General relativistic quasi-spherical accretion in a dark matter halo

¹ School of Astronomy, Institute for Research in Fundamental Sciences (IPM), P.O. Box 19395-5531 Tehran, Iran
² Departamento de Matemática da Universidade de Aveiro and Centre for Research and Development in Mathematics and Applications (CIDMA), Campus de Santiago, 3810-193 Aveiro, Portugal

^⋆ Corresponding author: r.ranjbar@ipm.ir

Received: 11 February 2025
Accepted: 4 July 2025

Abstract

Context. The Bondi spherical accretion solution has been used to model accretion onto compact objects in a variety of situations, from the interpretation of observations to subgrid models in cosmological simulations.

Aims. We investigate how the presence of DM alters the dynamics and physical properties of accretion onto SMBHs on scales ranging from ∼10 pc to the event horizon.

Methods. In particular, we investigated Bondi-like accretion flows with zero and low specific angular momentum around SMBH surrounded by DM halos by performing 1D and 2.5D GRHD simulations using the BHAC.

Results. We find notable differences in the dynamics and structure of spherical accretion flows in the presence of DM. The most significant effects include increases in density, temperature, and pressure, as well as variations in radial velocity both inside and outside the regions containing DM or even the production of outflow.

Conclusions. This investigation provides valuable insights into the role of cosmological effects, particularly DM, in shaping the behavior of accretion flows and BHs. Our simulations are directly applicable to model systems with a high BH-to-halo mass ratio that are expected to be found at very high redshifts.