Journal
ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES
Volume 192, Issue 1, Pages -Publisher
IOP PUBLISHING LTD
DOI: 10.1088/0067-0049/192/1/1
Keywords
cosmological parameters; cosmology: observations; supernovae: general
Categories
Funding
- NSERC
- CIAR
- CNRS/IN2P3
- CNRS/INSU
- CEA
- Fundacao para a Ciencia e Tecnologia
- STFC [ST/H000704/1, ST/H002456/1] Funding Source: UKRI
- Science and Technology Facilities Council [ST/H000704/1, ST/H002456/1] Funding Source: researchfish
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We combine high-redshift Type Ia supernovae from the first three years of the Supernova Legacy Survey (SNLS) with other supernova (SN) samples, primarily at lower redshifts, to form a high-quality joint sample of 472 SNe (123 low-z, 93 SDSS, 242 SNLS, and 14 Hubble Space Telescope). SN data alone require cosmic acceleration at > 99.999% confidence, including systematic effects. For the dark energy equation of state parameter (assumed constant out to at least z = 1.4) in a flat universe, we find w = -0.91(-0.20+)(0.16) (stat)(-0.14+)(0.07) (sys) from SNe only, consistent with a cosmological constant. Our fits include a correction for the recently discovered relationship between host-galaxy mass and SN absolute brightness. We pay particular attention to systematic uncertainties, characterizing them using a systematic covariance matrix that incorporates the redshift dependence of these effects, as well as the shape-luminosity and color-luminosity relationships. Unlike previous work, we include the effects of systematic terms on the empirical light-curve models. The total systematic uncertainty is dominated by calibration terms. We describe how the systematic uncertainties can be reduced with soon to be available improved nearby and intermediate-redshift samples, particularly those calibrated onto USNO/SDSS-like systems.
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