Quiescent X-ray variability in the neutron star Be/X-ray transient GRO J1750-27
Abstract
The Be/X-ray transient GRO J1750-27 exhibited a type-II (giant) outburst in 2015. After the source transited to quiescence, we triggered our multi-year Chandra monitoring programme to study its quiescent behaviour. The programme was designed to follow the cooling of a potentially heated neutron-star crust due to accretion of matter during the preceding outburst, similar to what we potentially have observed before in two other Be/X-ray transients, namely 4U 0115+63 and V 0332+53. However, unlike for these other two systems, we do not find any strong evidence that the neutron-star crust in GRO J1750-27 was indeed heated during the accretion phase. We detected the source at a rather low X-ray luminosity (∼1033 erg s-1) during only three of our five observations. When the source was not detected it had very low-luminosity upper limits (< 1032 erg s-1; depending on assumed spectral model). We interpret these detections and the variability observed as emission likely due to very low-level accretion onto the neutron star. We also discuss why the neutron-star crust in GRO J1750-27 might not have been heated while the ones in 4U 0115+63 and V 0332+53 possibly were.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- October 2019
- DOI:
- 10.1051/0004-6361/201834327
- arXiv:
- arXiv:1809.10264
- Bibcode:
- 2019A&A...630A.105R
- Keywords:
-
- X-rays: binaries;
- accretion;
- accretion disks;
- stars: neutron;
- pulsars: individual: GRO J1750-27;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 13 pages, 6 figures, 5 tables. Accepted for A&