2005/08/31 by K. Krisciunas, Kevin Krisciunas, Peter M. Garnavich +43
Physics and Astronomy · #Astronomy #Astrophysics #Galaxy #Gamma-ray bursts and supernovae #Hubble space telescope #Light curve #Photometry (optics) #Physics #Population #Pulsars and Gravitational Waves Research #Redshift #Stars #Stellar, planetary, and galactic studies #Supernova #astro-ph
paper · pdf · doi:10.1086/497640
published as Astron.J.130:2453-2472,2005 · 62 pages, 18 numbered figures, accepted for publication in the Astronomical Journal
arxiv created 2005/08/31 · openalex publication_date 2005/11/28 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We present broadband light curves of nine supernovae ranging in redshift from 0.5 to 0.8. The supernovae were discovered as part of the ESSENCE project, and the light curves are a combination of Cerro Tololo 4 m and Hubble Space Telescope ( HST ) photometry. On the basis of spectra and/or light-curve fitting, eight of these objects are definitely Type Ia supernovae, while the classification of one is problematic. The ESSENCE project is a 5 yr endeavor to discover about 200 high-redshift Type Ia supernovae, with the goal of tightly constraining the time average of the equation-of-state parameter [ w = p /(ρ c 2 )] of the "dark energy." To help minimize our systematic errors, all of our ground-based photometry is obtained with the same telescope and instrument. In 2003 the highest redshift subset of ESSENCE supernovae was selected for detailed study with HST . Here we present the first photometric results of the survey. We find that all but one of the ESSENCE supernovae have slowly declining light curves and that the sample is not representative of the low-redshift set of ESSENCE Type Ia supernovae. This is unlikely to be a sign of evolution in the population. We attribute the decline-rate distribution of HST events to a selection bias at the high-redshift edge of our sample and find that such a bias will infect other magnitude-limited Type Ia supernova searches unless appropriate precautions are taken.