Improved Standardization of Type II-P Supernovae: Application to an Expanded Sample

TL;DR

This study demonstrates that Type II-P supernovae can serve as reliable standard candles for cosmology, achieving a 10% distance accuracy using an improved methodology and a small sample of 17 supernovae.

Contribution

The paper introduces an improved standardization method for Type II-P supernovae, showing they are nearly as precise as Type Ia supernovae for distance measurements.

Findings

SN II-P are good standardizable candles with 10% dispersion.

A simplified correction method reduces dust extinction impact.

Distance can be measured with a single spectrum and sparse photometry.

Abstract

In the epoch of precise and accurate cosmology, cross-confirmation using a variety of cosmographic methods is paramount to circumvent systematic uncertainties. Owing to progenitor histories and explosion physics differing from those of Type Ia SNe (SNe Ia), Type II-plateau supernovae (SNe II-P) are unlikely to be affected by evolution in the same way. Based on a new analysis of 17 SNe II-P, and on an improved methodology, we find that SNe II-P are good standardizable candles, almost comparable to SNe Ia. We derive a tight Hubble diagram with a dispersion of 10% in distance, using the simple correlation between luminosity and photospheric velocity introduced by Hamuy & Pinto 2002. We show that the descendent method of Nugent et al. 2006 can be further simplified and that the correction for dust extinction has low statistical impact. We find that our SN sample favors, on average, a very steep dust law with total to selective extinction R_V<2. Such an extinction law has been recently inferred for many SNe Ia. Our results indicate that a distance measurement can be obtained with a single spectrum of a SN II-P during the plateau phase combined with sparse photometric measurements.