra can be done using UVOT photometry, but we warn that accurate results require an accurate model of the cause of the variations. The abundance of UV photometry now available should provide constraints on models that typically rely on UV spectroscopy for constraining metallicity, density, and other parameters. Nevertheless, UV spectroscopy for a variety of supernova explosions is still needed to guide the creation of accurate models. A better understanding of the influences affecting the UV is important for using SNe Ia as cosmological probes, as the UV light may test whether SNe Ia are significantly affected by evolutionary effects

NEAR-ULTRAVIOLET PROPERTIES OF A LARGE SAMPLE OF TYPE Ia SUPERNOVAE AS OBSERVED WITH THE Swift UVOT

International Nuclear Information System (INIS)

Milne, Peter A.; Brown, Peter J.; Roming, Peter W. A.; Vanden Berk, Daniel; Holland, Stephen T.; Immler, Stefan; Bufano, Filomena; Gehrels, Neil; Filippenko, Alexei V.; Ganeshalingam, Mohan; Li Weidong; Stritzinger, Maximilian; Phillips, Mark M.; Hicken, Malcolm; Kirshner, Robert P.; Challis, Peter J.; Mazzali, Paolo; Schmidt, Brian P.

2010-01-01

We present ultraviolet (UV) and optical photometry of 26 Type Ia supernovae (SNe Ia) observed from 2005 March to 2008 March with the NASA Swift Ultraviolet and Optical Telescope (UVOT). The dataset consists of 2133 individual observations, making it by far the most complete study of the UV emission from SNe Ia to date. Grouping the SNe into three subclasses as derived from optical observations, we investigate the evolution of the colors of these SNe, finding a high degree of homogeneity within the normal subclass, but dramatic differences between that group and the subluminous and SN 2002cx-like groups. For the normal events, the redder UV filters on UVOT (u, uvw1) show more homogeneity than do the bluer UV filters (uvm2, uvw2). Searching for purely UV characteristics to determine existing optically based groupings, we find the peak width to be a poor discriminant, but we do see a variation in the time delay between peak emission and the late, flat phase of the light curves. The UV light curves peak a few days before the B band for most subclasses (as was previously reported by Jha et al.), although the SN 2002cx-like objects peak at a very early epoch in the UV. That group also features the bluest emission observed among SNe Ia. As the observational campaign is ongoing, we discuss the critical times to observe, as determined by this study, in order to maximize the scientific output of future observations.

REAL-TIME ANALYSIS AND SELECTION BIASES IN THE SUPERNOVA LEGACY SURVEY

International Nuclear Information System (INIS)

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

2010-01-01

The Supernova Legacy Survey (SNLS) has produced a high-quality, homogeneous sample of Type Ia supernovae (SNe Ia) out to redshifts greater than z = 1. In its first four years of full operation (to 2007 June), the SNLS discovered more than 3000 transient candidates, 373 of which have been spectroscopically confirmed as SNe Ia. Use of these SNe Ia in precision cosmology critically depends on an analysis of the observational biases incurred in the SNLS survey due to the incomplete sampling of the underlying SN Ia population. This paper describes our real-time supernova detection and analysis procedures, and uses detailed Monte Carlo simulations to examine the effects of Malmquist bias and spectroscopic sampling. Such sampling effects are found to become apparent at z ∼ 0.6, with a significant shift in the average magnitude of the spectroscopically confirmed SN Ia sample toward brighter values for z ∼> 0.75. We describe our approach to correct for these selection biases in our three-year SNLS cosmological analysis (SNLS3) and present a breakdown of the systematic uncertainties involved.

On the Time Variation of Dust Extinction and Gas Absorption for Type Ia Supernovae Observed Through Non-uniform Interstellar Medium

Science.gov (United States)

Huang, Xiaosheng; Aldering, Gregory; Biederman, Moriah; Herger, Brendan

2018-01-01

For Type Ia supernovae (SNe Ia) observed through a non-uniform interstellar medium (ISM) in its host galaxy, we investigate whether the non-uniformity can cause observable time variations in dust extinction and in gas absorption due to the expansion of the SN photosphere with time. We show that, owing to the steep spectral index of the ISM density power spectrum, sizable density fluctuation amplitudes at the length scale of typical ISM structures (>~ 10 pc) will translate to much smaller fluctuations on the scales of a SN photosphere. Therefore the typical amplitude of time variation due to non-uniform ISM, of absorption equivalent widths and of extinction, would be small. As a result, we conclude that non-uniform ISM density should not impact cosmology measurements based on SNe Ia. We apply our predictions based on the ISM density power law power spectrum to the observations of two highly reddened SNe Ia, SN 2012cu and SN 2014J.

On the Time Variation of Dust Extinction and Gas Absorption for Type Ia Supernovae Observed through a Nonuniform Interstellar Medium

Science.gov (United States)

Huang, X.; Aldering, G.; Biederman, M.; Herger, B.

2017-11-01

For Type Ia supernovae (SNe Ia) observed through a nonuniform interstellar medium (ISM) in its host galaxy, we investigate whether the nonuniformity can cause observable time variations in dust extinction and in gas absorption due to the expansion of the SN photosphere with time. We show that, owing to the steep spectral index of the ISM density power spectrum, sizable density fluctuation amplitudes at the length scale of typical ISM structures (≳ 10 {pc}) will translate to much smaller fluctuations on the scales of an SN photosphere. Therefore, the typical amplitude of time variation due to a nonuniform ISM, of absorption equivalent widths, and of extinction, would be small. As a result, we conclude that nonuniform ISM density should not impact cosmology measurements based on SNe Ia. We apply our predictions based on the ISM density power-law power spectrum to the observations of two highly reddened SNe Ia, SN 2012cu and SN 2014J.

Nearby Type Ia Supernova Follow-up at the Thacher Observatory

Science.gov (United States)

Swift, Jonathan; O'Neill, Katie; Kilpatrick, Charles; Foley, Ryan

2018-06-01

Type Ia supernovae (SN Ia) provide an effective way to study the expansion of the universe through analyses of their photometry and spectroscopy. The interpretation of high-redshift SN Ia is dependent on accurate characterization of nearby, low-redshift targets. To help build up samples of nearby SN Ia, the Thacher Observatory has begun a photometric follow-up program in 4 photometric bands. Here we present the observations and analysis of multi-band photometry for several recent supernovae as well as FLOYDS spectra from the Las Cumbres Observatory.

Stochastic gravitational wave background from the single-degenerate channel of type Ia supernovae

International Nuclear Information System (INIS)

Falta, David; Fisher, Robert

2011-01-01

We demonstrate that the integrated gravitational wave signal of type Ia supernovae (SNe Ia) in the single-degenerate channel out to cosmological distances gives rise to a continuous background to spaceborne gravitational wave detectors, including the Big Bang Observer and Deci-Hertz Interferometer Gravitational wave Observatory planned missions. This gravitational wave background from SNe Ia acts as a noise background in the frequency range 0.1-10 Hz, which heretofore was thought to be relatively free from astrophysical sources apart from neutron-star and white-dwarf binaries, and therefore a key window in which to study primordial gravitational waves generated by inflation. While inflationary energy scales of > or approx. 10 16 GeV yield inflationary gravitational wave backgrounds in excess of our range of predicted backgrounds, for lower energy scales of ∼10 15 GeV, the inflationary gravitational wave background becomes comparable to the noise background from SNe Ia.

EVIDENCE FOR ASYMMETRIC DISTRIBUTION OF CIRCUMSTELLAR MATERIAL AROUND TYPE Ia SUPERNOVAE

Energy Technology Data Exchange (ETDEWEB)

Foerster, Francisco; Gonzalez-Gaitan, Santiago; Anderson, Joseph; Marchi, Sebastian; Gutierrez, Claudia; Hamuy, Mario; Cartier, Regis [Departamento de Astronomia, Universidad de Chile, Casilla 36-D, Santiago (Chile); Pignata, Giuliano [Departamento Ciencias Fisicas, Universidad Andres Bello, Av. Republica 252, Santiago (Chile)

2012-08-01

We study the properties of low-velocity material in the line of sight toward nearby Type Ia supernovae (SNe Ia) that have measured late phase nebular velocity shifts (v{sub neb}), thought to be an environment-independent observable. We have found that the distribution of equivalent widths of narrow blended Na I D1 and D2 and Ca II H and K absorption lines differs significantly between those SNe Ia with negative and positive v{sub neb}, with generally stronger absorption for SNe Ia with v{sub neb} {>=} 0. A similar result had been found previously for the distribution of colors of SNe Ia, which was interpreted as a dependence of the temperature of the ejecta with viewing angle. Our work suggests that (1) a significant part of these differences in color should be attributed to extinction, (2) this extinction is caused by an asymmetric distribution of circumstellar material (CSM), and (3) the CSM absorption is generally stronger on the side of the ejecta opposite to where the ignition occurs. Since it is difficult to explain (3) via any known physical processes that occur before explosion, we argue that the asymmetry of the CSM is originated after explosion by a stronger ionizing flux on the side of the ejecta where ignition occurs, probably due to a stronger shock breakout and/or more exposed radioactive material on one side of the ejecta. This result has important implications for both progenitor and explosion models.

Search for surviving companions in type Ia supernova remnants

International Nuclear Information System (INIS)

Pan, Kuo-Chuan; Ricker, Paul M.; Taam, Ronald E.

2014-01-01

The nature of the progenitor systems of type Ia supernovae (SNe Ia) is still unclear. One way to distinguish between the single-degenerate scenario and double-degenerate scenario for their progenitors is to search for the surviving companions (SCs). Using a technique that couples the results from multi-dimensional hydrodynamics simulations with calculations of the structure and evolution of main-sequence- (MS-) and helium-rich SCs, the color and magnitude of MS- and helium-rich SCs are predicted as functions of time. The SC candidates in Galactic type Ia supernova remnants (Ia SNR) and nearby extragalactic Ia SNRs are discussed. We find that the maximum detectable distance of MS SCs (helium-rich SCs) is 0.6-4 Mpc (0.4-16 Mpc), if the apparent magnitude limit is 27 in the absence of extinction, suggesting that the Large and Small Magellanic Clouds and the Andromeda Galaxy are excellent environments in which to search for SCs. However, only five Ia SNRs have been searched for SCs, showing little support for the standard channels in the singe-degenerate scenario. To better understand the progenitors of SNe Ia, we encourage the search for SCs in other nearby Ia SNRs.

Binary population synthesis study of the supersoft X-ray phase of single degenerate type Ia supernova progenitors

International Nuclear Information System (INIS)

Meng Xiangcun; Yang Wuming

2011-01-01

In the single degenerate (SD) scenario for type Ia supernovae (SNe Ia), a mass-accreting white dwarf is expected to experience a supersoft X-ray source (SSS) phase. However, some recent observations showed that the expected number of mass-accreting WDs is much lower than that predicted from theory, regardless of whether they are in spiral or elliptical galaxies. In this paper, we performed a binary population synthesis study on the relative duration of the SSS phase to their whole mass-increasing phase of WDs leading to SNe Ia. We found that for about 40% of the progenitor systems, the relative duration is shorter than 2% and the evolution of the mean relative duration shows that it is always smaller than 5%, both for young and old SNe Ia. In addition, before the SNe Ia explosions, more than 55% of the progenitor systems were experiencing a dwarf novae phase and no more than 10% were staying in the SSS phase. These results are consistent with the recent observations and imply that both in early- and late-type galaxies, only a small fraction of mass-accreting WDs resulting in SNe Ia contributes to the supersoft X-ray flux. So, although our results are not directly related to the X-ray output of the SN Ia progenitor, the low supersoft X-ray luminosity observed in early type galaxies may not be able to exclude the validity of the SD model. On the contrary, it is evidence to support the SD scenario.

SN 2006bt: A PERPLEXING, TROUBLESOME, AND POSSIBLY MISLEADING TYPE Ia SUPERNOVA

International Nuclear Information System (INIS)

Foley, Ryan J.; Narayan, Gautham; Challis, Peter J.; Kirshner, Robert P.; Filippenko, Alexei V.; Silverman, Jeffrey M.; Steele, Thea N.

2010-01-01

SN 2006bt displays characteristics unlike those of any other known Type Ia supernova (SN Ia). We present optical light curves and spectra of SN 2006bt which demonstrate the peculiar nature of this object. SN 2006bt has broad, slowly declining light curves indicative of a hot, high-luminosity SN, but lacks a prominent second maximum in the i band as do low-luminosity SNe Ia. Its spectra are similar to those of low-luminosity SNe Ia, containing features that are only present in cool SN photospheres. Light-curve fitting methods suggest that SN 2006bt is reddened by a significant amount of dust; however, it occurred in the outskirts of its early-type host galaxy and has no strong Na D absorption in any of its spectra, suggesting a negligible amount of host-galaxy dust absorption. C II is possibly detected in our pre-maximum spectra, but at a much lower velocity than other elements. The progenitor was likely very old, being a member of the halo population of a galaxy that shows no signs of recent star formation. SNe Ia have been very successfully modeled as a one-parameter family, and this is fundamental to their use as cosmological distance indicators. SN 2006bt is a challenge to that picture, yet its relatively normal light curves allowed SN 2006bt to be included in cosmological analyses. We generate mock SN Ia data sets which indicate that contamination by similar objects will both increase the scatter of a SN Ia Hubble diagram and systematically bias measurements of cosmological parameters. However, spectra and rest-frame i-band light curves should provide a definitive way to identify and eliminate such objects.

Evidence for a Sub-Chandrasekhar-mass Type Ia Supernova in the Ursa Minor Dwarf Galaxy

Science.gov (United States)

McWilliam, Andrew; Piro, Anthony L.; Badenes, Carles; Bravo, Eduardo

2018-04-01

A long-standing problem is identifying the elusive progenitors of Type Ia supernovae (SNe Ia), which can roughly be split into Chandraksekhar and sub-Chandrasekhar-mass events. An important difference between these two cases is the nucleosynthetic yield, which is altered by the increased neutron excess in Chandrasekhar progenitors due to their pre-explosion simmering and high central density. Based on these arguments, we show that the chemical composition of the most metal-rich star in the Ursa Minor dwarf galaxy, COS 171, is dominated by nucleosynthesis from a low-metallicity, low-mass, sub-Chandrasekhar-mass SN Ia. Key diagnostic abundance ratios include Mn/Fe and Ni/Fe, which could not have been produced by a Chandrasekhar-mass SN Ia. Large deficiencies of Ni/Fe, Cu/Fe and Zn/Fe also suggest the absence of alpha-rich freeze-out nucleosynthesis, favoring low-mass white dwarf progenitors of SNe Ia, near 0.95 M ⊙, from comparisons to numerical detonation models. We also compare Mn/Fe and Ni/Fe ratios to the recent yields predicted by Shen et al., finding consistent results. To explain the [Fe/H] at ‑1.35 dex for COS 171 would require dilution of the SN Ia ejecta with ∼104 M ⊙ of material, which is expected for an SN remnant expanding into a warm interstellar medium with n ∼ 1 cm‑3. In the future, finding more stars with the unique chemical signatures we highlight here will be important for constraining the rate and environments of sub-Chandrasekhar SNe Ia.

New Constraints on ΩM, ΩΛ, and w from an Independent Set of 11 High-Redshift Supernovae Observed with the Hubble Space Telescope

Science.gov (United States)

Knop, R. A.; Aldering, G.; Amanullah, R.; Astier, P.; Blanc, G.; Burns, M. S.; Conley, A.; Deustua, S. E.; Doi, M.; Ellis, R.; Fabbro, S.; Folatelli, G.; Fruchter, A. S.; Garavini, G.; Garmond, S.; Garton, K.; Gibbons, R.; Goldhaber, G.; Goobar, A.; Groom, D. E.; Hardin, D.; Hook, I.; Howell, D. A.; Kim, A. G.; Lee, B. C.; Lidman, C.; Mendez, J.; Nobili, S.; Nugent, P. E.; Pain, R.; Panagia, N.; Pennypacker, C. R.; Perlmutter, S.; Quimby, R.; Raux, J.; Regnault, N.; Ruiz-Lapuente, P.; Sainton, G.; Schaefer, B.; Schahmaneche, K.; Smith, E.; Spadafora, A. L.; Stanishev, V.; Sullivan, M.; Walton, N. A.; Wang, L.; Wood-Vasey, W. M.; Yasuda, N.

2003-11-01

We report measurements of ΩM, ΩΛ, and w from 11 supernovae (SNe) at z=0.36-0.86 with high-quality light curves measured using WFPC2 on the Hubble Space Telescope (HST). This is an independent set of high-redshift SNe that confirms previous SN evidence for an accelerating universe. The high-quality light curves available from photometry on WFPC2 make it possible for these 11 SNe alone to provide measurements of the cosmological parameters comparable in statistical weight to the previous results. Combined with earlier Supernova Cosmology Project data, the new SNe yield a measurement of the mass density ΩM=0.25+0.07-0.06(statistical)+/-0.04 (identified systematics), or equivalently, a cosmological constant of ΩΛ=0.75+0.06-0.07(statistical)+/-0.04 (identified systematics), under the assumptions of a flat universe and that the dark energy equation-of-state parameter has a constant value w=-1. When the SN results are combined with independent flat-universe measurements of ΩM from cosmic microwave background and galaxy redshift distortion data, they provide a measurement of w=-1.05+0.15-0.20(statistical)+/-0.09 (identified systematic), if w is assumed to be constant in time. In addition to high-precision light-curve measurements, the new data offer greatly improved color measurements of the high-redshift SNe and hence improved host galaxy extinction estimates. These extinction measurements show no anomalous negative E(B-V) at high redshift. The precision of the measurements is such that it is possible to perform a host galaxy extinction correction directly for individual SNe without any assumptions or priors on the parent E(B-V) distribution. Our cosmological fits using full extinction corrections confirm that dark energy is required with P(ΩΛ>0)>0.99, a result consistent with previous and current SN analyses that rely on the identification of a low-extinction subset or prior assumptions concerning the intrinsic extinction distribution. Based in part on

Distance measurements from supernovae and dark energy constraints

International Nuclear Information System (INIS)

Wang Yun

2009-01-01

Constraints on dark energy from current observational data are sensitive to how distances are measured from Type Ia supernova (SN Ia) data. We find that flux averaging of SNe Ia can be used to test the presence of unknown systematic uncertainties, and yield more robust distance measurements from SNe Ia. We have applied this approach to the nearby+SDSS+ESSENCE+SNLS+HST set of 288 SNe Ia, and the 'Constitution' set of 397 SNe Ia. Combining the SN Ia data with cosmic microwave background anisotropy data from Wilkinson Microwave Anisotropy Probe 5 yr observations, the Sloan Digital Sky Survey baryon acoustic oscillation measurements, the data of 69 gamma-ray bursts (GRBs) , and the Hubble constant measurement from the Hubble Space Telescope project SHOES, we measure the dark energy density function X(z)≡ρ X (z)/ρ X (0) as a free function of redshift (assumed to be a constant at z>1 or z>1.5). Without the flux averaging of SNe Ia, the combined data using the Constitution set of SNe Ia seem to indicate a deviation from a cosmological constant at ∼95% confidence level at 0 98% confidence level for z≤0.75 using the combined data with 288 SNe Ia from nearby+SDSS+ESSENCE+SNLS+HST, independent of the assumptions about X(z≥1). We quantify dark energy constraints without assuming a flat Universe using the dark energy figure of merit for both X(z) and a dark energy equation-of-state linear in the cosmic scale factor.

Theoretical uncertainties of the Type Ia supernova rate

NARCIS (Netherlands)

Claeys, J.S.W.; Pols, O.R.; Izzard, R.G.; Vink, J.; Verbunt, F.W.M.

2014-01-01

It is thought that Type Ia supernovae (SNe Ia) are explosions of carbon-oxygen white dwarfs (CO WDs). Two main evolutionary channels are proposed for the WD to reach the critical density required for a thermonuclear explosion: the single degenerate (SD) scenario, in which a CO WD accretes from a

Imprints of explosion conditions on late-time spectra of type Ia supernovae

Science.gov (United States)

Diamond, Tiara R.

Type Ia supernovae (SNe Ia) play a vital role in the discrimination of different cosmological models. These events have been shown to be standardizable based on properties of their light curves during the early-time photospheric phase. However, the distribution of types of progenitor system, the explosion trigger, and the physics of the explosion are still an active topic of discussion. The details of the progenitors and explosion may provide insight into the variation seen in Type Ia supernova light curves and spectra, and therefore, allow for additional methods of standardization among the group. Late-time near-infrared spectral observations for SNe Ia show numerous strong emission features of forbidden line transitions of cobalt and iron, tracing the central distribution of iron-group burning products. As the spectrum ages, the cobalt features fade as expected from the decay of 56Co to 56Fe. This work will show that the strong and isolated [Fe II] emission line at 1.644 mum provides a unique tool to analyze near-infrared spectra of SNe Ia. Several new methods of analysis will be demonstrated to determine some of the initial conditions of the system. The initial central density, rhoc, and the extent of mixing in the central regions of the explosion have signatures in the line profiles of late-time spectra. An embedded magnetic field, B, of the white dwarf can be determined using the evolution of the lines profiles. Currently magnetic field effects are not included in the hydrodynamics and radiation transport of simulations of SNe Ia. Normalization of spectra to the 1.644 mum line allows separation of features produced by stable versus unstable isotopes of iron group elements. Implications for potential progenitor systems, explosion mechanisms, and the origins and morphology of magnetic fields in SNe Ia, in addition to limitations of the method, are discussed. Observations of the late-time near-infrared emission spectrum at multiple epochs allow for the first ever

A Definitive Measurement of Time Dilation in the Spectral Evolution of the Moderate-Redshift Type Ia Supernova 1997ex

International Nuclear Information System (INIS)

Foley, Ryan J.; Filippenko, Alexei V.; Leonard, Douglas C.; Riess, Adam G.; Nugent, Peter; Perlmutter, Saul

2005-01-01

We have obtained high-quality Keck optical spectra at three epochs of the Type Ia supernova 1997ex, whose redshift z is 0.361. The elapsed calendar time between the first two spectra was 24.88 days, and that between the first and third spectra was 30.95 days. In an expanding universe where 1+z represents the factor by which space has expanded between the emission and detection of light, the amount of aging in the supernova rest frame should be a factor of 1/(1+z) smaller than the observed-frame aging; thus, we expect SN 1997ex to have aged 18.28 and 22.74 days between the first epoch and the second and third epochs, respectively. The quantitative method for determining the spectral-feature age of an SN Ia reveals that the corresponding elapsed times in the supernova rest frame were 16.97+/-2.75 and 18.01+/-3.14 days, respectively. This result is inconsistent with no time dilation with a significance level of 99.0 percent, providing evidence against ''tired light'' and other hypotheses in which no time dilation is expected. Moreover, the observed timescale of spectral evolution is inconsistent with that expected in the ''variable mass theory''. The result is within ∼1 of the aging expected from a universe in which redshift is produced by cosmic expansion

Multidimensional Models of Type Ia Supernova Nebular Spectra: Strong Emission Lines from Stripped Companion Gas Rule Out Classic Single-degenerate Systems

Science.gov (United States)

Botyánszki, János; Kasen, Daniel; Plewa, Tomasz

2018-01-01

The classic single-degenerate model for the progenitors of Type Ia supernova (SN Ia) predicts that the supernova ejecta should be enriched with solar-like abundance material stripped from the companion star. Spectroscopic observations of normal SNe Ia at late times, however, have not resulted in definite detection of hydrogen. In this Letter, we study line formation in SNe Ia at nebular times using non-LTE spectral modeling. We present, for the first time, multidimensional radiative transfer calculations of SNe Ia with stripped material mixed in the ejecta core, based on hydrodynamical simulations of ejecta–companion interaction. We find that interaction models with main-sequence companions produce significant Hα emission at late times, ruling out these types of binaries being viable progenitors of SNe Ia. We also predict significant He I line emission at optical and near-infrared wavelengths for both hydrogen-rich or helium-rich material, providing an additional observational probe of stripped ejecta. We produce models with reduced stripped masses and find a more stringent mass limit of M st ≲ 1 × 10‑4 M ⊙ of stripped companion material for SN 2011fe.

STRESS a SN survey at ESO

Science.gov (United States)

Botticella, M. T.

We performed the Southern inTermediate Redshift ESO Supernova Search (STRESS), a survey specifically designed to measure the rate of both SNe Ia and CC SNe, in order to obtain a direct comparison of the high redshift and local rates and to investigate the dependence of the rates on specific galaxy properties, most notably their colour. We found that the type Ia SN rate, at mean redshift z = 0.3, is 0.22+0.10+0.16-0.08-0.14 h270 SNu, while the CC SN rate, at z = 0.21, is 0.82+0.31+0.300.24-0.26 h270 SNu. The quoted errors are the statistical and systematic uncertainties. With respect to the local value, the CC SN rate at z = 0.2 is higher by a factor of ˜ 2, whereas the type Ia SN rate remains almost constant. We also measured the SN rates in the red and blue galaxies and found that the SN Ia rate seems to be constant in galaxies of different colour, whereas the CC SN rate seems to peak in blue galaxies, as in the local Universe. Finally we exploited the link between SFH and SN rates to predict the evolutionary behaviour of the SN rates and compare it with the path indicated by observations.

Supernovae anisotropy power spectrum

Energy Technology Data Exchange (ETDEWEB)

Ghodsi, Hoda; Baghram, Shant [Department of Physics, Sharif University of Technology, P.O. Box 11155-9161, Tehran (Iran, Islamic Republic of); Habibi, Farhang, E-mail: h.ghodsi@mehr.sharif.ir, E-mail: baghram@sharif.edu, E-mail: habibi@lal.in2p3.fr [LAL-IN2P3/CNRS, BP 34, 91898 Orsay Cedex (France)

2017-10-01

We contribute another anisotropy study to this field of research using Type Ia supernovae (SNe Ia). In this work, we utilise the power spectrum calculation method and apply it to both the current SNe Ia data and simulation. Using the Union2.1 data set at all redshifts, we compare the spectrum of the residuals of the observed distance moduli to that expected from an isotropic universe affected by the Union2.1 observational uncertainties at low multipoles. Through this comparison we find a dipolar anisotropy with tension of less that 2σ towards l = 171° ± 21° and b = −26° ± 28° which is mainly induced by anisotropic spatial distribution of the SNe with z > 0.2 rather than being a cosmic effect. Furthermore, we find a tension of ∼ 4σ at ℓ = 4 between the two spectra. Our simulations are constructed with the characteristics of the upcoming surveys like the Large Synoptic Survey Telescope (LSST), which shall bring us the largest SNe Ia collection to date. We make predictions for the amplitude of a possible dipolar anisotropy that would be detectable by future SNe Ia surveys.

MONTE CARLO POPULATION SYNTHESIS OF POST-COMMON-ENVELOPE WHITE DWARF BINARIES AND TYPE Ia SUPERNOVA RATE

Energy Technology Data Exchange (ETDEWEB)

Ablimit, Iminhaji [Key Laboratory for Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Maeda, Keiichi [Department of Astronomy, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto 606-8502 (Japan); Li, Xiang-Dong [Department of Astronomy, Nanjing University, Nanjing 210046 (China)

2016-07-20

Binary population synthesis (BPS) studies provide a comprehensive way to understand the evolution of binaries and their end products. Close white dwarf (WD) binaries have crucial characteristics for examining the influence of unresolved physical parameters on binary evolution. In this paper, we perform Monte Carlo BPS simulations, investigating the population of WD/main-sequence (WD/MS) binaries and double WD binaries using a publicly available binary star evolution code under 37 different assumptions for key physical processes and binary initial conditions. We considered different combinations of the binding energy parameter ( λ {sub g}: considering gravitational energy only; λ {sub b}: considering both gravitational energy and internal energy; and λ {sub e}: considering gravitational energy, internal energy, and entropy of the envelope, with values derived from the MESA code), CE efficiency, critical mass ratio, initial primary mass function, and metallicity. We find that a larger number of post-CE WD/MS binaries in tight orbits are formed when the binding energy parameters are set by λ {sub e} than in those cases where other prescriptions are adopted. We also determine the effects of the other input parameters on the orbital periods and mass distributions of post-CE WD/MS binaries. As they contain at least one CO WD, double WD systems that evolved from WD/MS binaries may explode as type Ia supernovae (SNe Ia) via merging. In this work, we also investigate the frequency of two WD mergers and compare it to the SNe Ia rate. The calculated Galactic SNe Ia rate with λ = λ {sub e} is comparable to the observed SNe Ia rate, ∼8.2 × 10{sup 5} yr{sup 1} – ∼4 × 10{sup 3} yr{sup 1} depending on the other BPS parameters, if a DD system does not require a mass ratio higher than ∼0.8 to become an SNe Ia. On the other hand, a violent merger scenario, which requires the combined mass of two CO WDs ≥ 1.6 M {sub ⊙} and a mass ratio >0.8, results in a much lower

UNBURNED MATERIAL IN THE EJECTA OF TYPE Ia SUPERNOVAE

International Nuclear Information System (INIS)

Folatelli, Gastón; Tanaka, Masaomi; Maeda, Keiichi; Nomoto, Ken'ichi; Phillips, M. M.; Morrell, Nidia; Campillay, Abdo; González, Sergio; Roth, Miguel; Stritzinger, Maximilian; Burns, Christopher R.; Freedman, W. L.; Madore, Barry F; Persson, S. E.; Hamuy, Mario; Mazzali, Paolo; Boldt, Luis; Contreras, Carlos; Salgado, Francisco; Suntzeff, Nicholas B.

2012-01-01

The presence of unburned material in the ejecta of normal Type Ia supernovae (SNe Ia) is investigated using early-time spectroscopy obtained by the Carnegie Supernova Project. The tell-tale signature of pristine material from a C+O white dwarf progenitor star is the presence of carbon, as oxygen is also a product of carbon burning. The most prominent carbon lines in optical spectra of SNe Ia are expected to arise from C II. We find that at least 30% of the objects in the sample show an absorption at ≈6300 Å which is attributed to C II λ6580. An alternative identification of this absorption as Hα is considered to be unlikely. These findings imply a larger incidence of carbon in SNe Ia ejecta than previously noted. We show how observational biases and physical conditions may hide the presence of weak C II lines, and account for the scarcity of previous carbon detections in the literature. This relatively large frequency of carbon detections has crucial implications on our understanding of the explosive process. Furthermore, the identification of the 6300 Å absorptions as carbon would imply that unburned material is present at very low expansion velocities, merely ≈1000 km s –1 above the bulk of Si II. Based on spectral modeling, it is found that the detections are consistent with a mass of carbon of 10 –3 to 10 –2 M ☉ . The presence of this material so deep in the ejecta would imply substantial mixing, which may be related to asymmetries of the flame propagation. Another possible explanation for the carbon absorptions may be the existence of clumps of unburned material along the line of sight. However, the uniformity of the relation between C II and Si II velocities is not consistent with such small-scale asymmetries. The spectroscopic and photometric properties of SNe Ia with and without carbon signatures are compared. A trend toward bluer color and lower luminosity at maximum light is found for objects which show carbon.

UNBURNED MATERIAL IN THE EJECTA OF TYPE Ia SUPERNOVAE

Energy Technology Data Exchange (ETDEWEB)

Folatelli, Gaston; Tanaka, Masaomi; Maeda, Keiichi; Nomoto, Ken' ichi [Institute for the Physics and Mathematics of the Universe (IPMU), University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583 (Japan); Phillips, M. M.; Morrell, Nidia; Campillay, Abdo; Gonzalez, Sergio; Roth, Miguel [Las Campanas Observatory, Carnegie Observatories, Casilla 601, La Serena (Chile); Stritzinger, Maximilian [The Oskar Klein Centre, Department of Astronomy, Stockholm University, AlbaNova, 10691 Stockholm (Sweden); Burns, Christopher R.; Freedman, W. L.; Madore, Barry F; Persson, S. E. [Observatories of the Carnegie Institution of Washington, 813 Santa Barbara St., Pasadena, CA 91101 (United States); Hamuy, Mario [Departamento de Astronomia, Universidad de Chile, Casilla 36-D, Santiago (Chile); Mazzali, Paolo [Max-Planck Institut fuer Astrophysik, Karl-Schwarzschild-Str. 1, 85748 Garching (Germany); Boldt, Luis [Argelander Institut fuer Astronomie, Universitaet Bonn, Auf dem Huegel 71, D-53111 Bonn (Germany); Contreras, Carlos [Centre for Astrophysics and Supercomputing, Swinburne University of Technology, P.O. Box 218, Victoria 3122 (Australia); Salgado, Francisco [Leiden Observatory, Leiden University, P.O. Box 9513, NL-2300 RA Leiden (Netherlands); Suntzeff, Nicholas B., E-mail: gaston.folatelli@ipmu.jp [George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics and Astronomy, Texas A and M University, College Station, TX 77843 (United States)

2012-01-20

The presence of unburned material in the ejecta of normal Type Ia supernovae (SNe Ia) is investigated using early-time spectroscopy obtained by the Carnegie Supernova Project. The tell-tale signature of pristine material from a C+O white dwarf progenitor star is the presence of carbon, as oxygen is also a product of carbon burning. The most prominent carbon lines in optical spectra of SNe Ia are expected to arise from C II. We find that at least 30% of the objects in the sample show an absorption at Almost-Equal-To 6300 A which is attributed to C II {lambda}6580. An alternative identification of this absorption as H{alpha} is considered to be unlikely. These findings imply a larger incidence of carbon in SNe Ia ejecta than previously noted. We show how observational biases and physical conditions may hide the presence of weak C II lines, and account for the scarcity of previous carbon detections in the literature. This relatively large frequency of carbon detections has crucial implications on our understanding of the explosive process. Furthermore, the identification of the 6300 A absorptions as carbon would imply that unburned material is present at very low expansion velocities, merely Almost-Equal-To 1000 km s{sup -1} above the bulk of Si II. Based on spectral modeling, it is found that the detections are consistent with a mass of carbon of 10{sup -3} to 10{sup -2} M{sub Sun }. The presence of this material so deep in the ejecta would imply substantial mixing, which may be related to asymmetries of the flame propagation. Another possible explanation for the carbon absorptions may be the existence of clumps of unburned material along the line of sight. However, the uniformity of the relation between C II and Si II velocities is not consistent with such small-scale asymmetries. The spectroscopic and photometric properties of SNe Ia with and without carbon signatures are compared. A trend toward bluer color and lower luminosity at maximum light is found for

TYPE Ia SUPERNOVA COLORS AND EJECTA VELOCITIES: HIERARCHICAL BAYESIAN REGRESSION WITH NON-GAUSSIAN DISTRIBUTIONS

International Nuclear Information System (INIS)

Mandel, Kaisey S.; Kirshner, Robert P.; Foley, Ryan J.

2014-01-01

We investigate the statistical dependence of the peak intrinsic colors of Type Ia supernovae (SNe Ia) on their expansion velocities at maximum light, measured from the Si II λ6355 spectral feature. We construct a new hierarchical Bayesian regression model, accounting for the random effects of intrinsic scatter, measurement error, and reddening by host galaxy dust, and implement a Gibbs sampler and deviance information criteria to estimate the correlation. The method is applied to the apparent colors from BVRI light curves and Si II velocity data for 79 nearby SNe Ia. The apparent color distributions of high-velocity (HV) and normal velocity (NV) supernovae exhibit significant discrepancies for B – V and B – R, but not other colors. Hence, they are likely due to intrinsic color differences originating in the B band, rather than dust reddening. The mean intrinsic B – V and B – R color differences between HV and NV groups are 0.06 ± 0.02 and 0.09 ± 0.02 mag, respectively. A linear model finds significant slopes of –0.021 ± 0.006 and –0.030 ± 0.009 mag (10 3 km s –1 ) –1 for intrinsic B – V and B – R colors versus velocity, respectively. Because the ejecta velocity distribution is skewed toward high velocities, these effects imply non-Gaussian intrinsic color distributions with skewness up to +0.3. Accounting for the intrinsic-color-velocity correlation results in corrections to A V extinction estimates as large as –0.12 mag for HV SNe Ia and +0.06 mag for NV events. Velocity measurements from SN Ia spectra have the potential to diminish systematic errors from the confounding of intrinsic colors and dust reddening affecting supernova distances

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

Energy Technology Data Exchange (ETDEWEB)

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

2017-09-01

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

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

International Nuclear Information System (INIS)

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

2017-01-01

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

The nearby supernova factory

International Nuclear Information System (INIS)

Wood-Vasey, W.M.; Aldering, G.; Lee, B.C.; Loken, S.; Nugent, P.; Perlmutter, S.; Siegrist, J.; Wang, L.; Antilogus, P.; Astier, P.; Hardin, D.; Pain, R.; Copin, Y.; Smadja, G.; Gangler, E.; Castera, A.; Adam, G.; Bacon, R.; Lemonnier, J.-P.; Pecontal, A.; Pecontal, E.; Kessler, R.

2004-01-01

The Nearby Supernova Factory (SNfactory) is an ambitious project to find and study in detail approximately 300 nearby Type Ia supernovae (SNe Ia) at redshifts 0.03 < z < 0.08. This program will provide an exceptional data set of well-studied SNe in the nearby smooth Hubble flow that can be used as calibration for the current and future programs designed to use SNe to measure the cosmological parameters. The first key ingredient for this program is a reliable supply of Hubble-flow SNe systematically discovered in unprecedented numbers using the same techniques as those used in distant SNe searches. In 2002, 35 SNe were found using our test-bed pipeline for automated SN search and discovery. The pipeline uses images from the asteroid search conducted by the Near Earth Asteroid Tracking group at JPL. Improvements in our subtraction techniques and analysis have allowed us to increase our effective SN discovery rate to ∼12 SNe/month in 2003

TYPE Ia SUPERNOVA PROGENITORS AND CHEMICAL ENRICHMENT IN HYDRODYNAMICAL SIMULATIONS. I. THE SINGLE-DEGENERATE SCENARIO

Energy Technology Data Exchange (ETDEWEB)

Jiménez, Noelia [School of Physics and Astronomy, University of St. Andrews, North Haugh, St. Andrews, KY16 9SS, Scotland (United Kingdom); Tissera, Patricia B. [Instituto de Astronomía y Física del Espacio (IAFE, CONICET-UBA), CC. 67 Suc. 28, C1428ZAA, Ciudad de Buenos Aires (Argentina); Matteucci, Francesca, E-mail: nj22@st-andrews.ac.uk [Dipartimento di Fisica, Universita’ di Trieste, Via G. B. Tiepolo, 11, I-34100, Trieste (Italy)

2015-09-10

The nature of the Type Ia supernova (SN Ia) progenitors remains uncertain. This is a major issue for galaxy evolution models since both chemical and energetic feedback plays a major role in the gas dynamics, star formation, and therefore the overall stellar evolution. The progenitor models for the SNe Ia available in the literature propose different distributions for regulating the explosion times of these events. These functions are known as the delay time distributions (DTDs). This work is the first one in a series of papers aiming at studying five different DTDs for SNe Ia. Here we implement and analyze the single-degenerate (SD) scenario in galaxies dominated by a rapid quenching of the star formation, displaying the majority of the stars concentrated in the bulge component. We find a good fit to both the present observed SN Ia rates in spheroidal-dominated galaxies and the [O/Fe] ratios shown by the bulge of the Milky Way. Additionally, the SD scenario is found to reproduce a correlation between the specific SN Ia rate and the specific star formation rate (sSFR), which closely resembles the observational trend, at variance with previous works. Our results suggest that SN Ia observations in galaxies with very low and very high sSFRs can help to impose more stringent constraints on the DTDs and therefore on SN Ia progenitors.

Measurements of Ω and Λ from 42 High-Redshift Supernovae

International Nuclear Information System (INIS)

Perlmutter, S.; Aldering, G.; Goldhaber, G.; Knop, R.A.; Nugent, P.; Castro, P.G.; Deustua, S.; Fabbro, S.; Goobar, A.; Groom, D.E.; Hook, I.M.; Kim, A.G.; Kim, M.Y.; Lee, J.C.; Nunes, N.J.; Pain, R.; Pennypacker, C.R.; Quimby, R.; Lidman, C.; Ellis, R.S.; Irwin, M.; McMahon, R.G.; Ruiz-Lapuente, P.; Walton, N.; Schaefer, B.; Boyle, B.J.; Filippenko, A.V.; Matheson, T.; Fruchter, A.S.; Panagia, N.; Newberg, H.J.; Couch, W.J.

1999-01-01

We report measurements of the mass density, Ω M , and cosmological-constant energy density, Ω Λ , of the universe based on the analysis of 42 type Ia supernovae discovered by the Supernova Cosmology Project. The magnitude-redshift data for these supernovae, at redshifts between 0.18 and 0.83, are fitted jointly with a set of supernovae from the Calacute an/Tololo Supernova Survey, at redshifts below 0.1, to yield values for the cosmological parameters. All supernova peak magnitudes are standardized using a SN Ia light-curve width-luminosity relation. The measurement yields a joint probability distribution of the cosmological parameters that is approximated by the relation 0.8Ω M -0.6Ω Λ ∼-0.2±0.1 in the region of interest (Ω M approx-lt 1.5). For a flat (Ω M +Ω Λ =1) cosmology we find Ω flat M =0.28 +0.09 -0.08 (1 σ statistical) +0.05 -0.04 (identified systematics). The data are strongly inconsistent with a Λ=0 flat cosmology, the simplest inflationary universe model. An open, Λ=0 cosmology also does not fit the data well: the data indicate that the cosmological constant is nonzero and positive, with a confidence of P(Λ>0)=99%, including the identified systematic uncertainties. The best-fit age of the universe relative to the Hubble time is t flat 0 =14.9 +1.4 -1.1 (0.63/h) Gyr for a flat cosmology. The size of our sample allows us to perform a variety of statistical tests to check for possible systematic errors and biases. We find no significant differences in either the host reddening distribution or Malmquist bias between the low-redshift Calacute an/Tololo sample and our high-redshift sample. Excluding those few supernovae that are outliers in color excess or fit residual does not significantly change the results. The conclusions are also robust whether or not a width-luminosity relation is used to standardize the supernova peak magnitudes. We discuss and constrain, where possible, hypothetical alternatives to a cosmological constant

Isotropy of low redshift type Ia supernovae: A Bayesian analysis

Science.gov (United States)

Andrade, U.; Bengaly, C. A. P.; Alcaniz, J. S.; Santos, B.

2018-04-01

The standard cosmology strongly relies upon the cosmological principle, which consists on the hypotheses of large scale isotropy and homogeneity of the Universe. Testing these assumptions is, therefore, crucial to determining if there are deviations from the standard cosmological paradigm. In this paper, we use the latest type Ia supernova compilations, namely JLA and Union2.1 to test the cosmological isotropy at low redshift ranges (z <0.1 ). This is performed through a Bayesian selection analysis, in which we compare the standard, isotropic model, with another one including a dipole correction due to peculiar velocities. The full covariance matrix of SN distance uncertainties are taken into account. We find that the JLA sample favors the standard model, whilst the Union2.1 results are inconclusive, yet the constraints from both compilations are in agreement with previous analyses. We conclude that there is no evidence for a dipole anisotropy from nearby supernova compilations, albeit this test should be greatly improved with the much-improved data sets from upcoming cosmological surveys.

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

Energy Technology Data Exchange (ETDEWEB)

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

2016-06-01

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

ON THE LIRA LAW AND THE NATURE OF EXTINCTION TOWARD TYPE Ia SUPERNOVAE

Energy Technology Data Exchange (ETDEWEB)

Foerster, Francisco; Gonzalez-Gaitan, Santiago [Departamento de Astronomia, Universidad de Chile, Casilla 36-D, Santiago (Chile); Folatelli, Gaston [Kavli Institute for the Physics and Mathematics of the Universe, Todai Institutes for Advanced Study (TODIAS), University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583 (Japan); Morrell, Nidia [Las Campanas Observatory, Carnegie Observatories, Casilla 601, La Serena (Chile)

2013-07-20

We have studied the relation between the color evolution of Type Ia supernovae (SNe Ia) from maximum light to the Lira law regime and the presence of narrow absorption features. Based on a nearby sample of 89 SNe Ia, we have found that the rate of change of B - V colors at late phases (between 35 and 80 days after maximum) varies significantly among different SNe Ia. At maximum light, faster Lira law B - V decliners have significantly higher equivalent widths of blended Na I D1 and D2 narrow absorption lines, redder colors, and lower R{sub V} reddening laws. We do not find faster Lira law B - V decliners to have a strong preference for younger galaxy environments, where higher interstellar material (ISM) column densities would be expected. We interpret these results as evidence for the presence of circumstellar material. The differences in colors and reddening laws found at maximum light are also present 55 days afterward, but unlike the colors at maximum they show a significant variation among different host galaxy morphological types. This suggests that the effect of ISM on the colors is more apparent at late times. Finally, we discuss how the transversal expansion of the ejecta in an inhomogeneous ISM could mimic some of these findings.

RADIOACTIVELY POWERED RISING LIGHT CURVES OF TYPE Ia SUPERNOVAE

International Nuclear Information System (INIS)

Piro, Anthony L.

2012-01-01

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

Clustering at high redshifts

International Nuclear Information System (INIS)

Shaver, P.A.

1986-01-01

Evidence for clustering of and with high-redshift QSOs is discussed. QSOs of different redshifts show no clustering, but QSOs of similar redshifts appear to be clustered on a scale comparable to that of galaxies at the present epoch. In addition, spectroscopic studies of close pairs of QSOs indicate that QSOs are surrounded by a relatively high density of absorbing matter, possibly clusters of galaxies

Cosmological constraints on radion evolution in the universal extra dimension model

International Nuclear Information System (INIS)

Chan, K. C.; Chu, M.-C.

2008-01-01

The constraints on the radion evolution in the universal extra dimension (UED) model from cosmic microwave background (CMB) and Type Ia supernovae (SNe Ia) data are studied. In the UED model, where both the gravity and standard model fields can propagate in the extra dimensions, the evolution of the extra-dimensional volume, the radion, induces variation of fundamental constants. We discuss the effects of variation of the relevant constants in the context of UED for the CMB power spectrum and SNe Ia data. We then use the three-year WMAP data to constrain the radion evolution at z∼1100, and the 2σ constraint on ρ/ρ 0 (ρ is a function of the radion, to be defined in the text) is [-8.8,6.6]x10 -13 yr -1 . The SNe Ia gold sample yields a constraint on ρ/ρ 0 , for redshift between 0 and 1, to be [-4.7,14]x10 -13 yr -1 . Furthermore, the constraints from SNe Ia can be interpreted as bounds on the evolution QCD scale parameter, Λ QCD /Λ QCD,0 , [-1.4,2.8]x10 -11 yr -1 , without reference to the UED model.

Pulsar-driven Jets In Sne, Grbs, Lmxbs, Ss 433, And The Universe

Science.gov (United States)

Middleditch, John

2011-05-01

The model of pulsar emission through superluminally induced polarization currents, (SLIP), predicts that pulsations produced by such currents at many light cylinder radii by a rotating, magnetized body, will drive pulsations close to the axis of rotation. In SN 1987A, the possible Rosetta Stone for 99% of SNe, GRBs, ms pulsars, and SS 433, such highly collimated (>1 in 10,000) 2.14 ms pulsations, and the similarly collimated jets of particles which they drove, including 1e-6 solar masses with velocities 0.95 c, were responsible for its very early light curve (days 3-20), its "Mystery Spot," observed slightly later (0.5 to 0.3 c, at days 30-50 and after), and still later, in less collimated form, its bipolarity. The axially driven pulsations enforce a toroidal geometry onto all early SNRs, rendering even SNe Ia unsuitable as standard candles. The numbers for Sco X-1's jet are identical, while those for SS 433 are lower (0.26 c), because of the absence of velocity "boosting" via collisions of heavy elements with lighter ones, due to the nearly pure hydrogen content of the supercritical accretion. SLIP also drives positrons from SNe to high energies, possibly accounting for the excess seen by PAMELA at scores of GeV, and predicts that almost all pulsars with very sharp single pulses have been detected because the Earth is in a favored direction where their fluxes diminish only as 1/distance, and this has been verified in the laboratory as well as for the Parkes Multibeam Survey. SLIP also predicts that GRB afterglows will be 100% pulsed at 500 Hz in their proper frame. Finally, SLIP jets from SNe of the first stars may allow galaxies to form without the need for dark matter. This work was supported in part by the Department of Energy through the Los Alamos Directed Research Grant DR20080085.

TYPE Ia SUPERNOVAE AS SITES OF THE p-PROCESS: TWO-DIMENSIONAL MODELS COUPLED TO NUCLEOSYNTHESIS

International Nuclear Information System (INIS)

Travaglio, C.; Gallino, R.; Roepke, F. K.; Hillebrandt, W.

2011-01-01

Beyond Fe, there is a class of 35 proton-rich nuclides, between 74 Se and 196 Hg, called p-nuclei. They are bypassed by the s and r neutron capture processes and are typically 10-1000 times less abundant than the s- and/or r-isotopes in the solar system. The bulk of p-isotopes is created in the 'gamma processes' by sequences of photodisintegrations and beta decays in explosive conditions in both core collapse supernovae (SNe II) and in Type Ia supernovae (SNe Ia). SNe II contribute to the production of p-nuclei through explosive neon and oxygen burning. However, the major problem in SN II ejecta is a general underproduction of the light p-nuclei for A 209 Bi. We select tracers within the typical temperature range for p-process production, (1.5-3.7) x 10 9 K, and analyze in detail their behavior, exploring the influence of different s-process distributions on the p-process nucleosynthesis. In addition, we discuss the sensitivity of p-process production to parameters of the explosion mechanism, taking into account the consequences on Fe and alpha elements. We find that SNe Ia can produce a large amount of p-nuclei, both the light p-nuclei below A = 120 and the heavy-p nuclei, at quite flat average production factors, tightly related to the s-process seed distribution. For the first time, we find a stellar source able to produce both light and heavy p-nuclei almost at the same level as 56 Fe, including the debated neutron magic 92, 94 Mo and 96, 98 Ru. We also find that there is an important contribution from the p-process nucleosynthesis to the s-only nuclei 80 Kr, 86 Sr, to the neutron magic 90 Zr, and to the neutron-rich 96 Zr. Finally, we investigate the metallicity effect on p-process production in our models. Starting with different s-process seed distributions for two metallicities Z = 0.02 and Z = 0.001, running two-dimensional SN Ia models with different initial composition, we estimate that SNe Ia can contribute to at least 50% of the solar p

[O I] λλ6300, 6364 IN THE NEBULAR SPECTRUM OF A SUBLUMINOUS TYPE Ia SUPERNOVA

International Nuclear Information System (INIS)

Taubenberger, S.; Kromer, M.; Hillebrandt, W.; Pakmor, R.; Pignata, G.; Maeda, K.; Hachinger, S.; Leibundgut, B.

2013-01-01

In this Letter, a late-phase spectrum of SN 2010lp, a subluminous Type Ia supernova (SN Ia), is presented and analyzed. As in 1991bg-like SNe Ia at comparable epochs, the spectrum is characterized by relatively broad [Fe II] and [Ca II] emission lines. However, instead of narrow [Fe III] and [Co III] lines that dominate the emission from the innermost regions of 1991bg-like supernovae (SNe), SN 2010lp shows [O I] λλ6300, 6364 emission, usually associated with core-collapse SNe and never previously observed in a subluminous thermonuclear explosion. The [O I] feature has a complex profile with two strong, narrow emission peaks. This suggests that oxygen is distributed in a non-spherical region close to the center of the ejecta, severely challenging most thermonuclear explosion models discussed in the literature. We conclude that, given these constraints, violent mergers are presently the most promising scenario to explain SN 2010lp

Observational Evidence for High Neutronization in Supernova Remnants: Implications for Type Ia Supernova Progenitors

International Nuclear Information System (INIS)

Martínez-Rodríguez, Héctor; Badenes, Carles; Andrews, Brett; Yamaguchi, Hiroya; Bravo, Eduardo; Timmes, F. X.; Miles, Broxton J.; Townsley, Dean M.; Piro, Anthony L.; Mori, Hideyuki; Park, Sangwook

2017-01-01

The physical process whereby a carbon–oxygen white dwarf explodes as a Type Ia supernova (SN Ia) remains highly uncertain. The degree of neutronization in SN Ia ejecta holds clues to this process because it depends on the mass and the metallicity of the stellar progenitor, and on the thermodynamic history prior to the explosion. We report on a new method to determine ejecta neutronization using Ca and S lines in the X-ray spectra of Type Ia supernova remnants (SNRs). Applying this method to Suzaku data of Tycho, Kepler , 3C 397, and G337.2−0.7 in the Milky Way, and N103B in the Large Magellanic Cloud, we find that the neutronization of the ejecta in N103B is comparable to that of Tycho and Kepler , which suggests that progenitor metallicity is not the only source of neutronization in SNe Ia. We then use a grid of SN Ia explosion models to infer the metallicities of the stellar progenitors of our SNRs. The implied metallicities of 3C 397, G337.2−0.7, and N103B are major outliers compared to the local stellar metallicity distribution functions, indicating that progenitor metallicity can be ruled out as the origin of neutronization for these SNRs. Although the relationship between ejecta neutronization and equivalent progenitor metallicity is subject to uncertainties stemming from the 12 C + 16 O reaction rate, which affects the Ca/S mass ratio, our main results are not sensitive to these details.

Observational Evidence for High Neutronization in Supernova Remnants: Implications for Type Ia Supernova Progenitors

Energy Technology Data Exchange (ETDEWEB)

Martínez-Rodríguez, Héctor; Badenes, Carles; Andrews, Brett [Department of Physics and Astronomy and Pittsburgh Particle Physics, Astrophysics and Cosmology Center (PITT PACC), University of Pittsburgh, 3941 O’Hara Street, Pittsburgh, PA 15260 (United States); Yamaguchi, Hiroya [NASA Goddard Space Flight Center, Code 662, Greenbelt, MD 20771 (United States); Bravo, Eduardo [E.T.S. Arquitectura del Vallès, Universitat Politècnica de Catalunya, Carrer Pere Serra 1-15, E-08173 Sant Cugat del Vallès (Spain); Timmes, F. X. [The Joint Institute for Nuclear Astrophysics (United States); Miles, Broxton J.; Townsley, Dean M. [Department of Physics and Astronomy, University of Alabama, Tuscaloosa, AL (United States); Piro, Anthony L. [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Mori, Hideyuki [CRESST and X-ray Astrophysics Laboratory, NASA Goddard Space Flight Center, Code 602, Greenbelt, MD 20771 (United States); Park, Sangwook, E-mail: hector.mr@pitt.edu [Department of Physics, University of Texas at Arlington, Box 19059, Arlington, TX 76019 (United States)

2017-07-01

The physical process whereby a carbon–oxygen white dwarf explodes as a Type Ia supernova (SN Ia) remains highly uncertain. The degree of neutronization in SN Ia ejecta holds clues to this process because it depends on the mass and the metallicity of the stellar progenitor, and on the thermodynamic history prior to the explosion. We report on a new method to determine ejecta neutronization using Ca and S lines in the X-ray spectra of Type Ia supernova remnants (SNRs). Applying this method to Suzaku data of Tycho, Kepler , 3C 397, and G337.2−0.7 in the Milky Way, and N103B in the Large Magellanic Cloud, we find that the neutronization of the ejecta in N103B is comparable to that of Tycho and Kepler , which suggests that progenitor metallicity is not the only source of neutronization in SNe Ia. We then use a grid of SN Ia explosion models to infer the metallicities of the stellar progenitors of our SNRs. The implied metallicities of 3C 397, G337.2−0.7, and N103B are major outliers compared to the local stellar metallicity distribution functions, indicating that progenitor metallicity can be ruled out as the origin of neutronization for these SNRs. Although the relationship between ejecta neutronization and equivalent progenitor metallicity is subject to uncertainties stemming from the {sup 12}C + {sup 16}O reaction rate, which affects the Ca/S mass ratio, our main results are not sensitive to these details.

The farthest known supernova: Support for an accelerating universe and a glimpse of the epoch of deceleration

International Nuclear Information System (INIS)

Riess, Adam G.; Nugent, Peter E.; Schmidt, Brian P.; Tonry, John; Dickinson, Mark; Gilliland, Ronald L.; Thompson, Rodger I.; Budavari, Tamas; Casertano, Stefano; Evans, Aaron S.; Filippenko, Alexei V.; Livio, Mario; Sanders, David B.; Shapley, Alice E.; Spinrad, Hyron; Steidel, Charles C.; Stern, Daniel; Surace, Jason; Veilleux, Sylvain

2001-01-01

We present photometric observations of an apparent Type Ia supernova (SN Ia) at a redshift of approximately 1.7, the farthest SN observed to date. The supernova, SN 1997, was discovered in a repeat observation by the Hubble Space Telescope (HST) of the Hubble Deep Field-North (HDF-N), and serendipitously monitored with NICMOS on HST throughout the Thompson et al. GTO campaign. The SN type can be determined from the host galaxy type: an evolved, red elliptical lacking enough recent star formation to provide a significant population of core-collapse supernovae. The classification is further supported by diagnostics available from the observed colors and temporal behavior of the SN, both of which match a typical SN Ia. The photometric record of the SN includes a dozen flux measurements in the I, J, and H bands spanning 35 days in the observed frame. The redshift derived from the SN photometry, z = 1:7 plus or minus 0:1, is in excellent agreement with the redshift estimate of z = 1:65 plus or minus 0.15 derived from the U-300B-450 V-606 I-814 J-110 J-125 H-160 H-165 K s photometry of the galaxy. Optical and near-infrared spectra of the host provide a very tentative spectroscopic redshift of 1.755. Fits to observations of the SN provide constraints for the redshift-distance relation of SNe Ia and a powerful test of the current accelerating Universe hypothesis. The apparent SN brightness is consistent with that expected in the decelerating phase of the preferred cosmological model, Omega M approximately equal to 1/3;Omega Lambda approximately equal to 2/3. It is inconsistent with grey dust or simple luminosity evolution, candidate astrophysical effects which could mimic previous evidence for an accelerating Universe from SNeIa at z approximately equal to 0.5. We consider several sources of potential systematic error including gravitational lensing, supernova misclassification, sample selection bias, and luminosity calibration errors. Currently, none of these effects

The sloan digital sky survey-II supernova survey

DEFF Research Database (Denmark)

Frieman, Joshua A.; Bassett, Bruce; Becker, Andrew

2008-01-01

The Sloan Digital Sky Survey-II (SDSS-II) has embarked on a multi-year project to identify and measure light curves for intermediate-redshift (0.05 < z < 0.35) Type Ia supernovae (SNe Ia) using repeated five-band (ugriz) imaging over an area of 300 sq. deg. The survey region is a stripe 2.5° wide...

SDSS-II SUPERNOVA SURVEY: AN ANALYSIS OF THE LARGEST SAMPLE OF TYPE IA SUPERNOVAE AND CORRELATIONS WITH HOST-GALAXY SPECTRAL PROPERTIES

International Nuclear Information System (INIS)

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

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 (HRs). Our sample consists of 345 photometrically classified or spectroscopically confirmed 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 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 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 σ significance of a nonzero linear slope. We also recover correlations between HR and host-galaxy gas-phase metallicity and specific star formation rate as they are reported in the literature. With our large data set, 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 data sets for future surveys.

THE PROGENITORS OF TYPE Ia SUPERNOVAE. II. ARE THEY DOUBLE-DEGENERATE BINARIES? THE SYMBIOTIC CHANNEL

International Nuclear Information System (INIS)

Di Stefano, R.

2010-01-01

In order for a white dwarf (WD) to achieve the Chandrasekhar mass, M C , and explode as a Type Ia supernova (SNIa), it must interact with another star, either accreting matter from or merging with it. The failure to identify the class or classes of binaries which produce SNeIa is the long-standing 'progenitor problem'. Its solution is required if we are to utilize the full potential of SNeIa to elucidate basic cosmological and physical principles. In single-degenerate models, a WD accretes and burns matter at high rates. Nuclear-burning white dwarfs (NBWDs) with mass close to M C are hot and luminous, potentially detectable as supersoft X-ray sources (SSSs). In previous work, we showed that >90%-99% of the required number of progenitors do not appear as SSSs during most of the crucial phase of mass increase. The obvious implication might be that double-degenerate binaries form the main class of progenitors. We show in this paper, however, that many binaries that later become double degenerates must pass through a long-lived NBWD phase during which they are potentially detectable as SSSs. The paucity of SSSs is therefore not a strong argument in favor of double-degenerate models. Those NBWDs that are the progenitors of double-degenerate binaries are likely to appear as symbiotic binaries for intervals >10 6 years. In fact, symbiotic pre-double-degenerates should be common, whether or not the WDs eventually produce SNeIa. The key to solving the Type Ia progenitor problem lies in understanding the appearance of NBWDs. Most of them do not appear as SSSs most of the time. We therefore consider the evolution of NBWDs to address the question of what their appearance may be and how we can hope to detect them.

An Empirical Fitting Method for Type Ia Supernova Light Curves: A Case Study of SN 2011fe

Energy Technology Data Exchange (ETDEWEB)

Zheng, WeiKang; Filippenko, Alexei V., E-mail: zwk@astro.berkeley.edu [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States)

2017-03-20

We present a new empirical fitting method for the optical light curves of Type Ia supernovae (SNe Ia). We find that a variant broken-power-law function provides a good fit, with the simple assumption that the optical emission is approximately the blackbody emission of the expanding fireball. This function is mathematically analytic and is derived directly from the photospheric velocity evolution. When deriving the function, we assume that both the blackbody temperature and photospheric velocity are constant, but the final function is able to accommodate these changes during the fitting procedure. Applying it to the case study of SN 2011fe gives a surprisingly good fit that can describe the light curves from the first-light time to a few weeks after peak brightness, as well as over a large range of fluxes (∼5 mag, and even ∼7 mag in the g band). Since SNe Ia share similar light-curve shapes, this fitting method has the potential to fit most other SNe Ia and characterize their properties in large statistical samples such as those already gathered and in the near future as new facilities become available.

The cooling time of white dwarfs produced from type Ia supernovae

International Nuclear Information System (INIS)

Meng Xiangcun; Yang Wuming; Li Zhongmu

2010-01-01

Type Ia supernovae (SNe Ia) play a key role in measuring cosmological parameters, in which the Phillips relation is adopted. However, the origin of the relation is still unclear. Several parameters are suggested, e.g. the relative content of carbon to oxygen (C/O) and the central density of the white dwarf (WD) at ignition. These parameters are mainly determined by the WD's initial mass and its cooling time, respectively. Using the progenitor model developed by Meng and Yang, we present the distributions of the initial WD mass and the cooling time. We do not find any correlation between these parameters. However, we notice that as the range of the WD's mass decreases, its average value increases with the cooling time. These results could provide a constraint when simulating the SN Ia explosion, i.e. the WDs with a high C/O ratio usually have a lower central density at ignition, while those having the highest central density at ignition generally have a lower C/O ratio. The cooling time is mainly determined by the evolutionary age of secondaries, and the scatter of the cooling time decreases with the evolutionary age. Our results may indicate that WDs with a long cooling time have more uniform properties than those with a short cooling time, which may be helpful to explain why SNe Ia in elliptical galaxies have a more uniform maximum luminosity than those in spiral galaxies. (research papers)

On the rates of type Ia supernovae originating from white dwarf collisions in quadruple star systems

Science.gov (United States)

Hamers, Adrian S.

2018-04-01

We consider the evolution of stellar hierarchical quadruple systems in the 2+2 (two binaries orbiting each other's barycentre) and 3+1 (triple orbited by a fourth star) configurations. In our simulations, we take into account the effects of secular dynamical evolution, stellar evolution, tidal evolution and encounters with passing stars. We focus on type Ia supernovae (SNe Ia) driven by collisions of carbon-oxygen (CO) white dwarfs (WDs). Such collisions can arise from several channels: (1) collisions due to extremely high eccentricities induced by secular evolution, (2) collisions following a dynamical instability of the system, and (3) collisions driven by semisecular evolution. The systems considered here have initially wide inner orbits, with initial semilatus recti larger than 12 {au}, implying no interaction if the orbits were isolated. However, taking into account dynamical evolution, we find that ≈0.4 (≈0.6) of 2+2 (3+1) systems interact. In particular, Roche Lobe overflow can be triggered possibly in highly eccentric orbits, dynamical instability can ensue due to mass-loss-driven orbital expansion or secular evolution, or a semisecular regime can be entered. We compute the delay-time distributions (DTDs) of collision-induced SNe Ia, and find that they are flatter compared to the observed DTD. Moreover, our combined SNe Ia rates are (3.7± 0.7) × 10^{-6} M_⊙^{-1} and (1.3± 0.2) × 10^{-6} M_⊙^{-1} for 2+2 and 3+1 systems, respectively, three orders of magnitude lower compared to the observed rate, of order 10^{-3} M_⊙^{-1}. The low rates can be ascribed to interactions before the stars evolve to CO WDs. However, our results are lower limits given that we considered a subset of quadruple systems.

The farthest known supernova: Support for an accelerating universeand a glimpse of the epoch of deceleration

Energy Technology Data Exchange (ETDEWEB)

Riess, Adam G.; Nugent, Peter E.; Schmidt, Brian P.; Tonry, John; Dickinson, Mark; Gilliland, Ronald L.; Thompson, Rodger I.; Budavari,Tamas; Casertano, Stefano; Evans, Aaron S.; Filippenko, Alexei V.; Livio,Mario; Sanders, David B.; Shapley, Alice E.; Spinrad, Hyron; Steidel,Charles C.; Stern, Daniel; Surace, Jason; Veilleux, Sylvain

2001-04-01

We present photometric observations of an apparent Type Iasupernova (SN Ia) at a redshift of approximately 1.7, the farthest SNobserved to date. The supernova, SN 1997, was discovered in a repeatobservation by the Hubble Space Telescope (HST) of the Hubble DeepField{North (HDF-N), and serendipitously monitored with NICMOS on HSTthroughout the Thompson et al. GTO campaign. The SN type can bedetermined from the host galaxy type: an evolved, red elliptical lackingenough recent star formation to provide a significant population ofcore-collapse supernovae. The classification is further supported bydiagnostics available from the observed colors and temporal behavior ofthe SN, both of which match a typical SN Ia. The photometric record ofthe SN includes a dozen flux measurements in the I, J, and H bandsspanning 35 days in the observed frame. The redshift derived from the SNphotometry, z = 1:7 plus or minus 0:1, is in excellent agreement with theredshift estimate of z = 1:65 plus or minus 0:15 derived from the U_300B_450 V_-606 I_814 J_110 J_125 H_160 H_165 K_s photometry of the galaxy.Optical and near-infrared spectra of the host provide a very tentativespectroscopic redshift of 1.755. Fits to observations of the SN provideconstraints for the redshift-distance relation of SNe Ia and a powerfultest of the current accelerating Universe hypothesis. The apparent SNbrightness is consistent with that expected in the decelerating phase ofthe preferred cosmological model, Omega_M approximately equal to 1/3;Omega_Lambda approximately equal to 2/3. It is inconsistent with greydust or simple luminosity evolution, candidate astrophysical effectswhich could mimic previous evidence for an accelerating Universe from SNeIa at z approximately equal to 0:5. We consider several sources ofpotential systematic error including gravitational lensing, supernovamisclassification, sample selection bias, and luminosity calibrationerrors. Currently, none of these effects alone appears likely

SHOCK BREAKOUT FROM TYPE Ia SUPERNOVA

International Nuclear Information System (INIS)

Piro, Anthony L.; Chang, Philip; Weinberg, Nevin N.

2010-01-01

The mode of explosive burning in Type Ia supernovae (SNe Ia) remains an outstanding problem. It is generally thought to begin as a subsonic deflagration, but this may transition into a supersonic detonation (the delayed detonation transition, DDT). We argue that this transition leads to a breakout shock, which would provide the first unambiguous evidence that DDTs occur. Its main features are a hard X-ray flash (∼20 keV) lasting ∼10 -2 s with a total radiated energy of ∼10 40 erg, followed by a cooling tail. This creates a distinct feature in the visual light curve, which is separate from the nickel decay. This cooling tail has a maximum absolute visual magnitude of M V ∼ -9 to -10 at ∼1 day, which depends most sensitively on the white dwarf radius at the time of the DDT. As the thermal diffusion wave moves in, the composition of these surface layers may be imprinted as spectral features, which would help to discern between SN Ia progenitor models. Since this feature should accompany every SNe Ia, future deep surveys (e.g., m = 24) will see it out to a distance of ∼80 Mpc, giving a maximum rate of ∼60 yr -1 . Archival data sets can also be used to study the early rise dictated by the shock heating (at ∼20 days before maximum B-band light). A similar and slightly brighter event may also accompany core bounce during the accretion-induced collapse to a neutron star, but with a lower occurrence rate.

THE DIFFERENCE IMAGING PIPELINE FOR THE TRANSIENT SEARCH IN THE DARK ENERGY SURVEY

Energy Technology Data Exchange (ETDEWEB)

Kessler, R.; Scolnic, D. [Kavli Institute for Cosmological Physics, University of Chicago, Chicago, IL 60637 (United States); Marriner, J.; Finley, D. A.; Wester, W. [Fermi National Accelerator Laboratory, P.O. Box 500, Batavia, IL 60510 (United States); Childress, M.; Yuan, F. [ARC Centre of Excellence for All-sky Astrophysics (CAASTRO), Australian National University, Canberra ACT 2611 (Canada); Covarrubias, R. [National Center for Supercomputing Applications, 1205 West Clark St., Urbana, IL 61801 (United States); D’Andrea, C. B.; Nichol, R. C.; Papadopoulos, A. [Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth, PO1 3FX (United Kingdom); Fischer, J.; Sako, M. [Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104 (United States); Foley, R. J. [Department of Astronomy, University of Illinois, 1002 W. Green Street, Urbana, IL 61801 (United States); Goldstein, D. [Department of Astronomy, University of California, Berkeley, 501 Campbell Hall, Berkeley, CA 94720 (United States); Gupta, R. R. [Argonne National Laboratory, 9700 South Cass Avenue, Lemont, IL 60439 (United States); Kuehn, K. [Australian Astronomical Observatory, North Ryde, NSW 2113 (Australia); Marcha, M. [Department of Physics and Astronomy, University College London, Gower Street, London, WC1E 6BT (United Kingdom); Smith, M.; Sullivan, M., E-mail: kessler@kicp.uchicago.edu [School of Physics and Astronomy, University of Southampton, Southampton, SO17 1BJ (United Kingdom); Collaboration: DES Collaboration; and others

2015-12-15

We describe the operation and performance of the difference imaging pipeline (DiffImg) used to detect transients in deep images from the Dark Energy Survey Supernova program (DES-SN) in its first observing season from 2013 August through 2014 February. DES-SN is a search for transients in which ten 3 deg{sup 2} fields are repeatedly observed in the g, r, i, z passbands with a cadence of about 1 week. The observing strategy has been optimized to measure high-quality light curves and redshifts for thousands of Type Ia supernovae (SNe Ia) with the goal of measuring dark energy parameters. The essential DiffImg functions are to align each search image to a deep reference image, do a pixel-by-pixel subtraction, and then examine the subtracted image for significant positive detections of point-source objects. The vast majority of detections are subtraction artifacts, but after selection requirements and image filtering with an automated scanning program, there are ∼130 detections per deg{sup 2} per observation in each band, of which only ∼25% are artifacts. Of the ∼7500 transients discovered by DES-SN in its first observing season, each requiring a detection on at least two separate nights, Monte Carlo (MC) simulations predict that 27% are expected to be SNe Ia or core-collapse SNe. Another ∼30% of the transients are artifacts in which a small number of observations satisfy the selection criteria for a single-epoch detection. Spectroscopic analysis shows that most of the remaining transients are AGNs and variable stars. Fake SNe Ia are overlaid onto the images to rigorously evaluate detection efficiencies and to understand the DiffImg performance. The DiffImg efficiency measured with fake SNe agrees well with expectations from a MC simulation that uses analytical calculations of the fluxes and their uncertainties. In our 8 “shallow” fields with single-epoch 50% completeness depth ∼23.5, the SN Ia efficiency falls to 1/2 at redshift z ≈ 0.7; in our 2 �

Two transitional type Ia supernovae located in the Fornax cluster member NGC 1404

DEFF Research Database (Denmark)

Gall, C.; Stritzinger, M. D.; Ashall, C.

2018-01-01

We present an analysis of ultraviolet (UV) to near-infrared observations of the fast-declining Type Ia supernovae (SNe Ia) 2007on and 2011iv, hosted by the Fornax cluster member NGC 1404. The B-band light curves of SN 2007on and SN 2011iv are characterised by Delta m(15)(B) decline-rate values of...

A simple and robust method for automated photometric classification of supernovae using neural networks

Science.gov (United States)

Karpenka, N. V.; Feroz, F.; Hobson, M. P.

2013-02-01

A method is presented for automated photometric classification of supernovae (SNe) as Type Ia or non-Ia. A two-step approach is adopted in which (i) the SN light curve flux measurements in each observing filter are fitted separately to an analytical parametrized function that is sufficiently flexible to accommodate virtually all types of SNe and (ii) the fitted function parameters and their associated uncertainties, along with the number of flux measurements, the maximum-likelihood value of the fit and Bayesian evidence for the model, are used as the input feature vector to a classification neural network that outputs the probability that the SN under consideration is of Type Ia. The method is trained and tested using data released following the Supernova Photometric Classification Challenge (SNPCC), consisting of light curves for 20 895 SNe in total. We consider several random divisions of the data into training and testing sets: for instance, for our sample D_1 (D_4), a total of 10 (40) per cent of the data are involved in training the algorithm and the remainder used for blind testing of the resulting classifier; we make no selection cuts. Assigning a canonical threshold probability of pth = 0.5 on the network output to class an SN as Type Ia, for the sample D_1 (D_4) we obtain a completeness of 0.78 (0.82), purity of 0.77 (0.82) and SNPCC figure of merit of 0.41 (0.50). Including the SN host-galaxy redshift and its uncertainty as additional inputs to the classification network results in a modest 5-10 per cent increase in these values. We find that the quality of the classification does not vary significantly with SN redshift. Moreover, our probabilistic classification method allows one to calculate the expected completeness, purity and figure of merit (or other measures of classification quality) as a function of the threshold probability pth, without knowing the true classes of the SNe in the testing sample, as is the case in the classification of real SNe

Progressive Red Shifts in the Late-Time Spectra of Type Ia Supernovae

Science.gov (United States)

Black, Christine; Fesen, Robert; Parrent, Jerod

2017-01-01

We examine the evolution of late-time, optical nebular features of Type Ia supernovae (SNe Ia) using a sample consisting of 160 spectra of 27 normal SNe Ia taken from the literature as well as unpublished spectra of SN 2008Q and ASASSN-14lp. Particular attention is given to nebular features between 4000-6000 Ang in terms of temporal changes in width and central wavelength. Analysis of the prominent late-time 4700 Ang feature shows a progressive central wavelength shift from ˜4600 Ang to longer wavelengths out to at least day +300 for our entire sample. We find no evidence for the feature’s red-ward shift slowing or halting at an [Fe III] blend centroid ˜4700 Ang as has been proposed. Two weaker adjacent features at around 4850 and 5000 Ang exhibit similar red shifts to that of the 4700 Ang feature. We conclude that the ubiquitous red shift of these common late-time SN Ia spectral features is not mainly due to a decrease in line velocities of forbidden Fe emissions, but the result of decreasing line velocities and opacity of permitted Fe absorption lines.

THE ORIGIN OF THE COSMIC GAMMA-RAY BACKGROUND IN THE MeV RANGE

International Nuclear Information System (INIS)

Ruiz-Lapuente, Pilar; The, Lih-Sin; Hartmann, Dieter H.; Ajello, Marco; Canal, Ramon; Röpke, Friedrich K.; Ohlmann, Sebastian T.; Hillebrandt, Wolfgang

2016-01-01

There has been much debate about the origin of the diffuse γ-ray background in the MeV range. At lower energies, AGNs and Seyfert galaxies can explain the background, but not above ≃0.3 MeV. Beyond ∼10 MeV blazars appear to account for the flux observed. That leaves an unexplained gap for which different candidates have been proposed, including annihilations of WIMPS. One candidate is Type Ia supernovae (SNe Ia). Early studies concluded that they were able to account for the γ-ray background in the gap, while later work attributed a significantly lower contribution to them. All those estimates were based on SN Ia explosion models that did not reflect the full 3D hydrodynamics of SN Ia explosions. In addition, new measurements obtained since 2010 have provided new, direct estimates of high-z SN Ia rates beyond z ∼ 2. We take into account these new advances to see the predicted contribution to the gamma-ray background. We use here a wide variety of explosion models and a plethora of new measurements of SN Ia rates. SNe Ia still fall short of the observed background. Only for a fit, which would imply ∼150% systematic error in detecting SN Ia events, do the theoretical predictions approach the observed fluxes. This fit is, however, at odds at the highest redshifts with recent SN Ia rate estimates. Other astrophysical sources such as flat-spectrum radio quasars do match the observed flux levels in the MeV regime, while SNe Ia make up to 30%–50% of the observed flux

THE ORIGIN OF THE COSMIC GAMMA-RAY BACKGROUND IN THE MeV RANGE

Energy Technology Data Exchange (ETDEWEB)

Ruiz-Lapuente, Pilar [Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas, c/. Serrano 121, E-28006, Madrid (Spain); The, Lih-Sin; Hartmann, Dieter H.; Ajello, Marco [Department of Physics and Astronomy, Clemson University, Clemson, SC 29634 (United States); Canal, Ramon [Institut de Ciències del Cosmos (UB-IEEC), c/. Martí i Franqués 1, E-08028, Barcelona (Spain); Röpke, Friedrich K.; Ohlmann, Sebastian T. [Institute of Theoretical Physics and Astrophysics, University of Würzburg, D-97074, Würzburg (Germany); Hillebrandt, Wolfgang [Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, D-85748 Garching bei München (Germany)

2016-04-01

There has been much debate about the origin of the diffuse γ-ray background in the MeV range. At lower energies, AGNs and Seyfert galaxies can explain the background, but not above ≃0.3 MeV. Beyond ∼10 MeV blazars appear to account for the flux observed. That leaves an unexplained gap for which different candidates have been proposed, including annihilations of WIMPS. One candidate is Type Ia supernovae (SNe Ia). Early studies concluded that they were able to account for the γ-ray background in the gap, while later work attributed a significantly lower contribution to them. All those estimates were based on SN Ia explosion models that did not reflect the full 3D hydrodynamics of SN Ia explosions. In addition, new measurements obtained since 2010 have provided new, direct estimates of high-z SN Ia rates beyond z ∼ 2. We take into account these new advances to see the predicted contribution to the gamma-ray background. We use here a wide variety of explosion models and a plethora of new measurements of SN Ia rates. SNe Ia still fall short of the observed background. Only for a fit, which would imply ∼150% systematic error in detecting SN Ia events, do the theoretical predictions approach the observed fluxes. This fit is, however, at odds at the highest redshifts with recent SN Ia rate estimates. Other astrophysical sources such as flat-spectrum radio quasars do match the observed flux levels in the MeV regime, while SNe Ia make up to 30%–50% of the observed flux.

Peculiar velocity measurement in a clumpy universe

Science.gov (United States)

Habibi, Farhang; Baghram, Shant; Tavasoli, Saeed

Aims: In this work, we address the issue of peculiar velocity measurement in a perturbed Friedmann universe using the deviations from measured luminosity distances of standard candles from background FRW universe. We want to show and quantify the statement that in intermediate redshifts (0.5 deviations from the background FRW model are not uniquely governed by peculiar velocities. Luminosity distances are modified by gravitational lensing. We also want to indicate the importance of relativistic calculations for peculiar velocity measurement at all redshifts. Methods: For this task, we discuss the relativistic correction on luminosity distance and redshift measurement and show the contribution of each of the corrections as lensing term, peculiar velocity of the source and Sachs-Wolfe effect. Then, we use the SNe Ia sample of Union 2, to investigate the relativistic effects, we consider. Results: We show that, using the conventional peculiar velocity method, that ignores the lensing effect, will result in an overestimate of the measured peculiar velocities at intermediate redshifts. Here, we quantify this effect. We show that at low redshifts the lensing effect is negligible compare to the effect of peculiar velocity. From the observational point of view, we show that the uncertainties on luminosity of the present SNe Ia data prevent us from precise measuring the peculiar velocities even at low redshifts (z < 0.2).

Supernovae in Low-Redshift Galaxy Clusters: Observations by the Wise Observatory Optical Transient Search (WOOTS)

OpenAIRE

Gal-Yam, Avishay; Maoz, Dan; Guhathakurta, Puragra; Filippenko, Alexei V.

2007-01-01

We describe the Wise Observatory Optical Transient Search (WOOTS), a survey for supernovae (SNe) and other variable and transient objects in the fields of redshift 0.06-0.2 Abell galaxy clusters. We present the survey design and data-analysis procedures, and our object detection and follow-up strategies. We have obtained follow-up spectroscopy for all viable SN candidates, and present the resulting SN sample here. Out of the 12 SNe we have discovered, seven are associated with our target clus...

Asymmetric Explosion of Type Ia Supernovae and Their Observational Signatures

International Nuclear Information System (INIS)

Maeda, Keiichi

2010-01-01

The nature of Type Ia supernova (SN Ia) explosions has not yet been clarified, despite their importance in astrophysics and cosmology. Recent theoretical investigations suggest that asymmetric distribution of initial thermonuclear sparks may be a key in the SN Ia explosion mechanism. In this paper, the first observational evidence of the asymmetry in SN Ia explosions is presented: We have found that late-time nebular spectra of various SNe Ia show a diversity in wavelengths of emission lines. This feature is inconsistent with any spherically symmetric explosion models, and indicates that the innermost region, a likely product of the deflagration wave propagation, shows an off-set with respect to the explosion center. The diversity in the emission-line wavelengths could naturally be explained by a combination of different viewing angles.

The Subaru FMOS galaxy redshift survey (FastSound). V. Intrinsic alignments of emission-line galaxies at z ˜ 1.4

Science.gov (United States)

Tonegawa, Motonari; Okumura, Teppei; Totani, Tomonori; Dalton, Gavin; Glazebrook, Karl; Yabe, Kiyoto

2018-04-01

Intrinsic alignments (IA), the coherent alignment of intrinsic galaxy orientations, can be a source of a systematic error of weak lensing surveys. The redshift evolution of IA also contains information about the physics of galaxy formation and evolution. This paper presents the first measurement of IA at high redshift, z ˜ 1.4, using the spectroscopic catalog of blue star-forming galaxies of the FastSound redshift survey, with the galaxy shape information from the Canada-Hawaii-France telescope lensing survey. The IA signal is consistent with zero with power-law amplitudes fitted to the projected correlation functions for density-shape and shape-shape correlation components, Aδ+ = -0.0071 ± 0.1340 and A++ = -0.0505 ± 0.0848, respectively. These results are consistent with those obtained from blue galaxies at lower redshifts (e.g., A _{δ +}=0.0035_{-0.0389}^{+0.0387} and A_{++}=0.0045_{-0.0168}^{+0.0166} at z = 0.51 from the WiggleZ survey). The upper limit of the constrained IA amplitude corresponds to a few percent contamination to the weak-lensing shear power spectrum, resulting in systematic uncertainties on the cosmological parameter estimations by -0.052 < Δσ8 < 0.039 and -0.039 < ΔΩm < 0.030.

An Investigation of Blazars without Redshifts: Not a Missing Population at High Redshift

Energy Technology Data Exchange (ETDEWEB)

Mao, Peiyuan; Urry, C. Megan [Yale Center for Astronomy and Astrophysics, Physics Department, New Haven, CT 06520 (United States)

2017-06-01

We investigate a sample of 622 blazars with measured fluxes at 12 wavebands across the radio-to-gamma-ray spectrum but without spectroscopic or photometric redshifts. This sample includes hundreds of sources with newly analyzed X-ray spectra reported here. From the synchrotron peak frequencies, estimated by fitting the broadband spectral energy distributions (SEDs), we find that the fraction of high-synchrotron-peaked blazars in these 622 sources is roughly the same as in larger samples of blazars that do have redshifts. We characterize the no-redshift blazars using their infrared colors, which lie in the distinct locus called the WISE blazar strip, then estimate their redshifts using a KNN regression based on the redshifts of the closest blazars in the WISE color–color plot. Finally, using randomly drawn values from plausible redshift distributions, we simulate the SEDs of these blazars and compare them to known blazar SEDs. Based on all these considerations, we conclude that blazars without redshift estimates are unlikely to be high-luminosity, high-synchrotron-peaked objects, which had been suggested in order to explain the “blazar sequence”—an observed trend of SED shape with luminosity—as a selection effect. Instead, the observed properties of no-redshift blazars are compatible with a causal connection between jet power and electron cooling, i.e., a true blazar sequence.

EVALUATING SYSTEMATIC DEPENDENCIES OF TYPE Ia SUPERNOVAE: THE INFLUENCE OF PROGENITOR 22Ne CONTENT ON DYNAMICS

International Nuclear Information System (INIS)

Townsley, Dean M.; Jackson, Aaron P.; Calder, Alan C.; Chamulak, David A.; Brown, Edward F.; Timmes, F. X.

2009-01-01

We present a theoretical framework for formal study of systematic effects in supernovae Type Ia (SNe Ia) that utilizes two-dimensional simulations to implement a form of the deflagration-detonation transition (DDT) explosion scenario. The framework is developed from a randomized initial condition that leads to a sample of simulated SNe Ia whose 56 Ni masses have a similar average and range to those observed, and have many other modestly realistic features such as the velocity extent of intermediate-mass elements. The intended purpose is to enable statistically well defined studies of both physical and theoretical parameters of the SNe Ia explosion simulation. We present here a thorough description of the outcome of the SNe Ia explosions produced by our current simulations. A first application of this framework is utilized to study the dependence of the SNe Ia on the 22 Ne content, which is known to be directly influenced by the progenitor stellar population's metallicity. Our study is very specifically tailored to measure how the 22 Ne content influences the competition between the rise of plumes of burned material and the expansion of the star before these plumes reach DDT conditions. This influence arises from the dependence of the energy release, progenitor structure, and laminar flame speed on 22 Ne content. For this study, we explore these three effects for a fixed carbon content and DDT density. By setting the density at which nucleosynthesis takes place during the detonation phase of the explosion, the competition between plume rise and stellar expansion controls the amount of material in nuclear statistical equilibrium (NSE) and therefore 56 Ni produced. Of particular interest is how this influence of 22 Ne content compares to the direct modification of the 56 Ni mass via the inherent neutron excess as discussed by Timmes et al. Although the outcome following from any particular ignition condition can change dramatically with 22 Ne content, with a sample of

The Type Ia Supernova Rate at z~0.5 from the Supernova Legacy Survey

Science.gov (United States)

Neill, J. D.; Sullivan, M.; Balam, D.; Pritchet, C. J.; Howell, D. A.; Perrett, K.; Astier, P.; Aubourg, E.; Basa, S.; Carlberg, R. G.; Conley, A.; Fabbro, S.; Fouchez, D.; Guy, J.; Hook, I.; Pain, R.; Palanque-Delabrouille, N.; Regnault, N.; Rich, J.; Taillet, R.; Aldering, G.; Antilogus, P.; Arsenijevic, V.; Balland, C.; Baumont, S.; Bronder, J.; Ellis, R. S.; Filiol, M.; Gonçalves, A. C.; Hardin, D.; Kowalski, M.; Lidman, C.; Lusset, V.; Mouchet, M.; Mourao, A.; Perlmutter, S.; Ripoche, P.; Schlegel, D.; Tao, C.

2006-09-01

We present a measurement of the distant Type Ia supernova (SN Ia) rate derived from the first 2 yr of the Canada-France-Hawaii Telescope Supernova Legacy Survey. We observed four 1deg×1deg fields with a typical temporal frequency of ~4 observer-frame days over time spans of 158-211 days per season for each field, with breaks during the full Moon. We used 8-10 m class telescopes for spectroscopic follow-up to confirm our candidates and determine their redshifts. Our starting sample consists of 73 spectroscopically verified SNe Ia in the redshift range 0.2=0.47)=[0.42+0.13-0.09(syst.)+/-0.06(stat.)×10-4 yr-1 Mpc3, assuming h=0.7, Ωm=0.3, and a flat cosmology. Using recently published galaxy luminosity functions derived in our redshift range, we derive a SN Ia rate per unit luminosity of rL(=0.47)=0.154+0.048-0.033(syst.)+0.039-0.031(stat.) SN units. Using our rate alone, we place an upper limit on the component of SN Ia production that tracks the cosmic star formation history of 1 SN Ia per 103 Msolar of stars formed. Our rate and other rates from surveys using spectroscopic sample confirmation display only a modest evolution out to z=0.55. Based on observations obtained with MegaPrime/MegaCam, a joint project of the Canada-France-Hawaii Telescope (CFHT) and CEA/DAPNIA, at CFHT, which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii. This work is based in part on data products produced at the Canadian Astronomy Data Centre as part of the Canada-France-Hawaii Telescope Legacy Survey, a collaborative project of NRC and CNRS. This work is also based on observations obtained at the European Southern Observatory using the Very Large Telescope on the Cerro Paranal (ESO Large Program 171.A-0486), and on observations (programs GN-2004A-Q-19, GS-2004A-Q-11, GN-2003B-Q-9, and GS-2003B-Q-8) obtained at the Gemini

THE DISTANCE TO NGC 1316 (FORNAX A) FROM OBSERVATIONS OF FOUR TYPE Ia SUPERNOVAE

International Nuclear Information System (INIS)

Stritzinger, Maximilian; Phillips, Mark M.; Boldt, Luis; Campillay, Abdo; Krzeminski, Wojtek; Morrell, Nidia; Salgado, Francisco; Roth, Miguel; Burns, Christopher R.; Persson, Sven E.; Freedman, Wendy L.; Madore, Barry F.; Folatelli, Gaston; Hamuy, Mario; Krisciunas, Kevin; Suntzeff, Nicholas B.; Kattner, ShiAnne; Contreras, Carlos

2010-01-01

The giant elliptical galaxy NGC 1316 (Fornax A) is a well-studied member of the Fornax Cluster and a prolific producer of Type Ia supernovae (SNe Ia), having hosted four observed events since 1980. Here, we present detailed optical- and near-infrared light curves of the spectroscopically normal SN 2006dd. These data are used, along with previously published photometry of the normal SN 1980N and SN 1981D, and the fast-declining, low-luminosity SN 2006mr, to compute independent estimates of the host reddening for each SN, and the distance to NGC 1316. From the three normal SNe, we find a distance of 17.8 ± 0.3 (random) ± 0.3 (systematic) Mpc for H o = 72. Distance moduli derived from the 'EBV' and Tripp methods give the values that are mutually consistent with 4%-8%. Moreover, the weighted means of the distance moduli for these three SNe for three methods agree to within 3%. This consistency is encouraging and supports the premise that Type Ia SNe are reliable distance indicators at the 5% precision level or better. On the other hand, the two methods used to estimate the distance of the fast-declining SN 2006mr both yield a distance to NGC 1316 which is 25%-30% larger. This disparity casts doubt on the suitability of fast-declining events for estimating extragalactic distances. Modest-to-negligible host galaxy reddening values are derived for all four SNe. Nevertheless, two of them (SN 2006dd and SN 2006mr) show strong Na I D interstellar lines in the host galaxy system. The strength of this absorption is completely inconsistent with the small reddening values derived from the SN light curves if the gas in NGC 1316 is typical of that found in the interstellar medium of the Milky Way. In addition, the equivalent width of the Na lines in SN 2006dd appears to have weakened significantly some 100-150 days after explosion.

Nebular Phase Spectra of SNe Ia from the CSP2 Sample

Science.gov (United States)

Diamond, Tiara; Carnegie Supernova Project II

2018-06-01

We present a comparison of late-time spectra in the near-infrared for some of the Type Ia supernovae from the Carnegie Supernova Project II. Particular attention is paid to the shape and evolution of several emission features, including the [Fe II] line at 1.6440 μm. We put our findings in context of several explosion scenarios and progenitor systems.

VizieR Online Data Catalog: Swift-UVOT obs. analysis of 29 SNe Ia (Brown+, 2017)

Science.gov (United States)

Brown, P. J.; Landez, N. J.; Milne, P. A.; Stritzinger, M. D.

2017-10-01

Swift/UVOT has observed over 500 SNe of all types in its 12 years of operation (see Brown+ 2015JHEAp...7..111B for a review of the first 10yrs). Most of the observations use six UV and optical filters. All photometry comes from the Swift Optical/Ultraviolet Supernova Archive (SOUSA; Brown+ 2014Ap&SS.354...89B) and is available at the Swift SN website and the Open Supernova Archive (Guillochon+ 2017ApJ...835...64G). (1 data file).

Gamma-ray Burst Prompt Correlations: Selection and Instrumental Effects

Science.gov (United States)

Dainotti, M. G.; Amati, L.

2018-05-01

The prompt emission mechanism of gamma-ray bursts (GRB) even after several decades remains a mystery. However, it is believed that correlations between observable GRB properties, given their huge luminosity/radiated energy and redshift distribution extending up to at least z ≈ 9, are promising possible cosmological tools. They also may help to discriminate among the most plausible theoretical models. Nowadays, the objective is to make GRBs standard candles, similar to supernovae (SNe) Ia, through well-established and robust correlations. However, differently from SNe Ia, GRBs span over several order of magnitude in their energetics, hence they cannot yet be considered standard candles. Additionally, being observed at very large distances, their physical properties are affected by selection biases, the so-called Malmquist bias or Eddington effect. We describe the state of the art on how GRB prompt correlations are corrected for these selection biases to employ them as redshift estimators and cosmological tools. We stress that only after an appropriate evaluation and correction for these effects, GRB correlations can be used to discriminate among the theoretical models of prompt emission, to estimate the cosmological parameters and to serve as distance indicators via redshift estimation.

SUPERNOVA CONSTRAINTS AND SYSTEMATIC UNCERTAINTIES FROM THE FIRST THREE YEARS OF THE SUPERNOVA LEGACY SURVEY

International Nuclear Information System (INIS)

Conley, A.; Carlberg, R. G.; Perrett, K. M.; Guy, J.; Regnault, N.; Astier, P.; Balland, C.; Hardin, D.; Pain, R.; Sullivan, M.; Hook, I. M.; Basa, S.; Fouchez, D.; Howell, D. A.; Palanque-Delabrouille, N.; Rich, J.; Ruhlmann-Kleider, V.; Pritchet, C. J.; Balam, D.; Baumont, S.

2011-01-01

We combine high-redshift Type Ia supernovae from the first three years of the Supernova Legacy Survey (SNLS) with other supernova (SN) samples, primarily at lower redshifts, to form a high-quality joint sample of 472 SNe (123 low-z, 93 SDSS, 242 SNLS, and 14 Hubble Space Telescope). SN data alone require cosmic acceleration at >99.999% confidence, including systematic effects. For the dark energy equation of state parameter (assumed constant out to at least z = 1.4) in a flat universe, we find w = -0.91 +0.16 -0.20 (stat) +0.07 -0.14 (sys) from SNe only, consistent with a cosmological constant. Our fits include a correction for the recently discovered relationship between host-galaxy mass and SN absolute brightness. We pay particular attention to systematic uncertainties, characterizing them using a systematic covariance matrix that incorporates the redshift dependence of these effects, as well as the shape-luminosity and color-luminosity relationships. Unlike previous work, we include the effects of systematic terms on the empirical light-curve models. The total systematic uncertainty is dominated by calibration terms. We describe how the systematic uncertainties can be reduced with soon to be available improved nearby and intermediate-redshift samples, particularly those calibrated onto USNO/SDSS-like systems.

On type Ia supernovae and the formation of single low-mass white dwarfs

OpenAIRE

Justham, Stephen; Wolf, Christian; Podsiadlowski, Philipp; Han, Zhanwen

2008-01-01

There is still considerable debate over the progenitors of type Ia supernovae (SNe Ia). Likewise, it is not agreed how single white dwarfs with masses less than ~0.5 Msun can be formed in the field, even though they are known to exist. We consider whether single low-mass white dwarfs (LMWDs) could have been formed in binary systems where their companions have exploded as a SN Ia. In this model, the observed single LMWDs are the remnants of giant-branch donor stars whose envelopes have been st...

No Evidence of Circumstellar Gas Surrounding Type Ia Supernova SN 2017cbv

Science.gov (United States)

Ferretti, Raphael; Amanullah, Rahman; Bulla, Mattia; Goobar, Ariel; Johansson, Joel; Lundqvist, Peter

2017-12-01

Nearby type Ia supernovae (SNe Ia), such as SN 2017cbv, are useful events to address the question of what the elusive progenitor systems of the explosions are. Hosseinzadeh et al. suggested that the early blue excess of the light curve of SN 2017cbv could be due to the supernova ejecta interacting with a non-degenerate companion star. Some SN Ia progenitor models suggest the existence of circumstellar (CS) environments in which strong outflows create low-density cavities of different radii. Matter deposited at the edges of the cavities should be at distances at which photoionization due to early ultraviolet (UV) radiation of SNe Ia causes detectable changes to the observable Na I D and Ca II H&K absorption lines. To study possible narrow absorption lines from such material, we obtained a time series of high-resolution spectra of SN 2017cbv at phases between ‑14.8 and +83 days with respect to B-band maximum, covering the time at which photoionization is predicted to occur. Both narrow Na I D and Ca II H&K are detected in all spectra, with no measurable changes between the epochs. We use photoionization models to rule out the presence of Na I and Ca II gas clouds along the line of sight of SN 2017cbv between ∼8 × 1016–2 × 1019 cm and ∼1015–1017 cm, respectively. Assuming typical abundances, the mass of a homogeneous spherical CS gas shell with radius R must be limited to {M}{{H} {{I}}}{CSM}R/{10}17[{cm}])}2 {M}ȯ . The bounds point to progenitor models that deposit little gas in their CS environment.

IMPACT OF NEW GAMOW–TELLER STRENGTHS ON EXPLOSIVE TYPE IA SUPERNOVA NUCLEOSYNTHESIS

Energy Technology Data Exchange (ETDEWEB)

Mori, Kanji; Famiano, Michael A.; Kajino, Toshitaka; Suzuki, Toshio [National Astronomical Observatory of Japan 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Hidaka, Jun [Mechanical Engineering Department, Meisei University, 2-1-1 Hodokubo, Hino, Tokyo 191-8506 (Japan); Honma, Michio [Center for Mathematical Sciences, University of Aizu, Aizu-Wakamatsu, Fukushima 965-8580 (Japan); Iwamoto, Koichi [Department of Physics, College of Science and Technology, Nihon University, Tokyo 101-8308 (Japan); Nomoto, Ken’ichi [Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo, Kashiwa, Chiba 277-8583 (Japan); Otsuka, Takaharu, E-mail: kanji.mori@nao.ac.jp, E-mail: kajino@nao.ac.jp, E-mail: michael.famiano@wmich.edu, E-mail: suzuki@phys.chs.nihon-u.ac.jp, E-mail: jun.hidaka@meisei-u.ac.jp, E-mail: m-honma@u-aizu.ac.jp, E-mail: iwamoto@phys.cst.nihon-u.ac.jp, E-mail: nomoto@astron.s.u-tokyo.ac.jp, E-mail: otsuka@phys.s.u-tokyo.ac.jp [Department of Physics, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)

2016-12-20

Recent experimental results have confirmed a possible reduction in the Gamow–Teller (GT{sub +}) strengths of pf-shell nuclei. These proton-rich nuclei are of relevance in the deflagration and explosive burning phases of SNe Ia. While prior GT strengths result in nucleosynthesis predictions with a lower-than-expected electron fraction, a reduction in the GT{sub +} strength can result in a slightly increased electron fraction compared to previous shell model predictions, though the enhancement is not as large as previous enhancements in going from rates computed by Fuller, Fowler, and Newman based on an independent particle model. A shell model parametrization has been developed that more closely matches experimental GT strengths. The resultant electron-capture rates are used in nucleosynthesis calculations for carbon deflagration and explosion phases of SNe Ia, and the final mass fractions are compared to those obtained using more commonly used rates.

THE CARNEGIE SUPERNOVA PROJECT: FIRST NEAR-INFRARED HUBBLE DIAGRAM TO z ∼ 0.7

International Nuclear Information System (INIS)

Freedman, Wendy L.; Burns, Christopher R.; Wyatt, Pamela; Persson, S. E.; Madore, Barry F.; Kelson, Daniel D.; Murphy, D. C.; Sturch, Laura; Phillips, M. M.; Contreras, Carlos; Folatelli, Gaston; Gonzalez, E. Sergio; Morrell, Nidia; Roth, Miguel; Stritzinger, Maximilian; Hamuy, Mario; Hsiao, Eric; Suntzeff, Nick B.; Astier, P.; Balland, C.

2009-01-01

The Carnegie Supernova Project (CSP) is designed to measure the luminosity distance for Type Ia supernovae (SNe Ia) as a function of redshift, and to set observational constraints on the dark energy contribution to the total energy content of the universe. The CSP differs from other projects to date in its goal of providing an I-band rest-frame Hubble diagram. Here, we present the first results from near-infrared observations obtained using the Magellan Baade telescope for SNe Ia with 0.1 m = 0.27 ± 0.02(statistical) and Ω DE = 0.76 ± 0.13(statistical) ± 0.09(systematic), for the matter and dark energy densities, respectively. If we parameterize the data in terms of an equation of state, w (with no time dependence), assume a flat geometry, and combine with baryon acoustic oscillations, we find that w = -1.05 ± 0.13(statistical) ± 0.09(systematic). The largest source of systematic uncertainty on w arises from uncertainties in the photometric calibration, signaling the importance of securing more accurate photometric calibrations for future supernova cosmology programs. Finally, we conclude that either the dust affecting the luminosities of SNe Ia has a different extinction law (R V = 1.8) than that in the Milky Way (where R V = 3.1), or that there is an additional intrinsic color term with luminosity for SNe Ia, independent of the decline rate. Understanding and disentangling these effects is critical for minimizing the systematic uncertainties in future SN Ia cosmology studies.

Constraining Magnetic Field Amplification in SN Shocks Using Radio Observations of SNe 2011fe and 2014J

Science.gov (United States)

Kundu, E.; Lundqvist, P.; Pérez-Torres, M. A.; Herrero-Illana, R.; Alberdi, A.

2017-06-01

We modeled the radio non-detection of two Type Ia supernovae (SNe), SN 2011fe and SN 2014J, considering synchrotron emission from the interaction between SN ejecta and the circumstellar medium. For ejecta whose outer parts have a power-law density structure, we compare synchrotron emission with radio observations. Assuming that 20% of the bulk shock energy is being shared equally between electrons and magnetic fields, we found a very low-density medium around both the SNe. A less tenuous medium with particle density ˜1 cm-3, which could be expected around both SNe, can be estimated when the magnetic field amplification is less than that presumed for energy equipartition. This conclusion also holds if the progenitor of SN 2014J was a rigidly rotating white dwarf (WD) with a main-sequence (MS) or red giant companion. For a He star companion, or a MS for SN 2014J, with 10% and 1% of bulk kinetic energy in magnetic fields, we obtain mass-loss rates of 99% onto the WD, but is less restricted for the latter case. However, if the tenuous medium is due to a recurrent nova, it is difficult from our model to predict synchrotron luminosities. Although the formation channels of SNe 2011fe and 2014J are not clear, the null detection in radio wavelengths could point toward a low amplification efficiency for magnetic fields in SN shocks.

THE SUBLUMINOUS AND PECULIAR TYPE Ia SUPERNOVA PTF 09dav

International Nuclear Information System (INIS)

Sullivan, M.; Ofek, E. O.; Blake, S.; Podsiadlowski, P.; Kasliwal, M. M.; Cooke, J.; Quimby, R.; Kulkarni, S. R.; Nugent, P. E.; Thomas, R. C.; Poznanski, D.; Howell, D. A.; Arcavi, I.; Gal-Yam, A.; Hook, I. M.; Mazzali, P.; Bildsten, L.; Bloom, J. S.; Cenko, S. B.; Law, N.

2011-01-01

PTF 09dav is a peculiar subluminous Type Ia supernova (SN) discovered by the Palomar Transient Factory (PTF). Spectroscopically, it appears superficially similar to the class of subluminous SN1991bg-like SNe, but it has several unusual features which make it stand out from this population. Its peak luminosity is fainter than any previously discovered SN1991bg-like SN Ia (M B ∼ -15.5), but without the unusually red optical colors expected if the faint luminosity were due to extinction. The photospheric optical spectra have very unusual strong lines of Sc II and Mg I, with possible Sr II, together with stronger than average Ti II and low velocities of ∼6000 km s -1 . The host galaxy of PTF09dav is ambiguous. The SN lies either on the extreme outskirts (∼41 kpc) of a spiral galaxy or in an very faint (M R ≥ -12.8) dwarf galaxy, unlike other 1991bg-like SNe which are invariably associated with massive, old stellar populations. PTF 09dav is also an outlier on the light-curve-width-luminosity and color-luminosity relations derived for other subluminous SNe Ia. The inferred 56 Ni mass is small (0.019 ± 0.003 M sun ), as is the estimated ejecta mass of 0.36 M sun . Taken together, these properties make PTF 09dav a remarkable event. We discuss various physical models that could explain PTF 09dav. Helium shell detonation or deflagration on the surface of a CO white dwarf can explain some of the features of PTF 09dav, including the presence of Sc and the low photospheric velocities, but the observed Si and Mg are not predicted to be very abundant in these models. We conclude that no single model is currently capable of explaining all of the observed signatures of PTF 09dav.

Galaxy luminosity function: evolution at high redshift

Science.gov (United States)

Martinet, N.; Durret, F.; Guennou, L.; Adami, C.

2014-12-01

There are some disagreements about the abundance of faint galaxies in high redshift clusters. DAFT/FADA (Dark energy American French Team) is a medium redshift (0.4redshifts for 30 clusters in B, V, R and I restframe bands. We show that completeness is a key parameter to understand the different observed behaviors when fitting the GLFs. We also investigate the evolution of GLFs with redshift for red and blue galaxy populations separately. We find a drop of the faint end of red GLFs which is more important at higher redshift while the blue GLF faint end remains flat in our redshift range. These results can be interpreted in terms of galaxy quenching. Faint blue galaxies transform into red ones which enrich the red sequence from high to low redshifts in clusters while some blue galaxies are still accreted from the environment, compensating for this evolution so that the global GLF does not seem to evolve.

X-RAY AND GAMMA-RAY FLASHES FROM TYPE Ia SUPERNOVAE?

International Nuclear Information System (INIS)

Hoeflich, Peter; Schaefer, Bradley E.

2009-01-01

and Transient Source Experiment (BATSE) about 12.9 ± 3.6 nearby SNe Ia should have been detected, but only 0.8 ± 0.7 non-coincidental matches have been found. With the High Energy Transient Explorer (HETE) and Swift satellites, we expect to see 5.6 ± 1.3 SN-Ia flashes from known nearby SNe Ia but, yet, no SN-Ia flashes were detected. With the trigger thresholds for these experiments and the upper limits on the SN-Ia distances, we show that the bolometric peak luminosity of SN-Ia flashes must be less ∼10 46 erg s -1 . Our observational limit is several orders-of-magnitude smaller than the peak luminosities predicted for both the early flashes. We attribute this difference to the absorption of the X- and γ-rays by the accretion disk of large-scale height or common envelope that would be smothering the WD.

Properties and Alignment of Interstellar Dust Grains toward Type Ia Supernovae with Anomalous Polarization Curves

Energy Technology Data Exchange (ETDEWEB)

Hoang, Thiem, E-mail: thiemhoang@kasi.re.kr [Korea Astronomy and Space Science Institute 776, Daedeokdae-ro, Yuseong-gu, Daejeon 34055 (Korea, Republic of); Canadian Institute for Theoretical Astrophysics, University of Toronto, 60 St. George Street, Toronto, ON M5S 3H8 (Canada); Institute of Theoretical Physics, Goethe Universität Frankfurt, D-60438 Frankfurt am Main (Germany)

2017-02-10

Recent photometric and polarimetric observations of Type Ia supernovae (SNe Ia) show unusually low total-to-selective extinction ratios ( R {sub V} < 2) and wavelengths of maximum polarization ( λ{sub max} < 0.4 μ m) for several SNe Ia, which indicates peculiar properties of interstellar (IS) dust in the SN-hosted galaxies and/or the presence of circumstellar (CS) dust. In this paper, we use an inversion technique to infer the best-fit grain size distribution and the alignment function of interstellar grains along the lines of sight toward four SNe Ia with anomalous extinction and polarization data (SN 1986G, SN 2006X, SN 2008fp, and SN 2014J). We find that to reproduce low values of R{sub V}, a significant enhancement in the mass of small grains of radius a < 0.1 μ m is required. For SN 2014J, a simultaneous fit to its observed extinction and polarization is unsuccessful if all the data are attributed to IS dust (model 1), but a good fit is obtained when accounting for the contribution of CS dust (model 2). For SN 2008fp, our best-fit results for model 1 show that in order to reproduce an extreme value of λ{sub max} ∼ 0.15 μ m, small silicate grains must be aligned as efficiently as big grains. For this case, we suggest that strong radiation from the SN can induce efficient alignment of small grains in a nearby intervening molecular cloud via the radiative torque (RAT) mechanism. The resulting time dependence polarization from this RAT alignment model can be tested by observing at ultraviolet wavelengths.

PRE-DISCOVERY AND FOLLOW-UP OBSERVATIONS OF THE NEARBY SN 2009nr: IMPLICATIONS FOR PROMPT TYPE Ia SUPERNOVAE

International Nuclear Information System (INIS)

Khan, Rubab; Stanek, K. Z.; Beacom, J. F.; Szczygiel, D. M.; Mogren, K.; Eastman, J. D.; Martini, P.; Stoll, R.; Prieto, J. L.; Pojmanski, G.; Pilecki, B.

2011-01-01

We present photometric and spectroscopic observations of the Type Ia supernova SN 2009nr in UGC 8255 (z = 0.0122). Following the discovery announcement at what turned out to be 10 days after peak, we detected it at V ≅15.7 mag in data collected by the All-Sky Automated Survey (ASAS) North telescope 2 weeks prior to the peak, and then followed it up with telescopes ranging in aperture from 10 cm to 6.5 m. Using early photometric data available only from ASAS, we find that the supernova is similar to the overluminous Type Ia SN 1991T, with a peak at M V ≅ -19.6 mag, and a slow decline rate of Δm 15 (B) ≅ 0.95 mag. The early post-maximum spectra closely resemble those of SN 1991T, while the late-time spectra are more similar to those of normal Type Ia supernovae (SNe Ia). Interestingly, SN 2009nr has a projected distance of 13.0 kpc (∼4.3 disk scale lengths) from the nucleus of the small star-forming host galaxy UGC 8255. This indicates that the progenitor of SN 2009nr is not associated with a young stellar population, calling into question the conventional association of luminous SNe Ia with the 'prompt' component directly correlated with current star formation. The pre-discovery observation of SN 2009nr using ASAS demonstrates the science utility of high-cadence all sky surveys conducted using small telescopes for the discovery of nearby (d ∼< 50 Mpc) supernovae.

The need for accurate redshifts in supernova cosmology

Energy Technology Data Exchange (ETDEWEB)

Calcino, Josh; Davis, Tamara, E-mail: j.calcino@uq.edu.au, E-mail: tamarad@physics.uq.edu.au [The School of Mathematics and Physics, University of Queensland, Cooper Road, Brisbane (Australia)

2017-01-01

Recent papers have shown that a small systematic redshift shift (Δ z ∼ 10{sup −5}) in measurements of type Ia supernovae can cause a significant bias (∼1%) in the recovery of cosmological parameters. Such a redshift shift could be caused, for example, by a gravitational redshift due to the density of our local environment. The sensitivity of supernova data to redshift shifts means supernovae make excellent probes of inhomogeneities. We therefore invert the analysis, and try to diagnose the nature of our local gravitational environment by fitting for Δ z as an extra free parameter alongside the usual cosmological parameters. Using the Joint Light-curve SN Ia dataset we find the best fit includes a systematic redshift shift of Δ z = (2.6{sup +2.7}{sub −2.8}) × 10{sup −4}. This is a larger shift than would be expected due to gravitational redshifts in a standard Λ-Cold Dark Matter universe (though still consistent with zero), and would correspond to a monopole Doppler shift of about 100 km s{sup −1} moving away from the Milky-Way. However, since most supernova measurements are made to a redshift precision of no better than 10{sup −3}, it is possible that a systematic error smaller than the statistical error remains in the data and is responsible for the shift; or that it is an insignificant statistical fluctuation. We find that when Δ z is included as a free parameter while fitting to the JLA SN Ia data, the constraints on the matter density shifts to Ω {sub m} = 0.313{sup +0.042}{sub −0.040}, bringing it into better agreement with the CMB cosmological parameter constraints from Planck. A positive Δ z ∼ 2.6×10{sup −4} would also cause us to overestimate the supernova measurement of Hubble's constant by Δ H {sub 0} ∼ 1 kms{sup −1}Mpc{sup −1}. However this overestimation should diminish as one increases the low-redshift cutoff, and this is not seen in the most recent data.

The CHilean Automatic Supernova sEarch (CHASE)

Science.gov (United States)

Pignata, G.; Maza, J.; Hamuy, M.; Antezana, R.; Gonzales, L.

2009-05-01

One of the most important challenges in modern cosmology will be to figure out the origin of the dark energy, to measure its equation of state and the time rate with which it changes (described by parameters w and w'). The measurement of these parameters will require high levels of accuracy in the Supernova (SN) Type Ia distances and various sources of systematic error such as reddening corrections and possible evolution in the SNcharacteristics which could couple with redshift and mimic the cosmological signal of interest. Fortunately, these concerns can be fully addressed through the comprehensive study of SNe in the local (z < 0.05) universe. Although Type II plateau SNe are not as luminous as SNe Ia, they afford two important, independent routes to cosmological distances using the Expanding Photosphere Method and the Standardized Candle Method. To assess the performance of these techniques a nearby sample of Type II SNe is necessary. With the purpose of addressing these issues the Millennium Center for Supernova Studies (MCSS) is teaming up with the Carnegie Supernova Project (CSP) to carry out an optical and near infrared (photometry, spectroscopy and polarimetry) follow up of nearby SNe. Unfortunately, the majority of the SNe observed by the MCSS and the CSP are discovered by searches carried out from the northern hemisphere. This entails a number of observational difficulties, in particular, it reduces the number of SNe for which the follow-up starts at very early epochs. The aim of the CHASE project is to remove this search bias by discovering young Southern SNe that will be extensively observed by the MCSS and the CSP. In the first nine-months of operation, CHASE has discovered two SNe: SN007oc (CBET 1114) and SN007pl (CBET 1130), thus demonstrating the feasibility of the survey.

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

International Nuclear Information System (INIS)

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

2001-01-01

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

Measurement of Omegam, OmegaLambda from a blind analysis of TypeIa supernovae with CMAGIC: Using color information to verify the acceleration of the Universe

International Nuclear Information System (INIS)

Conley, A.; Goldhaber, G.; Wang, L.; Aldering, G.; Amanullah, R.; Commins, E.D.; Fadeyev, V.; Folatelli, G.; Garavini, G.; Gibbons, R.; Goobar, A.; Groom, D.E.; Hook, I.; Howell, D.A.; Kim, A.G.; Knop, R.A.; Kowalski, M.; Kuznetsova, N.; Lidman, C.; Nobili, S.; Nugent, P.E.; Pain, R.; Perlmutter, S.; Smith, E.; Spadafora, A.L.; Stanishev, V.; Strovink, M.; Thomas, R.C.; Wood-Vasey, W.M.

2006-01-01

We present measurements of (Omega) m and (Omega) # Lambda# from a blind analysis of 21 high redshift supernovae using a new technique (CMAGIC) for fitting the multicolor lightcurves of Type Ia supernovae, first introduced in Wang et al. (2003). CMAGIC takes advantage of the remarkably simple behavior of Type Ia supernovae on color-magnitude diagrams, and has several advantages over current techniques based on maximum magnitudes. Among these are a reduced sensitivity to host galaxy dust extinction, a shallower luminosity-width relation, and the relative simplicity of the fitting procedure. This allows us to provide a cross check of previous supernova cosmology results, despite the fact that current data sets were not observed in a manner optimized for CMAGIC. We describe the details of our novel blindness procedure, which is designed to prevent experimenter bias. The data are broadly consistent with the picture of an accelerating Universe, and agree with a at Universe within 1.7σ, including systematics. We also compare the CMAGIC results directly with those of a maximum magnitude fit to the same SNe, finding that CMAGIC favors more acceleration at the 1.6σ level, including systematics and the correlation between the two measurements. A fit for w assuming a at Universe yields a value which is consistent with a cosmological constant within 1.2σ

Measurement of Omega_m, Omega_Lambda from a blind analysis of TypeIa supernovae with CMAGIC: Using color information to verify theacceleration of the Universe

Energy Technology Data Exchange (ETDEWEB)

Conley, A.; Goldhaber, G.; Wang, L.; Aldering, G.; Amanullah, R.; Commins, E.D.; Fadeyev, V.; Folatelli, G.; Garavini, G.; Gibbons, R.; Goobar, A.; Groom, D.E.; Hook, I.; Howell, D.A.; Kim, A.G.; Knop, R.A.; Kowalski, M.; Kuznetsova, N.; Lidman, C.; Nobili, S.; Nugent, P.E.; Pain,R.; Perlmutter, S.; Smith, E.; Spadafora, A.L.; Stanishev, V.; Strovink,M.; Thomas, R.C.; Wood-Vasey, W.M.

2006-02-21

We present measurements of {Omega}{sub m} and {Omega}{sub {Lambda}} from a blind analysis of 21 high redshift supernovae using a new technique (CMAGIC) for fitting the multicolor lightcurves of Type Ia supernovae, first introduced in Wang et al. (2003). CMAGIC takes advantage of the remarkably simple behavior of Type Ia supernovae on color-magnitude diagrams, and has several advantages over current techniques based on maximum magnitudes. Among these are a reduced sensitivity to host galaxy dust extinction, a shallower luminosity-width relation, and the relative simplicity of the fitting procedure. This allows us to provide a cross check of previous supernova cosmology results, despite the fact that current data sets were not observed in a manner optimized for CMAGIC. We describe the details of our novel blindness procedure, which is designed to prevent experimenter bias. The data are broadly consistent with the picture of an accelerating Universe, and agree with a at Universe within 1.7{sigma}, including systematics. We also compare the CMAGIC results directly with those of a maximum magnitude fit to the same SNe, finding that CMAGIC favors more acceleration at the 1.6{sigma} level, including systematics and the correlation between the two measurements. A fit for w assuming a at Universe yields a value which is consistent with a cosmological constant within 1.2{sigma}.

Dark energy equation of state parameter and its evolution at low redshift

Energy Technology Data Exchange (ETDEWEB)

Tripathi, Ashutosh; Sangwan, Archana; Jassal, H.K., E-mail: ashutosh_tripathi@fudan.edu.cn, E-mail: archanakumari@iisermohali.ac.in, E-mail: hkjassal@iisermohali.ac.in [Indian Institute of Science Education and Research Mohali, SAS Nagar, Mohali 140306, Punjab (India)

2017-06-01

In this paper, we constrain dark energy models using a compendium of observations at low redshifts. We consider the dark energy as a barotropic fluid, with the equation of state a constant as well the case where dark energy equation of state is a function of time. The observations considered here are Supernova Type Ia data, Baryon Acoustic Oscillation data and Hubble parameter measurements. We compare constraints obtained from these data and also do a combined analysis. The combined observational constraints put strong limits on variation of dark energy density with redshift. For varying dark energy models, the range of parameters preferred by the supernova type Ia data is in tension with the other low redshift distance measurements.

Observational Constraints on the Nature of the Dark Energy: First Cosmological Results From the ESSENCE Supernova Survey

Energy Technology Data Exchange (ETDEWEB)

Wood-Vasey, W.Michael; Miknaitis, G.; Stubbs, C.W.; Jha, S.; Riess, A.G.; Garnavich, P.M.; Kirshner, R.P.; Aguilera, C.; Becker, A.C.; Blackman, J.W.; Blondin, S.; Challis, P.; Clocchiatti, A.; Conley, A.; Covarrubias, R.; Davis, T.M.; Filippenko, A.V.; Foley, R.J.; Garg, A.; Hicken, M.; Krisciunas, K.; /Harvard-Smithsonian Ctr. Astrophys.

2007-01-05

We present constraints on the dark energy equation-of-state parameter, w = P/({rho}c{sup 2}), using 60 Type Ia supernovae (SNe Ia) from the ESSENCE supernova survey. We derive a set of constraints on the nature of the dark energy assuming a flat Universe. By including constraints on ({Omega}{sub M}, w) from baryon acoustic oscillations, we obtain a value for a static equation-of-state parameter w = -1.05{sub -0.12}{sup +0.13} (stat 1{sigma}) {+-} 0.13 (sys) and {Omega}{sub M} = 0.274{sub -0.020}{sup +0.033} (stat 1{sigma}) with a best-fit {chi}{sup 2}/DoF of 0.96. These results are consistent with those reported by the Super-Nova Legacy Survey in a similar program measuring supernova distances and redshifts. We evaluate sources of systematic error that afflict supernova observations and present Monte Carlo simulations that explore these effects. Currently, the largest systematic currently with the potential to affect our measurements is the treatment of extinction due to dust in the supernova host galaxies. Combining our set of ESSENCE SNe Ia with the SuperNova Legacy Survey SNe Ia, we obtain a joint constraint of w = -1.07{sub -0.09}{sup +0.09} (stat 1{sigma}) {+-} 0.13 (sys), {Omega}{sub M} = 0.267{sub -0.018}{sup +0.028} (stat 1{sigma}) with a best-fit {chi}{sup 2}/DoF of 0.91. The current SNe Ia data are fully consistent with a cosmological constant.

Highly Accreting Quasars at High Redshift

Science.gov (United States)

Martínez-Aldama, Mary L.; Del Olmo, Ascensión; Marziani, Paola; Sulentic, Jack W.; Negrete, C. Alenka; Dultzin, Deborah; Perea, Jaime; D'Onofrio, Mauro

2017-12-01

We present preliminary results of a spectroscopic analysis for a sample of type 1 highly accreting quasars (LLedd>0.2) at high redshift, z 2-3. The quasars were observed with the OSIRIS spectrograph on the GTC 10.4 m telescope located at the Observatorio del Roque de los Muchachos in La Palma. The highly accreting quasars were identified using the 4D Eigenvector 1 formalism, which is able to organize type 1 quasars over a broad range of redshift and luminosity. The kinematic and physical properties of the broad line region have been derived by fitting the profiles of strong UV emission lines such as AlIII, SiIII and CIII. The majority of our sources show strong blueshifts in the high-ionization lines and high Eddington ratios which are related with the productions of outflows. The importance of highly accreting quasars goes beyond a detailed understanding of their physics: their extreme Eddington ratio makes them candidates standard candles for cosmological studies.

Gamma-ray bursts at high redshift

NARCIS (Netherlands)

Wijers, R.A.M.J.

1999-01-01

Gamma-ray bursts are much brighter than supernovae, and could therefore possibly probe the Universe to high redshift. The presently established GRB redshifts range from 0.83 to 5, and quite possibly even beyond that. Since most proposed mechanisms for GRB link them closely to deaths of massive

The sloan digital sky Survey-II supernova survey: search algorithm and follow-up observations

Energy Technology Data Exchange (ETDEWEB)

Sako, Masao [Department of Physics and Astronomy, University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA 19104 (United States); Bassett, Bruce [Department of Mathematics and Applied Mathematics, University of Cape Town, Rondebosch 7701 (South Africa); Becker, Andrew; Hogan, Craig J. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Cinabro, David [Department of Physics, Wayne State University, Detroit, MI 48202 (United States); DeJongh, Fritz; Frieman, Joshua A.; Marriner, John; Miknaitis, Gajus [Center for Particle Astrophysics, Fermi National Accelerator Laboratory, P.O. Box 500, Batavia, IL 60510 (United States); Depoy, D. L.; Prieto, Jose Luis [Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210-1173 (United States); Dilday, Ben; Kessler, Richard [Kavli Institute for Cosmological Physics, The University of Chicago, 5640 South Ellis Avenue Chicago, IL 60637 (United States); Doi, Mamoru [Institute of Astronomy, Graduate School of Science, University of Tokyo 2-21-1, Osawa, Mitaka, Tokyo 181-0015 (Japan); Garnavich, Peter M. [University of Notre Dame, 225 Nieuwland Science, Notre Dame, IN 46556-5670 (United States); Holtzman, Jon [Department of Astronomy, MSC 4500, New Mexico State University, P.O. Box 30001, Las Cruces, NM 88003 (United States); Jha, Saurabh [Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, P.O. Box 20450, MS29, Stanford, CA 94309 (United States); Konishi, Kohki [Institute for Cosmic Ray Research, University of Tokyo, 5-1-5, Kashiwanoha, Kashiwa, Chiba, 277-8582 (Japan); Lampeitl, Hubert [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Nichol, Robert C. [Institute of Cosmology and Gravitation, Mercantile House, Hampshire Terrace, University of Portsmouth, Portsmouth PO1 2EG (United Kingdom); and others

2008-01-01

The Sloan Digital Sky Survey-II Supernova Survey has identified a large number of new transient sources in a 300 deg{sup 2} region along the celestial equator during its first two seasons of a three-season campaign. Multi-band (ugriz) light curves were measured for most of the sources, which include solar system objects, galactic variable stars, active galactic nuclei, supernovae (SNe), and other astronomical transients. The imaging survey is augmented by an extensive spectroscopic follow-up program to identify SNe, measure their redshifts, and study the physical conditions of the explosions and their environment through spectroscopic diagnostics. During the survey, light curves are rapidly evaluated to provide an initial photometric type of the SNe, and a selected sample of sources are targeted for spectroscopic observations. In the first two seasons, 476 sources were selected for spectroscopic observations, of which 403 were identified as SNe. For the type Ia SNe, the main driver for the survey, our photometric typing and targeting efficiency is 90%. Only 6% of the photometric SN Ia candidates were spectroscopically classified as non-SN Ia instead, and the remaining 4% resulted in low signal-to-noise, unclassified spectra. This paper describes the search algorithm and the software, and the real-time processing of the SDSS imaging data. We also present the details of the supernova candidate selection procedures and strategies for follow-up spectroscopic and imaging observations of the discovered sources.

The Sloan Digital Sky Survey-II Supernova Survey:Search Algorithm and Follow-up Observations

Energy Technology Data Exchange (ETDEWEB)

Sako, Masao; /Pennsylvania U. /KIPAC, Menlo Park; Bassett, Bruce; /Cape Town U. /South African Astron. Observ.; Becker, Andrew; /Washington U., Seattle, Astron. Dept.; Cinabro, David; /Wayne State U.; DeJongh, Don Frederic; /Fermilab; Depoy, D.L.; /Ohio State U.; Doi, Mamoru; /Tokyo U.; Garnavich, Peter M.; /Notre Dame U.; Craig, Hogan, J.; /Washington U., Seattle, Astron. Dept.; Holtzman, Jon; /New Mexico State U.; Jha, Saurabh; /Stanford U., Phys. Dept.; Konishi, Kohki; /Tokyo U.; Lampeitl, Hubert; /Baltimore, Space; Marriner, John; /Fermilab; Miknaitis, Gajus; /Fermilab; Nichol, Robert C.; /Portsmouth U.; Prieto, Jose Luis; /Ohio State U.; Richmond, Michael W.; /Rochester Inst.; Schneider, Donald P.; /Penn State U., Astron. Astrophys.; Smith, Mathew; /Portsmouth U.; SubbaRao, Mark; /Chicago U. /Tokyo U. /Tokyo U. /South African Astron. Observ. /Tokyo

2007-09-14

The Sloan Digital Sky Survey-II Supernova Survey has identified a large number of new transient sources in a 300 deg2 region along the celestial equator during its first two seasons of a three-season campaign. Multi-band (ugriz) light curves were measured for most of the sources, which include solar system objects, Galactic variable stars, active galactic nuclei, supernovae (SNe), and other astronomical transients. The imaging survey is augmented by an extensive spectroscopic follow-up program to identify SNe, measure their redshifts, and study the physical conditions of the explosions and their environment through spectroscopic diagnostics. During the survey, light curves are rapidly evaluated to provide an initial photometric type of the SNe, and a selected sample of sources are targeted for spectroscopic observations. In the first two seasons, 476 sources were selected for spectroscopic observations, of which 403 were identified as SNe. For the Type Ia SNe, the main driver for the Survey, our photometric typing and targeting efficiency is 90%. Only 6% of the photometric SN Ia candidates were spectroscopically classified as non-SN Ia instead, and the remaining 4% resulted in low signal-to-noise, unclassified spectra. This paper describes the search algorithm and the software, and the real-time processing of the SDSS imaging data. We also present the details of the supernova candidate selection procedures and strategies for follow-up spectroscopic and imaging observations of the discovered sources.

Requirements on the Redshift Accuracy for future Supernova and Number Count Surveys

International Nuclear Information System (INIS)

Huterer, Dragan; Kim, Alex; Broderick, Tamara

2004-01-01

We investigate the required redshift accuracy of type Ia supernova and cluster number-count surveys in order for the redshift uncertainties not to contribute appreciably to the dark energy parameter error budget. For the SNAP supernova experiment, we find that, without the assistance of ground-based measurements, individual supernova redshifts would need to be determined to about 0.002 or better, which is a challenging but feasible requirement for a low-resolution spectrograph. However, we find that accurate redshifts for z < 0.1 supernovae, obtained with ground-based experiments, are sufficient to immunize the results against even relatively large redshift errors at high z. For the future cluster number-count surveys such as the South Pole Telescope, Planck or DUET, we find that the purely statistical error in photometric redshift is less important, and that the irreducible, systematic bias in redshift drives the requirements. The redshift bias will have to be kept below 0.001-0.005 per redshift bin (which is determined by the filter set), depending on the sky coverage and details of the definition of the minimal mass of the survey. Furthermore, we find that X-ray surveys have a more stringent required redshift accuracy than Sunyaev-Zeldovich (SZ) effect surveys since they use a shorter lever arm in redshift; conversely, SZ surveys benefit from their high redshift reach only so long as some redshift information is available for distant (zgtrsim1) clusters

Gamma-Ray Bursts: Lighting Up the High-Redshift Universe

Science.gov (United States)

Toy, Vicki Louise

Gamma-ray bursts (GRBs) are the most luminous events in the Universe with Egamma,iso ˜ 1048-54 erg. Leading models hypothesize that GRBs are created from inter- nal collisions within collimated and ultrarelativistic jets. The jets then shock-heat the surrounding material (e.g. interstellar medium) to create GRB afterglows. These afterglows are extremely useful probes of the Universe because long GRBs are (1) bright events that can be used as backlights for absorption studies, (2) able to probe at all redshifts massive stars exist, and (3) transient events that allow us to follow- up on the host galaxies at late times. In this thesis we study the environments of GRBs. We first explore the relationship between GRB and supernova (SN) using a nearby GRB-SN (GRB 130702A/SN 2013dx) at z = 0.145. There are only nine other GRB-SNe that were close enough to have extensive spectroscopic and photometric follow-up of the SN at late times. We create a quasi-bolometic light curve of SN 2013dx and fit an analytical equation to the quasi-bolometric light curve combined with measurements of the photospheric velocity to determine SN parameters: mass of 56Ni, kinetic energy, and ejecta mass. We examine the relationship between SN parameters and E gamma,iso for the 10 well-studied GRB-SNe, but find no correlations despite numerical simulation predictions that the mass of 56Ni should correlate with the degree of asymmetry. We then move to larger distance scales and use GRB afterglows as bright back- lights to study distant galaxies. We examine the galactic environments of Damped Lyman-alpha systems (DLAs; NHI ≥ 1020.3 cm-2 ) identified with GRB afterglows at z ˜ 2 - 6. We use late-time photometry after the GRB afterglow has faded to determine star formation rates (SFRs) from rest-frame ultraviolet measurements or spectral energy distribution (SED) models from multiband photometry. We com- pare our sample's SFRs to a sample of quasars (QSOs) DLA host galaxies. Despite the

Moderate resolution spectrophotometry of high redshift quasars

Science.gov (United States)

Schneider, Donald P.; Schmidt, Maarten; Gunn, James E.

1991-01-01

A uniform set of photometry and high signal-to-noise moderate resolution spectroscopy of 33 quasars with redshifts larger than 3.1 is presented. The sample consists of 17 newly discovered quasars (two with redshifts in excess of 4.4) and 16 sources drawn from the literature. The objects in this sample have r magnitudes between 17.4 and 21.4; their luminosities range from -28.8 to -24.9. Three of the 33 objects are broad absorption line quasars. A number of possible high redshift damped Ly-alpha systems were found.

THE MULTI-EPOCH NEARBY CLUSTER SURVEY: TYPE Ia SUPERNOVA RATE MEASUREMENT IN z {approx} 0.1 CLUSTERS AND THE LATE-TIME DELAY TIME DISTRIBUTION

Energy Technology Data Exchange (ETDEWEB)

Sand, David J.; Graham, Melissa L. [Las Cumbres Observatory Global Telescope Network, 6740 Cortona Drive, Suite 102, Santa Barbara, CA 93117 (United States); Bildfell, Chris; Pritchet, Chris [Department of Physics and Astronomy, University of Victoria, P.O. Box 3055, STN CSC, Victoria BC V8W 3P6 (Canada); Zaritsky, Dennis; Just, Dennis W.; Herbert-Fort, Stephane [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States); Hoekstra, Henk [Leiden Observatory, Leiden University, Niels Bohrweg 2, NL-2333 CA Leiden (Netherlands); Sivanandam, Suresh [Dunlap Institute for Astronomy and Astrophysics, 50 St. George Street, Toronto, ON M5S 3H4 (Canada); Foley, Ryan J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Mahdavi, Andisheh, E-mail: dsand@lcogt.net [Department of Physics and Astronomy, San Francisco State University, San Francisco, CA 94132 (United States)

2012-02-20

We describe the Multi-Epoch Nearby Cluster Survey, designed to measure the cluster Type Ia supernova (SN Ia) rate in a sample of 57 X-ray selected galaxy clusters, with redshifts of 0.05 < z < 0.15. Utilizing our real-time analysis pipeline, we spectroscopically confirmed twenty-three cluster SNe Ia, four of which were intracluster events. Using our deep Canada-France-Hawaii Telescope/MegaCam imaging, we measured total stellar luminosities in each of our galaxy clusters, and we performed detailed supernova (SN) detection efficiency simulations. Bringing these ingredients together, we measure an overall cluster SN Ia rate within R{sub 200} (1 Mpc) of 0.042{sup +0.012}{sub -0.010}{sup +0.010}{sub -0.008} SNuM (0.049{sup +0.016}{sub -0.014}{sup +0.005}{sub -0.004} SNuM) and an SN Ia rate within red-sequence galaxies of 0.041{sup +0.015}{sub -0.015}{sup +0.005}{sub -0.010} SNuM (0.041{sup +0.019}{sub -0.015}{sup +0.005}{sub -0.004} SNuM). The red-sequence SN Ia rate is consistent with published rates in early-type/elliptical galaxies in the 'field'. Using our red-sequence SN Ia rate, and other cluster SN measurements in early-type galaxies up to z {approx} 1, we derive the late-time (>2 Gyr) delay time distribution (DTD) of SN Ia assuming a cluster early-type galaxy star formation epoch of z{sub f} = 3. Assuming a power-law form for the DTD, {Psi}(t){proportional_to}t{sup s} , we find s = -1.62 {+-} 0.54. This result is consistent with predictions for the double degenerate SN Ia progenitor scenario (s {approx} -1) and is also in line with recent calculations for the double detonation explosion mechanism (s {approx} -2). The most recent calculations of the single degenerate scenario DTD predicts an order-of-magnitude drop-off in SN Ia rate {approx}6-7 Gyr after stellar formation, and the observed cluster rates cannot rule this out.

THE PRODUCTION RATE OF SN Ia EVENTS IN GLOBULAR CLUSTERS

International Nuclear Information System (INIS)

Washabaugh, Pearce C.; Bregman, Joel N.

2013-01-01

In globular clusters, dynamical evolution produces luminous X-ray emitting binaries at a rate about 200 times greater than in the field. If globular clusters also produce SN Ia at a high rate, it would account for many of the SN Ia production in early-type galaxies and provide insight into their formation. Here we use archival Hubble Space Telescope (HST) images of nearby galaxies that have hosted an SN Ia to examine the rate at which globular clusters produce these events. The location of the SN Ia is registered on an HST image obtained before the event or after the supernova (SN) faded. Of the 36 nearby galaxies examined, 21 had sufficiently good data to search for globular cluster hosts. None of the 21 SNe have a definite globular cluster counterpart, although there are some ambiguous cases. This places an upper limit to the enhancement rate of SN Ia production in globular clusters of about 42 at the 95% confidence level, which is an order of magnitude lower than the enhancement rate for luminous X-ray binaries. Even if all of the ambiguous cases are considered as having a globular cluster counterpart, the upper bound for the enhancement rate is 82 at the 95% confidence level, still a factor of several below that needed to account for half of the SN Ia events. Barring unforeseen selection effects, we conclude that globular clusters are not responsible for producing a significant fraction of the SN Ia events in early-type galaxies.

The Carnegie Supernova Project: Intrinsic colors of type Ia supernovae

International Nuclear Information System (INIS)

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

2014-01-01

We present an updated analysis of the intrinsic colors of Type Ia supernova (SNe Ia) using the latest data release of the Carnegie Supernova Project. We introduce a new light-curve parameter very similar to stretch that is better suited for fast-declining events, and find that these peculiar types can be seen as extensions to the population of 'normal' SNe Ia. With a larger number of objects, an updated fit to the Lira relation is presented along with evidence for a dependence on the late-time slope of the B – V light-curves with stretch and color. Using the full wavelength range from u to H band, we place constraints on the reddening law for the sample as a whole and also for individual events/hosts based solely on the observed colors. The photometric data continue to favor low values of R V , though with large variations from event to event, indicating an intrinsic distribution. We confirm the findings of other groups that there appears to be a correlation between the derived reddening law, R V , and the color excess, E(B – V), such that larger E(B – V) tends to favor lower R V . The intrinsic u-band colors show a relatively large scatter that cannot be explained by variations in R V or by the Goobar power-law for circumstellar dust, but rather is correlated with spectroscopic features of the supernova and is therefore likely due to metallicity effects.

Highly Accreting Quasars at High Redshift

Directory of Open Access Journals (Sweden)

Mary L. Martínez-Aldama

2018-01-01

Full Text Available We present preliminary results of a spectroscopic analysis for a sample of type 1 highly accreting quasars (L/LEdd ~ 1.0 at high redshift, z ~2–3. The quasars were observed with the OSIRIS spectrograph on the GTC 10.4 m telescope located at the Observatorio del Roque de los Muchachos in La Palma. The highly accreting quasars were identified using the 4D Eigenvector 1 formalism, which is able to organize type 1 quasars over a broad range of redshift and luminosity. The kinematic and physical properties of the broad line region have been derived by fitting the profiles of strong UV emission lines such as Aliiiλ1860, Siiii]λ1892 and Ciii]λ1909. The majority of our sources show strong blueshifts in the high-ionization lines and high Eddington ratios which are related with the productions of outflows. The importance of highly accreting quasars goes beyond a detailed understanding of their physics: their extreme Eddington ratio makes them candidates standard candles for cosmological studies.

THE FAST DECLINING TYPE Ia SUPERNOVA 2003gs, AND EVIDENCE FOR A SIGNIFICANT DISPERSION IN NEAR-INFRARED ABSOLUTE MAGNITUDES OF FAST DECLINERS AT MAXIMUM LIGHT

International Nuclear Information System (INIS)

Krisciunas, Kevin; Marion, G. H.; Suntzeff, Nicholas B.

2009-01-01

We obtained optical photometry of SN 2003gs on 49 nights, from 2 to 494 days after T(B max ). We also obtained near-IR photometry on 21 nights. SN 2003gs was the first fast declining Type Ia SN that has been well observed since SN 1999by. While it was subluminous in optical bands compared to more slowly declining Type Ia SNe, it was not subluminous at maximum light in the near-IR bands. There appears to be a bimodal distribution in the near-IR absolute magnitudes of Type Ia SNe at maximum light. Those that peak in the near-IR after T(B max ) are subluminous in the all bands. Those that peak in the near-IR prior to T(B max ), such as SN 2003gs, have effectively the same near-IR absolute magnitudes at maximum light regardless of the decline rate Δm 15 (B). Near-IR spectral evidence suggests that opacities in the outer layers of SN 2003gs are reduced much earlier than for normal Type Ia SNe. That may allow γ rays that power the luminosity to escape more rapidly and accelerate the decline rate. This conclusion is consistent with the photometric behavior of SN 2003gs in the IR, which indicates a faster than normal decline from approximately normal peak brightness.

Early UV emission from disc-originated matter (DOM) in Type Ia supernovae in the double-degenerate scenario

Science.gov (United States)

Levanon, Naveh; Soker, Noam

2017-09-01

We show that the blue and UV excess emission in the first few days of some Type Ia supernovae (SNe Ia) can be accounted in the double-degenerate (DD) scenario by the collision of the SN ejecta with circumstellar matter that was blown by the accretion disc formed during the merger process of the two white dwarfs (WDs). We assume that in cases of excess early light, the disc blows the circumstellar matter, that we term disc-originated matter (DOM), hours to days before explosion. To perform our analysis, we first provide a model-based definition for early excess light, replacing the definition of excess light relative to a power-law fit to the rising luminosity. We then examine the light curves of the SNe Ia iPTF14atg and SN 2012cg, and find that the collision of the ejecta with a DOM in the frame of the DD scenario can account for their early excess emission. Thus, early excess light does not necessarily imply the presence of a stellar companion in the frame of the single-degenerate scenario. Our findings further increase the variety of phenomena that the DD scenario can account for, and emphasize the need to consider all different SN Ia scenarios when interpreting observations.

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

NARCIS (Netherlands)

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

2011-01-01

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

Supernovae type Ia data favour coupled phantom energy

OpenAIRE

Majerotto, Elisabetta; Sapone, Domenico; Amendola, Luca

2004-01-01

We estimate the constraints that the recent high-redshift sample of supernovae type Ia put on a phenomenological interaction between dark energy and dark matter. The interaction can be interpreted as arising from the time variation of the mass of dark matter particles. We find that the coupling correlates with the equation of state: roughly speaking, a negative coupling (in our sign convention) implies phantom energy ($w_{\\phi}

DETERMINING TYPE Ia SUPERNOVA HOST GALAXY EXTINCTION PROBABILITIES AND A STATISTICAL APPROACH TO ESTIMATING THE ABSORPTION-TO-REDDENING RATIO R{sub V}

Energy Technology Data Exchange (ETDEWEB)

Cikota, Aleksandar [European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching b. München (Germany); Deustua, Susana [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Marleau, Francine, E-mail: acikota@eso.org [Institute for Astro- and Particle Physics, University of Innsbruck, Technikerstrasse 25/8, A-6020 Innsbruck (Austria)

2016-03-10

We investigate limits on the extinction values of Type Ia supernovae (SNe Ia) to statistically determine the most probable color excess, E(B – V), with galactocentric distance, and use these statistics to determine the absorption-to-reddening ratio, R{sub V}, for dust in the host galaxies. We determined pixel-based dust mass surface density maps for 59 galaxies from the Key Insight on Nearby Galaxies: a Far-infrared Survey with Herschel (KINGFISH). We use SN Ia spectral templates to develop a Monte Carlo simulation of color excess E(B – V) with R{sub V} = 3.1 and investigate the color excess probabilities E(B – V) with projected radial galaxy center distance. Additionally, we tested our model using observed spectra of SN 1989B, SN 2002bo, and SN 2006X, which occurred in three KINGFISH galaxies. Finally, we determined the most probable reddening for Sa–Sap, Sab–Sbp, Sbc–Scp, Scd–Sdm, S0, and irregular galaxy classes as a function of R/R{sub 25}. We find that the largest expected reddening probabilities are in Sab–Sb and Sbc–Sc galaxies, while S0 and irregular galaxies are very dust poor. We present a new approach for determining the absorption-to-reddening ratio R{sub V} using color excess probability functions and find values of R{sub V} = 2.71 ± 1.58 for 21 SNe Ia observed in Sab–Sbp galaxies, and R{sub V} = 1.70 ± 0.38, for 34 SNe Ia observed in Sbc–Scp galaxies.

Discovery and spectrophotometry of high-redshift quasars

International Nuclear Information System (INIS)

MacAlpine, G.M.; Feldman, F.R.

1982-01-01

We report on the discovery and spectrophotometry of 30 new high-redshift quasars, which were detected using the Curtis Schmidt technique. We also discuss new follow-up spectrophotometry for 23 quasar candidates from University of Michigan Lists I--IV. Our program sample contains eight quasars with z>3, at least five objects exhibiting broad absorption troughs, and a pair of quasars which are 1' apart on the sky and nearly identical in redshift, at z near 2.13. The redshift distribution for the majority of quasars in UM List IV suggests that most of the single-line quasar candidates in the UM List have low to moderate redshifts, with the reported line often being Mg II lambda2798 or C III] lambda1909. For 17 high-redshift quasars where lambda912 at the emission-line redshift could be examined, we did not find any definite Lyman limit cutoffs. Although three objects show a decline of the continuum within 100 A of lambda912, we do not believe them to be unambiguous examples for emission-line clouds situated in the line of sight. When our O I lambda1304 measurements are combined with the data of others to yield a composite spectrum, we obtain O I lambda1304/lambda8446 = 1.35. This suggests reddening with E/sub B/-Vroughly-equal0.23. Finally, our data exhibit a correlation between Lyα emission line velocity widths and redshift. The higher z quasars in the sample tend to have narrower lines, due, at least in part, to bias in the detection technique

Dark Matter Ignition of Type Ia Supernovae.

Science.gov (United States)

Bramante, Joseph

2015-10-02

Recent studies of low redshift type Ia supernovae (SN Ia) indicate that half explode from less than Chandrasekhar mass white dwarfs, implying ignition must proceed from something besides the canonical criticality of Chandrasekhar mass SN Ia progenitors. We show that 1-100 PeV mass asymmetric dark matter, with imminently detectable nucleon scattering interactions, can accumulate to the point of self-gravitation in a white dwarf and collapse, shedding gravitational potential energy by scattering off nuclei, thereby heating the white dwarf and igniting the flame front that precedes SN Ia. We combine data on SN Ia masses with data on the ages of SN Ia-adjacent stars. This combination reveals a 2.8σ inverse correlation between SN Ia masses and ignition ages, which could result from increased capture of dark matter in 1.4 vs 1.1 solar mass white dwarfs. Future studies of SN Ia in galactic centers will provide additional tests of dark-matter-induced type Ia ignition. Remarkably, both bosonic and fermionic SN Ia-igniting dark matter also resolve the missing pulsar problem by forming black holes in ≳10  Myr old pulsars at the center of the Milky Way.

A cosmographic analysis of the transition to acceleration using SN-Ia and BAO

Energy Technology Data Exchange (ETDEWEB)

Muthukrishna, Daniel; Parkinson, David, E-mail: d.muthukrishna@uq.edu.au, E-mail: d.parkinson@uq.edu.au [School of Mathematics and Physics, University of Queensland, Brisbane, QLD 4072 (Australia)

2016-11-01

We explore the distance-redshift relation using a cosmographic methodology, and show how the cosmographic parameters can be used to determine the redshift of transition from deceleration to acceleration. Such a transition at a low redshift occupies only a small region of the available parameter space, and the prior assumption of an early period of deceleration can significantly change the posterior constraints. We use available type Ia Supernovae (SN-Ia) and Baryon Acoustic Oscillation (BAO) data sets to determine the cosmographic deceleration q {sub 0}, jerk j {sub 0}, snap s {sub 0} and lerk l {sub 0} parameters. The parameters are consistent with the ΛCDM model for a flat universe within 2-sigma. We derive constraints on the redshift of transition from deceleration to acceleration for the different expansions, and find z {sub acc} > 0.14 at 95% confidence in the most conservative case.

The Carnegie Supernova Project: Intrinsic colors of type Ia supernovae

Energy Technology Data Exchange (ETDEWEB)

Burns, Christopher R.; Persson, S. E.; Freedman, Wendy L.; Madore, Barry F. [Observatories of the Carnegie Institution for Science, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Stritzinger, Maximilian; Contreras, Carlos [Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C (Denmark); Phillips, M. M.; Hsiao, E. Y.; Boldt, Luis; Campillay, Abdo; Castellón, Sergio; Morrell, Nidia; Salgado, Francisco [Carnegie Institution of Washington, Las Campanas Observatory, Colina El Pino, Casilla 601 (Chile); Folatelli, Gaston [Kavli Institute for the Physics and Mathematics of the Universe, Todai Institutes for Advanced Study, the University of Tokyo, 277-8583 Kashiwa (Japan); Suntzeff, Nicholas B. [George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Texas A and M University, Department of Physics and Astronomy, College Station, TX 77843 (United States)

2014-07-01

We present an updated analysis of the intrinsic colors of Type Ia supernova (SNe Ia) using the latest data release of the Carnegie Supernova Project. We introduce a new light-curve parameter very similar to stretch that is better suited for fast-declining events, and find that these peculiar types can be seen as extensions to the population of 'normal' SNe Ia. With a larger number of objects, an updated fit to the Lira relation is presented along with evidence for a dependence on the late-time slope of the B – V light-curves with stretch and color. Using the full wavelength range from u to H band, we place constraints on the reddening law for the sample as a whole and also for individual events/hosts based solely on the observed colors. The photometric data continue to favor low values of R{sub V} , though with large variations from event to event, indicating an intrinsic distribution. We confirm the findings of other groups that there appears to be a correlation between the derived reddening law, R{sub V} , and the color excess, E(B – V), such that larger E(B – V) tends to favor lower R{sub V} . The intrinsic u-band colors show a relatively large scatter that cannot be explained by variations in R{sub V} or by the Goobar power-law for circumstellar dust, but rather is correlated with spectroscopic features of the supernova and is therefore likely due to metallicity effects.

EARLY RADIO AND X-RAY OBSERVATIONS OF THE YOUNGEST NEARBY TYPE Ia SUPERNOVA PTF 11kly (SN 2011fe)

International Nuclear Information System (INIS)

Horesh, Assaf; Kulkarni, S. R.; Carpenter, John; Kasliwal, Mansi M.; Ofek, Eran O.; Fox, Derek B.; Quimby, Robert; Gal-Yam, Avishay; Cenko, S. Bradley; De Bruyn, A. G.; Kamble, Atish; Wijers, Ralph A. M. J.; Van der Horst, Alexander J.; Kouveliotou, Chryssa; Podsiadlowski, Philipp; Sullivan, Mark; Maguire, Kate; Howell, D. Andrew; Nugent, Peter E.; Gehrels, Neil

2012-01-01

On 2011 August 24 (UT) the Palomar Transient Factory (PTF) discovered PTF11kly (SN 2011fe), the youngest and most nearby Type Ia supernova (SN Ia) in decades. We followed this event up in the radio (centimeter and millimeter bands) and X-ray bands, starting about a day after the estimated explosion time. We present our analysis of the radio and X-ray observations, yielding the tightest constraints yet placed on the pre-explosion mass-loss rate from the progenitor system of this supernova. We find a robust limit of M-dot ∼ -8 (w/100 km s -1 ) M sun yr -1 from sensitive X-ray non-detections, as well as a similar limit from radio data, which depends, however, on assumptions about microphysical parameters. We discuss our results in the context of single-degenerate models for SNe Ia and find that our observations modestly disfavor symbiotic progenitor models involving a red giant donor, but cannot constrain systems accreting from main-sequence or sub-giant stars, including the popular supersoft channel. In view of the proximity of PTF11kly and the sensitivity of our prompt observations, we would have to wait for a long time (a decade or longer) in order to more meaningfully probe the circumstellar matter of SNe Ia.

A likely candidate of type Ia supernova progenitors: the X-ray pulsating companion of the hot subdwarf HD 49798

International Nuclear Information System (INIS)

Wang Bo; Han Zhanwen

2010-01-01

HD 49798 is a hydrogen depleted subdwarf O6 star and has an X-ray pulsating companion (RX J0648.0-4418). The X-ray pulsating companion is a massive white dwarf. Employing Eggleton's stellar evolution code with the optically thick wind assumption, we find that the hot subdwarf HD 49798 and its X-ray pulsating companion could produce a type Ia supernova (SN Ia) in future evolution. This implies that the binary system is a likely candidate of an SN Ia progenitor. We also discuss the possibilities of some other WD + He star systems (e.g. V445 Pup and KPD 1930+2752) for producing SNe Ia. (research papers)

TYPE Iax SUPERNOVAE: A NEW CLASS OF STELLAR EXPLOSION

International Nuclear Information System (INIS)

Foley, Ryan J.; Challis, P. J.; Chornock, R.; Marion, G. H.; Kirshner, R. P.; Ganeshalingam, M.; Li, W.; Silverman, J. M.; Filippenko, A. V.; Morrell, N. I.; Phillips, M. M.; Pignata, G.; Stritzinger, M. D.; Wang, X.; Anderson, J. P.; Hamuy, M.; Freedman, W. L.; Persson, S. E.; Jha, S. W.; McCully, C.

2013-01-01

We describe observed properties of the Type Iax class of supernovae (SNe Iax), consisting of SNe observationally similar to its prototypical member, SN 2002cx. The class currently has 25 members, and we present optical photometry and/or optical spectroscopy for most of them. SNe Iax are spectroscopically similar to SNe Ia, but have lower maximum-light velocities (2000 ∼ –1 ), typically lower peak magnitudes (–14.2 ≥ M V, p eak ∼> –18.9 mag), and most have hot photospheres. Relative to SNe Ia, SNe Iax have low luminosities for their light-curve shape. There is a correlation between luminosity and light-curve shape, similar to that of SNe Ia, but offset from that of SNe Ia and with larger scatter. Despite a host-galaxy morphology distribution that is highly skewed to late-type galaxies without any SNe Iax discovered in elliptical galaxies, there are several indications that the progenitor stars are white dwarfs (WDs): evidence of C/O burning in their maximum-light spectra, low (typically ∼0.5 M ☉ ) ejecta masses, strong Fe lines in their late-time spectra, a lack of X-ray detections, and deep limits on massive stars and star formation at the SN sites. However, two SNe Iax show strong He lines in their spectra. The progenitor system and explosion model that best fits all of the data is a binary system of a C/O WD that accretes matter from a He star and has a deflagration. At least some of the time, this explosion will not disrupt the WD. The small number of SNe in this class prohibit a detailed analysis of the homogeneity and heterogeneity of the entire class. We estimate that in a given volume there are 31 +17 -13 SNe Iax for every 100 SNe Ia, and for every 1 M ☉ of iron generated by SNe Ia at z = 0, SNe Iax generate ∼0.036 M ☉ . Being the largest class of peculiar SNe, thousands of SNe Iax will be discovered by LSST. Future detailed observations of SNe Iax should further our understanding of both their progenitor systems and explosions as well

Luminosity function of high redshift quasars

International Nuclear Information System (INIS)

Vaucher, B.G.

1982-01-01

Data from ten different emission-line surveys are included in a study of the luminosity function of high redshift quasars. Five of the surveys are analyzed through microdensitometric techniques and the data for new quasars are given. The uncertainties in magnitudes, redshifts, and line equivalent widths are assessed and found to be +-0.3 mag. +-0.04 in z and approx. 30%, respectively. Criteria for selecting the redshift range 1.8 less than or equal to z - 1 Mpc - 1 for each of two cosmologies (q 0 = 1 and q 0 = 0). For either cosmology, the function exhibits a steep increase with magnitude at high luminosities and a gentler increase at intermediate luminosities. Data from the new surveys indicate a possible turnover at the faint end of the distribution. Total volume densities of quasars are computed for each of three extrapolations of the trend of the data to low luminosities. These densities are compared to those of active galaxies and field galaxies

Low-z Type Ia Supernova Calibration

Science.gov (United States)

Hamuy, Mario

The discovery of acceleration and dark energy in 1998 arguably constitutes one of the most revolutionary discoveries in astrophysics in recent years. This paradigm shift was possible thanks to one of the most traditional cosmological tests: the redshift-distance relation between galaxies. This discovery was based on a differential measurement of the expansion rate of the universe: the current one provided by nearby (low-z) type Ia supernovae and the one in the past measured from distant (high-z) supernovae. This paper focuses on the first part of this journey: the calibration of the type Ia supernova luminosities and the local expansion rate of the universe, which was made possible thanks to the introduction of digital CCD (charge-coupled device) digital photometry. The new technology permitted us in the early 1990s to convert supernovae as precise tools to measure extragalactic distances through two key surveys: (1) the "Tololo Supernova Program" which made possible the critical discovery of the "peak luminosity-decline rate" relation for type Ia supernovae, the key underlying idea today behind precise cosmology from supernovae, and (2) the Calán/Tololo project which provided the low - z type Ia supernova sample for the discovery of acceleration.

WHITE DWARF/M DWARF BINARIES AS SINGLE DEGENERATE PROGENITORS OF TYPE Ia SUPERNOVAE

International Nuclear Information System (INIS)

Wheeler, J. Craig

2012-01-01

Limits on the companions of white dwarfs in the single-degenerate scenario for the origin of Type Ia supernovae (SNe Ia) have gotten increasingly tight, yet igniting a nearly Chandrasekhar mass C/O white dwarf from a condition of near hydrostatic equilibrium provides compelling agreement with observed spectral evolution. The only type of non-degenerate stars that survive the tight limits, M V ∼> 8.4 on the SN Ia in SNR 0509-67.5 and M V ∼> 9.5 in the remnant of SN 1572, are M dwarfs. While M dwarfs are observed in cataclysmic variables, they have special properties that have not been considered in most work on the progenitors of SNe Ia: they have small but finite magnetic fields and they flare frequently. These properties are explored in the context of SN Ia progenitors. White dwarf/M dwarf pairs may be sufficiently plentiful to provide, in principle, an adequate rate of explosions even with slow orbital evolution due to magnetic braking or gravitational radiation. Even modest magnetic fields on the white dwarf and M dwarf will yield adequate torques to lock the two stars together, resulting in a slowly rotating white dwarf, with the magnetic poles pointing at one another in the orbital plane. The mass loss will be channeled by a 'magnetic bottle' connecting the two stars, landing on a concentrated polar area on the white dwarf. This enhances the effective rate of accretion compared to spherical accretion. Luminosity from accretion and hydrogen burning on the surface of the white dwarf may induce self-excited mass transfer. The combined effects of self-excited mass loss, polar accretion, and magnetic inhibition of mixing of accretion layers give possible means to beat the 'nova limit' and grow the white dwarf to the Chandrasekhar mass even at rather moderate mass accretion rates.

The type Ia supernova SNLS-03D3bb from a super-Chandrasekhar-mass white dwarf star.

Science.gov (United States)

Howell, D Andrew; Sullivan, Mark; Nugent, Peter E; Ellis, Richard S; Conley, Alexander J; Le Borgne, Damien; Carlberg, Raymond G; Guy, Julien; Balam, David; Basa, Stephane; Fouchez, Dominique; Hook, Isobel M; Hsiao, Eric Y; Neill, James D; Pain, Reynald; Perrett, Kathryn M; Pritchet, Christopher J

2006-09-21

The accelerating expansion of the Universe, and the need for dark energy, were inferred from observations of type Ia supernovae. There is a consensus that type Ia supernovae are thermonuclear explosions that destroy carbon-oxygen white dwarf stars that have accreted matter from a companion star, although the nature of this companion remains uncertain. These supernovae are thought to be reliable distance indicators because they have a standard amount of fuel and a uniform trigger: they are predicted to explode when the mass of the white dwarf nears the Chandrasekhar mass of 1.4 solar masses (M(o)). Here we show that the high-redshift supernova SNLS-03D3bb has an exceptionally high luminosity and low kinetic energy that both imply a super-Chandrasekhar-mass progenitor. Super-Chandrasekhar-mass supernovae should occur preferentially in a young stellar population, so this may provide an explanation for the observed trend that overluminous type Ia supernovae occur only in 'young' environments. As this supernova does not obey the relations that allow type Ia supernovae to be calibrated as standard candles, and as no counterparts have been found at low redshift, future cosmology studies will have to consider possible contamination from such events.

PHOTOMETRIC TYPE Ia SUPERNOVA CANDIDATES FROM THE THREE-YEAR SDSS-II SN SURVEY DATA

International Nuclear Information System (INIS)

Sako, Masao; Connolly, Brian; Gladney, Larry; Bassett, Bruce; Dilday, Benjamin; Cambell, Heather; Lampeitl, Hubert; Nichol, Robert C.; Frieman, Joshua A.; Kessler, Richard; Marriner, John; Miquel, Ramon; Schneider, Donald P.; Smith, Mathew; Sollerman, Jesper

2011-01-01

We analyze the three-year Sloan Digital Sky Survey II (SDSS-II) Supernova (SN) Survey data and identify a sample of 1070 photometric Type Ia supernova (SN Ia) candidates based on their multiband light curve data. This sample consists of SN candidates with no spectroscopic confirmation, with a subset of 210 candidates having spectroscopic redshifts of their host galaxies measured while the remaining 860 candidates are purely photometric in their identification. We describe a method for estimating the efficiency and purity of photometric SN Ia classification when spectroscopic confirmation of only a limited sample is available, and demonstrate that SN Ia candidates from SDSS-II can be identified photometrically with ∼91% efficiency and with a contamination of ∼6%. Although this is the largest uniform sample of SN candidates to date for studying photometric identification, we find that a larger spectroscopic sample of contaminating sources is required to obtain a better characterization of the background events. A Hubble diagram using SN candidates with no spectroscopic confirmation, but with host galaxy spectroscopic redshifts, yields a distance modulus dispersion that is only ∼20%-40% larger than that of the spectroscopically confirmed SN Ia sample alone with no significant bias. A Hubble diagram with purely photometric classification and redshift-distance measurements, however, exhibits biases that require further investigation for precision cosmology.

Photometric type Ia supernova candidates from the three-year SDSS-II SN survey data

Energy Technology Data Exchange (ETDEWEB)

Sako, Masao; /Pennsylvania U.; Bassett, Bruce; /South African Astron. Observ. /Cape Town U., Dept. Math.; Connolly, Brian; /Pennsylvania U.; Dilday, Benjamin; /Las Cumbres Observ. /UC, Santa Barbara /Rutgers U., Piscataway; Cambell, Heather; /Portsmouth U., ICG; Frieman, Joshua A.; /Chicago U. /Chicago U., KICP /Fermilab; Gladney, Larry; /Pennsylvania U.; Kessler, Richard; /Chicago U. /Chicago U., KICP; Lampeitl, Hubert; /Portsmouth U., ICG; Marriner, John; /Fermilab; Miquel, Ramon; /Barcelona, IFAE /ICREA, Barcelona /Portsmouth U., ICG

2011-07-01

We analyze the three-year Sloan Digital Sky Survey II (SDSS-II) Supernova (SN) Survey data and identify a sample of 1070 photometric Type Ia supernova (SN Ia) candidates based on their multiband light curve data. This sample consists of SN candidates with no spectroscopic confirmation, with a subset of 210 candidates having spectroscopic redshifts of their host galaxies measured while the remaining 860 candidates are purely photometric in their identification. We describe a method for estimating the efficiency and purity of photometric SN Ia classification when spectroscopic confirmation of only a limited sample is available, and demonstrate that SN Ia candidates from SDSS-II can be identified photometrically with {approx}91% efficiency and with a contamination of {approx}6%. Although this is the largest uniform sample of SN candidates to date for studying photometric identification, we find that a larger spectroscopic sample of contaminating sources is required to obtain a better characterization of the background events. A Hubble diagram using SN candidates with no spectroscopic confirmation, but with host galaxy spectroscopic redshifts, yields a distance modulus dispersion that is only {approx}20%-40% larger than that of the spectroscopically confirmed SN Ia sample alone with no significant bias. A Hubble diagram with purely photometric classification and redshift-distance measurements, however, exhibits biases that require further investigation for precision cosmology.

Extending Supernova Spectral Templates for Next Generation Space Telescope Observations

Science.gov (United States)

Roberts-Pierel, Justin; Rodney, Steven A.; Steven Rodney

2018-01-01

Widely used empirical supernova (SN) Spectral Energy Distributions (SEDs) have not historically extended meaningfully into the ultraviolet (UV), or the infrared (IR). However, both are critical for current and future aspects of SN research including UV spectra as probes of poorly understood SN Ia physical properties, and expanding our view of the universe with high-redshift James Webb Space Telescope (JWST) IR observations. We therefore present a comprehensive set of SN SED templates that have been extended into the UV and IR, as well as an open-source software package written in Python that enables a user to generate their own extrapolated SEDs. We have taken a sampling of core-collapse (CC) and Type Ia SNe to get a time-dependent distribution of UV and IR colors (U-B,r’-[JHK]), and then generated color curves are used to extrapolate SEDs into the UV and IR. The SED extrapolation process is now easily duplicated using a user’s own data and parameters via our open-source Python package: SNSEDextend. This work develops the tools necessary to explore the JWST’s ability to discriminate between CC and Type Ia SNe, as well as provides a repository of SN SEDs that will be invaluable to future JWST and WFIRST SN studies.

SNe Ia AND THEIR ENVIRONMENT: THEORY AND APPLICATIONS TO SN 2014J

International Nuclear Information System (INIS)

Dragulin, Paul; Hoeflich, Peter

2016-01-01

We present theoretical semi-analytic models for the interaction of stellar winds with the interstellar medium (ISM) or prior mass loss implemented in our code SPICE, assuming spherical symmetry and power-law ambient density profiles and using the Π-theorem. This allows us to test a wide variety of configurations, their functional dependencies, and to find classes of solutions for given observations. Here, we study Type Ia Supernova (SN Ia) surroundings of single and double degenerate systems, and their observational signatures. Winds may originate from the progenitor prior to the white dwarf (WD) stage, the WD, a donor star, or an accretion disk (AD). For M Ch explosions, the AD wind dominates and produces a low-density void several light years across, surrounded by a dense shell. The bubble explains the lack of observed interaction in late time SN light curves for, at least, several years. The shell produces narrow ISM lines Doppler shifted by 10–100 km s −1 , and equivalent widths of ≈100 mÅ and ≈1 mÅ in cases of ambient environments with constant density and produced by prior mass loss, respectively. For SN2014J, both mergers and M Ch mass explosions have been suggested based on radio and narrow lines. As a consistent and most likely solution, we find an AD wind running into an environment produced by the red giant wind of the progenitor during the pre-WD stage, and a short delay, 0.013–1.4 Myr, between the WD formation and the explosion. Our framework may be applied more generally to stellar winds and star formation feedback in large scale galactic evolution simulations

SNe Ia AND THEIR ENVIRONMENT: THEORY AND APPLICATIONS TO SN 2014J

Energy Technology Data Exchange (ETDEWEB)

Dragulin, Paul; Hoeflich, Peter, E-mail: pd09@my.fsu.edu, E-mail: phoeflich77@gmail.com [Department of Physics, Florida State University, Tallahassee, FL 32306 (United States)

2016-02-10

We present theoretical semi-analytic models for the interaction of stellar winds with the interstellar medium (ISM) or prior mass loss implemented in our code SPICE, assuming spherical symmetry and power-law ambient density profiles and using the Π-theorem. This allows us to test a wide variety of configurations, their functional dependencies, and to find classes of solutions for given observations. Here, we study Type Ia Supernova (SN Ia) surroundings of single and double degenerate systems, and their observational signatures. Winds may originate from the progenitor prior to the white dwarf (WD) stage, the WD, a donor star, or an accretion disk (AD). For M{sub Ch} explosions, the AD wind dominates and produces a low-density void several light years across, surrounded by a dense shell. The bubble explains the lack of observed interaction in late time SN light curves for, at least, several years. The shell produces narrow ISM lines Doppler shifted by 10–100 km s{sup −1}, and equivalent widths of ≈100 mÅ and ≈1 mÅ in cases of ambient environments with constant density and produced by prior mass loss, respectively. For SN2014J, both mergers and M{sub Ch} mass explosions have been suggested based on radio and narrow lines. As a consistent and most likely solution, we find an AD wind running into an environment produced by the red giant wind of the progenitor during the pre-WD stage, and a short delay, 0.013–1.4 Myr, between the WD formation and the explosion. Our framework may be applied more generally to stellar winds and star formation feedback in large scale galactic evolution simulations.

STUDY OF THE DETONATION PHASE IN THE GRAVITATIONALLY CONFINED DETONATION MODEL OF TYPE Ia SUPERNOVAE

International Nuclear Information System (INIS)

Meakin, Casey A.; Townsley, Dean; Jordan, George C.; Truran, James; Lamb, Don; Seitenzahl, Ivo

2009-01-01

We study the gravitationally confined detonation (GCD) model of Type Ia supernovae (SNe Ia) through the detonation phase and into homologous expansion. In the GCD model, a detonation is triggered by the surface flow due to single-point, off-center flame ignition in carbon-oxygen white dwarfs (WDs). The simulations are unique in terms of the degree to which nonidealized physics is used to treat the reactive flow, including weak reaction rates and a time-dependent treatment of material in nuclear statistical equilibrium (NSE). Careful attention is paid to accurately calculating the final composition of material which is burned to NSE and frozen out in the rapid expansion following the passage of a detonation wave over the high-density core of the WD; and an efficient method for nucleosynthesis postprocessing is developed which obviates the need for costly network calculations along tracer particle thermodynamic trajectories. Observational diagnostics are presented for the explosion models, including abundance stratifications and integrated yields. We find that for all of the ignition conditions studied here a self-regulating process comprised of neutronization and stellar expansion results in final 56 Ni masses of ∼1.1 M sun . But, more energetic models result in larger total NSE and stable Fe-peak yields. The total yield of intermediate mass elements is ∼0.1 M sun and the explosion energies are all around 1.5 x 10 51 erg. The explosion models are briefly compared to the inferred properties of recent SN Ia observations. The potential for surface detonation models to produce lower-luminosity (lower 56 Ni mass) SNe is discussed.

Data compression of measurements of peculiar velocities of supernovae type Ia

International Nuclear Information System (INIS)

Irsic, Vid; Slosar, Anze

2011-01-01

We study the compression of information present in the correlated perturbations to the luminosity distance in the low-redshift (z 2 P(k), where f is the logarithmic rate of growth of linear perturbations and P(k) is their power spectrum. We develop an optimal quadratic estimator and show that it recovers all information for ΛCDM models for surveys of N∼10,000 or more supernovae. We explicitly demonstrate robustness with respect to the assumed fiducial model and the number of power spectrum bins. Using mock catalogues of supernovae Ia we estimate that future low-redshift surveys will be able to probe σ 8 to 6% accuracy with 10 000 supernovae Ia.

SNE's methodological basis - web-based software in entrepreneurial surveys

DEFF Research Database (Denmark)

Madsen, Henning

This overhead based paper gives an introduction to the research methodology applied in the surveys carried out in the SNE-project.......This overhead based paper gives an introduction to the research methodology applied in the surveys carried out in the SNE-project....

THE PROGENITORS OF TYPE Ia SUPERNOVAE. I. ARE THEY SUPERSOFT SOURCES?

International Nuclear Information System (INIS)

Di Stefano, R.

2010-01-01

In a canonical model, the progenitors of Type Ia supernovae (SNe Ia) are accreting, nuclear-burning white dwarfs (NBWDs), which explode when the white dwarf reaches the Chandrasekhar mass, M C . Such massive NBWDs are hot (kT ∼ 100 eV), luminous (L ∼ 10 38 erg s -1 ), and are potentially observable as luminous supersoft X-ray sources (SSSs). During the past several years, surveys for soft X-ray sources in external galaxies have been conducted. This paper shows that the results falsify the hypothesis that a large fraction of progenitors are NBWDs which are presently observable as SSSs. The data also place limits on sub-M C models. While SN Ia progenitors may pass through one or more phases of SSS activity, these phases are far shorter than the time needed to accrete most of the matter that brings them close to M C .

Narrowing down the possible explanations of cosmic acceleration with geometric probes

Energy Technology Data Exchange (ETDEWEB)

Dhawan, Suhail; Goobar, Ariel; Mörtsell, Edvard; Amanullah, Rahman; Feindt, Ulrich, E-mail: suhail.dhawan@fysik.su.se, E-mail: ariel@fysik.su.se, E-mail: edvard@fysik.su.se, E-mail: rahman@fysik.su.se, E-mail: ulrich.feindt@fysik.su.se [Oskar Klein Centre, Department of Physics, Stockholm University, Roslagstullbacken 21, SE 106 91 Stockholm (Sweden)

2017-07-01

Recent re-calibration of the Type Ia supernova (SNe Ia) magnitude-redshift relation combined with cosmic microwave background (CMB) and baryon acoustic oscillation (BAO) data have provided excellent constraints on the standard cosmological model. Here, we examine particular classes of alternative cosmologies, motivated by various physical mechanisms, e.g. scalar fields, modified gravity and phase transitions to test their consistency with observations of SNe Ia and the ratio of the angular diameter distances from the CMB and BAO. Using a model selection criterion for a relative comparison of the models (the Bayes Factor), we find moderate to strong evidence that the data prefer flat ΛCDM over models invoking a thawing behaviour of the quintessence scalar field. However, some exotic models like the growing neutrino mass cosmology and vacuum metamorphosis still present acceptable evidence values. The bimetric gravity model with only the linear interaction term as well as a simplified Galileon model can be ruled out by the combination of SNe Ia and CMB/BAO datasets whereas the model with linear and quadratic interaction terms has a comparable evidence value to standard ΛCDM. Thawing models are found to have significantly poorer evidence compared to flat ΛCDM cosmology under the assumption that the CMB compressed likelihood provides an adequate description for these non-standard cosmologies. We also present estimates for constraints from future data and find that geometric probes from oncoming surveys can put severe limits on non-standard cosmological models.

The detonation of a sub-Chandrasekhar-mass white dwarf at the origin of the low-luminosity Type Ia supernova 1999by

Science.gov (United States)

Blondin, Stéphane; Dessart, Luc; Hillier, D. John

2018-03-01

While Chandrasekhar-mass (MCh) models with a low 56Ni yield can match the peak luminosities of fast-declining, 91bg-like Type Ia supernovae (SNe Ia), they systematically fail to reproduce their faster light-curve evolution. Here, we illustrate the impact of a low ejecta mass on the radiative display of low-luminosity SNe Ia, by comparing a sub-MCh model resulting from the pure central detonation of a C-O white dwarf (WD) to an MCh delayed-detonation model with the same 56Ni yield of 0.12 M⊙. Our sub-MCh model from a 0.90 M⊙ WD progenitor has a ˜5 d shorter rise time in the integrated UV-optical-IR (uvoir) luminosity, as well as in the B band, and a ˜20 per cent higher peak uvoir luminosity (˜1 mag brighter peak MB). This sub-MCh model also displays bluer maximum-light colours due to the larger specific heating rate, and larger post-maximum uvoir and B-band decline rates. The luminosity decline at nebular times is also more pronounced, reflecting the enhanced escape of gamma rays resulting from the lower density of the progenitor WD. The deficit of stable nickel in the innermost ejecta leads to a notable absence of forbidden lines of [Ni II] in the nebular spectra. In contrast, the MCh model displays a strong line due to [Ni II] 1.939 μm, which could in principle serve to distinguish between different progenitor scenarios. Our sub-MCh model offers an unprecedented agreement with optical and near-infrared observations of the 91bg-like SN 1999by, making a strong case for a WD progenitor significantly below the Chandrasekhar-mass limit for this event and other low-luminosity SNe Ia.

Measuring Dark Energy Properties with Photometrically Classified Pan-STARRS Supernovae. II. Cosmological Parameters

Science.gov (United States)

Jones, D. O.; Scolnic, D. M.; Riess, A. G.; Rest, A.; Kirshner, R. P.; Berger, E.; Kessler, R.; Pan, Y.-C.; Foley, R. J.; Chornock, R.; Ortega, C. A.; Challis, P. J.; Burgett, W. S.; Chambers, K. C.; Draper, P. W.; Flewelling, H.; Huber, M. E.; Kaiser, N.; Kudritzki, R.-P.; Metcalfe, N.; Tonry, J.; Wainscoat, R. J.; Waters, C.; Gall, E. E. E.; Kotak, R.; McCrum, M.; Smartt, S. J.; Smith, K. W.

2018-04-01

We use 1169 Pan-STARRS supernovae (SNe) and 195 low-z (z used to infer unbiased cosmological parameters by using a Bayesian methodology that marginalizes over core-collapse (CC) SN contamination. Our sample contains nearly twice as many SNe as the largest previous SN Ia compilation. Combining SNe with cosmic microwave background (CMB) constraints from Planck, we measure the dark energy equation-of-state parameter w to be ‑0.989 ± 0.057 (stat+sys). If w evolves with redshift as w(a) = w 0 + w a (1 ‑ a), we find w 0 = ‑0.912 ± 0.149 and w a = ‑0.513 ± 0.826. These results are consistent with cosmological parameters from the Joint Light-curve Analysis and the Pantheon sample. We try four different photometric classification priors for Pan-STARRS SNe and two alternate ways of modeling CC SN contamination, finding that no variant gives a w differing by more than 2% from the baseline measurement. The systematic uncertainty on w due to marginalizing over CC SN contamination, {σ }wCC}=0.012, is the third-smallest source of systematic uncertainty in this work. We find limited (1.6σ) evidence for evolution of the SN color-luminosity relation with redshift, a possible systematic that could constitute a significant uncertainty in future high-z analyses. Our data provide one of the best current constraints on w, demonstrating that samples with ∼5% CC SN contamination can give competitive cosmological constraints when the contaminating distribution is marginalized over in a Bayesian framework.

High-redshift quasars in the Cold Dark Matter cosmogony

International Nuclear Information System (INIS)

Efstathiou, G.; Rees, M.J.

1988-01-01

The relationship between high-redshift quasars and the epoch of galaxy formation in the Cold Dark Matter (CDM) cosmogony is investigated. Luminous quasars could only form after galactic sized systems had collapsed. A constant comoving density of luminous quasars between z = 2 and z = 4 is compatible with the CDM model if quasars are short-lived and radiate at about the Eddington limit. However, according to the CDM model the abundance of high-luminosity quasars must decline exponentially at higher redshifts. Even if all protogalaxies form quasars, and about 1 per cent of the baryons within a protogalaxy collapse into a compact object, a steep fall in the density of quasars with L > 10 47 erg s -1 at redshifts z ≥ 5. The existence of a 'cut-off' in the quasar numbers at high redshift could therefore supply an important test of the CDM theory. (author)

DETECTING RELATIVISTIC X-RAY JETS IN HIGH-REDSHIFT QUASARS

Energy Technology Data Exchange (ETDEWEB)

McKeough, Kathryn [Department of Statistics, Harvard University, Cambridge, MA 02138 (United States); Siemiginowska, Aneta; Kashyap, Vinay L.; Lee, N. P.; Harris, D. E.; Schwartz, D. A. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Cheung, C. C. [Space Science Division, Naval Research Laboratory, Washington, DC 20375-5352 (United States); Stawarz, Łukasz [Astronomical Observatory, Jagiellonian University, ul. Orla 171, 30-244, Kraków (Poland); Stein, Nathan [Department of Statistics, The Wharton School, University of Pennsylvania, 400 Jon M. Huntsman Hall, 3730 Walnut Street, Philadelphia, PA 19104-6340 (United States); Stampoulis, Vasileios; Dyk, David A. van [Statistics Section, Imperial College London, Huxley Building, South Kensington Campus, London SW7 (United Kingdom); Wardle, J. F. C. [Department of Physics, MS 057, Brandeis University, Waltham, MA 02454 (United States); Donato, Davide [CRESST and Astroparticle Physics Laboratory NASA/GSFC, Greenbelt, MD 20771 (United States); Maraschi, Laura; Tavecchio, Fabrizio, E-mail: kathrynmckeough@g.harvard.edu [INAF Osservatorio Astronomico di Brera, via Brera 28, I-20124, Milano (Italy)

2016-12-10

We analyze Chandra X-ray images of a sample of 11 quasars that are known to contain kiloparsec scale radio jets. The sample consists of five high-redshift ( z  ≥ 3.6) flat-spectrum radio quasars, and six intermediate redshift (2.1 <  z  < 2.9) quasars. The data set includes four sources with integrated steep radio spectra and seven with flat radio spectra. A total of 25 radio jet features are present in this sample. We apply a Bayesian multi-scale image reconstruction method to detect and measure the X-ray emission from the jets. We compute deviations from a baseline model that does not include the jet, and compare observed X-ray images with those computed with simulated images where no jet features exist. This allows us to compute p -value upper bounds on the significance that an X-ray jet is detected in a pre-determined region of interest. We detected 12 of the features unambiguously, and an additional six marginally. We also find residual emission in the cores of three quasars and in the background of one quasar that suggest the existence of unresolved X-ray jets. The dependence of the X-ray to radio luminosity ratio on redshift is a potential diagnostic of the emission mechanism, since the inverse Compton scattering of cosmic microwave background photons (IC/CMB) is thought to be redshift dependent, whereas in synchrotron models no clear redshift dependence is expected. We find that the high-redshift jets have X-ray to radio flux ratios that are marginally inconsistent with those from lower redshifts, suggesting that either the X-ray emissions are due to the IC/CMB rather than the synchrotron process, or that high-redshift jets are qualitatively different.

THE POST-MERGER MAGNETIZED EVOLUTION OF WHITE DWARF BINARIES: THE DOUBLE-DEGENERATE CHANNEL OF SUB-CHANDRASEKHAR TYPE Ia SUPERNOVAE AND THE FORMATION OF MAGNETIZED WHITE DWARFS

International Nuclear Information System (INIS)

Ji Suoqing; Fisher, Robert T.; García-Berro, Enrique; Tzeferacos, Petros; Jordan, George; Lee, Dongwook; Lorén-Aguilar, Pablo; Cremer, Pascal; Behrends, Jan

2013-01-01

Type Ia supernovae (SNe Ia) play a crucial role as standardizable cosmological candles, though the nature of their progenitors is a subject of active investigation. Recent observational and theoretical work has pointed to merging white dwarf binaries, referred to as the double-degenerate channel, as the possible progenitor systems for some SNe Ia. Additionally, recent theoretical work suggests that mergers which fail to detonate may produce magnetized, rapidly rotating white dwarfs. In this paper, we present the first multidimensional simulations of the post-merger evolution of white dwarf binaries to include the effect of the magnetic field. In these systems, the two white dwarfs complete a final merger on a dynamical timescale, and are tidally disrupted, producing a rapidly rotating white dwarf merger surrounded by a hot corona and a thick, differentially rotating disk. The disk is strongly susceptible to the magnetorotational instability (MRI), and we demonstrate that this leads to the rapid growth of an initially dynamically weak magnetic field in the disk, the spin-down of the white dwarf merger, and to the subsequent central ignition of the white dwarf merger. Additionally, these magnetized models exhibit new features not present in prior hydrodynamic studies of white dwarf mergers, including the development of MRI turbulence in the hot disk, magnetized outflows carrying a significant fraction of the disk mass, and the magnetization of the white dwarf merger to field strengths ∼2 × 10 8 G. We discuss the impact of our findings on the origins, circumstellar media, and observed properties of SNe Ia and magnetized white dwarfs

The Post-merger Magnetized Evolution of White Dwarf Binaries: The Double-degenerate Channel of Sub-Chandrasekhar Type Ia Supernovae and the Formation of Magnetized White Dwarfs

Science.gov (United States)

Ji, Suoqing; Fisher, Robert T.; García-Berro, Enrique; Tzeferacos, Petros; Jordan, George; Lee, Dongwook; Lorén-Aguilar, Pablo; Cremer, Pascal; Behrends, Jan

2013-08-01

Type Ia supernovae (SNe Ia) play a crucial role as standardizable cosmological candles, though the nature of their progenitors is a subject of active investigation. Recent observational and theoretical work has pointed to merging white dwarf binaries, referred to as the double-degenerate channel, as the possible progenitor systems for some SNe Ia. Additionally, recent theoretical work suggests that mergers which fail to detonate may produce magnetized, rapidly rotating white dwarfs. In this paper, we present the first multidimensional simulations of the post-merger evolution of white dwarf binaries to include the effect of the magnetic field. In these systems, the two white dwarfs complete a final merger on a dynamical timescale, and are tidally disrupted, producing a rapidly rotating white dwarf merger surrounded by a hot corona and a thick, differentially rotating disk. The disk is strongly susceptible to the magnetorotational instability (MRI), and we demonstrate that this leads to the rapid growth of an initially dynamically weak magnetic field in the disk, the spin-down of the white dwarf merger, and to the subsequent central ignition of the white dwarf merger. Additionally, these magnetized models exhibit new features not present in prior hydrodynamic studies of white dwarf mergers, including the development of MRI turbulence in the hot disk, magnetized outflows carrying a significant fraction of the disk mass, and the magnetization of the white dwarf merger to field strengths ~2 × 108 G. We discuss the impact of our findings on the origins, circumstellar media, and observed properties of SNe Ia and magnetized white dwarfs.

THE POST-MERGER MAGNETIZED EVOLUTION OF WHITE DWARF BINARIES: THE DOUBLE-DEGENERATE CHANNEL OF SUB-CHANDRASEKHAR TYPE Ia SUPERNOVAE AND THE FORMATION OF MAGNETIZED WHITE DWARFS

Energy Technology Data Exchange (ETDEWEB)

Ji Suoqing; Fisher, Robert T. [University of Massachusetts Dartmouth, Department of Physics, 285 Old Westport Road, North Dartmouth, MA 02740 (United States); Garcia-Berro, Enrique [Departament de Fisica Aplicada, Universitat Politecnica de Catalunya, c/Esteve Terrades, 5, E-08860 Castelldefels (Spain); Tzeferacos, Petros; Jordan, George; Lee, Dongwook [Center for Astrophysical Thermonuclear Flashes, The University of Chicago, Chicago, IL 60637 (United States); Loren-Aguilar, Pablo [School of Physics, University of Exeter, Stocker Road, Exeter EX4 4QL (United Kingdom); Cremer, Pascal [Bethe Center for Theoretical Physics, Universitaet Bonn, Nussallee 12, D-53115 Bonn (Germany); Behrends, Jan [Fachbereich Physik, Freie Universitaet Berlin, Arnimallee 14, D-14195 Berlin (Germany)

2013-08-20

Type Ia supernovae (SNe Ia) play a crucial role as standardizable cosmological candles, though the nature of their progenitors is a subject of active investigation. Recent observational and theoretical work has pointed to merging white dwarf binaries, referred to as the double-degenerate channel, as the possible progenitor systems for some SNe Ia. Additionally, recent theoretical work suggests that mergers which fail to detonate may produce magnetized, rapidly rotating white dwarfs. In this paper, we present the first multidimensional simulations of the post-merger evolution of white dwarf binaries to include the effect of the magnetic field. In these systems, the two white dwarfs complete a final merger on a dynamical timescale, and are tidally disrupted, producing a rapidly rotating white dwarf merger surrounded by a hot corona and a thick, differentially rotating disk. The disk is strongly susceptible to the magnetorotational instability (MRI), and we demonstrate that this leads to the rapid growth of an initially dynamically weak magnetic field in the disk, the spin-down of the white dwarf merger, and to the subsequent central ignition of the white dwarf merger. Additionally, these magnetized models exhibit new features not present in prior hydrodynamic studies of white dwarf mergers, including the development of MRI turbulence in the hot disk, magnetized outflows carrying a significant fraction of the disk mass, and the magnetization of the white dwarf merger to field strengths {approx}2 Multiplication-Sign 10{sup 8} G. We discuss the impact of our findings on the origins, circumstellar media, and observed properties of SNe Ia and magnetized white dwarfs.

zBEAMS: a unified solution for supernova cosmology with redshift uncertainties

International Nuclear Information System (INIS)

Roberts, Ethan; Lochner, Michelle; Bassett, Bruce A.; Lablanche, Pierre-Yves; Agarwal, Shankar; Fonseca, José

2017-01-01

Supernova cosmology without spectra will be an important component of future surveys such as LSST. This lack of supernova spectra results in uncertainty in the redshifts which, if ignored, leads to significantly biased estimates of cosmological parameters. Here we present a hierarchical Bayesian formalism— zBEAMS—that addresses this problem by marginalising over the unknown or uncertain supernova redshifts to produce unbiased cosmological estimates that are competitive with supernova data with spectroscopically confirmed redshifts. zBEAMS provides a unified treatment of both photometric redshifts and host galaxy misidentification (occurring due to chance galaxy alignments or faint hosts), effectively correcting the inevitable contamination in the Hubble diagram. Like its predecessor BEAMS, our formalism also takes care of non-Ia supernova contamination by marginalising over the unknown supernova type. We illustrate this technique with simulations of supernovae with photometric redshifts and host galaxy misidentification. A novel feature of the photometric redshift case is the important role played by the redshift distribution of the supernovae.

zBEAMS: a unified solution for supernova cosmology with redshift uncertainties

Energy Technology Data Exchange (ETDEWEB)

Roberts, Ethan; Lochner, Michelle; Bassett, Bruce A.; Lablanche, Pierre-Yves; Agarwal, Shankar [African Institute for Mathematical Sciences, 6 Melrose Road, Muizenberg, 7945, Cape Town (South Africa); Fonseca, José, E-mail: rbreth001@myuct.ac.za, E-mail: michelle@aims.ac.za, E-mail: jfonseca@uwc.ac.za, E-mail: bruce.a.bassett@gmail.com, E-mail: plablanche@aims.ac.za, E-mail: agarwalshankar@aims.ac.za [Department of Physics and Astronomy, University of the Western Cape, Cape Town 7535 (South Africa)

2017-10-01

Supernova cosmology without spectra will be an important component of future surveys such as LSST. This lack of supernova spectra results in uncertainty in the redshifts which, if ignored, leads to significantly biased estimates of cosmological parameters. Here we present a hierarchical Bayesian formalism— zBEAMS—that addresses this problem by marginalising over the unknown or uncertain supernova redshifts to produce unbiased cosmological estimates that are competitive with supernova data with spectroscopically confirmed redshifts. zBEAMS provides a unified treatment of both photometric redshifts and host galaxy misidentification (occurring due to chance galaxy alignments or faint hosts), effectively correcting the inevitable contamination in the Hubble diagram. Like its predecessor BEAMS, our formalism also takes care of non-Ia supernova contamination by marginalising over the unknown supernova type. We illustrate this technique with simulations of supernovae with photometric redshifts and host galaxy misidentification. A novel feature of the photometric redshift case is the important role played by the redshift distribution of the supernovae.

Gravitational lensing of the SNLS supernovae

International Nuclear Information System (INIS)

Kronborg, T.

2011-01-01

Type Ia supernovae have become an essential tool of modern observational cosmology. By studying the distance-redshift relation of a large number of supernovae, the nature of dark energy can be unveiled. Distances to Type Ia SNe are however affected by gravitational lensing which can induce systematic effects in the measurement of cosmology. The majority of the supernovae is slightly de-magnified whereas a small fraction is significantly magnified due to the mass distribution along the line of sight. This causes naturally an additional dispersion in the observed magnitudes. There are two different ways to estimate the magnification of a supernova. A first method consists in comparing the supernova luminosity, which is measured to about 15% precision, to the mean SN luminosity at the same redshift. Another estimate can be obtained from predicting the magnification induced by the foreground matter density modeled from the measurements of the luminosity of the galaxies with an initial prior on the mass-luminosity relation of the galaxies. A correlation between these 2 estimates will make it possible to tune the initially used mass-luminosity relation resulting in an independent measurement of the dark matter clustering based on the luminosity of SNe Ia. Evidently, this measurement depends crucially on the detection of this correlation also referred to as the lensing signal. This thesis is dedicated to the measurement of the lensing signal in the SNLS 3-year sample. (author)

The nebular spectra of the transitional Type Ia Supernovae 2007on and 2011iv

DEFF Research Database (Denmark)

Mazzali, P. A.; Ashall, C.; Pian, E.

2018-01-01

The nebular-epoch spectrum of the rapidly declining, 'transitional' Type Ia supernova (SN) 2007on showed double emission peaks, which have been interpreted as indicating that the SN was the result of the direct collision of two white dwarfs. The spectrum can be reproduced using two distinct...... be expected for the bolometric luminosity of the SN. This is the case for both SNe 2007on and 2011iv, also a transitional SN Ia that exploded in the same elliptical galaxy, NGC1404. Although SN 2011iv does not show double-peaked emission line profiles, the width of its emission lines is such that a two...

Type Iax Supernovae: A New Class of Stellar Explosion

DEFF Research Database (Denmark)

Foley, Ryan J.; Challis, P. J.; Chornock, R.

2013-01-01

We describe observed properties of the Type Iax class of supernovae (SNe Iax), consisting of SNe observationally similar to its prototypical member, SN 2002cx. The class currently has 25 members, and we present optical photometry and/or optical spectroscopy for most of them. SNe Iax...... are spectroscopically similar to SNe Ia, but have lower maximum-light velocities (2000 lower peak magnitudes (-14.2 > M_V,peak > -18.9 mag), and most have hot photospheres. Relative to SNe Ia, SNe Iax have low luminosities for their light-curve shape. There is a correlation between......^+17_-13 SNe Iax for every 100 SNe Ia, and for every 1 M_sun of iron generated by SNe Ia at z = 0, SNe Iax generate 0.052^+0.017_-0.014 M_sun. Being the largest class of peculiar SNe, thousands of SNe Iax will be discovered by LSST. Future detailed observations of SNe Iax should further our understanding...

Long Gamma-Ray Bursts without Visible Supernovae A Case Study of Redshift Estimators and Alleged Novel Objects

CERN Document Server

Dado, Shlomo; De Rújula, A; Plaga, Rainer

2008-01-01

It has been argued that the observational limits on a supernova (SN) associated with GRB 060614 convincingly exclude a SN akin to SN 1998bw as its originator and provide evidence for a new class of long-duration GRBs. We discuss this issue in the contexts of indirect "redshift estimators" and of the fireball and cannonball models of GRBs. The latter explains the unusual properties of GRB 060614: at its debated but favored low redshift (0.125), they are predicted, as opposed to exceptional, if the associated core-collapse SN is of a recently discovered, very faint type. We take the occasion to discuss the association between GRBs and SNe.

Simulating the detection and classification of high-redshift supernovae with HARMONI on the ELT

Science.gov (United States)

Bounissou, S.; Thatte, N.; Zieleniewski, S.; Houghton, R. C. W.; Tecza, M.; Hook, I.; Neichel, B.; Fusco, T.

2018-02-01

We present detailed simulations of integral field spectroscopic observations of a supernova in a host galaxy at z ˜ 3, as observed by the HARMONI spectrograph on the Extremely Large Telescope, asssisted by laser tomographic adaptive optics. The goal of the simulations, using the HSIM simulation tool, is to determine whether HARMONI can discern the supernova Type from spectral features in the supernova spectrum. We find that in a 3 hour observation, covering the near-infrared H and K bands, at a spectral resolving power of ˜3000, and using the 20×20 mas spaxel scale, we can classify supernova Type Ia and their redshift robustly up to 80 days past maximum light (20 days in the supernova rest frame). We show that HARMONI will provide spectra at z ˜ 3 that are of comparable (or better) quality to the best spectra we can currently obtain at z ˜ 1, thus allowing studies of cosmic expansion rates to be pushed to substantially higher redshifts.

New solution to the problem of the tension between the high-redshift and low-redshift measurements of the Hubble constant

Science.gov (United States)

Bolejko, Krzysztof

2018-01-01

During my talk I will present results suggesting that the phenomenon of emerging spatial curvature could resolve the conflict between Planck's (high-redshift) and Riess et al. (low-redshift) measurements of the Hubble constant. The phenomenon of emerging spatial curvature is absent in the Standard Cosmological Model, which has a flat and fixed spatial curvature (small perturbations are considered in the Standard Cosmological Model but their global average vanishes, leading to spatial flatness at all times).In my talk I will show that with the nonlinear growth of cosmic structures the global average deviates from zero. As a result, the spatial curvature evolves from spatial flatness of the early universe to a negatively curved universe at the present day, with Omega_K ~ 0.1. Consequently, the present day expansion rate, as measured by the Hubble constant, is a few percent higher compared to the high-redshift constraints. This provides an explanation why there is a tension between high-redshift (Planck) and low-redshift (Riess et al.) measurements of the Hubble constant. In the presence of emerging spatial curvature these two measurements should in fact be different: high redshift measurements should be slightly lower than the Hubble constant inferred from the low-redshift data.The presentation will be based on the results described in arXiv:1707.01800 and arXiv:1708.09143 (which discuss the phenomenon of emerging spatial curvature) and on a paper that is still work in progress but is expected to be posted on arxiv by the AAS meeting (this paper uses mock low-redshift data to show that starting from the Planck's cosmological models (in the early universe) but with the emerging spatial curvature taken into account, the low-redshift Hubble constant should be 72.4 km/s/Mpc.

The MUSE Hubble Ultra Deep Field Survey. II. Spectroscopic redshifts and comparisons to color selections of high-redshift galaxies

Science.gov (United States)

Inami, H.; Bacon, R.; Brinchmann, J.; Richard, J.; Contini, T.; Conseil, S.; Hamer, S.; Akhlaghi, M.; Bouché, N.; Clément, B.; Desprez, G.; Drake, A. B.; Hashimoto, T.; Leclercq, F.; Maseda, M.; Michel-Dansac, L.; Paalvast, M.; Tresse, L.; Ventou, E.; Kollatschny, W.; Boogaard, L. A.; Finley, H.; Marino, R. A.; Schaye, J.; Wisotzki, L.

2017-11-01

We have conducted a two-layered spectroscopic survey (1' × 1' ultra deep and 3' × 3' deep regions) in the Hubble Ultra Deep Field (HUDF) with the Multi Unit Spectroscopic Explorer (MUSE). The combination of a large field of view, high sensitivity, and wide wavelength coverage provides an order of magnitude improvement in spectroscopically confirmed redshifts in the HUDF; i.e., 1206 secure spectroscopic redshifts for Hubble Space Telescope (HST) continuum selected objects, which corresponds to 15% of the total (7904). The redshift distribution extends well beyond z> 3 and to HST/F775W magnitudes as faint as ≈ 30 mag (AB, 1σ). In addition, 132 secure redshifts were obtained for sources with no HST counterparts that were discovered in the MUSE data cubes by a blind search for emission-line features. In total, we present 1338 high quality redshifts, which is a factor of eight increase compared with the previously known spectroscopic redshifts in the same field. We assessed redshifts mainly with the spectral features [O II] at zcolor selection (dropout) diagrams of high-z galaxies. The selection condition for F336W dropouts successfully captures ≈ 80% of the targeted z 2.7 galaxies. However, for higher redshift selections (F435W, F606W, and F775W dropouts), the success rates decrease to ≈ 20-40%. We empirically redefine the selection boundaries to make an attempt to improve them to ≈ 60%. The revised boundaries allow bluer colors that capture Lyα emitters with high Lyα equivalent widths falling in the broadbands used for the color-color selection. Along with this paper, we release the redshift and line flux catalog. Based on observations made with ESO telescopes at the La Silla Paranal Observatory under program IDs 094.A-0289(B), 095.A-0010(A), 096.A-0045(A) and 096.A-0045(B).MUSE Ultra Deep Field redshift catalogs (Full Table A.1) are available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http

The First Data Release from SweetSpot: 74 Supernovae in 36 Nights on WIYN+WHIRC

Science.gov (United States)

Weyant, Anja; Wood-Vasey, W. M.; Joyce, Richard; Allen, Lori; Garnavich, Peter; Jha, Saurabh W.; Kroboth, Jessica R.; Matheson, Thomas; Ponder, Kara A.

2018-05-01

SweetSpot is a 3 yr National Optical Astronomy Observatory (NOAO) survey program to observe Type Ia supernovae (SNe Ia) in the smooth Hubble flow with the WIYN High-resolution Infrared Camera (WHIRC) on the WIYN 3.5 m telescope. We present data from the first half of this survey, covering the 2011B–2013B NOAO semesters and consisting of 493 calibrated images of 74 SNe Ia observed in the rest-frame near-infrared (NIR) in the range 0.02 2MASS) systems, along with light curves for 786 2MASS stars observed alongside the SNe Ia. This work is the first in a planned series of three SweetSpot Data Releases. Future releases will include the full set of images from all 3 yr of the survey, including host-galaxy reference images and updated data processing with host-galaxy reference subtraction. SweetSpot will provide a well-calibrated sample that will help improve our ability to standardize distance measurements to SNe Ia, examine the intrinsic optical–NIR colors of SNe Ia at different epochs, explore the nature of dust in other galaxies, and act as a stepping-stone for more distant, potentially space-based surveys.

Detectability of Gravitational Waves from High-Redshift Binaries.

Science.gov (United States)

Rosado, Pablo A; Lasky, Paul D; Thrane, Eric; Zhu, Xingjiang; Mandel, Ilya; Sesana, Alberto

2016-03-11

Recent nondetection of gravitational-wave backgrounds from pulsar timing arrays casts further uncertainty on the evolution of supermassive black hole binaries. We study the capabilities of current gravitational-wave observatories to detect individual binaries and demonstrate that, contrary to conventional wisdom, some are, in principle, detectable throughout the Universe. In particular, a binary with rest-frame mass ≳10^{10}M_{⊙} can be detected by current timing arrays at arbitrarily high redshifts. The same claim will apply for less massive binaries with more sensitive future arrays. As a consequence, future searches for nanohertz gravitational waves could be expanded to target evolving high-redshift binaries. We calculate the maximum distance at which binaries can be observed with pulsar timing arrays and other detectors, properly accounting for redshift and using realistic binary waveforms.

The nebular spectra of the transitional Type Ia Supernovae 2007on and 2011iv: broad, multiple components indicate aspherical explosion cores

Science.gov (United States)

Mazzali, P. A.; Ashall, C.; Pian, E.; Stritzinger, M. D.; Gall, C.; Phillips, M. M.; Höflich, P.; Hsiao, E.

2018-05-01

The nebular-epoch spectrum of the rapidly declining, `transitional' Type Ia supernova (SN) 2007on showed double emission peaks, which have been interpreted as indicating that the SN was the result of the direct collision of two white dwarfs. The spectrum can be reproduced using two distinct emission components, one redshifted and one blueshifted. These components are similar in mass but have slightly different degrees of ionization. They recede from one another at a line-of-sight speed larger than the sum of the combined expansion velocities of their emitting cores, thereby acting as two independent nebulae. While this configuration appears to be consistent with the scenario of two white dwarfs colliding, it may also indicate an off-centre delayed detonation explosion of a near-Chandrasekhar-mass white dwarf. In either case, broad emission line widths and a rapidly evolving light curve can be expected for the bolometric luminosity of the SN. This is the case for both SNe 2007on and 2011iv, also a transitional SN Ia that exploded in the same elliptical galaxy, NGC 1404. Although SN 2011iv does not show double-peaked emission line profiles, the width of its emission lines is such that a two-component model yields somewhat better results than a single-component model. Most of the mass ejected is in one component, however, which suggests that SN 2011iv was the result of the off-centre ignition of a Chandrasekhar-mass white dwarf.

DUST PROPERTIES IN THE AFTERGLOW OF GRB 071025 AT z {approx} 5

Energy Technology Data Exchange (ETDEWEB)

Jang, Minsung; Im, Myungshin [Center for the Exploration of the Origin of the Universe (CEOU), Astronomy Program, Department of Physics and Astronomy, Seoul National University, Shillim-Dong, Kwanak-Gu, Seoul 151-742 (Korea, Republic of); Lee, Induk; Urata, Yuji [Institute of Astronomy, National Central University, Chung-Li 32054, Taiwan (China); Huang, Kuiyun; Hirashita, Hiroyuki [Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan (China); Fan Xiaohui; Jiang Linhua, E-mail: msjang.astro@gmail.com, E-mail: mim@astro.snu.ac.kr [Steward Observatory, University of Arizona, Tucson, AZ (United States)

2011-11-15

At high redshift, the universe is so young that core-collapse supernovae (SNe) are suspected to be the dominant source of dust production. However, some observations indicate that the dust production by SNe is an inefficient process, casting doubts on the existence of abundant SNe-dust in the early universe. Recently, Perley et al. reported that the afterglow of GRB 071025-an unusually red gamma-ray burst (GRB) at z {approx} 5-shows evidence for SNe-produced dust. Since this is perhaps the only high-redshift GRB exhibiting compelling evidence for SNe-dust but the result could easily be affected by small systematics in photometry, we re-examined the extinction properties of GRB 071025 using our own optical/near-infrared data at a different epoch. In addition, we tested SNe-dust models with different progenitor masses and dust destruction efficiencies to constrain the dust formation mechanisms. By searching for the best-fit model of the afterglow spectral energy distribution, we confirm the previous claim that the dust in GRB 071025 is most likely to originate from SNe. We also find that the SNe-dust model of 13 or 25 M{sub Sun} without dust destruction fits the extinction property of GRB 071025 best, while pair-instability SNe models with a 170 M{sub Sun} progenitor poorly fit the data. Our results indicate that, at least in some systems at high redshift, SNe with intermediate initial masses within 10-30 M{sub Sun} were the main contributors for the dust enrichment, and the dust destruction effect due to reverse shock was negligible.

Identifying high-redshift gamma-ray bursts with RATIR

Energy Technology Data Exchange (ETDEWEB)

Littlejohns, O. M.; Butler, N. R. [School of Earth and Space Exploration, Arizona State University, AZ 85287 (United States); Cucchiara, A. [Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Watson, A. M.; Lee, W. H.; Richer, M. G.; De Diego, J. A.; Georgiev, L.; González, J.; Román-Zúñiga, C. G. [Instituto de Astronomía, Universidad Nacional Autónoma de México, Apartado Postal 70-264, 04510 México, D. F. (Mexico); Kutyrev, A. S.; Troja, E.; Gehrels, N.; Moseley, H. [NASA, Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Klein, C. R.; Fox, O. D.; Bloom, J. S. [Astronomy Department, University of California, Berkeley, CA 94720-7450 (United States); Prochaska, J. X.; Ramirez-Ruiz, E. [Department of Astronomy and Astrophysics, UCO/Lick Observatory, University of California, 1156 High Street, Santa Cruz, CA 95064 (United States)

2014-07-01

We present a template-fitting algorithm for determining photometric redshifts, z {sub phot}, of candidate high-redshift gamma-ray bursts (GRBs). Using afterglow photometry, obtained by the Reionization and Transients InfraRed (RATIR) camera, this algorithm accounts for the intrinsic GRB afterglow spectral energy distribution, host dust extinction, and the effect of neutral hydrogen (local and cosmological) along the line of sight. We present the results obtained by this algorithm and the RATIR photometry of GRB 130606A, finding a range of best-fit solutions, 5.6 < z {sub phot} < 6.0, for models of several host dust extinction laws (none, the Milky Way, Large Magellanic Clouds, and Small Magellanic Clouds), consistent with spectroscopic measurements of the redshift of this GRB. Using simulated RATIR photometry, we find that our algorithm provides precise measures of z {sub phot} in the ranges of 4 < z {sub phot} ≲ 8 and 9 < z {sub phot} < 10 and can robustly determine when z {sub phot} > 4. Further testing highlights the required caution in cases of highly dust-extincted host galaxies. These tests also show that our algorithm does not erroneously find z {sub phot} < 4 when z {sub sim} > 4, thereby minimizing false negatives and allowing us to rapidly identify all potential high-redshift events.

Identifying high-redshift gamma-ray bursts with RATIR

International Nuclear Information System (INIS)

Littlejohns, O. M.; Butler, N. R.; Cucchiara, A.; Watson, A. M.; Lee, W. H.; Richer, M. G.; De Diego, J. A.; Georgiev, L.; González, J.; Román-Zúñiga, C. G.; Kutyrev, A. S.; Troja, E.; Gehrels, N.; Moseley, H.; Klein, C. R.; Fox, O. D.; Bloom, J. S.; Prochaska, J. X.; Ramirez-Ruiz, E.

2014-01-01

We present a template-fitting algorithm for determining photometric redshifts, z phot , of candidate high-redshift gamma-ray bursts (GRBs). Using afterglow photometry, obtained by the Reionization and Transients InfraRed (RATIR) camera, this algorithm accounts for the intrinsic GRB afterglow spectral energy distribution, host dust extinction, and the effect of neutral hydrogen (local and cosmological) along the line of sight. We present the results obtained by this algorithm and the RATIR photometry of GRB 130606A, finding a range of best-fit solutions, 5.6 < z phot < 6.0, for models of several host dust extinction laws (none, the Milky Way, Large Magellanic Clouds, and Small Magellanic Clouds), consistent with spectroscopic measurements of the redshift of this GRB. Using simulated RATIR photometry, we find that our algorithm provides precise measures of z phot in the ranges of 4 < z phot ≲ 8 and 9 < z phot < 10 and can robustly determine when z phot > 4. Further testing highlights the required caution in cases of highly dust-extincted host galaxies. These tests also show that our algorithm does not erroneously find z phot < 4 when z sim > 4, thereby minimizing false negatives and allowing us to rapidly identify all potential high-redshift events.

Dust in High-Redshift Galaxies

Science.gov (United States)

Pettini, Max; King, David L.; Smith, Linda J.; Hunstead, Richard W.

1997-03-01

Measurements of Zn and Cr abundances in 18 damped Lyα systems (DLAs) at absorption redshifts zabs = 0.692-3.390 (but mostly between zabs ~= 2 and 3) show that metals and dust are much less abundant in high-redshift galaxies than in the Milky Way today. Typically, [Zn/H] ~= -1.2 as Zn tracks Fe closely in Galactic stars of all metallicities and is only lightly depleted onto interstellar grains, we conclude that the overall degree of metal enrichment of damped Lyα galaxies ~13.5 Gyr ago (H0 = 50 km s-1 Mpc-1, q0 = 0.05) was ~1/15 solar. Values of [Cr/Zn] span the range from ~=0 to account correctly, it is possible to misinterpret the clues to early nucleosynthesis provided by nonsolar element ratios.

High-Dimensional Modeling for Cytometry: Building Rock Solid Models Using GemStone™ and Verity Cen-se'™ High-Definition t-SNE Mapping.

Science.gov (United States)

Bruce Bagwell, C

2018-01-01

This chapter outlines how to approach the complex tasks associated with designing models for high-dimensional cytometry data. Unlike gating approaches, modeling lends itself to automation and accounts for measurement overlap among cellular populations. Designing these models is now easier because of a new technique called high-definition t-SNE mapping. Nontrivial examples are provided that serve as a guide to create models that are consistent with data.

Constraining the Single-degenerate Channel of Type Ia Supernovae with Stable Iron-group Elements in SNR 3C 397

Energy Technology Data Exchange (ETDEWEB)

Dave, Pranav; Kashyap, Rahul; Fisher, Robert [Department of Physics, University of Massachusetts Dartmouth, 285 Old Westport Road, North Dartmouth, MA 02740 (United States); Timmes, Frank [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287 (United States); Townsley, Dean [Department of Physics and Astronomy, Box 870324, University of Alabama, Tuscaloosa, AL 35487 (United States); Byrohl, Chris [Institut für Astrophysik, Georg August Universität Göttingen, Friedrich-Hund-Platz 1, D-37077 Göttingen (Germany)

2017-05-20

Recent Suzaku X-ray spectra of supernova remnant (SNR) 3C 397 indicate enhanced stable iron group element abundances of Ni, Mn, Cr, and Fe. Seeking to address key questions about the progenitor and explosion mechanism of 3C 397, we compute nucleosynthetic yields from a suite of multidimensional hydrodynamics models in the near-Chandrasekhar-mass, single-degenerate paradigm for Type Ia supernovae (SNe Ia). Varying the progenitor white dwarf (WD) internal structure, composition, ignition, and explosion mechanism, we find that the best match to the observed iron peak elements of 3C 397 are dense (central density ≥6 × 10{sup 9} g cm{sup −3}), low-carbon WDs that undergo a weak, centrally ignited deflagration, followed by a subsequent detonation. The amount of {sup 56}Ni produced is consistent with a normal or bright normal SNe Ia. A pure deflagration of a centrally ignited, low central density (≃2 × 10{sup 9} g cm{sup −3}) progenitor WD, frequently considered in the literature, is also found to produce good agreement with 3C 397 nucleosynthetic yields, but leads to a subluminous SN Ia event, in conflict with X-ray line width data. Additionally, in contrast to prior work that suggested a large supersolar metallicity for the WD progenitor for SNR 3C 397, we find satisfactory agreement for solar- and subsolar-metallicity progenitors. We discuss a range of implications our results have for the single-degenerate channel.

Exploring Cosmology with Supernovae

DEFF Research Database (Denmark)

Li, Xue

distribution of strong gravitational lensing is developed. For Type Ia supernova (SNe Ia), the rate is lower than core-collapse supernovae (CC SNe). The rate of SNe Ia declines beyond z 1:5. Based on these reasons, we investigate a potential candidate to measure cosmological distance: GRB......-SNe. They are a subclass of CC SNe. Light curves of GRB-SNe are obtained and their properties are studied. We ascertain that the properties of GRB-SNe make them another candidate for standardizable candles in measuring the cosmic distance. Cosmological parameters M and are constrained with the help of GRB-SNe. The first...

GALAXY CLUSTERS AT HIGH REDSHIFT AND EVOLUTION OF BRIGHTEST CLUSTER GALAXIES

International Nuclear Information System (INIS)

Wen, Z. L.; Han, J. L.

2011-01-01

Identification of high-redshift clusters is important for studies of cosmology and cluster evolution. Using photometric redshifts of galaxies, we identify 631 clusters from the Canada-France-Hawaii Telescope (CFHT) wide field, 202 clusters from the CFHT deep field, 187 clusters from the Cosmic Evolution Survey (COSMOS) field, and 737 clusters from the Spitzer Wide-area InfraRed Extragalactic Survey (SWIRE) field. The redshifts of these clusters are in the range 0.1 ∼ + - m 3.6 μ m colors of the BCGs are consistent with a stellar population synthesis model in which the BCGs are formed at redshift z f ≥ 2 and evolved passively. The g' - z' and B - m 3.6μm colors of the BCGs at redshifts z > 0.8 are systematically bluer than the passive evolution model for galaxies formed at z f ∼ 2, indicating star formation in high-redshift BCGs.

Close companions to two high-redshift quasars

Energy Technology Data Exchange (ETDEWEB)

McGreer, Ian D.; Fan, Xiaohui; Bian, Fuyan [Steward Observatory, The University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721-0065 (United States); Strauss, Michael A. [Princeton University Observatory, Peyton Hall, Princeton, NJ 08544 (United States); Haiman, Zoltàn [Department of Astronomy, Columbia University, 550 West 120th Street, New York, NY 10027 (United States); Richards, Gordon T. [Department of Physics, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104 (United States); Jiang, Linhua [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287 (United States); Schneider, Donald P., E-mail: imcgreer@as.arizona.edu [Department of Astronomy and Astrophysics and the Institute for Gravitation and the Cosmos, The Pennsylvania State University, University Park, PA 16802 (United States)

2014-10-01

We report the serendipitous discoveries of companion galaxies to two high-redshift quasars. SDSS J025617.7+001904 is a z = 4.79 quasar included in our recent survey of faint quasars in the SDSS Stripe 82 region. The initial MMT slit spectroscopy shows excess Lyα emission extending well beyond the quasar's light profile. Further imaging and spectroscopy with LBT/MODS1 confirms the presence of a bright galaxy (i {sub AB} = 23.6) located 2'' (12 kpc projected) from the quasar with strong Lyα emission (EW{sub 0} ≈ 100 Å) at the redshift of the quasar, as well as faint continuum. The second quasar, CFHQS J005006.6+344522 (z = 6.25), is included in our recent HST SNAP survey of z ∼ 6 quasars searching for evidence of gravitational lensing. Deep imaging with ACS and WFC3 confirms an optical dropout ∼4.5 mag fainter than the quasar (Y {sub AB} = 25) at a separation of 0.''9. The red i {sub 775} – Y {sub 105} color of the galaxy and its proximity to the quasar (5 kpc projected if at the quasar redshift) strongly favor an association with the quasar. Although it is much fainter than the quasar, it is remarkably bright when compared to field galaxies at this redshift, while showing no evidence for lensing. Both systems may represent late-stage mergers of two massive galaxies, with the observed light for one dominated by powerful ongoing star formation and for the other by rapid black hole growth. Observations of close companions are rare; if major mergers are primarily responsible for high-redshift quasar fueling then the phase when progenitor galaxies can be observed as bright companions is relatively short.

Spectro-photometric calibration of the SuperNova Integral Field Spectrograph in the Nearby Supernova Factory collaboration framework

International Nuclear Information System (INIS)

Buton, Clement

2009-01-01

Ten years ago, type Ia supernovae used as distances indicators led to the discovery of the accelerating expansion of the universe. Today, a second generation of surveys has significantly increased the high-redshift type Ia supernovae sample. The low-redshift sample was however still limiting the cosmological analysis using SNe. In this framework, the Nearby Supernova Factory has followed 200 nearby type Ia supernovae using the dedicated Supernovae Integral Field Spectrograph with spectro-photometric capacities. My PhD thesis has been carried out at the Institut de Physique Nucleaire de Lyon and at the Lawrence Berkeley National Laboratory in the framework of the international cosmological project SNfactory. In order to reach the design spectrophotometric accuracy, attention has been focused on several key aspects of the calibration procedure, including: determination of a dedicated point spread function for 3D point source extraction, estimating the nightly photometric quality, derivation of the nightly sky extinction over the extended optical domain, its modeling in terms of physical components and its variability within a given night. A full multi-standards calibration pipeline has been implemented using approximately 4000 observations of spectrophotometric standard stars taken throughout the night over nearly 500 individual nights. Preliminary scientific results of the whole SNfactory collaboration will be presented at the end of this thesis. (author)

Supernovae Ia in 2017: a long time delay from merger/accretion to explosion

Science.gov (United States)

Soker, Noam

2018-04-01

I use recent observational and theoretical studies of type Ia supernovae (SNe Ia) to further constrain the viable SN Ia scenarios and to argue that there must be a substantial time delay between the end of the merger of the white dwarf (WD) with a companion or the end of mass accretion on to the WD and its terminal explosion. This merger/accretion to explosion delay (MED) is required to allow the binary system to lead to a more or less spherical explosion and to prevent a pre-explosion ionizing radiation. Considering these recent results and the required MED, I conclude that the core degenerate scenario is somewhat more favorable over the other scenarios, followed by the double degenerate scenario. Although the single degenerate scenario is viable as well, it is less likely to account for common (normal) SN Ia. As all scenarios require substantial MED, the MED has turned from a disadvantage of the core degenerate scenario to a challenge that theory should overcome. I hope that the requirement for a MED will stimulate the discussion of the different SN Ia scenarios and the comparison of the scenarios to each other.

Detecting First Supernovae with JWST

Science.gov (United States)

Regos, Eniko; FLARE

2018-01-01

We have applied for a JWST ERS First Transients Survey, FLARE to answer empirically how the Universe made its first stars. To quest the epoch of reionization we target what happened to these first stars by observing the most luminous events, supernovae. These transients provide direct constraints on star formation rates and the initial mass function.These very rare events can be reached by JWST at 27 mag AB in 2 micron and 4.4 micron over a field of 0.1 square degree visited multiple times each year.The survey may detect massive Pop III SNe at redshifts up to 10, pinpointing the redshift of first stars, a key scientific goal of JWST.We explore all models of star formation history (derived from UV luminosity densities and IR data), DTD, top heavy IMF of early, low metallicity stars, and normalizations to data of SN Ia, II rates (SNLS, CLASH, CANDELS, SDSS, SVISS), as well as SLSN (ROTSE, SNLS) to estimate the expected SN rates as function of redshift.Population synthesis of double degenerate and single degenerate scenarios of SN Ia shows that the shape of the DTD is rather insensitive to the assumptions (common envelope prescription and metallicities, or retention efficiency of accreted H to white dwarf core and mass transfer rate).Indeed GOODS High z SN Ia rates imply substantial delay in their progenitor model, and Hubble Higher z SN search constrains delay time distribution models as well.SLSN (I, II /H/ and extreme rare pulsational pair instability) are magnetars (ULGRB) in high local star formation rate, faint, low metallicity galaxies.

A tomographic test of cosmological principle using the JLA compilation of type Ia supernovae

Science.gov (United States)

Chang, Zhe; Lin, Hai-Nan; Sang, Yu; Wang, Sai

2018-05-01

We test the cosmological principle by fitting a dipolar modulation of distance modulus and searching for an evolution of this modulation with respect to cosmological redshift. Based on a redshift tomographic method, we divide the Joint Light-curve Analysis compilation of supernovae of type Ia into different redshift bins, and employ a Markov-Chain Monte-Carlo method to infer the anisotropic amplitude and direction in each redshift bin. However, we do not find any significant deviations from the cosmological principle, and the anisotropic amplitude is stringently constrained to be less than a few thousandths at 95% confidence level.

SPIRAL INSTABILITY CAN DRIVE THERMONUCLEAR EXPLOSIONS IN BINARY WHITE DWARF MERGERS

International Nuclear Information System (INIS)

Kashyap, Rahul; Fisher, Robert; García-Berro, Enrique; Aznar-Siguán, Gabriela; Ji, Suoqing; Lorén-Aguilar, Pablo

2015-01-01

Thermonuclear, or Type Ia supernovae (SNe Ia), originate from the explosion of carbon–oxygen white dwarfs, and serve as standardizable cosmological candles. However, despite their importance, the nature of the progenitor systems that give rise to SNe Ia has not been hitherto elucidated. Observational evidence favors the double-degenerate channel in which merging white dwarf binaries lead to SNe Ia. Furthermore, significant discrepancies exist between observations and theory, and to date, there has been no self-consistent merger model that yields a SNe Ia. Here we show that a spiral mode instability in the accretion disk formed during a binary white dwarf merger leads to a detonation on a dynamical timescale. This mechanism sheds light on how white dwarf mergers may frequently yield SNe Ia

SPIRAL INSTABILITY CAN DRIVE THERMONUCLEAR EXPLOSIONS IN BINARY WHITE DWARF MERGERS

Energy Technology Data Exchange (ETDEWEB)

Kashyap, Rahul; Fisher, Robert [Department of Physics, University of Massachusetts Dartmouth, 285 Old Westport Road, North Dartmouth, MA 02740 (United States); García-Berro, Enrique; Aznar-Siguán, Gabriela [Departament de Física Aplicada, Universitat Politècnica de Catalunya, c/Esteve Terrades, 5, E-08860 Castelldefels (Spain); Ji, Suoqing [Department of Physics, Broida Hall, University of California Santa Barbara, Santa Barbara, CA 93106–9530 (United States); Lorén-Aguilar, Pablo [School of Physics, University of Exeter, Stocker Road, Exeter EX4 4QL (United Kingdom)

2015-02-10

Thermonuclear, or Type Ia supernovae (SNe Ia), originate from the explosion of carbon–oxygen white dwarfs, and serve as standardizable cosmological candles. However, despite their importance, the nature of the progenitor systems that give rise to SNe Ia has not been hitherto elucidated. Observational evidence favors the double-degenerate channel in which merging white dwarf binaries lead to SNe Ia. Furthermore, significant discrepancies exist between observations and theory, and to date, there has been no self-consistent merger model that yields a SNe Ia. Here we show that a spiral mode instability in the accretion disk formed during a binary white dwarf merger leads to a detonation on a dynamical timescale. This mechanism sheds light on how white dwarf mergers may frequently yield SNe Ia.

Infrared-faint radio sources are at high redshifts. Spectroscopic redshift determination of infrared-faint radio sources using the Very Large Telescope

Science.gov (United States)

Herzog, A.; Middelberg, E.; Norris, R. P.; Sharp, R.; Spitler, L. R.; Parker, Q. A.

2014-07-01

Context. Infrared-faint radio sources (IFRS) are characterised by relatively high radio flux densities and associated faint or even absent infrared and optical counterparts. The resulting extremely high radio-to-infrared flux density ratios up to several thousands were previously known only for high-redshift radio galaxies (HzRGs), suggesting a link between the two classes of object. However, the optical and infrared faintness of IFRS makes their study difficult. Prior to this work, no redshift was known for any IFRS in the Australia Telescope Large Area Survey (ATLAS) fields which would help to put IFRS in the context of other classes of object, especially of HzRGs. Aims: This work aims at measuring the first redshifts of IFRS in the ATLAS fields. Furthermore, we test the hypothesis that IFRS are similar to HzRGs, that they are higher-redshift or dust-obscured versions of these massive galaxies. Methods: A sample of IFRS was spectroscopically observed using the Focal Reducer and Low Dispersion Spectrograph 2 (FORS2) at the Very Large Telescope (VLT). The data were calibrated based on the Image Reduction and Analysis Facility (IRAF) and redshifts extracted from the final spectra, where possible. This information was then used to calculate rest-frame luminosities, and to perform the first spectral energy distribution modelling of IFRS based on redshifts. Results: We found redshifts of 1.84, 2.13, and 2.76, for three IFRS, confirming the suggested high-redshift character of this class of object. These redshifts and the resulting luminosities show IFRS to be similar to HzRGs, supporting our hypothesis. We found further evidence that fainter IFRS are at even higher redshifts. Conclusions: Considering the similarities between IFRS and HzRGs substantiated in this work, the detection of IFRS, which have a significantly higher sky density than HzRGs, increases the number of active galactic nuclei in the early universe and adds to the problems of explaining the formation of

NEUTRONIZATION DURING CARBON SIMMERING IN TYPE IA SUPERNOVA PROGENITORS

Energy Technology Data Exchange (ETDEWEB)

Martínez-Rodríguez, Héctor; Badenes, Carles [Department of Physics and Astronomy and Pittsburgh Particle Physics, Astrophysics and Cosmology Center (PITT PACC), University of Pittsburgh, 3941 O’Hara Street, Pittsburgh, PA 15260 (United States); Piro, Anthony L. [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Schwab, Josiah, E-mail: hector.mr@pitt.edu [Department of Physics, University of California, Berkeley, CA 94720 (United States)

2016-07-01

When a Type Ia supernova (SN Ia) progenitor first ignites carbon in its core, it undergoes ∼10{sup 3}–10{sup 4} years of convective burning prior to the onset of thermonuclear runaway. This carbon simmering phase is important for setting the thermal profile and composition of the white dwarf. Using the MESA stellar evolution code, we follow this convective burning and examine the production of neutron-rich isotopes. The neutron content of the SN fuel has important consequences for the ensuing nucleosynthesis, and in particular, for the production of secondary Fe-peak nuclei like Mn and stable Ni. These elements have been observed in the X-ray spectra of SN remnants like Tycho, Kepler, and 3C 397, and their yields can provide valuable insights into the physics of SNe Ia and the properties of their progenitors. We find that weak reactions during simmering can at most generate a neutron excess of ≈ 3 × 10{sup −4}. This is ≈ 70% lower than that found in previous studies that do not take the full density and temperature profile of the simmering region into account. Our results imply that the progenitor metallicity is the main contributor to the neutron excess in SN Ia fuel for Z ≳ 1/3 Z {sub ⊙}. Alternatively, at lower metallicities, this neutron excess provides a floor that should be present in any centrally-ignited SN Ia scenario.

NEUTRONIZATION DURING CARBON SIMMERING IN TYPE IA SUPERNOVA PROGENITORS

International Nuclear Information System (INIS)

Martínez-Rodríguez, Héctor; Badenes, Carles; Piro, Anthony L.; Schwab, Josiah

2016-01-01

When a Type Ia supernova (SN Ia) progenitor first ignites carbon in its core, it undergoes ∼10 3 –10 4 years of convective burning prior to the onset of thermonuclear runaway. This carbon simmering phase is important for setting the thermal profile and composition of the white dwarf. Using the MESA stellar evolution code, we follow this convective burning and examine the production of neutron-rich isotopes. The neutron content of the SN fuel has important consequences for the ensuing nucleosynthesis, and in particular, for the production of secondary Fe-peak nuclei like Mn and stable Ni. These elements have been observed in the X-ray spectra of SN remnants like Tycho, Kepler, and 3C 397, and their yields can provide valuable insights into the physics of SNe Ia and the properties of their progenitors. We find that weak reactions during simmering can at most generate a neutron excess of ≈ 3 × 10 −4 . This is ≈ 70% lower than that found in previous studies that do not take the full density and temperature profile of the simmering region into account. Our results imply that the progenitor metallicity is the main contributor to the neutron excess in SN Ia fuel for Z ≳ 1/3 Z ⊙ . Alternatively, at lower metallicities, this neutron excess provides a floor that should be present in any centrally-ignited SN Ia scenario.

A high deuterium abundance at redshift z = 0.7.

Science.gov (United States)

Webb, J K; Carswell, R F; Lanzetta, K M; Ferlet, R; Lemoine, M; Vidal-Madjar, A; Bowen, D V

1997-07-17

Of the light elements, the primordial abundance of deuterium relative to hydrogen, (D/H)p, provides the most sensitive diagnostic for the cosmological mass density parameter, omegaB. Recent high-redshift D/H measurements are highly discrepant, although this may reflect observational uncertainties. The larger primordial D/H values imply a low omegaB (requiring the Universe to be dominated by non-baryonic matter), and cause problems for galactic chemical evolution models, which have difficulty in reproducing the steep decline in D/H to the present-day values. Conversely, the lower D/H values measured at high redshift imply an omegaB greater than that derived from 7Li and 4He abundance measurements, and may require a deuterium-abundance evolution that is too low to easily explain. Here we report the first measurement of D/H at intermediate redshift (z = 0.7010), in a gas cloud selected to minimize observational uncertainties. Our analysis yields a value of D/H ((2.0 +/- 0.5) x 10[-4]) which is at the upper end of the range of values measured at high redshifts. This finding, together with other independent observations, suggests that there may be inhomogeneity in (D/H)p of at least a factor of ten.

SU(2)CMB at high redshifts and the value of H0

Science.gov (United States)

Hahn, Steffen; Hofmann, Ralf

2017-07-01

We investigate a high-z cosmological model to compute the comoving sound horizon rs at baryon-velocity freeze-out towards the end of hydrogen recombination. This model assumes a replacement of the conventional cosmic microwave background (CMB) photon gas by deconfining SU(2) Yang-Mills thermodynamics, three flavours of massless neutrinos (Nν = 3) and a purely baryonic matter sector [no cold dark-matter (CDM)]. The according SU(2) temperature-redshift relation of the CMB is contrasted with recent measurements appealing to the thermal Sunyaev-Zel'dovich effect and CMB-photon absorption by molecular rotation bands or atomic hyperfine levels. Relying on a realistic simulation of the ionization history throughout recombination, we obtain z* = 1693.55 ± 6.98 and zdrag = 1812.66 ± 7.01. Due to considerable widths of the visibility functions in the solutions to the associated Boltzmann hierarchy and Euler equation, we conclude that z* and zdrag overestimate the redshifts for the respective photon and baryon-velocity freeze-out. Realistic decoupling values turn out to be zlf,* = 1554.89 ± 5.18 and zlf, drag = 1659.30 ± 5.48. With rs(zlf, drag) = (137.19 ± 0.45) Mpc and the essentially model independent extraction of rsH0 = constant from low-z data in Bernal, Verde & Riess, we obtain a good match with the value H0 = (73.24 ± 1.74) km s-1 Mpc-1 extracted in Riess et al. by appealing to Cepheid-calibrated Type Ia supernovae, new parallax measurements, stronger constraints on the Hubble flow and a refined computation of distance to NGC 4258 from maser data. We briefly comment on a possible interpolation of our high-z model, invoking percolated and unpercolated U(1) topological solitons of a Planck-scale axion field, to the phenomenologically successful low-z ΛCDM cosmology.

TIME VARIATION OF AV AND RV FOR TYPE Ia SUPERNOVAE BEHIND INTERSTELLAR DUST

Science.gov (United States)

Huang, Xiaosheng; Biederman, M.; Herger, B.; Aldering, G. S.

2014-01-01

TIME VARIATION OF AV AND RV FOR TYPE Ia SUPERNOVAE BEHIND NON-UNIFORM INTERSTELLAR DUST ABSTRACT We investigate the time variation of the visual extinction, AV, and the total-to-selective extinction ratio, RV, resulting from interstellar dust in front of an expanding photospheric disk of a type Ia supernova (SN Ia). We simulate interstellar dust clouds according to a power law power spectrum and produce extinction maps that either follow a pseudo-Gaussian distribution or a lognormal distribution. The RV maps are produced through a correlation between AV and RV. With maps of AV and RV generated in each case (pseudo-Gaussian and lognormal), we then compute the effective AV and RV for a SN as its photospheric disk expands behind the dust screen. We find for a small percentage of SNe the AV and RV values can vary by a large factor from day to day in the first 40 days after explosion.

Radio polarization properties of quasars and active galaxies at high redshifts

Science.gov (United States)

Vernstrom, T.; Gaensler, B. M.; Vacca, V.; Farnes, J. S.; Haverkorn, M.; O'Sullivan, S. P.

2018-04-01

We present the largest ever sample of radio polarization properties for z > 4 sources, with 14 sources having significant polarization detections. Using wide-band data from the Karl G. Jansky Very Large Array, we obtained the rest-frame total intensity and polarization properties of 37 radio sources, nine of which have spectroscopic redshifts in the range 1 ≤ z ≤ 1.4, with the other 28 having spectroscopic redshifts in the range 3.5 ≤ z ≤ 6.21. Fits are performed for the Stokes I and fractional polarization spectra, and Faraday rotation measures are derived using rotation measure synthesis and QU fitting. Using archival data of 476 polarized sources, we compare high-redshift (z > 3) source properties to a 15 GHz rest-frame luminosity matched sample of low-redshift (z 3 sources and 57 ± 4 rad m-2 for z < 3. Although there is some indication of lower intrinsic rotation measures at high-z possibly due to higher depolarization from the high-density environments, using several statistical tests we detect no significant difference between low- and high-redshift sources. Larger samples are necessary to determine any true physical difference.

Close Companions to Two High-redshift Quasars

Science.gov (United States)

McGreer, Ian D.; Fan, Xiaohui; Strauss, Michael A.; Haiman, Zoltàn; Richards, Gordon T.; Jiang, Linhua; Bian, Fuyan; Schneider, Donald P.

2014-10-01

We report the serendipitous discoveries of companion galaxies to two high-redshift quasars. SDSS J025617.7+001904 is a z = 4.79 quasar included in our recent survey of faint quasars in the SDSS Stripe 82 region. The initial MMT slit spectroscopy shows excess Lyα emission extending well beyond the quasar's light profile. Further imaging and spectroscopy with LBT/MODS1 confirms the presence of a bright galaxy (i AB = 23.6) located 2'' (12 kpc projected) from the quasar with strong Lyα emission (EW0 ≈ 100 Å) at the redshift of the quasar, as well as faint continuum. The second quasar, CFHQS J005006.6+344522 (z = 6.25), is included in our recent HST SNAP survey of z ~ 6 quasars searching for evidence of gravitational lensing. Deep imaging with ACS and WFC3 confirms an optical dropout ~4.5 mag fainter than the quasar (Y AB = 25) at a separation of 0.''9. The red i 775 - Y 105 color of the galaxy and its proximity to the quasar (5 kpc projected if at the quasar redshift) strongly favor an association with the quasar. Although it is much fainter than the quasar, it is remarkably bright when compared to field galaxies at this redshift, while showing no evidence for lensing. Both systems may represent late-stage mergers of two massive galaxies, with the observed light for one dominated by powerful ongoing star formation and for the other by rapid black hole growth. Observations of close companions are rare; if major mergers are primarily responsible for high-redshift quasar fueling then the phase when progenitor galaxies can be observed as bright companions is relatively short. Based in part on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with programs #12184 and #12493. Observations were also made with the LBT and MMT.

Bounds on the possible evolution of the gravitational constant from cosmological type-Ia supernovae

International Nuclear Information System (INIS)

Gaztanaga, E.; Garcia-Berro, E.; Isern, J.; Bravo, E.; Dominguez, I.

2002-01-01

Recent high-redshift type-Ia supernovae results can be used to set new bounds on a possible variation of the gravitational constant G. If the local value of G at the space-time location of distant supernovae is different, it would change both the kinetic energy release and the amount of 56 Ni synthesized in the supernova outburst. Both effects are related to a change in the Chandrasekhar mass M Ch ∝G -3/2 . In addition, the integrated variation of G with time would also affect the cosmic evolution and therefore the luminosity distance relation. We show that the later effect in the magnitudes of type-Ia supernovae is typically several times smaller than the change produced by the corresponding variation of the Chandrasekhar mass. We investigate in a consistent way how a varying G could modify the Hubble diagram of type-Ia supernovae and how these results can be used to set upper bounds to a hypothetical variation of G. We find G/G 0 (less-or-similar sign)1.1 and G/G(less-or-similar sign)10 -11 yr -1 at redshifts z≅0.5. These new bounds extend the currently available constraints on the evolution of G all the way from solar and stellar distances to typical scales of Gpc/Gyr, i.e., by more than 15 orders of magnitude in time and distance

Bimodal star formation - constraints from galaxy colors at high redshift

International Nuclear Information System (INIS)

Wyse, R.F.G.; Silk, J.

1987-01-01

The possibility that at early epochs the light from elliptical galaxies is dominated by stars with an initial mass function (IMF) which is deficient in low-mass stars, relative to the solar neighborhood is investigated. V-R colors for the optical counterparts of 3CR radio sources offer the most severe constraints on the models. Reasonable fits are obtained to both the blue, high-redshift colors and the redder, low-redshift colors with a model galaxy which forms with initially equal star formation rates in each of two IMF modes: one lacking low-mass stars, and one with stars of all masses. The net effect is that the time-integrated IMF has twice as many high-mass stars as the solar neighborhood IMF, relative to low mass stars. A conventional solar neighborhood IMF does not simultaneously account for both the range in colors at high redshift and the redness of nearby ellipticals, with any single star formation epoch. Models with a standard IMF require half the stellar population to be formed in a burst at low redshift z of about 1. 38 references

Measuring Cosmological Parameters with Photometrically Classified Pan-STARRS Supernovae

Science.gov (United States)

Jones, David; Scolnic, Daniel; Riess, Adam; Rest, Armin; Kirshner, Robert; Berger, Edo; Kessler, Rick; Pan, Yen-Chen; Foley, Ryan; Chornock, Ryan; Ortega, Carolyn; Challis, Peter; Burgett, William; Chambers, Kenneth; Draper, Peter; Flewelling, Heather; Huber, Mark; Kaiser, Nick; Kudritzki, Rolf; Metcalfe, Nigel; Tonry, John; Wainscoat, Richard J.; Waters, Chris; Gall, E. E. E.; Kotak, Rubina; McCrum, Matt; Smartt, Stephen; Smith, Ken

2018-01-01

We use nearly 1,200 supernovae (SNe) from Pan-STARRS and ~200 low-z (z energy equation of state parameter w to be -0.986±0.058 (stat+sys). If we allow w to evolve with redshift as w(a) = w0 + wa(1-a), we find w0 = -0.923±0.148 and wa = -0.404±0.797. These results are consistent with measurements of cosmological parameters from the JLA and from a new analysis of 1049 spectroscopically confirmed SNe Ia (Scolnic et al. 2017). We try four different photometric classification priors for Pan-STARRS SNe and two alternate ways of modeling the CC SN contamination, finding that none of these variants gives a w that differs by more than 1% from the baseline measurement. The systematic uncertainty on w due to marginalizing over the CC SN contamination, σwCC = 0.019, is approximately equal to the photometric calibration uncertainty and is lower than the systematic uncertainty in the SN\\,Ia dispersion model (σwdisp = 0.024). Our data provide one of the best current constraints on w, demonstrating that samples with ~5% CC SN contamination can give competitive cosmological constraints when the contaminating distribution is marginalized over in a Bayesian framework.

New Cosmic Center Universe Model Matches Eight of Big Bang's Major Predictions Without The F-L Paradigm

CERN Document Server

Gentry, R V

2003-01-01

Accompanying disproof of the F-L expansion paradigm eliminates the basis for expansion redshifts, which in turn eliminates the basis for the Cosmological Principle. The universe is not the same everywhere. Instead the spherical symmetry of the cosmos demanded by the Hubble redshift relation proves the universe is isotropic about a nearby universal Center. This is the foundation of the relatively new Cosmic Center Universe (CCU) model, which accounts for, explains, or predicts: (i) The Hubble redshift relation, (ii) a CBR redshift relation that fits all current CBR measurements, (iii) the recently discovered velocity dipole distribution of radiogalaxies, (iv) the well-known time dilation of SNeIa light curves, (v) the Sunyaev-Zeldovich thermal effect, (vi) Olber's paradox, (vii) SN dimming for z 1 an enhanced brightness that fits SN 1997ff measurements, (ix) the existence of extreme redshift (z > 10) objects which, when observed, will further distinguish it from the big bang. The CCU model also plausibly expl...

A CHANDRASEKHAR MASS PROGENITOR FOR THE TYPE Ia SUPERNOVA REMNANT 3C 397 FROM THE ENHANCED ABUNDANCES OF NICKEL AND MANGANESE

Energy Technology Data Exchange (ETDEWEB)

Yamaguchi, Hiroya; Williams, Brian J.; Petre, Robert [NASA Goddard Space Flight Center, Code 662, Greenbelt, MD 20771 (United States); Badenes, Carles [Department of Physics and Astronomy and Pittsburgh Particle Physics, Astrophysics and Cosmology Center (PITT PACC), University of Pittsburgh, 3941 O’Hara Street, Pittsburgh, PA 15260 (United States); Foster, Adam R.; Brickhouse, Nancy S. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Bravo, Eduardo [E.T.S. Arquitectura del Vallès, Universitat Politècnica de Catalunya, Carrer Pere Serra 1-15, E-08173 Sant Cugat del Vallès (Spain); Maeda, Keiichi [Department of Astronomy, Kyoto University, Kitashirakawa-oiwake-cho, Sakyo-ku, Kyoto 606-8502 (Japan); Nobukawa, Masayoshi; Koyama, Katsuji [Department of Physics, Kyoto University, Kitashirakawa-oiwake-cho, Sakyo-ku, Kyoto 606-8502 (Japan); Eriksen, Kristoffer A., E-mail: hiroya.yamaguchi@nasa.gov [Theoretical Design Division, Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545 (United States)

2015-03-10

Despite decades of intense efforts, many fundamental aspects of Type Ia supernovae (SNe Ia) remain elusive. One of the major open questions is whether the mass of an exploding white dwarf (WD) is close to the Chandrasekhar limit. Here, we report the detection of strong K-shell emission from stable Fe-peak elements in the Suzaku X-ray spectrum of the Type Ia supernova remnant (SNR) 3C 397. The high Ni/Fe and Mn/Fe mass ratios (0.11–0.24 and 0.018–0.033, respectively) in the hot plasma component that dominates the K-shell emission lines indicate a degree of neutronization in the supernova ejecta that can only be achieved by electron capture in the dense cores of exploding WDs with a near-Chandrasekhar mass. This suggests a single-degenerate origin for 3C 397, since Chandrasekhar mass progenitors are expected naturally if the WD accretes mass slowly from a companion. Together with other results supporting the double-degenerate scenario, our work adds to the mounting evidence that both progenitor channels make a significant contribution to the SN Ia rate in star-forming galaxies.

A CHANDRASEKHAR MASS PROGENITOR FOR THE TYPE Ia SUPERNOVA REMNANT 3C 397 FROM THE ENHANCED ABUNDANCES OF NICKEL AND MANGANESE

International Nuclear Information System (INIS)

Yamaguchi, Hiroya; Williams, Brian J.; Petre, Robert; Badenes, Carles; Foster, Adam R.; Brickhouse, Nancy S.; Bravo, Eduardo; Maeda, Keiichi; Nobukawa, Masayoshi; Koyama, Katsuji; Eriksen, Kristoffer A.

2015-01-01

Despite decades of intense efforts, many fundamental aspects of Type Ia supernovae (SNe Ia) remain elusive. One of the major open questions is whether the mass of an exploding white dwarf (WD) is close to the Chandrasekhar limit. Here, we report the detection of strong K-shell emission from stable Fe-peak elements in the Suzaku X-ray spectrum of the Type Ia supernova remnant (SNR) 3C 397. The high Ni/Fe and Mn/Fe mass ratios (0.11–0.24 and 0.018–0.033, respectively) in the hot plasma component that dominates the K-shell emission lines indicate a degree of neutronization in the supernova ejecta that can only be achieved by electron capture in the dense cores of exploding WDs with a near-Chandrasekhar mass. This suggests a single-degenerate origin for 3C 397, since Chandrasekhar mass progenitors are expected naturally if the WD accretes mass slowly from a companion. Together with other results supporting the double-degenerate scenario, our work adds to the mounting evidence that both progenitor channels make a significant contribution to the SN Ia rate in star-forming galaxies

RUNAWAY STARS AND THE ESCAPE OF IONIZING RADIATION FROM HIGH-REDSHIFT GALAXIES

International Nuclear Information System (INIS)

Conroy, Charlie; Kratter, Kaitlin M.

2012-01-01

Approximately 30% of all massive stars in the Galaxy are runaways with velocities exceeding 30 km s –1 . Their high speeds allow them to travel ∼0.1-1 kpc away from their birthplace before they explode at the end of their several Myr lifetimes. At high redshift, when galaxies were much smaller than in the local universe, runaways could venture far from the dense inner regions of their host galaxies. From these large radii, and therefore low column densities, much of their ionizing radiation is able to escape into the intergalactic medium. Runaways may therefore significantly enhance the overall escape fraction of ionizing radiation, f esc , from small galaxies at high redshift. We present simple models of the high-redshift runaway population and its impact on f esc as a function of halo mass, size, and redshift. We find that the inclusion of runaways enhances f esc by factors of ≈1.1-8, depending on halo mass, galaxy geometry, and the mechanism of runaway production, implying that runaways may contribute 50%-90% of the total ionizing radiation escaping from high-redshift galaxies. Runaways may therefore play an important role in reionizing the universe.

A problem with the analysis of type Ia supernovae

Directory of Open Access Journals (Sweden)

Crawford David F.

2017-12-01

Full Text Available Type Ia supernovae have light curves that have widths and magnitudes that can be used for testing cosmologies and they provide one of the few direct measurements of time dilation. It is shown that the standard analysis that calibrates the light curve against a rest-frame average (such as SALT2 removes all the cosmological information from the calibrated light curves. Consequently type Ia supernovae calibrated with these methods cannot be used to investigate cosmology. The major evidence that supports the hypothesis of a static universe is that the measurements of the widths of the rawlight curves of type Ia supernovae do not show any time dilation. The intrinsicwavelength dependence shown by the SALT2 calibration templates is also consistent with no time dilation. Using a static cosmological model the peak absolute magnitudes of raw type Ia supernovae observations are also independent of redshift. These results support the hypothesis of a static universe.

Type Ia Supernovae Progenitor Problem and the Variation of Fundamental Constants

Directory of Open Access Journals (Sweden)

Rybicki M.

2016-01-01

Full Text Available Cosmological observations strongly suggest our universe is the interior of an expanding black hole. If the constant mass of the universe is assumed then from the equation for Schwarzschild radius: r S = 2 Gmc it follows that proportionality constant Gc depends linearly on the universe’s radius R u , identified with r S , i.e. Gc Because the Chandrasekhar limit M Ch relates to the speed of light and to the Newton’s constant as M Ch ( c = G 3 = 2 so expansion involves gradual decrease of M Ch . In result, a single white dwarf can alone become the Type Ia supernova progenitor, which provides a complementary solution to single-degenerate and double-degenerate models for SNe Ia. Both alternative scenarios: G R u and c R are analyzed in regard of their consistence with observations, and their consequences to cosmology.

High-Redshift Radio Galaxies from Deep Fields

Indian Academy of Sciences (India)

2016-01-27

Jan 27, 2016 ... High-Redshift Radio Galaxies from Deep Fields ... Here we present results from the deep 150 MHz observations of LBDS-Lynx field, which has been imaged at 327, ... Articles are also visible in Web of Science immediately.

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

Science.gov (United States)

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

2010-01-01

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

High redshift quasars and high metallicities

Science.gov (United States)

Ferland, Gary J.

1997-01-01

A large-scale code called Cloudy was designed to simulate non-equilibrium plasmas and predict their spectra. The goal was to apply it to studies of galactic and extragalactic emission line objects in order to reliably deduce abundances and luminosities. Quasars are of particular interest because they are the most luminous objects in the universe and the highest redshift objects that can be observed spectroscopically, and their emission lines can reveal the composition of the interstellar medium (ISM) of the universe when it was well under a billion years old. The lines are produced by warm (approximately 10(sup 4)K) gas with moderate to low density (n less than or equal to 10(sup 12) cm(sup -3)). Cloudy has been extended to include approximately 10(sup 4) resonance lines from the 495 possible stages of ionization of the lightest 30 elements, an extension that required several steps. The charge transfer database was expanded to complete the needed reactions between hydrogen and the first four ions and fit all reactions with a common approximation. Radiative recombination rate coefficients were derived for recombination from all closed shells, where this process should dominate. Analytical fits to Opacity Project (OP) and other recent photoionization cross sections were produced. Finally, rescaled OP oscillator strengths were used to compile a complete set of data for 5971 resonance lines. The major discovery has been that high redshift quasars have very high metallicities and there is strong evidence that the quasar phenomenon is associated with the birth of massive elliptical galaxies.

Bulge Growth Through Disc Instabilities in High-Redshift Galaxies

Science.gov (United States)

Bournaud, Frédéric

The role of disc instabilities, such as bars and spiral arms, and the associated resonances, in growing bulges in the inner regions of disc galaxies have long been studied in the low-redshift nearby Universe. There it has long been probed observationally, in particular through peanut-shaped bulges (Chap. 14 10.1007/978-3-319-19378-6_14"). This secular growth of bulges in modern disc galaxies is driven by weak, non-axisymmetric instabilities: it mostly produces pseudobulges at slow rates and with long star-formation timescales. Disc instabilities at high redshift (z > 1) in moderate-mass to massive galaxies (1010 to a few 1011 M⊙ of stars) are very different from those found in modern spiral galaxies. High-redshift discs are globally unstable and fragment into giant clumps containing 108-9 M⊙ of gas and stars each, which results in highly irregular galaxy morphologies. The clumps and other features associated to the violent instability drive disc evolution and bulge growth through various mechanisms on short timescales. The giant clumps can migrate inward and coalesce into the bulge in a few 108 years. The instability in the very turbulent media drives intense gas inflows toward the bulge and nuclear region. Thick discs and supermassive black holes can grow concurrently as a result of the violent instability. This chapter reviews the properties of high-redshift disc instabilities, the evolution of giant clumps and other features associated to the instability, and the resulting growth of bulges and associated sub-galactic components.

Learning from the scatter in type ia supernovae

Energy Technology Data Exchange (ETDEWEB)

Dodelson, Scott; /Fermilab /Chicago U., Astron. Astrophys. Ctr.; Vallinotto, Alberto; /Fermilab /Chicago U.

2005-11-01

Type Ia Supernovae are standard candles so their mean apparent magnitude has been exploited to learn about the redshift-distance relationship. Besides intrinsic scatter in this standard candle, additional scatter is caused by gravitational magnification by large scale structure. Here they probe the dependence of this dispersion on cosmological parameters and show that information about the amplitude of clustering, {sigma}{sub s}, is contained in the scatter. In principle, it will be possible to constrain {sigma}{sub s} to within 5% with observations of 2000 Type Ia Supernovae. They identify three sources of systematic error--evolution of intrinsic scatter, baryon contributions to lensing, and non-Gaussianity of lensing--which will make this measurement difficult.

Spiral Disk Instability Can Drive Thermonuclear Explosions in Binary White Dwarf Mergers

OpenAIRE

Kashyap, Rahul; Fisher, Robert; García-Berro, Enrique; Aznar-Siguán, Gabriela; Ji, Suoqing; Lorén-Aguilar, Pablo

2015-01-01

Thermonuclear, or Type Ia supernovae (SNe Ia), originate from the explosion of carbon-oxygen white dwarfs, and serve as standardizable cosmological candles. However, despite their importance, the nature of the progenitor systems that give rise to SNe Ia has not been hitherto elucidated. Observational evidence favors the double-degenerate channel in which merging white dwarf binaries lead to SNe Ia. Furthermore, significant discrepancies exist between observations and theory, and to date, ther...

Cosmological Results from High-z Supernovae

Science.gov (United States)

Tonry, John L.; Schmidt, Brian P.; Barris, Brian; Candia, Pablo; Challis, Peter; Clocchiatti, Alejandro; Coil, Alison L.; Filippenko, Alexei V.; Garnavich, Peter; Hogan, Craig; Holland, Stephen T.; Jha, Saurabh; Kirshner, Robert P.; Krisciunas, Kevin; Leibundgut, Bruno; Li, Weidong; Matheson, Thomas; Phillips, Mark M.; Riess, Adam G.; Schommer, Robert; Smith, R. Chris; Sollerman, Jesper; Spyromilio, Jason; Stubbs, Christopher W.; Suntzeff, Nicholas B.

2003-09-01

The High-z Supernova Search Team has discovered and observed eight new supernovae in the redshift interval z=0.3-1.2. These independent observations, analyzed by similar but distinct methods, confirm the results of Riess and Perlmutter and coworkers that supernova luminosity distances imply an accelerating universe. More importantly, they extend the redshift range of consistently observed Type Ia supernovae (SNe Ia) to z~1, where the signature of cosmological effects has the opposite sign of some plausible systematic effects. Consequently, these measurements not only provide another quantitative confirmation of the importance of dark energy, but also constitute a powerful qualitative test for the cosmological origin of cosmic acceleration. We find a rate for SN Ia of (1.4+/-0.5)×10-4h3Mpc-3yr-1 at a mean redshift of 0.5. We present distances and host extinctions for 230 SN Ia. These place the following constraints on cosmological quantities: if the equation of state parameter of the dark energy is w=-1, then H0t0=0.96+/-0.04, and ΩΛ-1.4ΩM=0.35+/-0.14. Including the constraint of a flat universe, we find ΩM=0.28+/-0.05, independent of any large-scale structure measurements. Adopting a prior based on the Two Degree Field (2dF) Redshift Survey constraint on ΩM and assuming a flat universe, we find that the equation of state parameter of the dark energy lies in the range -1.48-1, we obtain wInstitute, which is operated by the Association of Universities for Research in Astronomy (AURA), Inc., under NASA contract NAS 5-26555. This research is primarily associated with proposal GO-8177, but also uses and reports results from proposals GO-7505, 7588, 8641, and 9118. Based in part on observations taken with the Canada-France-Hawaii Telescope, operated by the National Research Council of Canada, le Centre National de la Recherche Scientifique de France, and the University of Hawaii. CTIO: Based in part on observations taken at the Cerro Tololo Inter

Early Observations of the Type Ia Supernova iPTF 16abc: A Case of Interaction with Nearby, Unbound Material and/or Strong Ejecta Mixing

Science.gov (United States)

Miller, A. A.; Cao, Y.; Piro, A. L.; Blagorodnova, N.; Bue, B. D.; Cenko, S. B.; Dhawan, S.; Ferretti, R.; Fox, O. D.; Fremling, C.; Goobar, A.; Howell, D. A.; Hosseinzadeh, G.; Kasliwal, M. M.; Laher, R. R.; Lunnan, R.; Masci, F. J.; McCully, C.; Nugent, P. E.; Sollerman, J.; Taddia, F.; Kulkarni, S. R.

2018-01-01

Early observations of Type Ia supernovae (SNe Ia) provide a unique probe of their progenitor systems and explosion physics. Here we report the intermediate Palomar Transient Factory (iPTF) discovery of an extraordinarily young SN Ia, iPTF 16abc. By fitting a power law to our early light curve, we infer that first light for the SN, that is, when the SN could have first been detected by our survey, occurred only 0.15{+/- }0.070.15 days before our first detection. In the ∼24 hr after discovery, iPTF 16abc rose by ∼2 mag, featuring a near-linear rise in flux for ≳ 3 days. Early spectra show strong C II absorption, which disappears after ∼7 days. Unlike the extensively observed Type Ia SN 2011fe, the {(B-V)}0 colors of iPTF 16abc are blue and nearly constant in the days after explosion. We show that our early observations of iPTF 16abc cannot be explained by either SN shock breakout and the associated, subsequent cooling or the SN ejecta colliding with a stellar companion. Instead, we argue that the early characteristics of iPTF 16abc, including (i) the rapid, near-linear rise, (ii) the nonevolving blue colors, and (iii) the strong C II absorption, are the result of either ejecta interaction with nearby, unbound material or vigorous mixing of radioactive 56Ni in the SN ejecta, or a combination of the two. In the next few years, dozens of very young normal SNe Ia will be discovered, and observations similar to those presented here will constrain the white dwarf explosion mechanism.

Constraining Dark Energy with X-ray Clusters, SNe Ia and the CMB

International Nuclear Information System (INIS)

Rapetti, D

2005-01-01

In [1] we present new constraints on the evolution of dark energy from an analysis of Cosmic Microwave Background, supernova and X-ray galaxy cluster data. From a combined analysis of all three data sets and assuming that the Universe is at, we examine a series of dark energy models with up to three free parameters: the current dark energy equation of state w 0 , the early time equation of state w et and the scale factor at transition, a t . Allowing the transition scale factor to vary over the range 0.5 t 0 = -1.27 -0.39 +0.33 and w et = -0.66 -0.62 +0.44 . They find no significant evidence for evolution in the dark energy equation of state parameter with redshift. The complementary nature of the data sets leads to a tight constraint on the mean matter density, (Omega) m , alleviates a number of other parameter degeneracies, including that between the scalar spectral index n s , the physical baryon density (Omega) b h 2 and the optical depth τ and also allows us to examine models dropping the flatness prior. As required for the energy-momentum conservation our analysis includes spatial perturbations in the dark energy component. We show that not including them leads to spuriously tighter constraints on w 0 and especially on wet

A supernova origin for dust in a high-redshift quasar.

Science.gov (United States)

Maiolino, R; Schneider, R; Oliva, E; Bianchi, S; Ferrara, A; Mannucci, F; Pedani, M; Sogorb, M Roca

2004-09-30

Interstellar dust plays a crucial role in the evolution of the Universe by assisting the formation of molecules, by triggering the formation of the first low-mass stars, and by absorbing stellar ultraviolet-optical light and subsequently re-emitting it at infrared/millimetre wavelengths. Dust is thought to be produced predominantly in the envelopes of evolved (age >1 Gyr), low-mass stars. This picture has, however, recently been brought into question by the discovery of large masses of dust in the host galaxies of quasars at redshift z > 6, when the age of the Universe was less than 1 Gyr. Theoretical studies, corroborated by observations of nearby supernova remnants, have suggested that supernovae provide a fast and efficient dust formation environment in the early Universe. Here we report infrared observations of a quasar at redshift 6.2, which are used to obtain directly its dust extinction curve. We then show that such a curve is in excellent agreement with supernova dust models. This result demonstrates a supernova origin for dust in this high-redshift quasar, from which we infer that most of the dust at high redshifts probably has the same origin.

YOUNG REMNANTS OF TYPE Ia SUPERNOVAE AND THEIR PROGENITORS: A STUDY OF SNR G1.9+0.3

International Nuclear Information System (INIS)

Chakraborti, Sayan; Childs, Francesca; Soderberg, Alicia

2016-01-01

SNe Ia, with their remarkably homogeneous light curves and spectra, have been used as standardizable candles to measure the accelerating expansion of the universe. Yet, their progenitors remain elusive. Common explanations invoke a degenerate star (white dwarf) that explodes upon almost reaching the Chandrasekhar limit, by either steadily accreting mass from a companion star or violently merging with another degenerate star. We show that circumstellar interaction in young Galactic supernova remnants can be used to distinguish between these single and double degenerate (DD) progenitor scenarios. Here we propose a new diagnostic, the surface brightness index, which can be computed from theory and compared with Chandra and Very Large Array (VLA) observations. We use this method to demonstrate that a DD progenitor can explain the decades-long flux rise and size increase of the youngest known galactic supernova remnant (SNR), G1.9+0.3. We disfavor a single degenerate scenario for SNR G1.9+0.3. We attribute the observed properties to the interaction between a steep ejecta profile and a constant density environment. We suggest using the upgraded VLA, ASKAP, and MeerKAT to detect circumstellar interaction in the remnants of historical SNe Ia in the Local Group of galaxies. This may settle the long-standing debate over their progenitors

YOUNG REMNANTS OF TYPE Ia SUPERNOVAE AND THEIR PROGENITORS: A STUDY OF SNR G1.9+0.3

Energy Technology Data Exchange (ETDEWEB)

Chakraborti, Sayan; Childs, Francesca; Soderberg, Alicia, E-mail: schakraborti@post.harvard.edu [Institute for Theory and Computation, Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

2016-03-01

SNe Ia, with their remarkably homogeneous light curves and spectra, have been used as standardizable candles to measure the accelerating expansion of the universe. Yet, their progenitors remain elusive. Common explanations invoke a degenerate star (white dwarf) that explodes upon almost reaching the Chandrasekhar limit, by either steadily accreting mass from a companion star or violently merging with another degenerate star. We show that circumstellar interaction in young Galactic supernova remnants can be used to distinguish between these single and double degenerate (DD) progenitor scenarios. Here we propose a new diagnostic, the surface brightness index, which can be computed from theory and compared with Chandra and Very Large Array (VLA) observations. We use this method to demonstrate that a DD progenitor can explain the decades-long flux rise and size increase of the youngest known galactic supernova remnant (SNR), G1.9+0.3. We disfavor a single degenerate scenario for SNR G1.9+0.3. We attribute the observed properties to the interaction between a steep ejecta profile and a constant density environment. We suggest using the upgraded VLA, ASKAP, and MeerKAT to detect circumstellar interaction in the remnants of historical SNe Ia in the Local Group of galaxies. This may settle the long-standing debate over their progenitors.

Comparison of distance information given by SN Ia, BAO and CMB

International Nuclear Information System (INIS)

Li Hong

2011-01-01

The observations of Type Ia supernovae (SN Ia), Baryon Acoustic Oscillations (BAO) and Cosmic Microwave Background radiation (CMB) provide powerful tools for the measurement of cosmological parameters. One of the most useful information encodes in the distance measured by those probes. In this Letter, we test the coherence of the observational information provided by SN Ia, BAO and CMB experiments. We make two kinds of comparison: the first is the constraints on cosmological parameters of the equation of state parameter (EoS) of dark energy (DE) and matter budget parameter Ω m from the latest data by global fitting, and we find the large discrepancy from those different probes. The second comparison is performed among the derived distance information from these observations at certain appointed redshift, the results show that the distance provided by WMAP5 are larger than those from SN Ia and BAO on the whole.

A TRACER METHOD FOR COMPUTING TYPE IA SUPERNOVA YIELDS: BURNING MODEL CALIBRATION, RECONSTRUCTION OF THICKENED FLAMES, AND VERIFICATION FOR PLANAR DETONATIONS

Energy Technology Data Exchange (ETDEWEB)

Townsley, Dean M.; Miles, Broxton J. [Department of Physics and Astronomy, University of Alabama, Tuscaloosa, AL (United States); Timmes, F. X. [School of Earth and Space Exploration, Arizona State University, Tempe, AZ (United States); Calder, Alan C. [Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY (United States); Brown, Edward F., E-mail: Dean.M.Townsley@ua.edu [The Joint Institute for Nuclear Astrophysics, Michigan State University, East Lansing, MI (United States)

2016-07-01

We refine our previously introduced parameterized model for explosive carbon–oxygen fusion during thermonuclear Type Ia supernovae (SNe Ia) by adding corrections to post-processing of recorded Lagrangian fluid-element histories to obtain more accurate isotopic yields. Deflagration and detonation products are verified for propagation in a medium of uniform density. A new method is introduced for reconstructing the temperature–density history within the artificially thick model deflagration front. We obtain better than 5% consistency between the electron capture computed by the burning model and yields from post-processing. For detonations, we compare to a benchmark calculation of the structure of driven steady-state planar detonations performed with a large nuclear reaction network and error-controlled integration. We verify that, for steady-state planar detonations down to a density of 5 × 10{sup 6} g cm{sup −3}, our post-processing matches the major abundances in the benchmark solution typically to better than 10% for times greater than 0.01 s after the passage of the shock front. As a test case to demonstrate the method, presented here with post-processing for the first time, we perform a two-dimensional simulation of a SN Ia in the scenario of a Chandrasekhar-mass deflagration–detonation transition (DDT). We find that reconstruction of deflagration tracks leads to slightly more complete silicon burning than without reconstruction. The resulting abundance structure of the ejecta is consistent with inferences from spectroscopic studies of observed SNe Ia. We confirm the absence of a central region of stable Fe-group material for the multi-dimensional DDT scenario. Detailed isotopic yields are tabulated and change only modestly when using deflagration reconstruction.

Early Blue Excess from the Type Ia Supernova 2017cbv and Implications for Its Progenitor

Energy Technology Data Exchange (ETDEWEB)

Hosseinzadeh, Griffin; Howell, D. Andrew; McCully, Curtis; Arcavi, Iair [Las Cumbres Observatory, 6740 Cortona Drive, Suite 102, Goleta, CA 93117-5575 (United States); Sand, David J.; Tartaglia, Leonardo [Department of Astronomy/Steward Observatory, 933 North Cherry Avenue, Room N204, Tucson, AZ 85721-0065 (United States); Valenti, Stefano; Bostroem, K. Azalee [Department of Physics, University of California, 1 Shields Avenue, Davis, CA 95616-5270 (United States); Brown, Peter [Mitchell Institute for Fundamental Physics and Astronomy, Texas A and M University, College Station, TX 77843-4242 (United States); Kasen, Daniel [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720-8169 (United States); Hsiao, Eric Y.; Davis, Scott; Shahbandeh, Melissa [Department of Physics, Florida State University, 77 Chieftain Way, Tallahassee, FL 32306-4350 (United States); Stritzinger, Maximilian D., E-mail: griffin@lco.global [Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C (Denmark)

2017-08-20

We present very early, high-cadence photometric observations of the nearby Type Ia SN 2017cbv. The light curve is unique in that it has a blue bump during the first five days of observations in the U , B , and g bands, which is clearly resolved given our photometric cadence of 5.7 hr during that time span. We model the light curve as the combination of early shocking of the supernova ejecta against a nondegenerate companion star plus a standard SN Ia component. Our best-fit model suggests the presence of a subgiant star 56 R {sub ☉} from the exploding white dwarf, although this number is highly model-dependent. While this model matches the optical light curve well, it overpredicts the observed flux in the ultraviolet bands. This may indicate that the shock is not a blackbody, perhaps because of line blanketing in the UV. Alternatively, it could point to another physical explanation for the optical blue bump, such as interaction with circumstellar material or an unusual nickel distribution. Early optical spectra of SN 2017cbv show strong carbon (C ii λ 6580) absorption up through day −13 with respect to maximum light, suggesting that the progenitor system contains a significant amount of unburned material. These early results on SN 2017cbv illustrate the power of early discovery and intense follow-up of nearby supernovae to resolve standing questions about the progenitor systems and explosion mechanisms of SNe Ia.

Early Blue Excess from the Type Ia Supernova 2017cbv and Implications for Its Progenitor

International Nuclear Information System (INIS)

Hosseinzadeh, Griffin; Howell, D. Andrew; McCully, Curtis; Arcavi, Iair; Sand, David J.; Tartaglia, Leonardo; Valenti, Stefano; Bostroem, K. Azalee; Brown, Peter; Kasen, Daniel; Hsiao, Eric Y.; Davis, Scott; Shahbandeh, Melissa; Stritzinger, Maximilian D.

2017-01-01

We present very early, high-cadence photometric observations of the nearby Type Ia SN 2017cbv. The light curve is unique in that it has a blue bump during the first five days of observations in the U , B , and g bands, which is clearly resolved given our photometric cadence of 5.7 hr during that time span. We model the light curve as the combination of early shocking of the supernova ejecta against a nondegenerate companion star plus a standard SN Ia component. Our best-fit model suggests the presence of a subgiant star 56 R _☉ from the exploding white dwarf, although this number is highly model-dependent. While this model matches the optical light curve well, it overpredicts the observed flux in the ultraviolet bands. This may indicate that the shock is not a blackbody, perhaps because of line blanketing in the UV. Alternatively, it could point to another physical explanation for the optical blue bump, such as interaction with circumstellar material or an unusual nickel distribution. Early optical spectra of SN 2017cbv show strong carbon (C ii λ 6580) absorption up through day −13 with respect to maximum light, suggesting that the progenitor system contains a significant amount of unburned material. These early results on SN 2017cbv illustrate the power of early discovery and intense follow-up of nearby supernovae to resolve standing questions about the progenitor systems and explosion mechanisms of SNe Ia.

The fate of high redshift massive compact galaxies in dense environments

Energy Technology Data Exchange (ETDEWEB)

Kaufmann, Tobias; /Zurich, ETH; Mayer, Lucio; /Zurich U.; Carollo, Marcella; /Zurich, ETH; Feldmann, Robert; /Fermilab /Chicago U., KICP

2012-01-01

Massive compact galaxies seem to be more common at high redshift than in the local universe, especially in denser environments. To investigate the fate of such massive galaxies identified at z {approx} 2 we analyse the evolution of their properties in three cosmological hydrodynamical simulations that form virialized galaxy groups of mass {approx} 10{sup 13} M{sub {circle_dot}} hosting a central massive elliptical/S0 galaxy by redshift zero. We find that at redshift {approx} 2 the population of galaxies with M{sub *} > 2 x 10{sup 10} M{sub {circle_dot}} is diverse in terms of mass, velocity dispersion, star formation and effective radius, containing both very compact and relatively extended objects. In each simulation all the compact satellite galaxies have merged into the central galaxy by redshift 0 (with the exception of one simulation where one of such satellite galaxy survives). Satellites of similar mass at z = 0 are all less compact than their high redshift counterparts. They form later than the galaxies in the z = 2 sample and enter the group potential at z < 1, when dynamical friction times are longer than the Hubble time. Also, by z = 0 the central galaxies have increased substantially their characteristic radius via a combination of in situ star formation and mergers. Hence in a group environment descendants of compact galaxies either evolve towards larger sizes or they disappear before the present time as a result of the environment in which they evolve. Since the group-sized halos that we consider are representative of dense environments in the {Lambda}CDM cosmology, we conclude that the majority of high redshift compact massive galaxies do not survive until today as a result of the environment.

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

Energy Technology Data Exchange (ETDEWEB)

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

2013-10-20

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

On the Number of Galaxies at High Redshift

Directory of Open Access Journals (Sweden)

Lorenzo Zaninetti

2015-09-01

Full Text Available The number of galaxies at a given flux as a function of the redshift, z, is derived when the z-distance relation is non-standard. In order to compare different models, the same formalism is also applied to the standard cosmology. The observed luminosity function for galaxies of the zCOSMOS catalog at different redshifts is modeled by a new luminosity function for galaxies, which is derived by the truncated beta probability density function. Three astronomical tests, which are the photometric maximum as a function of the redshift for a fixed flux, the mean value of the redshift for a fixed flux, and the luminosity function for galaxies as a function of the redshift, compare the theoretical values of the standard and non-standard model with the observed value. The tests are performed on the FORS Deep Field (FDF catalog up to redshift z = 1.5 and on the zCOSMOS catalog extending beyond z = 4. These three tests show minimal differences between the standard and the non-standard models.

BINARY QUASARS AT HIGH REDSHIFT. I. 24 NEW QUASAR PAIRS AT z ∼ 3-4

International Nuclear Information System (INIS)

Hennawi, Joseph F.; Myers, Adam D.; Shen, Yue; Strauss, Michael A.; Djorgovski, S. G.; Glikman, Eilat; Mahabal, Ashish; Fan Xiaohui; Martin, Crystal L.; Richards, Gordon T.; Schneider, Donald P.; Shankar, Francesco

2010-01-01

The clustering of quasars on small scales yields fundamental constraints on models of quasar evolution and the buildup of supermassive black holes. This paper describes the first systematic survey to discover high-redshift binary quasars. Using color-selection and photometric redshift techniques, we searched 8142 deg 2 of Sloan Digital Sky Survey imaging data for binary quasar candidates, and confirmed them with follow-up spectroscopy. Our sample of 27 high-redshift binaries (24 of them new discoveries) at redshifts 2.9 perpendicular perpendicular 3.5. The completeness and efficiency of our well-defined selection algorithm are quantified using simulated photometry and we find that our sample is ∼50% complete. Our companion paper uses this knowledge to make the first measurement of the small-scale clustering (R -1 Mpc comoving) of high-redshift quasars. High-redshift binaries constitute exponentially rare coincidences of two extreme (M ∼> 10 9 M sun ) supermassive black holes. At z ∼ 4, there is about one close binary per 10 Gpc 3 , thus these could be the highest sigma peaks, the analogs of superclusters, in the early universe.

Testing averaged cosmology with type Ia supernovae and BAO data

Energy Technology Data Exchange (ETDEWEB)

Santos, B.; Alcaniz, J.S. [Departamento de Astronomia, Observatório Nacional, 20921-400, Rio de Janeiro – RJ (Brazil); Coley, A.A. [Department of Mathematics and Statistics, Dalhousie University, Halifax, B3H 3J5 Canada (Canada); Devi, N. Chandrachani, E-mail: thoven@on.br, E-mail: aac@mathstat.dal.ca, E-mail: chandrachaniningombam@astro.unam.mx, E-mail: alcaniz@on.br [Instituto de Astronomía, Universidad Nacional Autónoma de México, Box 70-264, México City, México (Mexico)

2017-02-01

An important problem in precision cosmology is the determination of the effects of averaging and backreaction on observational predictions, particularly in view of the wealth of new observational data and improved statistical techniques. In this paper, we discuss the observational viability of a class of averaged cosmologies which consist of a simple parametrized phenomenological two-scale backreaction model with decoupled spatial curvature parameters. We perform a Bayesian model selection analysis and find that this class of averaged phenomenological cosmological models is favored with respect to the standard ΛCDM cosmological scenario when a joint analysis of current SNe Ia and BAO data is performed. In particular, the analysis provides observational evidence for non-trivial spatial curvature.

Testing averaged cosmology with type Ia supernovae and BAO data

International Nuclear Information System (INIS)

Santos, B.; Alcaniz, J.S.; Coley, A.A.; Devi, N. Chandrachani

2017-01-01

An important problem in precision cosmology is the determination of the effects of averaging and backreaction on observational predictions, particularly in view of the wealth of new observational data and improved statistical techniques. In this paper, we discuss the observational viability of a class of averaged cosmologies which consist of a simple parametrized phenomenological two-scale backreaction model with decoupled spatial curvature parameters. We perform a Bayesian model selection analysis and find that this class of averaged phenomenological cosmological models is favored with respect to the standard ΛCDM cosmological scenario when a joint analysis of current SNe Ia and BAO data is performed. In particular, the analysis provides observational evidence for non-trivial spatial curvature.

THE EARLIEST NEAR-INFRARED TIME-SERIES SPECTROSCOPY OF A TYPE Ia SUPERNOVA

Energy Technology Data Exchange (ETDEWEB)

Hsiao, E. Y.; Phillips, M. M.; Morrell, N.; Contreras, C.; Roth, M. [Carnegie Observatories, Las Campanas Observatory, Colina El Pino, Casilla 601 (Chile); Marion, G. H.; Kirshner, R. P. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Burns, C. R.; Freedman, W. L.; Persson, S. E. [Carnegie Observatories, 813 Santa Barbara St, Pasadena, CA 91101 (United States); Winge, C. [Gemini South Observatory, c/o AURA Inc., Casilla 603, La Serena (Chile); Kromer, M.; Gall, E. E. E. [Max-Planck-Institut fuer Astrophysik, Karl-Schwarzschild-Str. 1, D-85741 Garching bei Muenchen (Germany); Gerardy, C. L.; Hoeflich, P. [Department of Physics, Florida State University, Tallahassee, FL 32306 (United States); Im, M.; Jeon, Y. [CEOU/Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul (Korea, Republic of); Nugent, P. E. [Computational Cosmology Center, Computational Research Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road MS 50B-4206, Berkeley, CA 94611 (United States); Pignata, G. [Departamento de Ciencias Fisicas, Universidad Andres Bello, Avda. Republica 252, Santiago (Chile); Stanishev, V., E-mail: hsiao@lco.cl [CENTRA - Centro Multidisciplinar de Astrofisica, Instituto Superior Tecnico, Av. Rovisco Pais 1, 1049-001 Lisbon (Portugal); and others

2013-04-01

We present ten medium-resolution, high signal-to-noise ratio near-infrared (NIR) spectra of SN 2011fe from SpeX on the NASA Infrared Telescope Facility (IRTF) and Gemini Near-Infrared Spectrograph (GNIRS) on Gemini North, obtained as part of the Carnegie Supernova Project. This data set constitutes the earliest time-series NIR spectroscopy of a Type Ia supernova (SN Ia), with the first spectrum obtained at 2.58 days past the explosion and covering -14.6 to +17.3 days relative to B-band maximum. C I {lambda}1.0693 {mu}m is detected in SN 2011fe with increasing strength up to maximum light. The delay in the onset of the NIR C I line demonstrates its potential to be an effective tracer of unprocessed material. For the first time in a SN Ia, the early rapid decline of the Mg II {lambda}1.0927 {mu}m velocity was observed, and the subsequent velocity is remarkably constant. The Mg II velocity during this constant phase locates the inner edge of carbon burning and probes the conditions under which the transition from deflagration to detonation occurs. We show that the Mg II velocity does not correlate with the optical light-curve decline rate {Delta}m{sub 15}(B). The prominent break at {approx}1.5 {mu}m is the main source of concern for NIR k-correction calculations. We demonstrate here that the feature has a uniform time evolution among SNe Ia, with the flux ratio across the break strongly correlated with {Delta}m{sub 15}(B). The predictability of the strength and the onset of this feature suggests that the associated k-correction uncertainties can be minimized with improved spectral templates.

SODIUM ABSORPTION SYSTEMS TOWARD SN Ia 2014J ORIGINATE ON INTERSTELLAR SCALES

Energy Technology Data Exchange (ETDEWEB)

Maeda, K.; Nogami, D. [Department of Astronomy, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto 606-8502 (Japan); Tajitsu, A. [Subaru Telescope, National Astronomical Observatory of Japan, 650 North A’ohoku Place, Hilo, HI 96720 (United States); Kawabata, K. S. [Hiroshima Astrophysical Science Center, Hiroshima University, Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Foley, R. J. [Astronomy Department, University of Illinois at Urbana-Champaign, 1002 W. Green Street, Urbana, IL 61801 (United States); Honda, S.; Arai, A. [Nishi-Harima Astronomical Observatory, Center for Astronomy, University of Hyogo, 407-2, Nishigaichi, Sayo-cho, Sayo, Hyogo 679-5313 (Japan); Moritani, Y.; Ishigaki, M.; Nomoto, K.; Schramm, M. [Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583 (Japan); Tanaka, M.; Aoki, W. [National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan); Hashimoto, O. [Gunma Astronomical Observatory, Takayama, Gunma 377-0702 (Japan); Simon, J. D. [Observatories of the Carnegie Institution for Science, 813 Santa Barbara St, Pasadena, CA 91101 (United States); Phillips, M. M. [Carnegie Observatories, Las Campanas Observatory, Casilla 601, La Serena (Chile); Yamanaka, M. [Department of Physics, Faculty of Science and Engineering, Konan University, Okamoto, Kobe, Hyogo 658-8501 (Japan); Milisavljevic, D.; Soderberg, A. M. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Mazzali, P. A., E-mail: keiichi.maeda@kusastro.kyoto-u.ac.jp [Astrophysics Research Institute, Liverpool John Moores University, Liverpool L3 5RF (United Kingdom); and others

2016-01-10

Na i D absorbing systems toward Type Ia supernovae (SNe Ia) have been intensively studied over the last decade with the aim of finding circumstellar material (CSM), which is an indirect probe of the progenitor system. However, it is difficult to deconvolve CSM components from non-variable, and often dominant, components created by interstellar material (ISM). We present a series of high-resolution spectra of SN Ia 2014J from before maximum brightness to ≳250 days after maximum brightness. The late-time spectrum provides unique information for determining the origin of the Na i D absorption systems. The deep late-time observation allows us to probe the environment around the SN at a large scale, extending to ≳40 pc. We find that a spectrum of diffuse light in the vicinity, but not directly in the line of sight, of the SN has absorbing systems nearly identical to those obtained for the “pure” SN line of sight. Therefore, basically all Na i D systems seen toward SN 2014J must originate from foreground material that extends to at least ∼40 pc in projection and none at the CSM scale. A fluctuation in the column densities at a scale of ∼20 pc is also identified. After subtracting the diffuse, “background” spectrum, the late-time Na i D profile along the SN line of sight is consistent with profiles near maximum brightness. The lack of variability on a ∼1 year timescale is consistent with the ISM interpretation for the gas.

The rest-frame submillimeter spectrum of high-redshift, dusty, star-forming galaxies

Energy Technology Data Exchange (ETDEWEB)

Spilker, J. S.; Marrone, D. P. [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Aguirre, J. E. [University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA 19104 (United States); Aravena, M. [European Southern Observatory, Alonso de Cordova 3107, Casilla 19001 Vitacura Santiago (Chile); Ashby, M. L. N. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Béthermin, M. [Laboratoire AIM-Paris-Saclay, CEA/DSM/Irfu-CNRS-Université Paris Diderot, CEA-Saclay, Orme des Merisiers, F-91191 Gif-sur-Yvette (France); Bradford, C. M. [Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Bothwell, M. S. [Cavendish Laboratory, University of Cambridge, JJ Thompson Ave, Cambridge CB3 0HA (United Kingdom); Brodwin, M. [Department of Physics and Astronomy, University of Missouri, 5110 Rockhill Road, Kansas City, MO 64110 (United States); Carlstrom, J. E.; Crawford, T. M. [Kavli Institute for Cosmological Physics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States); Chapman, S. C. [Dalhousie University, Halifax, Nova Scotia (Canada); De Breuck, C.; Gullberg, B. [European Southern Observatory, Karl Schwarzschild Straße 2, D-85748 Garching (Germany); Fassnacht, C. D. [Department of Physics, University of California, One Shields Avenue, Davis, CA 95616 (United States); Gonzalez, A. H. [Department of Astronomy, University of Florida, Gainesville, FL 32611 (United States); Greve, T. R. [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom); Hezaveh, Y. [Department of Physics, McGill University, 3600 Rue University, Montreal, Quebec H3A 2T8 (Canada); Holzapfel, W. L., E-mail: jspilker@as.arizona.edu [Department of Physics, University of California, Berkeley, CA 94720 (United States); and others

2014-04-20

We present the average rest-frame spectrum of high-redshift dusty, star-forming galaxies from 250 to 770 GHz. This spectrum was constructed by stacking Atacama Large Millimeter/submillimeter Array (ALMA) 3 mm spectra of 22 such sources discovered by the South Pole Telescope and spanning z = 2.0-5.7. In addition to multiple bright spectral features of {sup 12}CO, [C I], and H{sub 2}O, we also detect several faint transitions of {sup 13}CO, HCN, HNC, HCO{sup +}, and CN, and use the observed line strengths to characterize the typical properties of the interstellar medium of these high-redshift starburst galaxies. We find that the {sup 13}CO brightness in these objects is comparable to that of the only other z > 2 star-forming galaxy in which {sup 13}CO has been observed. We show that the emission from the high-critical density molecules HCN, HNC, HCO{sup +}, and CN is consistent with a warm, dense medium with T {sub kin} ∼ 55 K and n{sub H{sub 2}}≳10{sup 5.5} cm{sup –3}. High molecular hydrogen densities are required to reproduce the observed line ratios, and we demonstrate that alternatives to purely collisional excitation are unlikely to be significant for the bulk of these systems. We quantify the average emission from several species with no individually detected transitions, and find emission from the hydride CH and the linear molecule CCH for the first time at high redshift, indicating that these molecules may be powerful probes of interstellar chemistry in high-redshift systems. These observations represent the first constraints on many molecular species with rest-frame transitions from 0.4 to 1.2 mm in star-forming systems at high redshift, and will be invaluable in making effective use of ALMA in full science operations.

ON THE EFFECT OF THE COSMIC MICROWAVE BACKGROUND IN HIGH-REDSHIFT (SUB-)MILLIMETER OBSERVATIONS

Energy Technology Data Exchange (ETDEWEB)

Da Cunha, Elisabete; Groves, Brent; Walter, Fabian; Decarli, Roberto; Rix, Hans-Walter [Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, D-69117 Heidelberg (Germany); Weiss, Axel [Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, D-53121 Bonn (Germany); Bertoldi, Frank [Argelander Institute for Astronomy, University of Bonn, Auf dem Huegel 71, D-53121 Bonn (Germany); Carilli, Chris [National Radio Astronomy Observatory, Pete V. Domenici Array Science Center, P.O. Box O, Socorro, NM 87801 (United States); Daddi, Emanuele; Sargent, Mark [Laboratoire AIM, CEA/DSM-CNRS-Universite Paris Diderot, Irfu/Service d' Astrophysique, CEA Saclay, Orme des Merisiers, F-91191 Gif-sur-Yvette Cedex (France); Elbaz, David; Ivison, Rob [UK Astronomy Technology Centre, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Maiolino, Roberto [Cavendish Laboratory, University of Cambridge, 19 J. J. Thomson Avenue, Cambridge, CB3 0HE (United Kingdom); Riechers, Dominik [Department of Astronomy, Cornell University, Ithaca, NY 14853 (United States); Smail, Ian, E-mail: cunha@mpia.de [Institute for Computational Cosmology, Durham University, South Road, Durham DH1 3LE (United Kingdom)

2013-03-20

Modern (sub-)millimeter interferometers enable the measurement of the cool gas and dust emission of high-redshift galaxies (z > 5). However, at these redshifts the cosmic microwave background (CMB) temperature is higher, approaching, and even exceeding, the temperature of cold dust and molecular gas observed in the local universe. In this paper, we discuss the impact of the warmer CMB on (sub-)millimeter observations of high-redshift galaxies. The CMB affects the observed (sub-)millimeter dust continuum and the line emission (e.g., carbon monoxide, CO) in two ways: (1) it provides an additional source of (both dust and gas) heating and (2) it is a non-negligible background against which the line and continuum emission are measured. We show that these two competing processes affect the way we interpret the dust and gas properties of high-redshift galaxies using spectral energy distribution models. We quantify these effects and provide correction factors to compute what fraction of the intrinsic dust (and line) emission can be detected against the CMB as a function of frequency, redshift, and temperature. We discuss implications on the derived properties of high-redshift galaxies from (sub-)millimeter data. Specifically, the inferred dust and molecular gas masses can be severely underestimated for cold systems if the impact of the CMB is not properly taken into account.

High resolution spectroscopy of Red Giant Branch stars and the chemical evolution of the Fornax dwarf spheroidal galaxy

NARCIS (Netherlands)

Lemasle, B.; de Boer, T. J. L.; Hill, V.; Tolstoy, E.; Irwin, M. J.; Jablonka, P.; Venn, K.; Battaglia, G.; Starkenburg, E.; Shetrone, M.; Letarte, B.; Francois, P.; Helmi, A.; Primas, F.; Kaufer, A.; Szeifert, T.; Ballet, J.; Martins, F.; Bournaud, F.; Monier, R.; Reylé, C.

2014-01-01

From VLT-FLAMES high-resolution spectra, we determine the abundances of several α, iron-peak and neutron-capture elements in 47 Red Giant Branch stars in the Fornax dwarf spheroidal galaxy. We confirm that SNe Ia started to contribute to the chemical enrichment of Fornax at [Fe/H] between --2.0 and

Single Degenerate Models for Type Ia Supernovae: Progenitor's Evolution and Nucleosynthesis Yields

Science.gov (United States)

Nomoto, Ken'ichi; Leung, Shing-Chi

2018-06-01

We review how the single degenerate models for Type Ia supernovae (SNe Ia) works. In the binary star system of a white dwarf (WD) and its non-degenerate companion star, the WD accretes either hydrogen-rich matter or helium and undergoes hydrogen and helium shell-burning. We summarize how the stability and non-linear behavior of such shell-burning depend on the accretion rate and the WD mass and how the WD blows strong wind. We identify the following evolutionary routes for the accreting WD to trigger a thermonuclear explosion. Typically, the accretion rate is quite high in the early stage and gradually decreases as a result of mass transfer. With decreasing rate, the WD evolves as follows: (1) At a rapid accretion phase, the WD increase its mass by stable H burning and blows a strong wind to keep its moderate radius. The wind is strong enough to strip a part of the companion star's envelope to control the accretion rate and forms circumstellar matter (CSM). If the WD explodes within CSM, it is observed as an "SN Ia-CSM". (X-rays emitted by the WD are absorbed by CSM.) (2) If the WD continues to accrete at a lower rate, the wind stops and an SN Ia is triggered under steady-stable H shell-burning, which is observed as a super-soft X-ray source: "SN Ia-SSXS". (3) If the accretion continues at a still lower rate, H shell-burning becomes unstable and many flashes recur. The WD undergoes recurrent nova (RN) whose mass ejection is smaller than the accreted matter. Then the WD evolves to an "SN Ia-RN". (4) If the companion is a He star (or a He WD), the accretion of He can trigger He and C double detonations at the sub-Chandrasekhar mass or the WD grows to the Chandrasekhar mass while producing a He-wind: "SN Ia-He CSM". (5) If the accreting WD rotates quite rapidly, the WD mass can exceed the Chandrasekhar mass of the spherical WD, which delays the trigger of an SN Ia. After angular momentum is lost from the WD, the (super-Chandra) WD contracts to become a delayed SN Ia

High-Redshift galaxies light from the early universe

CERN Document Server

Appenzeller, Immo

2008-01-01

This book provides a comprehensive account of the scientific results on high-redshift galaxies accumulated during the past ten years. Apart from summarizing and critically discussing the wealth of observational data, the observational methods which made it possible to study these very distant and extremely faint objects are described in detail. Moreover, the technical feasibilities and physical limitations for existing and for future ground-based and space-based telescopes are discussed. Thus, apart from summarizing the knowledge accumulated so far, the book is designed as a tool for planning future observational and instrumental programs and projects. In view of the potential importance of the observational results of the high-redshift universe for basic physics the book is written for astronomers as well as for physicists without prior astronomical knowledge. For this purpose it contains introductory chapters describing the basic concepts and notations used in modern astronomy and a brief overview of the pr...

THE FIRST HIGH-REDSHIFT QUASAR FROM Pan-STARRS

Energy Technology Data Exchange (ETDEWEB)

Morganson, Eric; De Rosa, Gisella; Decarli, Roberto; Walter, Fabian; Rix, Hans-Walter [Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, 69117 Heidelberg (Germany); Chambers, Ken; Burgett, William; Flewelling, Heather; Hodapp, Klaus; Kaiser, Nick; Magnier, Eugene; Sweeney, Bill; Waters, Christopher [Institute for Astronomy, University of Hawaii at Manoa, Honolulu, HI 96822 (United States); McGreer, Ian; Fan, Xiaohui [Steward Observatory, University of Arizona, 933 N Cherry Ave., Tucson, AZ 85721 (United States); Greiner, Jochen [Max-Planck-Institut fuer extraterrestrische Physik, Giessenbachstrasse 1, 85748 Garching (Germany); Price, Paul, E-mail: morganson@mpia.de [Princeton University Observatory, 4 Ivy Lane, Peyton Hall, Princeton University, Princeton, NJ 08544 (United States)

2012-06-15

We present the discovery of the first high-redshift (z > 5.7) quasar from the Panoramic Survey Telescope and Rapid Response System 1 (Pan-STARRS1 or PS1). This quasar was initially detected as an i{sub P1} dropout in PS1, confirmed photometrically with the SAO Wide-field InfraRed Camera at Arizona's Multiple Mirror Telescope (MMT) and the Gamma-Ray Burst Optical/Near-Infrared Detector at the MPG 2.2 m telescope in La Silla. The quasar was verified spectroscopically with the MMT Spectrograph, Red Channel and the Cassegrain Twin Spectrograph at the Calar Alto 3.5 m telescope. Its near-infrared spectrum was taken at the Large Binocular Telescope Observatory (LBT) with the LBT Near-Infrared Spectroscopic Utility with Camera and Integral Field Unit for Extragalactic Research. It has a redshift of 5.73, an AB z{sub P1} magnitude of 19.4, a luminosity of 3.8 Multiplication-Sign 10{sup 47} erg s{sup -1}, and a black hole mass of 6.9 Multiplication-Sign 10{sup 9} M{sub Sun }. It is a broad absorption line quasar with a prominent Ly{beta} peak and a very blue continuum spectrum. This quasar is the first result from the PS1 high-redshift quasar search that is projected to discover more than 100 i{sub P1} dropout quasars and could potentially find more than 10 z{sub P1} dropout (z > 6.8) quasars.

THE FIRST HIGH-REDSHIFT QUASAR FROM Pan-STARRS

International Nuclear Information System (INIS)

Morganson, Eric; De Rosa, Gisella; Decarli, Roberto; Walter, Fabian; Rix, Hans-Walter; Chambers, Ken; Burgett, William; Flewelling, Heather; Hodapp, Klaus; Kaiser, Nick; Magnier, Eugene; Sweeney, Bill; Waters, Christopher; McGreer, Ian; Fan, Xiaohui; Greiner, Jochen; Price, Paul

2012-01-01

We present the discovery of the first high-redshift (z > 5.7) quasar from the Panoramic Survey Telescope and Rapid Response System 1 (Pan-STARRS1 or PS1). This quasar was initially detected as an i P1 dropout in PS1, confirmed photometrically with the SAO Wide-field InfraRed Camera at Arizona's Multiple Mirror Telescope (MMT) and the Gamma-Ray Burst Optical/Near-Infrared Detector at the MPG 2.2 m telescope in La Silla. The quasar was verified spectroscopically with the MMT Spectrograph, Red Channel and the Cassegrain Twin Spectrograph at the Calar Alto 3.5 m telescope. Its near-infrared spectrum was taken at the Large Binocular Telescope Observatory (LBT) with the LBT Near-Infrared Spectroscopic Utility with Camera and Integral Field Unit for Extragalactic Research. It has a redshift of 5.73, an AB z P1 magnitude of 19.4, a luminosity of 3.8 × 10 47 erg s –1 , and a black hole mass of 6.9 × 10 9 M ☉ . It is a broad absorption line quasar with a prominent Lyβ peak and a very blue continuum spectrum. This quasar is the first result from the PS1 high-redshift quasar search that is projected to discover more than 100 i P1 dropout quasars and could potentially find more than 10 z P1 dropout (z > 6.8) quasars.

VizieR Online Data Catalog: VANDELS High-Redshift Galaxy Evolution (McLure+, 2017)

Science.gov (United States)

McLure, R.; Pentericci, L.; Vandels Team

2017-11-01

This is the first data release (DR1) of the VANDELS survey, an ESO public spectroscopy survey targeting the high-redshift Universe. The VANDELS survey uses the VIMOS spectrograph on ESO's VLT to obtain ultra-deep, medium resolution, optical spectra of galaxies within the UKIDSS Ultra Deep Survey (UDS) and Chandra Deep Field South (CDFS) survey fields (0.2 sq. degree total area). Using robust photometric redshift pre-selection, VANDELS is targeting ~2100 galaxies in the redshift interval 1.0=3. In addition, VANDELS is targeting a substantial number of passive galaxies in the redshift interval 1.0filter, which covers the wavelength range 4800-10000Å at a dispersion of 2.5Å/pix and a spectral resolution of R~600. Each galaxy receives between a minimum of 20-hours and a maximum of 80-hours of on-source integration time. The fundamental aim of the survey is to provide the high signal-to-noise spectra necessary to measure key physical properties such as stellar population ages, metallicities and outflow velocities from detailed absorption-line studies. By targeting two extra-galactic survey fields with superb multi-wavelength imaging data, VANDELS is designed to produce a unique legacy dataset for exploring the physics underpinning high-redshift galaxy evolution. (2 data files).

Spectroscopy of 10 γ -Ray BL Lac Objects at High Redshift

Energy Technology Data Exchange (ETDEWEB)

Paiano, Simona; Falomo, Renato [INAF, Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, I-35122 Padova (Italy); Landoni, Marco [INAF, Osservatorio Astronomico di Brera, Via E. Bianchi 46, I-23807 Merate (Italy); Treves, Aldo [Università degli Studi dell’Insubria, Via Valleggio 11, I-22100 Como (Italy); Scarpa, Riccardo [Instituto de Astrofisica de Canarias, C/O Via Lactea, s/n E-38205 La Laguna, Tenerife (Spain)

2017-08-01

We present optical spectra with high signal-to-noise ratio of 10 BL Lac objects detected at GeV energies by the Fermi satellite (3FGL catalog), which previous observations suggested are at relatively high redshift. The new observations, obtained at the 10 m Gran Telescopio Canarias, allowed us to find the redshift for J0814.5+2943 ( z = 0.703), and we can set a spectroscopic lower limit for J0008.0+4713 ( z > 1.659) and J1107.7+0222 ( z > 1.0735) on the basis of Mg ii intervening absorption features. In addition we confirm the redshifts for J0505.5+0416 ( z = 0.423) and J1450+5200 ( z > 2.470). Finally we contradict the previous z estimates for five objects (J0049.7+0237, J0243.5+7119, J0802.0+1005, J1109.4+2411, and J2116.1+3339).

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

International Nuclear Information System (INIS)

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

2009-01-01

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

Millimeter Astronomy at High Redshift

Science.gov (United States)

Decarli, Roberto

2017-11-01

Our understanding of galaxy formation and evolution critically depends on our ability of exposing the properties of the gaseous content of galaxies throughout cosmic history: how much gas is there, in which phase (ionized, atomic, molecular?), in which physical conditions (temperature, density), how efficiently does it turn into stars? We are now entering an exciting era where these questions can be addressed via observations of various gas tracers, especially at mm and sub-mm wavelengths. I will review how to observe various gas phases at high redshift, and discuss lessons we have learned so far from campaigns aimed at characterizing the gas content in galaxies in various cosmic epochs.

High-redshift SDSS Quasars with Weak Emission Lines

DEFF Research Database (Denmark)

Diamond-Stanic, Aleksandar M.; Fan, Xiaohui; Brandt, W. N.

2009-01-01

We identify a sample of 74 high-redshift quasars (z > 3) with weak emission lines from the Fifth Data Release of the Sloan Digital Sky Survey and present infrared, optical, and radio observations of a subsample of four objects at z > 4. These weak emission-line quasars (WLQs) constitute a promine...

Leveraging 3D-HST Grism Redshifts to Quantify Photometric Redshift Performance

Science.gov (United States)

Bezanson, Rachel; Wake, David A.; Brammer, Gabriel B.; van Dokkum, Pieter G.; Franx, Marijn; Labbé, Ivo; Leja, Joel; Momcheva, Ivelina G.; Nelson, Erica J.; Quadri, Ryan F.; Skelton, Rosalind E.; Weiner, Benjamin J.; Whitaker, Katherine E.

2016-05-01

We present a study of photometric redshift accuracy in the 3D-HST photometric catalogs, using 3D-HST grism redshifts to quantify and dissect trends in redshift accuracy for galaxies brighter than JH IR > 24 with an unprecedented and representative high-redshift galaxy sample. We find an average scatter of 0.0197 ± 0.0003(1 + z) in the Skelton et al. photometric redshifts. Photometric redshift accuracy decreases with magnitude and redshift, but does not vary monotonically with color or stellar mass. The 1σ scatter lies between 0.01 and 0.03 (1 + z) for galaxies of all masses and colors below z 2), dusty star-forming galaxies for which the scatter increases to ˜0.1 (1 + z). We find that photometric redshifts depend significantly on galaxy size; the largest galaxies at fixed magnitude have photo-zs with up to ˜30% more scatter and ˜5 times the outlier rate. Although the overall photometric redshift accuracy for quiescent galaxies is better than that for star-forming galaxies, scatter depends more strongly on magnitude and redshift than on galaxy type. We verify these trends using the redshift distributions of close pairs and extend the analysis to fainter objects, where photometric redshift errors further increase to ˜0.046 (1 + z) at {H}F160W=26. We demonstrate that photometric redshift accuracy is strongly filter dependent and quantify the contribution of multiple filter combinations. We evaluate the widths of redshift probability distribution functions and find that error estimates are underestimated by a factor of ˜1.1-1.6, but that uniformly broadening the distribution does not adequately account for fitting outliers. Finally, we suggest possible applications of these data in planning for current and future surveys and simulate photometric redshift performance in the Large Synoptic Survey Telescope, Dark Energy Survey (DES), and combined DES and Vista Hemisphere surveys.

Population III Stars and Remnants in High-redshift Galaxies

Science.gov (United States)

Xu, Hao; Wise, John H.; Norman, Michael L.

2013-08-01

Recent simulations of Population III star formation have suggested that some fraction form in binary systems, in addition to having a characteristic mass of tens of solar masses. The deaths of metal-free stars result in the initial chemical enrichment of the universe and the production of the first stellar-mass black holes. Here we present a cosmological adaptive mesh refinement simulation of an overdense region that forms a few 109 M ⊙ dark matter halos and over 13,000 Population III stars by redshift 15. We find that most halos do not form Population III stars until they reach M vir ~ 107 M ⊙ because this biased region is quickly enriched from both Population III and galaxies, which also produce high levels of ultraviolet radiation that suppress H2 formation. Nevertheless, Population III stars continue to form, albeit in more massive halos, at a rate of ~10-4 M ⊙ yr-1 Mpc-3 at redshift 15. The most massive starless halo has a mass of 7 × 107 M ⊙, which could host massive black hole formation through the direct gaseous collapse scenario. We show that the multiplicity of the Population III remnants grows with halo mass above 108 M ⊙, culminating in 50 remnants located in 109 M ⊙ halos on average. This has implications that high-mass X-ray binaries and intermediate-mass black holes that originate from metal-free stars may be abundant in high-redshift galaxies.

Science from the Avo 1ST Light: the High Redshift Universe

Science.gov (United States)

Walton, Nicholas A.

The Astrophysical Virtual Observatory science working group defined a number of key science drivers for which the AVO should develop capabilities. At the AVO's Jan 2003 'First Light' event the AVO prototype data access and manipulation tool was demonstrated. In particular its use in enabling discovery in deep multi wavelength data sets was highlighted. In this presentation I will describe how the AVO demonstrator has enabled investigation into the high redshift universe and in particular its use in discovering rare populations of high redshift galaxies from deep Hubble and ground based imaging data obtained through the Great Observatories Origins Deep Survey (GOODS) programme.

THE TYPE II SUPERNOVA RATE IN z {approx} 0.1 GALAXY CLUSTERS FROM THE MULTI-EPOCH NEARBY CLUSTER SURVEY