Radiative AGN feedback on a moving mesh: the impact of the galactic disc and dust physics on outflow properties

Abstract

© 2020 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society Feedback from accreting supermassive black holes (BHs), active galactic nuclei (AGNs), is now a cornerstone of galaxy formation models. In this work, we present radiation-hydrodynamic simulations of radiative AGN feedback using the novel AREPO-RT code. A central BH emits radiation at a constant luminosity and drives an outflow via radiation pressure on dust grains. Utilizing an isolated Navarro-Frenk-White (NFW) halo we validate our setup in the single- and multiscattering regimes, with the simulated shock front propagation in excellent agreement with the expected analytic result. For a spherically symmetric NFW halo, an examination of the simulated outflow properties with radiation collimation demonstrates a decreasing mass outflow rate and momentum flux, but increasing kinetic power and outflow velocity with decreasing opening angle. We then explore the impact of a central disc galaxy and the assumed dust model on the outflow properties. The contraction of the halo during the galaxy's formation and modelling the production of dust grains result in a factor 100 increase in the halo's optical depth. Radiation then couples momentum more efficiently to the gas, driving a stronger shock and producing a mass-loaded ∼ 103 M☉ yr−1 outflow with a velocity of ∼ 2000 km s−1. However, the inclusion of dust destruction mechanisms, like thermal sputtering, leads to the rapid destruction of dust grains within the outflow, reducing its properties below the initial NFW halo. We conclude that radiative AGN feedback can drive outflows, but a thorough numerical and physical treatment is required to assess its true impact.