Skip to main content
OSTI.GOVU.S. Department of Energy Office of Scientific and Technical Information
U.S. Department of Energy
Office of Scientific and Technical Information
 

The Hubble Space Telescope Cluster Supernova Survey. II. The Type la Supernova rate in high-redshift galaxy clusters

Journal Article · · The Astrophysical Journal
 [1];  [2];  [3];  [4];  [5];  [6];  [7];  [8];  [2];  [9];  [1];  [10];  [11];  [12];  [1];  [13];  [14];  [2];  [15];  [16] more »;  [17];  [18];  [19];  [20];  [21];  [22];  [1];  [23];  [24];  [10];  [1];  [10];  [2];  [25];  [1];  [2];  [2];  [26];  [1];  [2];  [17];  [16];  [19] « less
  1. Univ. of California, Berkeley, CA (United States). Dept. of Physics; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  3. Univ. of California, Berkeley, CA (United States). Dept. of Physics; Oskar Klein Centre for Cosmo Particle Physics, AlbaNova, Stockholm (Sweden)
  4. Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States)
  5. Hamilton College, Clinton, NY (United States). Dept. of Physics
  6. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of Utah, Salt Lake City, UT (United States). Dept. of Physics and Astronomy
  7. Univ. of Tokyo (Japan). Inst. of Astronomy. Graduate School of Science
  8. California Inst. of Technology (CalTech), La Canada Flintridge, CA (United States). Jet Propulsion Lab.
  9. Univ. of California, Santa Cruz, CA (United States). Santa Cruz Inst. for Particle Physics
  10. Space Telescope Science Inst., Baltimore, MD (United States)
  11. Univ. of Waterloo, ON (Canada). Dept. of Physics and Astronomy
  12. Univ. of Chicago, IL (United States). Dept. of Astronomy and Astrophysics
  13. Oskar Klein Centre for Cosmo Particle Physics, AlbaNova, Stockholm (Sweden); Stockholm Univ. (Sweden). Albanova University Center, Dept. of Physics
  14. National Astronomical Observatory of Japan, Hilo, HI (United States). Subaru Telescope
  15. Univ. of California, Berkeley, CA (United States). Dept. of Physics
  16. Univ. of Tokyo (Japan). Inst. of Astronomy. Graduate School of Science
  17. National Astronomical Observatory of Japan, Tokyo (Japan)
  18. Univ. of Chicago, IL (United States). Dept. of Astronomy and Astrophysics; Univ. of Chicago, IL (United States). Kavli Inst. for Cosmological Physics (KICP)
  19. Univ. of Tokyo (Japan). Inst. for Cosmic Ray Research
  20. Univ. of Bonn (Germany). Physikalisches Inst.
  21. Australian Astronomical Observatory, Epping, NSW (Australia)
  22. Univ. of California, Davis, CA (United States). Dept. of Physics
  23. Univ. of Tokyo (Japan). Inst. of Astronomy. Graduate School of Science; National Astronomical Observatory of Japan, Tokyo (Japan)
  24. Kyoto Univ., Kyoto (Japan). Dept. of Astronomy
  25. European Southern Observatory (ESO), Garching (Germany)
  26. Univ. of California, Davis, CA (United States). Dept. of Physics; Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Inst. of Geophysics and Planetary Physics
+ Show Author Affiliations
Here we report a measurement of the Type Ia supernova (SN Ia) rate in galaxy clusters at 0.9 < z < 1.46 from the Hubble Space Telescope Cluster Supernova Survey. This is the first cluster SN Ia rate measurement with detected z > 0.9 SNe. Finding 8 ± 1 cluster SNe Ia, we determine an SN Ia rate of 0.50+0.23-0.19 (stat) +0.10 -0.09 (sys) h2 70 SNuB (SNuB ≡ 10-12 SNe L-1 ⊙,B yr-1). In units of stellar mass, this translates to 0.36 + 0.16 -0.13 (stat) +0.07 -0.06 (sys) h2 70 SNuM (SNuM ≡ 10-12 SNe M –1 ⊙ yr–1). This represents a factor of ≈ 5 ± 2 increase over measurements of the cluster rate at z < 0.2. We parameterize the late-time SN Ia delay time distribution (DTD) with a power law: Ψ(t)∝ts . Under the approximation of a single-burst cluster formation redshift of zf = 3, our rate measurement in combination with lower-redshift cluster SN Ia rates constrains s = –1.41+0.47 –0.40, consistent with measurements of the DTD in the field. This measurement is generally consistent with expectations for the "double degenerate" scenario and inconsistent with some models for the "single degenerate" scenario predicting a steeper DTD at large delay times. We check for environmental dependence and the influence of younger stellar populations by calculating the rate specifically in cluster red-sequence galaxies and in morphologically early-type galaxies, finding results similar to the full cluster rate. Finally, the upper limit of one hostless cluster SN Ia detected in the survey implies that the fraction of stars in the intra-cluster medium is less than 0.47 (95% confidence), consistent with measurements at lower redshifts.
Research Organization:
Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
Sponsoring Organization:
Australian Research Council (ARC); Japan Society for the Promotion of Science (JSPS); National Aeronautic and Space Administration (NASA); USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25); USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26)
Contributing Organization:
The Supernova Cosmology Project (SCP)
Grant/Contract Number:
AC02-05CH11231
OSTI ID:
1407144
Alternate ID(s):
OSTI ID: 22011995
Journal Information:
The Astrophysical Journal, Journal Name: The Astrophysical Journal Journal Issue: 1 Vol. 745; ISSN 0004-637X
Publisher:
Institute of Physics (IOP)Copyright Statement
Country of Publication:
United States
Language:
English

References (137)

Population Synthesis for Progenitors of Type Ia Supernovae book January 2005
Galactic vs. extragalactic origin of the peculiar transient SCP 06F6 journal February 2010
Detection of intergalactic red-giant-branch stars in the Virgo cluster journal January 1998
Hydrogen-poor superluminous stellar explosions journal June 2011
Supernovae in deep Hubble Space Telescope galaxy cluster fields: cluster rates and field counts journal May 2002
Stellar population synthesis at the resolution of 2003 journal October 2003
Multiwavelength observations of a rich galaxy cluster at z $\thicksim$ 1 : The HST/ACS colour–magnitude diagram journal April 2009
Multi-wavelength study of XMMU J2235.3-2557: the most massive galaxy cluster at z  > 1 journal October 2009
The delay-time distribution of Type Ia supernovae: a comparison between theory and observation journal June 2010
Cluster galaxies in XMMU J2235-2557: galaxy population properties in most massive environments at z   ~  1.4 journal November 2010
The supernova rate per unit mass journal March 2005
The rates of type Ia supernovae: I. Analytical formulations journal September 2005
SALT: a spectral adaptive light curve template for type Ia supernovae journal November 2005
The buildup of stellar mass and the 3.6 μ m luminosity function in clusters from z  = 1.25 to z  = 0.2 journal February 2006
The Supernova Legacy Survey: measurement of $\Omega_{\mathsf{M}}$, $\Omega_\mathsf{\Lambda}$ and w from the first year data set journal January 2006
The near-infrared luminosity function of cluster galaxies beyond redshift one journal April 2006
Stellar populations of early-type galaxies in different environments: II. Ages and metallicities journal September 2006
Star formation histories of early-type galaxies at z = 1.2 in cluster and field environments journal July 2008
Evidence of short-lived SN Ia progenitors journal November 2008
Early-type galaxies with core collapse supernovae journal June 2008
SExtractor: Software for source extraction journal June 1996
The Luminosity Function and Stellar Evolution. journal January 1955
Binaries and Supernovae of Type I journal December 1973
An analytic expression for the luminosity function for galaxies. journal January 1976
The evolution of galaxies in clusters. I - ISIT photometry of C1 0024+1654 and 3C 295 journal January 1978
Double white dwarfs as progenitors of R Coronae Borealis stars and Type I supernovae journal February 1984
The evolution of galaxies in clusters. V - A study of populations since Z approximately equal to 0.5 journal October 1984
The relationship between infrared, optical, and ultraviolet extinction journal October 1989
Core-Collapse Supernovae and Their Ejecta journal March 1996
A supernova at Z = 0.458 and implications for measuring the cosmological deceleration journal February 1995
Supernovae of type I as end products of the evolution of binaries with components of moderate initial mass (M not greater than about 9 solar masses) journal January 1984
Observational Evidence from Supernovae for an Accelerating Universe and a Cosmological Constant journal September 1998
An X-Ray–Selected Galaxy Cluster at [CLC][ITAL]z[/ITAL][/CLC] = 1.26 journal July 1999
A Search for Environmental Effects on Type I[CLC]a[/CLC] Supernovae journal September 2000
Measurements of the Cosmological Parameters Ω and Λ from the First Seven Supernovae at z ≥ 0.35 journal July 1997
The Evolution of Early‐Type Galaxies in Distant Clusters journal January 1998
Intracluster Planetary Nebulae in the Virgo Cluster. I. Initial Results journal August 1998
Measurements of Ω and Λ from 42 High‐Redshift Supernovae journal June 1999
Supernova Rates: A Cosmic History journal January 2000
Measuring the Diffuse Optical Light in Abell 1651 journal June 2000
Type I[CLC]a[/CLC] Supernova Scenarios and the Hubble Sequence journal July 1995
Type I[CLC]a[/CLC] Supernova Counts at High [CLC][ITAL]z[/ITAL][/CLC]: Signatures of Cosmological Models and Progenitors journal April 1998
Stellar Mass‐to‐Light Ratios and the Tully‐Fisher Relation journal March 2001
Luminosity Evolution of Field Early-Type Galaxies to [CLC][ITAL]z[/ITAL][/CLC] = 0.55 journal May 2001
A Study of Nine High-Redshift Clusters of Galaxies. IV. Photometry and Spectra of Clusters 1324+3011 and 1604+4321 journal September 2001
On the Typical Timescale for the Chemical Enrichment from Type Ia Supernovae in Galaxies journal September 2001
A Comparative Study of the Absolute Magnitude Distributions of Supernovae journal February 2002
Drizzle: A Method for the Linear Reconstruction of Undersampled Images journal February 2002
An X-Ray–Selected Galaxy Cluster at [ITAL][CLC]z[/CLC][/ITAL] = 1.11 in the [ITAL]ROSAT[/ITAL] Deep Cluster Survey journal February 2002
The WARPS Survey. VI. Galaxy Cluster and Source Identifications from Phase I
  • Perlman, Eric S.; Horner, Donald J.; Jones, Laurence R.
  • The Astrophysical Journal Supplement Series, Vol. 140, Issue 2 https://doi.org/10.1086/339685
journal June 2002
Detailed Structural Decomposition of Galaxy Images journal July 2002
K ‐Corrections and Extinction Corrections for Type Ia Supernovae
  • Nugent, Peter; Kim, Alex; Perlmutter, Saul
  • Publications of the Astronomical Society of the Pacific, Vol. 114, Issue 798 https://doi.org/10.1086/341707
journal August 2002
A Population of Intergalactic Supernovae in Galaxy Clusters journal March 2003
The Optical and Near‐Infrared Properties of Galaxies. I. Luminosity and Stellar Mass Functions journal December 2003
The Great Observatories Origins Deep Survey: Initial Results from Optical and Near-Infrared Imaging journal January 2004
Chandra and XMM-Newton Observations of RDCS 1252.9-2927, A Massive Cluster at z =1.24 journal January 2004
GEMS: Galaxy Evolution from Morphologies and SEDs
  • Rix, Hans‐Walter; Barden, Marco; Beckwith, Steven V. W.
  • The Astrophysical Journal Supplement Series, Vol. 152, Issue 2 https://doi.org/10.1086/420885
journal June 2004
The Hubble Higher z Supernova Search: Supernovae to z ≈ 1.6 and Constraints on Type Ia Progenitor Models journal September 2004
Intracluster Planetary Nebulae in the Virgo Cluster. III. Luminosity of the Intracluster Light and Tests of the Spatial Distribution journal November 2004
K ‐band Properties of Galaxy Clusters and Groups: Brightest Cluster Galaxies and Intracluster Light journal December 2004
Intracluster Light in Nearby Galaxy Clusters: Relationship to the Halos of Brightest Cluster Galaxies journal January 2005
The Epochs of Early‐Type Galaxy Formation as a Function of Environment journal March 2005
Luminosity Functions of the Galaxy Cluster MS 1054−0321 at z  = 0.83 based on ACS Photometry journal March 2005
Discovery of an X-Ray-luminous Galaxy Cluster at z  = 1.4 journal March 2005
New Constraints on Type Ia Supernova Progenitor Models journal August 2005
The Type Ia Supernova Rate journal August 2005
Diffuse Light in the Virgo Cluster journal August 2005
Diffuse Optical Light in Galaxy Clusters. I. Abell 3888 journal January 2006
An IR-selected Galaxy Cluster at z = 1.41 journal November 2005
The FLAMINGOS Extragalactic Survey journal March 2006
On Iron Enrichment, Star Formation, and Type Ia Supernovae in Galaxy Clusters journal September 2006
Rates and Properties of Type Ia Supernovae as a Function of Mass and Star Formation in Their Host Galaxies journal September 2006
The XMM Cluster Survey: A Massive Galaxy Cluster at z = 1.45 journal July 2006
Photometric Redshifts in the IRAC Shallow Survey journal November 2006
A Probabilistic Approach to Classifying Supernovae Using Photometric Information journal April 2007
Supernovae in Low‐Redshift Galaxy Clusters: The Type Ia Supernova Rate journal May 2007
Rest-Frame R -band Light Curve of a z ~ 1.3 Supernova Obtained with Keck Laser Adaptive Optics journal April 2007
K ‐Corrections and Spectral Templates of Type Ia Supernovae journal July 2007
Bayesian Single-Epoch Photometric Classification of Supernovae journal July 2007
The XMM Cluster Survey: The Dynamical State of XMMXCS J2215.9−1738 at z = 1.457 journal December 2007
A New Determination of the High‐Redshift Type Ia Supernova Rates with the Hubble Space Telescope Advanced Camera for Surveys journal February 2008
Cosmic Variance and Its Effect on the Luminosity Function Determination in Deep High‐ z Surveys journal April 2008
Evidence for Line‐of‐Sight Structure in a Comparison of X‐Ray and Optical Observations of the High‐Redshift Cluster RCS 043938‐2904.7 journal May 2008
Chandra X‐Ray Observations of the 0.6 < z < 1.1 Red‐Sequence Cluster Survey Sample journal June 2008
A z = 0.9 Supercluster of X-Ray Luminous, Optically Selected, Massive Galaxy Clusters journal March 2008
Improved Cosmological Constraints from New, Old, and Combined Supernova Data Sets journal October 2008
Clusters of Galaxies in the First Half of the Universe from the IRAC Shallow Survey journal September 2008
The Progenitors of Type Ia Supernovae journal July 2008
The Delay-Time Distribution of Type Ia Supernovae and the Single-Degenerate Model journal July 2008
Implications of Two Type Ia Supernova Populations for Cosmological Measurements journal August 2008
AN INTENSIVE HUBBLE SPACE TELESCOPE SURVEY FOR z >1 TYPE Ia SUPERNOVAE BY TARGETING GALAXY CLUSTERS journal September 2009
THE AGES OF TYPE Ia SUPERNOVA PROGENITORS journal August 2010
The Red-Sequence Cluster Survey-2 (Rcs-2): Survey Details and Photometric Catalog Construction journal February 2011
The Red-Sequence Luminosity Function in Massive Intermediate-Redshift Galaxy Clusters journal December 2008
DISCOVERY OF AN UNUSUAL OPTICAL TRANSIENT WITH THE HUBBLE SPACE TELESCOPE journal December 2008
The Enrichment of the Intracluster Medium journal February 2009
THE XMM CLUSTER SURVEY: GALAXY MORPHOLOGIES AND THE COLOR-MAGNITUDE RELATION IN XMMXCS J2215.9 – 1738 AT z = 1.46 journal May 2009
SCP 06F6: A CARBON-RICH EXTRAGALACTIC TRANSIENT AT REDSHIFT z ≃ 0.14? journal May 2009
RATES AND DELAY TIMES OF TYPE Ia SUPERNOVAE journal June 2009
IMPROVED DARK ENERGY CONSTRAINTS FROM ∼100 NEW CfA SUPERNOVA TYPE Ia LIGHT CURVES journal July 2009
HUBBLE SPACE TELESCOPE WEAK-LENSING STUDY OF THE GALAXY CLUSTER XMMU J2235.3 – 2557 AT z ∼ 1.4: A SURPRISINGLY MASSIVE GALAXY CLUSTER WHEN THE UNIVERSE IS ONE-THIRD OF ITS CURRENT AGE journal September 2009
Modeling the Light Curve of the Transient Scp06f6 journal September 2009
HUBBLE SPACE TELESCOPE DISCOVERY OF A z = 3.9 MULTIPLY IMAGED GALAXY BEHIND THE COMPLEX CLUSTER LENS WARPS J1415.1+36 AT z = 1.026 journal November 2009
THE ROLE OF TYPE Ia SUPERNOVAE IN CHEMICAL EVOLUTION. I. LIFETIME OF TYPE Ia SUPERNOVAE AND METALLICITY EFFECT journal December 2009
MEASUREMENTS OF THE RATE OF TYPE Ia SUPERNOVAE AT REDSHIFT ≲0.3 FROM THE SLOAN DIGITAL SKY SURVEY II SUPERNOVA SURVEY journal March 2010
SPECTRA AND HUBBLE SPACE TELESCOPE LIGHT CURVES OF SIX TYPE Ia SUPERNOVAE AT 0.511 < z < 1.12 AND THE UNION2 COMPILATION journal May 2010
THE TYPE Ia SUPERNOVA RATE IN REDSHIFT 0.5-0.9 GALAXY CLUSTERS journal July 2010
THE SUPERNOVA DELAY TIME DISTRIBUTION IN GALAXY CLUSTERS AND IMPLICATIONS FOR TYPE-Ia PROGENITORS AND METAL ENRICHMENT journal October 2010
Intracluster Supernovae in the Multi-Epoch Nearby Cluster Survey journal February 2011
X-RAY EMISSION FROM TWO INFRARED-SELECTED GALAXY CLUSTERS AT z > 1.4 IN THE IRAC SHALLOW CLUSTER SURVEY journal April 2011
SCALING RELATIONS AND OVERABUNDANCE OF MASSIVE CLUSTERS AT z ≳ 1 FROM WEAK-LENSING STUDIES WITH THE HUBBLE SPACE TELESCOPE journal August 2011
Grb 081029: a Gamma-Ray Burst with a Multi-Component Afterglow journal December 2011
First-Year Sloan Digital sky Survey-Ii Supernova Results: Hubble Diagram and Cosmological Parameters journal October 2009
ULTRA-BRIGHT OPTICAL TRANSIENTS ARE LINKED WITH TYPE Ic SUPERNOVAE journal October 2010
Type I SNe from double degenerate CO dwarfs and their rate in the solar neighbourhood journal November 1986
On the merging rates of envelope-deprived components of binary systems which can give rise to supernova events journal August 1989
Merging of binary white dwarfs, neutron stars and black holes under the influence of gravitational wave radiation journal June 1994
Relative frequencies of Type Ia and Type II supernovae in the chemical evolution of the Galaxy, LMC and SMC journal December 1995
Composite Luminosity Functions Based on the Sloan Digital Sky Survey “Cut and Enhance” Galaxy Cluster Catalog journal August 2002
Delay Time Distribution Measurement of Type Ia Supernovae by the Subaru/XMM-Newton Deep Survey and Implications for the Progenitor journal December 2008
Subaru FOCAS Spectroscopic Observations of High-Redshift Supernovae journal February 2010
The type Ia supernova rate in z <= 1 galaxy clusters: implications for progenitors and the source of cluster iron journal January 2004
Intergalactic stars in z   0.25 galaxy clusters: systematic properties from stacking of Sloan Digital Sky Survey imaging data journal April 2005
Batch discovery of nine z ∼ 1 clusters using X-ray and K or R , z ′ images journal June 2005
The build-up of the red sequence in the galaxy cluster MS1054−0321 at z= 0.831: The build-up of the red sequence in MS1054 journal May 2006
Two populations of progenitors for Type Ia supernovae? journal August 2006
XMM -LSS discovery of a galaxy cluster journal September 2006
Feedback and metal enrichment in cosmological SPH simulations ��� II. A multiphase model with supernova energy feedback journal September 2006
Supernovae in the Subaru Deep Field: an initial sample and Type Ia rate out to redshift 1.6: Supernovae in the SDF journal November 2007
Scaling relations of the colour-detected cluster RzCS 052 at z= 1.016 and some other high-redshift clusters journal January 2008
The supernova rate in local galaxy clusters: SN rate in local galaxy clusters journal December 2007
Galaxy evolution in the high-redshift, colour-selected cluster RzCS 052 at z = 1.02 journal April 2008
The history of mass assembly of faint red galaxies in 28 galaxy clusters since z =  1.3 journal May 2008
Rates, progenitors and cosmic mix of Type Ia supernovae journal August 2008
How old are SN Ia progenitor systems? New observational constraints on the distribution of time delays from GALEX journal August 2009
Nearby supernova rates from the Lick Observatory Supernova Search - II. The observed luminosity functions and fractions of supernovae in a complete sample: Nearby supernova rates from LOSS - II journal March 2011
On the evolution of the Fe abundance and of the Type Ia supernova rate in clusters of galaxies journal June 2007

Cited By (12)

High-redshift supernova rates measured with the gravitational telescope A 1689 journal October 2016
THE HUBBLE SPACE TELESCOPE CLUSTER SUPERNOVA SURVEY. VI. THE VOLUMETRIC TYPE Ia SUPERNOVA RATE journal December 2011
THE HUBBLE SPACE TELESCOPE CLUSTER SUPERNOVA SURVEY. V. IMPROVING THE DARK-ENERGY CONSTRAINTS ABOVE z > 1 AND BUILDING AN EARLY-TYPE-HOSTED SUPERNOVA SAMPLE journal January 2012
HOST GALAXIES OF TYPE Ia SUPERNOVAE FROM THE NEARBY SUPERNOVA FACTORY journal May 2013
Unity: Confronting Supernova Cosmology’S Statistical and Systematic Uncertainties in a Unified Bayesian Framework journal November 2015
On rates of supernovae strongly lensed by galactic haloes in Millennium Simulation journal December 2012
Discovery of 90 Type Ia supernovae among 700 000 Sloan spectra: the Type Ia supernova rate versus galaxy mass and star formation rate at redshift ∼0.1 journal February 2013
Type Ia Supernova Distances at Redshift >1.5 from the Hubble Space Telescope Multi-cycle Treasury Programs: The Early Expansion Rate journal January 2018
The Hubble Space Telescope Cluster Supernova Survey: VI. The Volumetric Type Ia Supernova Rate text January 2011
Discovery of 90 Type Ia supernovae among 700,000 Sloan spectra: the Type-Ia supernova rate versus galaxy mass and star-formation rate at redshift ~0.1 text January 2012
Host Galaxies of Type Ia Supernovae from the Nearby Supernova Factory text January 2013
UNITY: Confronting Supernova Cosmology's Statistical and Systematic Uncertainties in a Unified Bayesian Framework text January 2015

Similar Records

THE HUBBLE SPACE TELESCOPE CLUSTER SUPERNOVA SURVEY. II. THE TYPE Ia SUPERNOVA RATE IN HIGH-REDSHIFT GALAXY CLUSTERS
Journal Article · Thu Jan 19 23:00:00 EST 2012 · Astrophysical Journal · OSTI ID:22011995
THE TYPE II SUPERNOVA RATE IN z {approx} 0.1 GALAXY CLUSTERS FROM THE MULTI-EPOCH NEARBY CLUSTER SURVEY
Journal Article · Sun Jul 01 00:00:00 EDT 2012 · Astrophysical Journal · OSTI ID:22036887
THE MULTI-EPOCH NEARBY CLUSTER SURVEY: TYPE Ia SUPERNOVA RATE MEASUREMENT IN z {approx} 0.1 CLUSTERS AND THE LATE-TIME DELAY TIME DISTRIBUTION
Journal Article · Sun Feb 19 23:00:00 EST 2012 · Astrophysical Journal · OSTI ID:22011693

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
cosmology observations
supernovae general
white dwarfs