Clustering of supernova Ia host galaxies

For the first time the cross-correlation between Type Ia supernova host galaxies and surrounding field galaxies is measured using the Supernova Legacy Survey sample. Over the redshift range we find that z = 0.2-0.9 supernova hosts are correlated an average of 60% more strongly than similarly selected field galaxies over the 3"-100" range and about a factor of 3 more strongly below 10". The correlation errors are empirically established 10 with a jackknife analysis of the four SNLS fields. The hosts are more correlated than the field at a significance of 99% in the fitted amplitude and slope, with the point-by-point difference of the two correlation functions having a reduced chi(2) for 8 degrees of freedom of 4.3, which has a probability of random occurrence of less than 3 x 10(-5). The correlation angle is 1.5" +/- 0.5", which deprojects to a fixed comoving correlation length of approximately 6.5 +/- 2 h(-1) Mpc. Weighting the field galaxies with the mass and star formation rate supernova frequencies of the simple model produces good agreement with the observed clustering. We conclude that A + B these supernova clustering differences are primarily the expected outcome of the dependence of supernova rates on galaxy masses and stellar populations with their clustering environment.