Recoiling black holes in static and evolving dark matter halo potential

Abstract

We follow trajectories of kicked black holes in static and evolving dark matter halo potential. We explore both NFW and Einasto dark matter density distributions. Considered dark matter halos represent hosts of massive spiral and elliptical field galaxies. We study critical amplitude of kick velocity necessary for complete black hole ejection at various redshifts and find that ~40% lower kick velocities can remove black holes from their host haloes at z = 7 compared to z = 1. The greatest difference between static and evolving potential occurs near the critical velocity for black hole ejection and at high redshifts. When NFW and Einasto density distributions are compared ~30% higher kick velocities are needed for complete removal of BHs from dark matter halo described by NFW profile. [Projekat Ministarstva nauke Republike Srbije, br. 176021: Visible and invisible matter in nearby galaxies: Theory and observations]

Recoiling supermassive black hole escape velocities from dark matter haloes

“…(viii) Smole (2015) studied recoiling SMBHs in an evolving potential using an average halo accretion rate for the specific cases of two DM-only halos with z = 0 masses of 10 12 M and 2 · 10 13 M (their "Halo 1" and "Halo 2" respectively). Based on the assumption that gaseous dynamical friction forces are very strong near the center of the host halo, in their model if the SMBH passed through the center of the host it was assumed to instantaneously lose all momentum and stay there; they then define the "critical velocity" as the kick needed such that the SMBH never returns to pass through the host's center.…”

“…The host will also grow, both through mergers with other halos as well as through smooth accretion from the intergalactic medium (IGM). As discussed in §1, halo growth has previously been modeled only in hydrodynamic simulations and Smole (2015). An alternative approach is to instead apply an average mass accretion rate, M h (M h , z), for which Behroozi & Silk (2015) derived a fitting function using halos in the Bolshoi and Bolshoi-Planck simulations ( Fig.…”

“…Rather than model halos derived from either semi-analytic merger trees or cosmological simulations, we employ analytical formulae for halo density profiles and dynamical friction, but also include effects previously captured mostly in hydrodynamic simulations -i.e., host halo accretion and motion as well as Hubble acceleration. A preliminary step in this direction occured with Smole (2015), who considered the effect of analytical accretion rates for a restricted range of halos. Here, we explore a large parameter space of halo properties and quantify how these affect SMBH escape velocities, and similarly consider effects of varying dynamical friction strength and seed black hole masses.…”

Recoiling supermassive black holes in analytical and numerical galaxy potential

“…Effects of the host halo accretion on the recoiling SMBH trajectories have been studied analytically by Smole (2015) and Choksi et al (2017). Both works have shown that host halo growth significantly influences SMBH escape velocities since SMBHs can be easily ejected from low mass galaxies at high redshifts, while halo accretion at later times makes the ejection harder.…”