The thermodynamics of stellar multiplicity: dynamical evolution of binary star populations in dense stellar environments
Abstract
We recently derived, using the densityofstates approximation, analytic distribution functions for the outcomes of direct singlebinary scatterings (Stone & Leigh 2019). Using these outcome distribution functions, we present in this paper a selfconsistent statistical mechanicsbased analytic model obtained using the FokkerPlanck limit of the Boltzmann equation. Our model quantifies the dominant gravitational physics, combining both strong and weak singlebinary interactions, that drives the time evolution of binary orbital parameter distributions in dense stellar environments. We focus in particular the distributions of binary orbital energies and eccentricities. We find a novel steady state distribution of binary eccentricities, featuring strong depletions of both the highest and the lowest eccentricity binaries. In energy space, we compare the predictions of our analytic model to the results of numerical Nbody simulations, and find that the agreement is good for the initial conditions considered here. This work is a first step toward the development of a fully selfconsistent semianalytic model for dynamically evolving binary star populations in dense stellar environments due to direct fewbody interactions.
 Publication:

arXiv eprints
 Pub Date:
 May 2022
 DOI:
 10.48550/arXiv.2205.15351
 arXiv:
 arXiv:2205.15351
 Bibcode:
 2022arXiv220515351L
 Keywords:

 Astrophysics  Astrophysics of Galaxies
 EPrint:
 12 pages, 8 figures, 2 appendices