The failed state transition of the ATOLL source GRS 1724-308
Abstract
The 2004-2012 X-ray time history of the NS LMXB GRS 1724-308 shows, along with the episodic brightenings associated to the low-high state transitions typical of the ATOLL sources, a peculiar, long lasting (about 300 d) flaring event, observed in 2008. This rare episode, characterised by a high-flux hard state, has never been observed before for GRS 1724-308 , and in any case is not common among ATOLL sources. We discuss here different hypotheses on the origin of this peculiar event that displayed the spectral signatures of a failed transition, similar in shape and duration to those rarely observed in Black Hole binaries. We also suggest the possibility that the atypical flare occurred in coincidence with a new rising phase of the 12-years super-orbital modulation that has been previously reported by other authors. The analysed data also confirm for GRS 1724-308 the already reported orbital period of about 90 d.
Keywords
Cite
@article{arxiv.1803.11350,
title = {The failed state transition of the ATOLL source GRS 1724-308},
author = {A. Tarana and F. Capitanio and M. Cocchi},
journal= {arXiv preprint arXiv:1803.11350},
year = {2018}
}
Comments
accepted for publication in MNRAS