How We Can Account for Type Ia Supernova Environment in Cosmological Analysis

Among the other types of supernovae, Type Ia Supernovae (SNe Ia) have less luminosity dispersion at maximum light and show higher optical luminosities. These properties allow to use them as cosmological distance indicators that led to the discovery of the accelerating expansion of the Universe. However, even after the luminosity correction for stretch and color parameters—“standardization”, there is a remaining dispersion on the Hubble diagram of ~0.11 mag. This dispersion can be due to SN environmental effects—progenitor age, chemical composition, surrounding dust. In this work we study the impact of SN galactocentric distance (376 Pantheon SNe Ia) and host-galaxy morphology (275 Pantheon SNe Ia) on the light curve parameters. We confirm that the stretch-parameter depends on galactocentric distance and host morphology, but there is no significant correlation for the color. In the epoch of large transient surveys such as the Vera Rubin Observatory’s Legacy Survey of Space and Time, a study of environment and other possible sources of systematical uncertainties in the cosmological analysis is of high priority.