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A BeppoSAX view of transient black hole candidates in quiescence

S. Campana·A. N. Parmar·L. Stella
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Abstract

We report on BeppoSAX observations of five transient black hole candidates during their quiescent phase. We confirm these sources are X-ray faint, improving on and complementing existing upper limits. We derive 1-10 keV upper limits for GRO J0422+32, GRS 1009-45, 4U 1630-47 and XTE J1748-288, which range from 2x10^32 erg/s to 5x10^34 erg/s. We positively detect GS 2023+338. Its X-ray spectrum can be fit by a power law (photon index Gamma=1.9) or a thermal bremsstrahlung (with kT= 7$ keV), converting in both cases to a 1-10 keV unabsorbed luminosity of ~10^33 erg/s. These values are comparable to the ones derived during an ASCA observation in 1994, indicating that the source remains stable over a ~5 yr baseline.

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S. Campana, A. N. Parmar, L. Stella. 2001-04-04. A BeppoSAX view of transient black hole candidates in quiescence. https://doi.org/10.1051/0004-6361%3A20010490

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