Correlations between SNe Ia Rates and Host Galaxy Properties
  Studying the correlation of type Ia supernova rates (SNR) with host galaxy
properties is an important step in understanding the exact nature of type Ia
supernovae. We use SNe Ia from the SDSS-II sample, spectroscopically determined
masses and star formation rates, and a new maximum likelihood method, to fit
the Scannapieco and Bildsten rate model $SNR = A{\times}M + B{\times}SFR$,
where $M$ is galaxy mass and $SFR$ is star formation rate. We find $A =
3.5^{+0.9}_{-0.7}\times10^{-14}(\text{SNe/yr})(M_{\odot})^{-1}$ and $B
=1.3^{+0.4}_{-0.3}\times10^{-3}(\text{SNe/yr})(M_{\odot}$yr$^{-1})^{-1}$,
assuming overall efficiency of 0.5. This is in reasonable agreement with other
determinations. However we find strong evidence that this model is a poor fit
to other projections of the data: it fails to correctly predict the
distribution of supernovae with host mass or SFR. An additional model parameter
is required; most likely this parameter is related to host galaxy mass. Some
implications of this result are discussed.
