Journal Article

Gravitational drag on a point mass in hypersonic motion through a gaseous medium

J. Cantó, A. C. Raga, A. Esquivel and F. J. Sánchez-Salcedo

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 418, issue 2, pages 1238-1245
Published in print December 2011 | ISSN: 0035-8711
Published online November 2011 | e-ISSN: 1365-2966 | DOI:
Gravitational drag on a point mass in hypersonic motion through a gaseous medium

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We explore a ballistic orbit model to infer the gravitational drag force on an accreting point mass M, such as a black hole, moving at a hypersonic velocity v0 through a gaseous environment of density ρ0. The streamlines blend in the flow past the body and transfer momentum to it. The total drag force acting on the body, including the non-linear contribution of those streamlines with small impact parameter that bend significantly and pass through a shock, can be calculated by imposing conservation of momentum. In this fully analytic approach, the ambiguity in the definition of the lower cut-off distance rmin in calculations of the effect of dynamical friction is removed. It turns out that . Using spherical surfaces of control of different sizes, we carry out a successful comparison between the predicted drag force and the one obtained from a high-resolution, axisymmetric, isothermal flow simulation. We demonstrate that ballistic models are reasonably successful in accounting for both the accretion rate and the gravitational drag.

Keywords: black hole physics; hydrodynamics; stars: formation; ISM: clouds; ISM: kinematics and dynamics

Journal Article.  4757 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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