Diskoseismology: Probing Accretion Disks. I. Trapped Adiabatic Oscillations
Abstract
The normal modes of acoustic oscillations within thin accretion disks which are terminated by an innermost stable orbit around a slowly rotating black hole or weakly magnetized compact neutron star are analyzed. The dominant relativistic effects which allow modes to be trapped within the inner region of the disk are approximated via a modified Newtonian potential. A general formalism is developed for investigating the adiabatic oscillations of arbitrary unperturbed disk models. The generic behavior is explored by way of an expansion of the Lagrangian displacement about the plane of symmetry and by assuming separable solutions with the same radial wavelength for the horizontal and vertical perturbations. The lowest eigenfrequencies and eigenfunctions of a particular set of radial and quadrupole modes which have minimum motion normal for the plane are obtained. These modes correspond to the standard dispersion relation of disk theory.
 Publication:

The Astrophysical Journal
 Pub Date:
 September 1991
 DOI:
 10.1086/170465
 Bibcode:
 1991ApJ...378..656N
 Keywords:

 Accretion Disks;
 Black Holes (Astronomy);
 Hydrodynamics;
 Stellar Mass Accretion;
 Stellar Oscillations;
 Wave Propagation;
 Formalism;
 Numerical Analysis;
 Propagation Modes;
 Seismology;
 Series Expansion;
 Astrophysics;
 BLACK HOLES;
 HYDRODYNAMICS;
 STARS: ACCRETION;
 WAVE MOTIONS