Spectroscopic properties of star-forming host galaxies and Type Ia supernova hubble residuals in a nearly unbiased sample

Chris D'Andrea, Ravi R. Gupta, Masao Sako, Matt Morris, Robert C. Nichol, Peter J. Brown, Heather C. Campbell, Matthew D. Olmstead, Joshua A. Frieman, Peter M. Garnavich, Saurabh W. Jha, Richard Kessler, Hubert Lampeitl, John P. Marriner, Donald P. Schneider, Mathew Smith

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Abstract

We examine the correlation between supernova (SN) host-galaxy properties and their residuals in the Hubble diagram. We use SNe discovered during the Sloan Digital Sky Survey-II Supernova Survey, and focus on objects at a redshift of z < 0.15, where the selection effects of the survey are known to yield a complete Type Ia supernova (SN Ia) sample. To minimize the bias in our analysis with respect to measured host-galaxy properties, spectra were obtained for nearly all hosts, spanning a range in magnitude of –23 < Mr < –17. In contrast to previous works that use photometric estimates of host mass as a proxy for global metallicity, we analyze host-galaxy spectra to obtain gas-phase metallicities and star formation rates (SFRs) from host galaxies with active star formation. From a final sample of ~40 emission-line galaxies, we find that light-curve-corrected SNe Ia are ~0.1 mag brighter in high-metallicity hosts than in low-metallicity hosts. We also find a significant (>3σ) correlation between the Hubble Residuals of SNe Ia and the specific SFR of the host galaxy. We comment on the importance of SN/host-galaxy correlations as a source of systematic bias in future deep SN surveys.
Original languageEnglish
Pages (from-to)172
JournalThe Astrophysical Journal
Volume743
Issue number2
DOIs
Publication statusPublished - 20 Dec 2011

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