Cosmology with photometrically classified type IA supernovae from the SDSS-II supernova survey
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Date
2013
Journal Title
Journal ISSN
Volume Title
Publisher
The American Astronomical Society
Abstract
We present the cosmological analysis of 752 photometrically–classified Type Ia Supernovae (SNe Ia)
obtained from the full Sloan Digital Sky Survey II (SDSS-II) Supernova (SN) Survey, supplemented
with host–galaxy spectroscopy from the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS).
Our photometric–classificationmethod is based on the SN typing technique of Sako et al. (2011), aided
by host galaxy redshifts (0.05 < z < 0.55). SNANA simulations of our methodology estimate that
we have a SN Ia typing efficiency of 70.8%, with only 3.9% contamination from core-collapse (non-Ia)
SNe. We demonstrate that this level of contamination has no effect on our cosmological constraints.
We quantify and correct for our selection effects (e.g., Malmquist bias) using simulations. When fitting
to a flat _CDM cosmological model, we find that our photometric sample alone gives Ωm = 0.24+0.07/−0.05
(statistical errors only). If we relax the constraint on flatness, then our sample provides competitive
joint statistical constraints on Ωm and Ω∆, comparable to those derived from the spectroscopically-
confirmed three-year Supernova Legacy Survey (SNLS3). Using only our data, the statistics–only
result favors an accelerating universe at 99.96% confidence. Assuming a constant wCDM cosmological
model, and combining with H0, CMB and LRG data, we obtain w = −0.96+0.10/−0.10, Ωm = 0.29+0.02/−0.02 and Ωk = 0.00+0.03/−0.02 (statistical errors only), which is competitive with similar spectroscopically confirmed
SNe Ia analyses. Overall this comparison is reassuring, considering the lower redshift leverage of the
SDSS-II SN sample (z < 0.55) and the lack of spectroscopic confirmation used herein. These results
demonstrate the potential of photometrically–classified SNe Ia samples in improving cosmological
constraints.
Description
Keywords
Supernovae, General, Cosmology, Observations, Surveys, Distance scale
Citation
Campbell, H. et al. (2013). Cosmology with photometrically classified type IA supernovae from the SDSS-II supernova survey. Astrophysical Journal Letters, 763(2): 88