2001/04/04 by S. Campana, A. N. Parmar, L. Stella · 3 citations
Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics and Cosmic Phenomena #Black hole (networking) #Bremsstrahlung #Luminosity #Power law #Pulsars and Gravitational Waves Research #Thermal #Transient (computer programming) #X-ray transient #astro-ph
paper · pdf · doi:10.1051/0004-6361:20010490
4 pages, 1 figure. Accepted for publication on A&A (including new A&A macro)
arxiv created 2001/04/04 · openalex publication_date 2001/06/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
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 to . We positively detect GS 2023+338. Its X-ray spectrum can be fit by a power law (photon index ) or a thermal bremsstrahlung (with keV), converting in both cases to a 1-10 keV unabsorbed luminosity of ~. 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.