Registration of the First Thermonuclear X-ray Burst from AX J1754.2-2754

TL;DR

This paper reports the first detection and analysis of a thermonuclear X-ray burst from AX J1754.2-2754, confirming it as an X-ray burster and estimating its distance based on burst characteristics.

Contribution

The study identifies AX J1754.2-2754 as an X-ray burster through the first observed thermonuclear burst and provides distance estimates assuming different neutron star atmospheres.

Findings

Confirmed AX J1754.2-2754 as an X-ray burster.

Estimated the source distance as approximately 6.6 kpc (hydrogen) and 9.2 kpc (helium).

Detected features indicating radiation pressure-driven photospheric expansion.

Abstract

During the analysis of the INTEGRAL observatory archival data we found a powerful X-ray burst, registered by JEM-X and IBIS/ISGRI telescopes on April 16, 2005 from a weak and poorly known source AX J1754.2-2754. Analysis of the burst profiles and spectrum shows, that it was a type I burst, which result from thermonuclear explosion on the surface of nutron star. It means that we can consider AX J1754.2-2754 as an X-ray burster. Certain features of burst profile at its initial stage witness of a radiation presure driven strong expansion and a corresponding cooling of the nutron star photosphere. Assuming, that the luminosity of the source at this phase was close to the Eddington limit, we estimated the distance to the burst source d=6.6+/-0.3 kpc (for hidrogen atmosphere of the neutron star) and d=9.2+/-0.4 kpc (for helium atmosphere).