Cosmology with photometrically-classified Type Ia Supernovae from the SDSS-II Supernova Survey

Heather C. Campbell, Chris B. D’Andrea, Robert C. Nichol, Masao Sako, Mathew Smith, Hubert Lampeitl, Matthew D. Olmstead, Bruce A. Bassett, Rahul Biswas, Peter J. Brown, David Cinabro, Kyle S. Dawson, Benjamin Dilday, Ryan J. Foley, Joshua A. Frieman, Peter M. Garnavich, Renee Hlozek, Saurabh W. Jha, Steve Kuhlmann, Martin KunzJohn P. Marriner, Ramon Miquel, Michael W. Richmond, Adam G. Riess, Donald P. Schneider, Jesper Sollerman, Matt Taylor, Gong-Bo Zhao

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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. Our photometric-classification method is based on the SN classification technique of Sako et al., aided by host-galaxy redshifts (0.05 < z < 0.55). SuperNova ANAlysis simulations of our methodology estimate that we have an SN Ia classification 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 ΛCDM cosmological model, we find that our photometric sample alone gives Ω m = 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 Ω m and ΩΛ, 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 H 0, cosmic microwave background, and luminous red galaxy data, we obtain w = –0.96+0.10 –0.10, Ω m = 0.29+0.02 –0.02, and Ω k = 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 SN Ia samples in improving cosmological constraints.
Original languageEnglish
Pages (from-to)88
JournalThe Astrophysical Journal
Issue number2
Early online date14 Jan 2013
Publication statusPublished - 1 Feb 2013


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