Resonance in Forced Oscillations of an Accretion Disk and Kilohertz Quasiperiodic Oscillations
Abstract
We have performed numerical simulations of a radially perturbed ``accretion'' torus around a black hole or neutron star and find that the torus performs radial and vertical motions at the appropriate epicyclic frequencies. We find clear evidence that vertical motions are excited in a nonlinear resonance when the applied perturbation is periodic in time. The strongest resonant response occurs when the frequency difference of the two oscillations is equal to onehalf the forcing frequency, precisely as recently observed in the accreting pulsar SAX J1808.43658, where the observed kilohertz quasiperiodic oscillation peak separation is half the spin frequency of 401 Hz.
 Publication:

The Astrophysical Journal
 Pub Date:
 March 2004
 DOI:
 10.1086/383245
 arXiv:
 arXiv:astroph/0402084
 Bibcode:
 2004ApJ...603L..93L
 Keywords:

 Accretion;
 Accretion Disks;
 Hydrodynamics;
 Stars: Neutron;
 XRays: Binaries;
 Astrophysics
 EPrint:
 Matches published version. One important typo corrected in section 2.2