Fast and energetic AGN-driven outflows in simulated dwarf galaxies

The systematic analysis of optical large-scale surveys has revealed a population of dwarf galaxies hosting active galactic nuclei (AGN), which have been confirmed by X-ray follow-up observations. Recently, the MaNGA survey identified six dwarf galaxies that appear to have an AGN that is preventing on-going star formation. It is therefore timely to study the physical properties of dwarf galaxies, in particular whether the presence of an AGN can affect their evolution. Using the moving mesh code AREPO, we have investigated different models of AGN activity, ranging from simple energy-driven spherical winds to collimated, mass-loaded, bipolar outflows in high-resolution simulations of isolated dwarf galaxies hosting an active black hole. Our simulations also include a novel implementation of star formation and mechanical supernova (SN) feedback. We find that AGN outflows have a small but systematic effect on the central star formation rates (SFRs) for all set-ups explored, while substantial effects on the global SFR are only obtained with strong SNe and a sustained high-luminosity AGN with an isotropic wind. This suggests that AGN feedback in dwarf galaxies is unlikely to directly regulate their global SFRs. There is, however, a significant effect on outflow properties, which are notably enhanced by the AGN to much higher outflow temperatures and velocities, in agreement with kinematic signatures from the MaNGA survey. This indicates that AGN may play an indirect role in regulating the baryon cycle in dwarf galaxies by hindering cosmic gas inflows.