Evolution of compact binary population in dense stellar systems: a Boltzmann approach
Abstract
We introduce a Boltzmann scheme for studying the evolution of compact-binary populations in globular clusters, wherein dynamical formation processes like tidal capture and exchange encounters, and destruction processes like dissociation are incorporated, as well the binary-hardening processes. Our approach is in two steps - we first study in a continuous limit, introducing the inherent stochasticity of the dynamical processes in the next step, using a stochastic version of the Boltzmann equation. We show that the continuous limit is indeed an excellent representation of the average of many ``realizations'' of the stochastic calculations. We focus on the evolution of the number of X-ray binaries N_XB in globular clusters, and also their orbital period distribution. In particular, we study the dependence of N_XB on two globular cluster parameters, characterizing the star-star and star-binary encounter rates, which we call Verbunt parameters. We show that our computed theoretical trends in N_XB with the Verbunt parameters are in good agreement with the recent observations of Galactic globular-cluster X-ray binaries.
- Publication:
-
Astronomische Nachrichten
- Pub Date:
- December 2008
- DOI:
- 10.1002/asna.200811096
- Bibcode:
- 2008AN....329..988B
- Keywords:
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- celestial mechanics;
- stellar dynamics;
- binaries: close;
- globular clusters: general;
- methods: numerical;
- X-rays: binaries