Estimating the Spin of Stellar-Mass Black Holes by Spectral Fitting of the X-Ray Continuum
Abstract
We fit X-ray spectral data in the thermal-dominant, or high-soft, state of two dynamically confirmed black holes, GRO J1655-40 and 4U 1543-47, and estimate the dimensionless spin parameters a*≡a/M of the two holes. For GRO J1655-40, using a spectral hardening factor computed for a non-LTE relativistic accretion disk, we estimate a*~0.75 and a*~0.65-0.75, respectively, from ASCA and RXTE data. For 4U 1543-47, we estimate a*~ 0.75-0.85 from RXTE data. Thus, neither black hole has a spin approaching the theoretical maximum a*=1.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- January 2006
- DOI:
- arXiv:
- arXiv:astro-ph/0508302
- Bibcode:
- 2006ApJ...636L.113S
- Keywords:
-
- Accretion;
- Accretion Disks;
- Stars: Binaries: Close;
- Black Hole Physics;
- Stars: Individual: Alphanumeric: 4U 1543-47;
- Stars: Individual: Alphanumeric: GRO J1655-40;
- X-Rays: Stars;
- Astrophysics;
- General Relativity and Quantum Cosmology
- E-Print:
- Accepted for publication in ApJ Letters, 13 pages, 3 figures
