Modeling the X-Ray Timing Properties of Cygnus X-1 Caused by Waves Propagating in a Transition Disk
Abstract
We show that waves propagating in a transition disk can explain the short-term temporal behavior of Cygnus X-1. In the transition-disk model, the spectrum is produced by saturated Comptonization within the inner region of the accretion disk where the temperature varies rapidly with radius. Recently, the spectrum from such a disk has been shown to fit the average broadband spectrum of this source better than that predicted by the soft-photon Comptonization model. Here we consider a simple model in which waves are propagating cylindrically symmetrically in the transition disk with a uniform propagation speed (cp). We show that this model can qualitatively explain (1) the variation of the power spectral density with energy, (2) the hard lags as a function of frequency, and (3) the hard lags as a function of energy for various frequencies. Thus, the transition-disk model can explain the average spectrum and the short-term temporal behavior of Cyg X-1.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- February 2000
- DOI:
- 10.1086/312470
- arXiv:
- arXiv:astro-ph/9912177
- Bibcode:
- 2000ApJ...529L..95M
- Keywords:
-
- ACCRETION;
- ACCRETION DISKS;
- BLACK HOLE PHYSICS;
- RADIATION MECHANISMS: THERMAL;
- RELATIVITY;
- STARS: INDIVIDUAL: CONSTELLATION NAME: CYGNUS X-1;
- Accretion;
- Accretion Disks;
- Black Hole Physics;
- Radiation Mechanisms: Thermal;
- Relativity;
- Stars: Individual: Constellation Name: Cygnus X-1;
- Astrophysics
- E-Print:
- accepted for publication in APJ letters