An extremely luminous panchromatic outburst from the nucleus of a distant galaxy

TL;DR

This paper reports the discovery of a unique, extremely luminous multiwavelength outburst from the nucleus of a distant galaxy, likely caused by a rare black hole-related event, with unprecedented luminosity and duration.

Contribution

It presents the first detailed multiwavelength observations of a gamma-ray transient with properties unlike any previously known source, indicating a new black hole-related phenomenon.

Findings

Peak luminosity about 100 times higher than the brightest active galactic nuclei

Event lasted much longer than typical gamma-ray bursts

Located at the galaxy's nucleus, suggesting a black hole origin

Abstract

Variable X-ray and gamma-ray emission is characteristic of the most extreme physical processes in the Universe, and studying the sources of these energetic photons has been a major driver in astronomy for the past 50 years. Here we present multiwavelength observations of a unique gamma-ray selected transient, discovered by Swift, which was accompanied by bright emission across the electromagnetic spectrum, and whose properties are unlike any previously observed source. We pinpoint the event to the center of a small, star-forming galaxy at redshift z=0.3534. Its high-energy emission has lasted much longer than any gamma-ray burst, while its peak luminosity was about 100 times higher than the brightest active galactic nuclei. The association of the outburst with the center of its host galaxy suggests that this phenomenon has its origin in a new, rare mechanism associated with a massive black hole in the nucleus of a galaxy.