Improved Dark Energy Constraints from ~100 New CfA Supernova Type Ia Light Curves

Details 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

2009-01-29

arxiv.org/abs/0901.4804v3

Astrophys.J.700:1097-1140,2009

Astronomy and Astrophysics

Astrophysics

Cosmology and Extragalactic Astrophysics

Accepted to the Astrophysical Journal. Minor changes from last version. 101 pages, 21 figures

Scientific paper

10.1088/0004-637X/700/2/1097

We combine the CfA3 supernova 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. (2008) to form the Constitution set and, combined with a BAO prior, produces 1+w=0.013 +0.066/-0.068 (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_V=3.1), and MLCS2k2 (R_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_V=3.1 overestimates host-galaxy extinction while R_V=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 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.

Affiliated with

Also associated with

No associations

Rating

Improved Dark Energy Constraints from ~100 New CfA Supernova Type Ia Light Curves does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Improved Dark Energy Constraints from ~100 New CfA Supernova Type Ia Light Curves, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Improved Dark Energy Constraints from ~100 New CfA Supernova Type Ia Light Curves will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-424319