Should Type Ia Supernova Distances Be Corrected for Their Local Environments?

Abstract Recent analyses suggest that distance residuals measured from Type Ia supernovae (SNe Ia) are correlated with local host galaxy properties within a few kiloparsecs of the SN explosion. However, the well-established correlation with global host galaxy properties is nearly as significant, with a shift of 0.06 mag across a low to high mass boundary (the mass step). Here, with 273 SNe Ia at z 2 σ after global mass correction, and we conservatively estimate a systematic shift in H 0 measurements of −0.14 km s −1 Mpc −1 with an additional uncertainty of 0.14 km s −1 Mpc −1 , ∼10% of the present uncertainty.