IMAGING AND DEMOGRAPHY OF THE HOST GALAXIES OF HIGH-REDSHIFT TYPE Ia SUPERNOVAE

We present the results of a study of the host galaxies of high-redshift Type Ia supernovae (SNe Ia). We provide a catalog of 18 hosts of SNe Ia observed with the Hubble Space Telescope (HST) by the High-z Supernova Search Team, including images, scale lengths, measurements of integrated (Hubble-equivalent) BVRIZ photometry in bands where the galaxies are brighter than m 25 mag, and galactocentric distances of the supernovae. We compare the residuals of SN Ia distance measurements from cosmological fits with measurable properties of the supernova host galaxies that might be expected to correlate with variable properties of the progenitor population, such as host-galaxy color and position of the supernova. We find mostly null results; the current data are generally consistent with no correlations of the distance residuals with host-galaxy properties in the redshift range 0.42 < z < 1.06. Although a subsample of SN hosts shows a formally significant (3 ) correlation between apparent V R host color and distance residuals, the correlation is not consistent with the null results from other host colors probed by our largest samples. There is also evidence for the same correlations between SN Ia properties and host type at low redshift and high redshift. These similarities support the current practice of extrapolating properties of the nearby population to high redshifts, pending more robust detections of any correlations between distance residuals from cosmological fits and host properties.Support for this work at the University of Washington was provided by NSF grant AST 00-9855 and by NASA grant AR-09201 from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. A. V. F.’s group at the University of California, Berkeley, is supported by NSF grant AST 02-06329 and by NASA grant GO-09118 from STScI. A. C. acknowledges the support of CONICYT (Chile) through FONDECYT grants 1000524 and 7000524