An X-ray and UV flare from the galaxy XMMSL1 J061927.1-655311

TL;DR

This paper reports a significant X-ray and UV flare from galaxy XMMSL1 J061927.1-655311, likely caused by a tidal disruption event or increased accretion in an active galactic nucleus, with detailed observational analysis.

Contribution

It presents the discovery and analysis of a dramatic flare in an extragalactic source, highlighting possible mechanisms like tidal disruption or accretion rate increase.

Findings

X-ray flux increased by a factor of 140 compared to 20 years earlier.

X-ray and UV fluxes decreased over a year by factors of 20 and 4.

The galaxy is classified as a Seyfert I at redshift 0.0729.

Abstract

New high variability extragalactic sources may be identified by comparing the flux of sources seen in the XMM-Newton Slew Survey with detections and upper limits from the ROSAT All Sky Survey. In November 2012, X-ray emission was detected from the galaxy XMMSL1 J061927.1-655311 (a.k.a. 2MASX 06192755-6553079), a factor 140 times higher than an upper limit from 20 years earlier. Both the X-ray and UV flux subsequently fell, over the following year, by factors of 20 and 4 respectively. Optically, the galaxy appears to be a Seyfert I with broad Balmer lines and weak, narrow, low-ionisation emission lines, at a redshift of 0.0729. The X-ray luminosity peaks at Lx ~ 8x10^43 ergs/s with a typical Sy I-like power-law X-ray spectrum of index ~ 2. The flare has either been caused by a tidal disruption event or by an increase in the accretion rate of a persistent AGN.