From Sloan Digital Sky Survey u ’ g ’ r ’ i ’ z ’ imaging , we estimate the stellar masses of the host galaxies of 70 low redshift SN Ia ( 0.015 < z < 0.08 ) from the hosts ’ absolute luminosities and mass-to-light ratios .
These nearby SN were discovered largely by searches targeting luminous galaxies , and we find that their host galaxies are substantially more massive than the hosts of SN discovered by the flux-limited Supernova Legacy Survey .
Testing four separate light curve fitters , we detect \sim 2.5 \sigma correlations of Hubble residuals with both host galaxy size and stellar mass , such that SN Ia occurring in physically larger , more massive hosts are \sim 10 % brighter after light curve correction .
The Hubble residual is the deviation of the inferred distance modulus to the SN , calculated from its apparent luminosity and light curve properties , away from the expected value at the SN redshift .
Marginalizing over linear trends in Hubble residuals with light curve parameters shows that the correlations can not be attributed to a light curve-dependent calibration error .
Combining 180 higher-redshift ESSENCE , SNLS , and HigherZ SN with 30 nearby SN whose host masses are less than 10 ^ { 10.8 } M _ { \sun } in a cosmology fit yields 1 + w = 0.22 ^ { +0.152 } _ { -0.108 } , while a combination where the 30 nearby SN instead have host masses greater than 10 ^ { 10.8 } M _ { \sun } yields 1 + w = -0.03 ^ { +0.217 } _ { -0.143 } .
Progenitor metallicity , stellar population age , and dust extinction correlate with galaxy mass and may be responsible for these systematic effects .
Host galaxy measurements will yield improved distances to SN Ia .