Browsing by Author "D\'Andrea, Chris B"

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    Spectroscopic properties of star-forming host galaxies and type Ia supernova hubble residuals in a nearly unbiased sample
    (2011) D\'Andrea, Chris B; Gupta, Ravi R; Sako, Masao; Morris, Matt; Nichol, Robert C; Brown, Peter J; Campbell, Heather; Olmstead, Matthew D; Frieman, Joshua A; Garnavich, Peter; Jha, Saurabh W; Kessler, Richard; Lampeitl, Hubert; Marriner, John; Schneider, Donald P; Smith, Mathew
    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 < M{sub r} < -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 {approx}40 emission-line galaxies, we find that light-curve-corrected SNe Ia are {approx}0.1 mag brighter in high-metallicity hosts than in low-metallicity hosts. We also find a significant (>3{sigma}) 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.
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    THE EFFECT OF WEAK LENSING ON DISTANCE ESTIMATES FROM SUPERNOVAE
    (2014) Smith, Mathew; Bacon, David J; Nichol, Robert C; Campbell, Heather; Clarkson, Chris; Maartens, Roy; D\'Andrea, Chris B; Bassett, Bruce A; Cinabro, David; Finley, David A; Frieman, Joshua A; Galbany, Lluís; Garnavich, Peter M; Olmstead, Matthew D; Schneider, Donald P; Shapiro, Charles; Sollerman, Jesper
    Using a sample of 608 Type Ia supernovae from the SDSS-II and BOSS surveys, combined with a sample of foreground galaxies from SDSS-II, we estimate the weak lensing convergence for each supernova l ...