Browsing by Author "Jha, Saurabh W"

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    Improved constraints on type Ia supernova host galaxy properties using multi-wavelength photometry and their correlations with supernova properties
    (2011) Gupta, Ravi R; D’Andrea, Chris B; Sako, Masao; Conroy, Charlie; Smith, Mathew; Bassett, Bruce; Frieman, Joshua A; Garnavich, Peter M; Jha, Saurabh W; Kessler, Richard; Lampeitl, Hubert; Marriner, John; Nichol, Robert C; Schneider, Donald P
    We improve estimates of the stellar mass and mass-weighted average age of Type Ia supernova (SN Ia) host galaxies by combining UV and near-IR photometry with optical photometry in our analysis. Using 206 SNe Ia drawn from the full three-year Sloan Digital Sky Survey (SDSS-II) Supernova Survey (median redshift of z 0.2) and multi-wavelength host-galaxy photometry from SDSS, the Galaxy Evolution Explorer, and the United Kingdom Infrared Telescope Infrared Deep Sky Survey, we present evidence of a correlation (1.9σ confidence level) between the residuals of SNe Ia about the best-fit Hubble relation and the mass-weighted average age of their host galaxies. The trend is such that older galaxies host SNe Ia that are brighter than average after standard light-curve corrections are made. We also confirm, at the 3.0σ level, the trend seen by previous studies that more massive galaxies often host brighter SNe Ia after light-curve correction.
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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 SDSS-II SUPERNOVA SURVEY: PARAMETERIZING THE TYPE Ia SUPERNOVA RATE AS A FUNCTION OF HOST GALAXY PROPERTIES
    (2012) Smith, Mathew; Nichol, Robert C; Dilday, Benjamin; Marriner, John; Kessler, Richard; Bassett, Bruce; Cinabro, David; Frieman, Joshua; Garnavich, Peter; Jha, Saurabh W; Lampeitl, Hubert; Sako, Masao; Schneider, Donald P; Sollerman, Jesper
    Using data from the Sloan Digital Sky Supernova Survey-II (SDSS-II SN Survey), we measure the rate of Type Ia supernovae (SNe Ia) as a function of galaxy properties at intermediate redshift. A samp ...