Parameters of Black Holes in Sources with Periodic Variability
Abstract
We propose a way to deduce the parameters of accreting black holes. The method employs the properties of the spectral features observed in radiation from an accretion disk. It is applicable to sources which exhibit periodic modulation of variability, provided: (i) the gravitational field is determined by the black hole and described by the Kerr metric; (ii) a thin accretion disk of negligible mass lies in the equatorial plane of the hole; (iii) a secondary object (also with negligible mass) moves on a slightly inclined almost circular orbit around the black hole and passes periodically through the disk; (iv) the collisions result in observable photometric and spectroscopic features (temporal variability of the radiation flux and of spectral-line profiles produced in the disk), which show frequencies of the orbital motion and of latitudinal oscillations; (v) one can measure the width of the spectral line from hot spots arising in the disk due to collisions with the orbiter, and/or detect predicted low-frequency oscillations induced in the disk. These frequencies and the line width provide enough information to determine in physical units three parameters characterizing the source: the mass and angular momentum of the central black hole, and radius of the orbit of the secondary.
- Publication:
-
Publications of the Astronomical Society of Japan
- Pub Date:
- October 1999
- DOI:
- 10.1093/pasj/51.5.571
- arXiv:
- arXiv:astro-ph/9802025
- Bibcode:
- 1999PASJ...51..571S
- Keywords:
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- ACCRETION DISKS;
- BLACK HOLES;
- X-RAYS: SOURCES;
- Astrophysics
- E-Print:
- 17 pages, 4 figures, 2 tables