A Revised SALT2 Surface for Fitting Type Ia Supernova Light Curves

Understand

We present a revised SALT2 surface (`SALT2-2021') for fitting the light curves of Type Ia supernovae (SNe Ia), which incorporates new measurements of zero-point calibration offsets and Milky Way extinction.

• The most notable change in the new surface occurs in the UV region.
• This new surface alters the distance measurements of SNe~Ia, which can be used to investigate the nature of dark energy by probing the expansion history of the Universe.
• Using the revised SALT2 surface on public data from the first three years of the Dark Energy Survey Supernova Program (combined with an external low-$z$ SNe Ia sample) and combining with cosmic microwave background constraints, we find a change in the dark energy equation of state parameter, $\Delta w = 0.015 \pm 0.004$.