Stability of Self-Similar Spherical Accretion：（自相似球形吸积的稳定）.pdfVIP

Stability of Self-Similar Spherical Accretion José Gaite Instituto de Matemáticas y Física Fundamental, CSIC, Serrano 113bis, 28006 Madrid, Spain 5 Abstract. Spherical accretion flows are simple enough for analytical study, by solution of the 0 corresponding fluid dynamic equations. The solutions of stationary spherical flow are due to Bondi. 0 2 The questions of the choice of a physical solution and of stability have been widely discussed. The answer to these questions is very dependent on the problem of boundary conditions, which vary c according to whether the accretor is a compact object or a black hole. We introduce a particular, e simple form of stationary spherical flow, namely, self-similar Bondi flow, as a case with physical D interest in which analytic solutions for perturbations can be found. With suitable no matter-flux- 2 perturbation boundary conditions, we will show that acoustic modes are stable in time and have no 1 spatial instability at r = 0. Furthermore, their evolution eventually becomes ergodic-like and shows no trace of instability or of acquiring any remarkable pattern. 1 v 1 6 RELATIVISTIC POTENTIAL FLUID FLOW 0 2 1 We consider the adiabatic downfall of a perfect fluid onto a compact spherical body 5 or a non-rotating black hole. In particular, we intend to analyse the stability of simple 0 spherical, stationary flows (Bondi flows) [1]. General stability arguments have been / c given by Garlick [2] and Moncrief [3], but there are no exact solutions for perturbations, q - except in the WKB approximation. So we