SciTech Connect

Title: Improved Dark Energy Constraints From ~ 100 New CfA Supernova Type Ia Light Curves

Improved Dark Energy Constraints From ~ 100 New CfA Supernova Type Ia Light Curves We combine the CfA3 supernovae Type Ia (SN Ia) sample with samples from the literature to calculate improved constraints on the dark energy equation of state parameter, w. The CfA3 sample is added to the Union set of Kowalski et al. to form the Constitution set and, combined with a BAO prior, produces 1 + w = 0.013{sub -0.068}{sup +0.066} (0.11 syst), consistent with the cosmological constant. The CfA3 addition makes the cosmologically useful sample of nearby SN Ia between 2.6 and 2.9 times larger than before, reducing the statistical uncertainty to the point where systematics play the largest role. We use four light-curve fitters to test for systematic differences: SALT, SALT2, MLCS2k2 (R{sub V} = 3.1), and MLCS2k2 (R{sub V} = 1.7). SALT produces high-redshift Hubble residuals with systematic trends versus color and larger scatter than MLCS2k2. MLCS2k2 overestimates the intrinsic luminosity of SN Ia with 0.7 < {Delta} < 1.2. MLCS2k2 with R{sub V} = 3.1 overestimates host-galaxy extinction while R{sub V} {approx} 1.7 does not. Our investigation is consistent with no Hubble bubble. We also find that, after light-curve correction, SN Ia in Scd/Sd/Irr hosts are intrinsically fainter than those in E/S0 hosts by 2{sigma}, suggesting that more » they may come from different populations. We also find that SN Ia in Scd/Sd/Irr hosts have low scatter (0.1 mag) and reddening. Current systematic errors can be reduced by improving SN Ia photometric accuracy, by including the CfA3 sample to retrain light-curve fitters, by combining optical SN Ia photometry with near-infrared photometry to understand host-galaxy extinction, and by determining if different environments give rise to different intrinsic SN Ia luminosity after correction for light-curve shape and color. « less
Authors: ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;
Publication Date:
OSTI Identifier:1038033
Report Number(s):SLAC-PUB-14938
Journal ID: ISSN 0004-637X; ASJOAB; arXiv:0901.4804; TRN: US201208%%161
DOE Contract Number:AC02-76SF00515
Resource Type:Journal Article
Resource Relation:Journal Name: Astrophysical Journal; Journal Volume: 700; Journal Issue: 2
Research Org:SLAC National Accelerator Laboratory (SLAC)
Sponsoring Org:USDOE
Country of Publication:United States
Language:English
Subject: 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ACCURACY; COLOR; COSMOLOGICAL CONSTANT; LUMINOSITY; PHOTOMETRY; SHAPE; SUPERNOVAE Astrophysics,ASTRO