The correlation of SN Ia parameters with host galaxy properties
Cosmology Beyond the Standard Model
Dr Heather Campbll
Morgan Fraser (IoA)
Institute of Astronomy, University of Cambridge
I will be presented a systematic study of the relationship between Type Ia Supernova (SN Ia) properties, and the properties of their host galaxies, using a sample of 581 SNe Ia from the full Sloan Digital Sky Survey II (SDSS-II) SN Survey. I will also discuss the investigation of the effects of this on the cosmological constraints derived from SNe Ia. Compared to previous studies, our sample is larger by a factor of > 4, and covers a substantially larger range of redshifts (up to z 0.5), which is directly applicable to the region of cosmological interest.

We measure a significant correlation between the host-galaxy stellar-mass and the SNe Ia Hubble Residuals (HR). The correlation between host-galaxy stellar mass and the SNe Ia Hubble residuals is likely to be due to an underlying physical property such as metallicity, for which the mass of the galaxy (which is easy to measure) is simply acting as a proxy. We find a weak correlation between the host-galaxy metallicity and the SNe Ia HR.

We apply a linear correction to the distance modulus, based on either host-galaxy stellar mass or metallicity, and then test the effect of these on a cosmological analysis.We see a shift towards a more negative equations of state parameter w and a shift to lower values of Omega_m when using both the mass and metallicity correction. The shift with host-galaxy stellar-mass correction is consistent with previous studies and we also see a small reduction in the size of the contours.


09:00 - 10:30