http://arxiv.org/abs/1809.10264
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 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, contrary to these two systems, we do not find any evidence that the neutron-star crust in GRO J1750-27 was indeed heated during the accretion phase. We detected the source at a very low X-ray luminosity (~10^33 erg/s; lower than the other two sources just after their type-II outbursts) during only two of our five observations. In between these two observations the source was not detected with very low luminosity upper limits (<10^32 erg/s). 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 033+53 possibly were.
A. Escorial, R. Wijnands, L. Ootes, et. al.
Fri, 28 Sep 18
1/52
Comments: 12 pages, 6 figures, 7 tables. Submitted to A&A
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