Timing Noise Properties of GRO J0422+32
Abstract
OSSE observed the transient black hole candidate GRO J0422+32 (XN Persei 92) between 1992 August 11 and 1992 September 17. High time resolution data were obtained in several energy bands over the ~=35-600 keV range with a timing resolution of 8 ms. Power spectra at energies below 175 keV show substantial low-frequency red noise with a shoulder at a few times 10-2 Hz, peaked noise with characteristic frequency near 0.2 Hz, and a second shoulder at a few Hz. The frequencies of the shoulders and the peak are independent of energy and source intensity. The complex cross spectrum indicates that photons in the 75-175 keV band lag photons in the 35-60 keV band by a time roughly proportional to the inverse of the Fourier frequency. The maximum lag observed is ~=300 ms. The power and lag spectra are consistent with the production of the γ-rays through thermal Comptonization in an extended hot corona with a power-law density profile.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- July 1998
- DOI:
- 10.1086/311481
- arXiv:
- arXiv:astro-ph/9805256
- Bibcode:
- 1998ApJ...502L..45G
- Keywords:
-
- ACCRETION;
- ACCRETION DISKS;
- BLACK HOLE PHYSICS;
- GAMMA RAYS: OBSERVATIONS;
- STARS: INDIVIDUAL ALPHANUMERIC: GRO J0422+32;
- Accretion;
- Accretion Disks;
- Black Hole Physics;
- Gamma Rays: Observations;
- Stars: Individual: Alphanumeric: GRO J0422+32;
- Astrophysics
- E-Print:
- 14 pages, 2 figs, uses psfig, accepted for pub in ApJ Letters