A BeppoSAX view of transient black hole candidates in quiescence
Abstract
We report BeppoSAX observations of five transient black hole candidates during their quiescent phase. We confirm that 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 2x 1032 erg s-1 to 5x 1034 erg s-1. 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 k Tbr= 7 keV), converting in both cases to a 1-10 keV unabsorbed luminosity of ~ 1033 erg s-1. 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.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- June 2001
- DOI:
- 10.1051/0004-6361:20010490
- arXiv:
- arXiv:astro-ph/0104073
- Bibcode:
- 2001A&A...372..241C
- Keywords:
-
- BINARIES: GENERAL;
- BLACK HOLE PHYSICS;
- X-RAYS: STARS;
- Astrophysics
- E-Print:
- 4 pages, 1 figure. Accepted for publication on A&