The Standardized Candle Method for Type II Plateau Supernovae

TL;DR

This study refines the standardized candle method for Type II plateau supernovae, demonstrating their potential for precise distance measurements with a new approach to reddening correction and velocity-luminosity relation.

Contribution

It introduces an analytic procedure for fitting supernova light, color, and velocity curves, improving distance estimation accuracy by optimizing reddening law parameters.

Findings

V-I color at the end of the plateau estimates host-galaxy reddening with 0.2 mag precision.

The velocity-luminosity correlation is confirmed and used for distance calculations.

Distances can be measured with 12-14% precision using the optimized reddening law.

Abstract

In this paper we study the "standardized candle method" using a sample of 37 nearby (z<0.06) Type II plateau supernovae having BVRI photometry and optical spectroscopy. An analytic procedure is implemented to fit light curves, color curves, and velocity curves. We find that the V-I color toward the end of the plateau can be used to estimate the host-galaxy reddening with a precision of 0.2 mag. The correlation between plateau luminosity and expansion velocity previously reported in the literature is recovered. Using this relation and assuming a standard reddening law (Rv = 3.1), we obtain Hubble diagrams in the BVI bands with dispersions of ~0.4 mag. Allowing Rv to vary and minimizing the spread in the Hubble diagrams, we obtain a dispersion range of 0.25-0.30 mag, which implies that these objects can deliver relative distances with precisions of 12-14%. The resulting best-fit value of Rv is 1.4 +/- 0.1.