The Chandra Dust-scattering Halo of Galactic Center Transient Swift J174540.7-290015
Abstract
We report the detection of a dust-scattering halo around a recently discovered X-ray transient, Swift J174540.7-290015, which in early 2016 February underwent one of the brightest outbursts (F X ≈ 5 × 10-10 erg cm-2 s-1) observed from a compact object in the Galactic Center field. We analyze four Chandra images that were taken as follow-up observations to Swift discoveries of new Galactic Center transients. After adjusting our spectral extraction for the effects of detector pile-up, we construct a point-spread function for each observation and compare it to the GC field before the outburst. We find residual surface brightness around Swift J174540.7-290015, which has a shape and temporal evolution consistent with the behavior expected from X-rays scattered by foreground dust. We examine the spectral properties of the source, which shows evidence that the object transitioned from a soft to hard spectral state as it faded below L X ∼ 1036 erg s-1. This behavior is consistent with the hypothesis that the object is a low-mass X-ray binary in the Galactic Center.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- April 2017
- DOI:
- 10.3847/1538-4357/aa68dd
- arXiv:
- arXiv:1703.07855
- Bibcode:
- 2017ApJ...839...76C
- Keywords:
-
- dust;
- extinction;
- Galaxy: center;
- X-rays: binaries;
- X-rays: bursts;
- X-rays: ISM;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- Accepted for publication in ApJ