Distance determination to 12 Type II Supernovae using the Expanding Photosphere Method

TL;DR

This study applies the Expanding Photosphere Method to 12 Type II Supernovae using various models and filters, achieving a Hubble constant estimate and validating distances with Cepheid measurements.

Contribution

It provides a detailed analysis of supernova distances using multiple models and filters, improving the accuracy of the EPM and estimating the Hubble constant.

Findings

Hubble diagram dispersion of 0.32 mag with VI filters and D05 models

Hubble constant estimated at 52.4 +/- 4.3 km s-1 Mpc-1

Distance to SN 1999em consistent with Cepheid measurement

Abstract

We used early time photometry and spectroscopy of 12 Type II plateau Supernovae (SNe IIP) to derive their distances using the Expanding Photosphere Method (EPM). We performed this study using two sets of Type II supernovae (SNe II) atmosphere models (E96, D05), three filter subsets (BV, BVI, VI) and two methods for the host galaxy extinctions, which led to 12 Hubble diagrams. Using the VI filter subset and the D05 models we obtained a dispersion in the Hubble diagram of sigma = 0.32 mag and a Hubble constant of H0 = 52.4 +/- 4.3 km s-1 Mpc-1. We also applied the EPM analysis to the well-observed SN IIP SN 1999em. With the VI filter subset and the D05 models we derived a distance of 13.9 +/- 1.4 Mpc, agreement with the Cepheid distance of 11.7 +/- 1.0 Mpc to the SN 1999em host galaxy (NGC 1637).