Absolute Distances to Nearby Type Ia Supernovae via Light Curve Fitting Methods

TL;DR

This study compares different light curve fitting methods to determine precise absolute distances to nearby Type Ia supernovae, finding that current techniques can achieve less than 0.2 mag uncertainty, with room for further accuracy improvements.

Contribution

It provides a homogeneous dataset and a comparative analysis of multiple light curve fitters, demonstrating their consistency and limitations in measuring supernova distances.

Findings

Distance moduli agree within ~0.2 mag for most SNe

High signal-to-noise data improves agreement to <0.1 mag

Distances are consistent with Cepheid measurements

Abstract

We present a comparative study of absolute distances to a sample of very nearby, bright Type Ia supernovae (SNe) derived from high cadence, high signal-to-noise, multi-band photometric data. Our sample consists of four SNe: 2012cg, 2012ht, 2013dy and 2014J. We present new homogeneous, high-cadence photometric data in Johnson-Cousins BVRI and Sloan g'r'i'z' bands taken from two sites (Piszkesteto and Baja, Hungary), and the light curves are analyzed with publicly available light curve fitters (MLCS2k2, SNooPy2 and SALT2.4). When comparing the best-fit parameters provided by the different codes, it is found that the distance moduli of moderately-reddened SNe Ia agree within ~0.2 mag, and the agreement is even better (< 0.1 mag) for the highest signal-to-noise BVRI data. For the highly-reddened SN~2014J the dispersion of the inferred distance moduli is slightly higher. These SN-based distances are in good agreement with the Cepheid distances to their host galaxies. We conclude that the current state-of-the-art light curve fitters for Type Ia SNe can provide consistent absolute distance moduli having less than ~0.1 -- 0.2 mag uncertainty for nearby SNe. Still, there is room for future improvements to reach the desired ~0.05 mag accuracy in the absolute distance modulus.