Negative Energy And Angular Momentum Modes Of Thin Accretion Disks

Authors: Zhang, L.¹; Lovelace, R.²

Source: Astrophysics and Space Science, Volume 300, Number 4, December 2005 , pp. 395-414(20)

Publisher: Springer

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Abstract:

This work derives the linearized equations of motion, the Lagrangian density, the Hamiltonian density, and the canonical angular momentum density for general perturbations [∝ exp (imφ) with m = 0, ± 1, ...] of a geometrically thin self-gravitating, homentropic fluid disk including the pressure. The theory is applied to “eccentric,” m = ± 1 perturbations of a geometrically thin Keplerian disk. We find m = 1 modes at low frequencies relative to the Keplerian frequency. Further, it is shown that these modes can have negative energy and negative angular momentum. The radial propagation of these low-frequency m = 1 modes can transport angular momentum away from the inner region of a disk and thus increase the rate of mass accretion. Depending on the radial boundary conditions there can be discrete low-frequency, negative-energy, m = 1 modes.

Keywords: accretion; accretion disks – instabilities – galaxies: kinematics and dynamics

Document Type: Research article

DOI: http://dx.doi.org/10.1007/s10509-005-8792-2

Affiliations: 1: Email: LXZ1@psu.edu 2: Email: RVL1@cornell.edu

Publication date: 2005-12-01