Swift detection of an intermediately long X-ray burst from the very faint X-ray binary XMMU J174716.1-281048

TL;DR

This paper reports the detection and analysis of an intermediately long thermonuclear X-ray burst from the very-faint neutron star binary XMMU J174716.1-281048, providing insights into its burst properties and persistent activity.

Contribution

First detection of an intermediately long X-ray burst from this very-faint X-ray binary, with detailed spectral and temporal analysis revealing its characteristics and source activity.

Findings

Burst duration of ~3 hours and energy of ~9E40 erg.

Source distance estimated at <8.4 kpc.

Persistent activity since 2003 despite transient behavior.

Abstract

We report on the Swift detection of a thermonuclear X-ray burst from the very-faint quasi-persistent neutron star X-ray binary XMMU J174716.1-281048, which triggered the satellite's Burst Alert Telescope (BAT) on 2010 August 13. Analysis of the BAT spectrum yields an observed bolometric peak flux of ~4.5E-8 erg/cm2/s, from which we infer a source distance of <8.4 kpc. Follow-up observations with Swift's X-ray Telescope (XRT) suggest that the event had a duration of ~3 h and a total radiated energy of ~9E40 erg, which classify it as an intermediately long X-ray burst. This is only the second X-ray burst ever reported from this source. Inspection of Swift/XRT observations performed between 2007-2010 suggests that the 2-10 keV accretion luminosity of the system is only ~5E34 erg/s for an assumed distance of 8.4 kpc. Despite being transient, XMMU J174716.1-281048 appears to have been continuously active since its discovery in 2003.