Improved Dark Energy Constraints From ~ 100 New CfA Supernova Type Ia Light Curves
Description/Abstract
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 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.
| Creator/Author: | Hicken, Malcolm ; /Harvard-Smithsonian Ctr. Astrophys. /Harvard U. ; Wood-Vasey, W.Michael ; /Pittsburgh U. ; Blondin, Stephane ; /European Southern Observ. ; Challis, Peter ; /Harvard-Smithsonian Ctr. Astrophys. ; Jha, Saurabh ; /Rutgers U., Piscataway ; Kelly, Patrick L. ; /KIPAC, Menlo Park ; Rest, Armin ; /Harvard U. /Cerro-Tololo InterAmerican Obs. ; Kirshner, Robert P. ; /Harvard-Smithsonian Ctr. Astrophys. |
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| Publication Date: | 2012 Apr 06 |
| OSTI Identifier: | OSTI ID: 1038033 |
| Report Number(s): | SLAC-PUB-14938 |
| DOE Contract Number: | AC02-76SF00515 |
| Other Number(s): | Journal ID: ISSN 0004-637X; ASJOAB; Other: arXiv:0901.4804; TRN: US201208%%161 |
| 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 |
| Subject: | 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ACCURACY; COLOR; COSMOLOGICAL CONSTANT; LUMINOSITY; PHOTOMETRY; SHAPE; SUPERNOVAE |
| Related Subject: | Astrophysics,ASTRO |
| Country of Publication: | United States |
| Language: | English |
| Format: | Size: 101 pages |
| Availability: | http://www.slac.stanford.edu/cgi-wrap/pubpage?slac-pub-14938.html |
| Update Date: | 2012 Dec 05 |
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