| Issue |
A&A
Volume 372, Number 1, June II 2001
|
|
|---|---|---|
| Page(s) | 241 - 244 | |
| Section | Interstellar and circumstellar matter | |
| DOI | https://doi.org/10.1051/0004-6361:20010490 | |
| Published online | 15 June 2001 | |
A BeppoSAX view of transient black hole candidates in quiescence
1
Osservatorio Astronomico di Brera, Via E. Bianchi 46, 23807 Merate (Lecco), Italy
2
Astrophysics Division, Space Science Department of ESA, ESTEC, PO Box 299, 2200 AG Noordwijk, The Netherlands
3
Osservatorio Astronomico di Roma, Via Frascati 33, 00040 Monteporzio Catone (Roma), Italy
Corresponding author: S. Campana, campana@mera te.mi.astro.it
Received:
5
March
2001
Accepted:
2
April
2001
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.
Key words: binaries: general / black hole physics / X-rays: stars
© ESO, 2001
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