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| Union Supernova Compilation | |
|---|---|
| Name | Union Supernova Compilation |
| Type | Supernova compilation |
| Epoch | 2000s |
| Objects | Type Ia supernovae |
| Data release | Multiple |
Union Supernova Compilation is a consolidated dataset of Type Ia supernova observations assembled to improve cosmological distance measurements and constrain parameters such as the Hubble constant and dark energy equation of state. The compilation aggregates photometric and spectroscopic measurements from multiple surveys and observatories to produce a homogeneous sample for analysis. It has been used in studies connected to Hubble Space Telescope, Sloan Digital Sky Survey, Supernova Cosmology Project, High-Z Supernova Search Team, and follow-up programs at facilities such as Keck Observatory and European Southern Observatory.
The compilation was developed to reconcile heterogeneous datasets from projects including ESSENCE, SDSS-II Supernova Survey, SNLS, CfA Supernova Program, and archival data from Nearby Supernova Factory and individual efforts by teams at Harvard–Smithsonian Center for Astrophysics, Carnegie Observatories, and Lawrence Berkeley National Laboratory. It provided a standardized basis for joint analyses with cosmic microwave background constraints from Wilkinson Microwave Anisotropy Probe and baryon acoustic oscillation measurements from Sloan Digital Sky Survey and 2dF Galaxy Redshift Survey. Key collaborative institutions involved range from University of California, Berkeley to Paris Observatory and Max Planck Institute for Astrophysics.
Photometry and spectra were culled from public archives and team releases such as CfA Supernova Program data releases, the SUSPECT database, and survey-specific catalogs from SNLS and SDSS. Observational contributions came from telescopes including Subaru Telescope, Gemini Observatory, Magellan Telescopes, Very Large Telescope, and the Hale Telescope. The compilation reconciled photometric systems tied to standards like those used by Landolt photometric system and spectrophotometric references from Oke Standards and instrument calibrations at Keck Observatory and European Southern Observatory.
The sample selection prioritized spectroscopically confirmed Type Ia events identified by teams such as Supernova Cosmology Project and High-Z Supernova Search Team and cross-checked with classifications from Sternberg Astronomical Institute follow-ups and catalogs maintained by the International Astronomical Union supernova working group. Selection cuts addressed criteria used by Riess et al., Perlmutter et al., and later compilations from Conley et al. and Suzuki et al., ensuring uniformity in redshift coverage spanning nearby hosts cataloged in Revised Shapley-Ames Catalog to high-redshift objects discovered in surveys associated with Hubble Space Telescope deep fields. Host galaxy identifications referenced databases such as NASA/IPAC Extragalactic Database and redshift confirmations from Sloan Digital Sky Survey and 2dF Galaxy Redshift Survey.
Light curves were reprocessed using fitting frameworks inspired by models like SALT2, MLCS2k2, and methods adopted by teams including Guy et al. and Jha et al., with cross-calibration to photometric systems employed by Landolt photometric system and the AB magnitude system. The compilation applied corrections for Milky Way extinction using maps from Schlegel, Finkbeiner & Davis and color-law treatments paralleling work by Cardelli, Clayton & Mathis. Photometric zeropoints were reconciled via secondary standards observed at Cerro Tololo Inter-American Observatory, Las Campanas Observatory, and Kitt Peak National Observatory to minimize inter-survey offsets noted in analyses by Betoule et al. and Conley et al..
Spectroscopic data provided redshift determination, classification, and host-galaxy velocity dispersion estimates, with spectra obtained at facilities including Keck Observatory, Very Large Telescope, Gemini Observatory, and Subaru Telescope. Redshift precision relied on narrow host-galaxy emission/absorption features cataloged in NASA/IPAC Extragalactic Database and line identifications consistent with templates from SNID and spectral libraries used by Blondin et al.. Spectroscopic phases were tied to light-curve maxima following prescriptions from Phillips relation studies and spectral sequence work by Branch et al..
Analyses using the compilation combined distance modulus estimates with external probes from WMAP cosmic microwave background constraints, Baryon Acoustic Oscillations results from SDSS and 2dF Galaxy Redshift Survey, and local distance ladder measurements tied to Cepheid variable studies by Riess et al. The dataset contributed to constraints on the matter density parameter in concordance with results from Planck (ESA) and investigations of the dark energy equation-of-state parameter w in the tradition of analyses by Perlmutter et al. and Riess et al.. Results informed discussions involving the Hubble tension between local and cosmological determinations and were used in joint likelihood studies interfacing with teams at University of Oxford and Institute of Astronomy, Cambridge.
Systematic error treatment followed approaches outlined by Amanullah et al., Conley et al., and Suzuki et al., addressing photometric calibration, selection bias (Malmquist bias) characterized against simulations from groups at Kavli Institute for Cosmological Physics, host-galaxy correlations explored by Sullivan et al., and cross-survey zeropoint offsets. Calibration strategies referenced spectrophotometric standards observed with Hubble Space Telescope and laboratory standards maintained at NIST. The compilation quantified systematics impacting cosmological inferences and motivated subsequent efforts by collaborations such as Dark Energy Survey and LSST Science Collaboration to produce more uniformly calibrated supernova samples.
Category:Supernova datasets