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Evolution of compact binary population in dense stellar systems: A Boltzmann approach
Author(s) -
Banerjee S.,
Ghosh P.
Publication year - 2008
Publication title -
astronomische nachrichten
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.394
H-Index - 63
eISSN - 1521-3994
pISSN - 0004-6337
DOI - 10.1002/asna.200811096
Subject(s) - globular cluster , physics , binary number , statistical physics , boltzmann equation , astrophysics , star cluster , boltzmann constant , stars , quantum mechanics , mathematics , arithmetic
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. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)