Dynamical friction of a massive black hole in a turbulent gaseous medium - Archive ouverte HAL Access content directly
Preprints, Working Papers, ... Year : 2022

Dynamical friction of a massive black hole in a turbulent gaseous medium

Abstract

The orbital decay of massive black holes in galaxies in the aftermath of mergers is at the heart of whether massive black holes successfully pair and merge, leading to emission of low-frequency gravitational waves. The role of dynamical friction sourced from the gas distribution has been uncertain because many analytical and numerical studies have either focused on a homogeneous medium or have not reached resolutions below the scales relevant to the problem, namely the Bondi-Hoyle-Lyttleton radius. We perform numerical simulations of a massive black hole moving in a turbulent medium in order to study dynamical friction from turbulent gas. We find that the black hole slows down to the sound speed, rather than the turbulent speed, and that the orbital decay is well captured if the Bondi-Hoyle-Lyttleton radius is resolved with at least five resolution elements. We find that the larger the turbulent eddies, the larger the scatter in dynamical friction magnitude, because of the stochastic nature of the problem, and also of the larger over- and under-densities encountered by the black hole along its trajectory. Compared to the classic solution in a homogeneous medium, the magnitude of the force depends more weakly on the Mach number, and dynamical friction is overall more efficient for high Mach numbers, but less efficient towards and at the transonic regime.

Dates and versions

hal-03998992 , version 1 (21-02-2023)

Identifiers

Cite

Sandrine Lescaudron, Yohan Dubois, Ricarda S. Beckmann, Marta Volonteri. Dynamical friction of a massive black hole in a turbulent gaseous medium. 2022. ⟨hal-03998992⟩
0 View
0 Download

Altmetric

Share

Gmail Facebook Twitter LinkedIn More