Parameterizing the Outflow from a Central Black Hole in Dwarf Spheroidal Galaxies: A 3D Hydrodynamic Simulation

TL;DR

This study uses 3D hydrodynamic simulations to analyze how intermediate-mass black hole outflows influence gas dynamics in dwarf spheroidal galaxies over 3 billion years, revealing that inhomogeneities significantly reduce outflow impact.

Contribution

First detailed simulation of IMBH outflows in dwarf spheroidal galaxies considering inhomogeneous ISM conditions, highlighting the importance of medium structure on outflow effectiveness.

Findings

Outflows require a minimum speed and density to propagate.

In homogeneous media, outflows can remove a small gas fraction.

In inhomogeneous media, outflows have negligible impact.

Abstract

Large galaxies harbor massive central black holes and their feedback causes a substantial impact in their evolution. Recently, observations suggested that dwarf galaxies might host black holes in their centers, but with lower masses (intermediate-mass black holes - IMBH). The impact of such IMBHs on the evolution of the dwarf spheroidal galaxies (dSphs), however, has not been so far properly analysed. In this work, we investigate the effects of an outflow from an IMBH on the gas dynamics in dSph galaxies by means of non-cosmological, three-dimensional hydrodynamic simulations, letting the galactic gas distribution evolve over 3 Gyr under the influence of the IMBH's outflow and supernova feedback. All simulations have a numerical resolution of 20.0 pc cell$^{-1}$. Two scenarios are considered to infer the differences in the propagation of the outflow, one with a homogeneous ISM and another one with inhomogeneities caused by supernovae feedback. A minimal initial speed and a minimal initial density are required for the outflow to propagate, with the values depending on the conditions of the medium. In an unperturbed medium, the outflow propagates freely in both directions with the same velocity (lower than the initial one), removing a small fraction of the gas from the galaxy (the exact fraction depends on the initial physical conditions of the outflow). However, in an inhomogeneous ISM, the impact of the outflow is substantially reduced, and its contribution to the removal of gas from the galaxy is almost negligible.