The Red Supergiant Problem: As Seen from the Local Group's Red Supergiant Populations

TL;DR

This study re-evaluates the red supergiant problem by analyzing local group RSG populations, finding no significant evidence of missing high-luminosity progenitors in Type II supernovae due to uncertainties in measurements.

Contribution

It introduces a comprehensive analysis of RSG populations across the Local Group, accounting for uncertainties, and challenges previous claims of missing high-luminosity progenitors.

Findings

No evidence of missing high-luminosity progenitors in SN II pre-images.

Uncertainties in luminosity measurements are too large to confirm population differences.

Only late-type M3 or later RSGs match the observed SN progenitor luminosity distribution.

Abstract

The red supergiant (RSG) problem, which describes the apparent lack of high-luminosity progenitors detected in Type II supernova (SN) pre-images, has been a contentious topic for two decades. We re-assess this problem using a new RSG population of the Milky Way supplemented with RSGs from other galaxies in the Local Group. In particular, we quantify the uncertainties inherent to assumptions made regarding the star's temperature or spectral type and the corresponding bolometric correction. We find that only M3 or later RSGs reproduce the steepness seen from the SN II pre-imaged sample. To assess the significance of the RSG problem, we build a metallicity-weighted cumulative luminosity distribution of M3 or later RSGs and directly compare it to the luminosity distribution of SN II pre-imaged progenitors. We find no evidence of missing high-luminosity pre-imaged progenitors since the uncertainties on the pre-imaged SN progenitors and single-band derived luminosity are too large to meaningfully infer population differences.