The Search for Failed Supernovae with The Large Binocular Telescope: First Candidates

TL;DR

This study uses the Large Binocular Telescope to search for failed supernovae by monitoring nearby galaxies, identifying candidates through star disappearance and low luminosity transients, and estimates the fraction of core collapses resulting in failed SNe.

Contribution

First direct search for failed supernovae using long-term monitoring, providing initial candidate and statistical constraints on failure rates.

Findings

One candidate for a failed supernova identified, requiring further confirmation.

Estimated failed supernova fraction of about 30%, with wide confidence intervals.

Upper limit on failed supernova fraction set at 40% at 90% confidence.

Abstract

We are monitoring 27 galaxies within 10 Mpc using the Large Binocular Telescope to search for failed supernovae (SNe), massive stars that collapse to form a black hole without a SN explosion. We present the results from the first 4 years of survey data, during which these galaxies were observed to produce 3 successful core-collapse SNe. We search for stars that have "vanished" over the course of our survey, by examining all stars showing a decrease in luminosity of $\Delta \nu L_{\nu} \ge 10^4L_{\odot}$ from the first to the last observation. We also search for the low luminosity, long duration transients predicted by \citet{lovegrove2013} for failed explosions of red supergiants. After analyzing the first 4 years of data in this first direct search for failed SNe, we are left with one candidate requiring further study. This candidate has an estimated mass of 18-25$M_{\odot}$, a mass range likely associated with failed SNe and, if real, implies that failed SN represent a median fraction of $f \simeq 0.30$ of core-collapses, with symmetric 90% confidence limits of $0.07 \le f \le 0.62$. If follow up data eliminate this candidate, we find an upper limit on the fraction of core collapses leading to a failed SN of $f<0.40$ at 90% confidence. As the duration of the survey continues to increase, it will begin to constrain the $f \simeq$ 10-30% failure rates needed to explain the deficit of massive SN progenitors and the observed black hole mass function.