Failed Supernova Remnants

TL;DR

This paper explores the properties and detectability of remnants from failed supernovae, which are characterized by soft X-ray emission, small size, and slow expansion, especially in the context of the Large Magellanic Cloud.

Contribution

It introduces the concept of failed supernova remnants, analyzing their emission characteristics and assessing their detectability with current and future X-ray surveys.

Findings

Failed SNRs are bright in soft X-rays.

They are small (less than 10 pc) and slow (hundreds of km/s).

Detection prospects are better in the LMC with deep surveys.

Abstract

In a failed supernova, partial ejection of the progenitor's outer envelope can occur due to weakening of the core's gravity by neutrino emission in the protoneutron star phase. We consider emission when this ejecta sweeps up the circumstellar material, analogous to supernova remnants (SNRs). We focus on failed explosions of blue supergiants, and find that the emission can be bright in soft X-rays. Due to its soft emission, we find that sources in the Large Magellanic Cloud (LMC) are more promising to detect than those in the Galactic disk. These remnants are characteristic in smallness ($\lesssim 10$ pc) and slowness (100s of ${\rm km\ s^{-1}}$) compared to typical SNRs. Although the expected number of detectable sources is small (up to a few by eROSITA 4-year all-sky survey), prospects are better for deeper surveys targeting the LMC. Detection of these failed SNRs will realize observational studies of mass ejection upon black hole formation.