The distinctive feature of relativistic stellar systems

Abstract

In this paper we adopt the method of relativistic fluid dynamics to examine the number density distribution of stars around a massive black hole in the core of stellar clusters. We obtain extensive results,n(r) ∝ r ^−a, 3/2≤a≤9/2, which include, respectively, then(r) ∝ r ^−7/4 power law obtained by Bahcall and Wolf and then(r) ∝ r ^−9/4 power law by Peebles. Sincen(r) is not an observable quantity for star clusters, we also consider general relativity effects, i.e., the consequence of the bending of light, in calculating the projected density of stars in such a system. As an example we employ a massive black hole ∼10³ M _⊙ inlaid in the center of a globular cluster and calculate various projected densities of stars. The results show that cusp construction occurs in all cases unless the central black hole massM=0, and the polytropic index does not affect at all the position of the capture radiusr _a. The obvious differences in the surface density is only embodied in the interior of the capture radius. At the outer regions of the core, the surface density of stars σ declines rapidly with ar ⁻⁵ power law in all cases. These results can be applied to cases of unequal-mass and non-steady state.