Issue |
A&A
Volume 374, Number 3, August II 2001
|
|
---|---|---|
Page(s) | L19 - L20 | |
Section | Letters | |
DOI | https://doi.org/10.1051/0004-6361:20010791 | |
Published online | 15 August 2001 |
A precise determination of black hole spin in GRO J1655-40
1
Department of Astronomy and Astrophysics, Chalmers University, 412-96 Göteborg, Sweden
2
Institut d'Astrophysique de Paris, 98bis boulevard Arago, 75014 Paris, France
3
Université Pierre & Marie Curie (Paris VI), France
4
Institute of Astronomy , University of Zielona Góra, ul. Lubuska 2, 65-265 Zielona Góra, Poland
Corresponding author: W. Kluźniak, wlodek@camk.edu.pl
Received:
21
May
2001
Accepted:
5
June
2001
We note that the recently discovered 450 Hz frequency in the X-ray flux of
the black hole candidate GRO J1655-40 is in a 3:2 ratio to
the previously known 300 Hz frequency of quasi-periodic oscillations (QPO)
in the same source. If the origin of high frequency QPOs in black hole
systems is a resonance between orbital and epicyclic motion of
accreting matter, as suggested previously, the angular momentum of the black
hole can be accurately determined, given its mass. We find that the
dimensionless angular momentum is in the range
if the mass is in the (corresponding) range of 5.5 to 7.9 solar masses.
Key words: equation of state / relativity / stars: black holes / X-rays
© ESO, 2001
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