AGN feeding and feedback in Fornax A. Kinematical analysis of the multi-phase ISM

Abstract

We present a multi-wavelength study of the gaseous medium surrounding the nearby active galactic nucleus (AGN) Fornax A. Using MeerKAT, ALMA and MUSE observations we reveal a complex distribution of the atomic (H i), molecular (CO), and ionised gas in its centre and along the radio jets. By studying the multi-scale kinematics of the multi-phase gas, we reveal the presence of concurrent AGN feeding and feedback phenomena. Several clouds and an extended 3 kpc filament – perpendicular to the radio jets and the inner disk (r . 4.5 kpc) – show highly-turbulent kinematics, which likely induces nonlinear condensation and subsequent Chaotic Cold Accretion (CCA) onto the AGN. In the wake of the radio jets and in an external (r & 4.5 kpc) ring, we identify an entrained massive (∼ 107 M ) multi-phase outflow (vOUT ∼ 2000 km s−1). The rapid flickering of the nuclear activity of Fornax A (∼ 3 Myr) and the gas experiencing turbulent condensation raining onto the AGN provide quantitative evidence that a recurrent, tight feeding and feedback cycle may be self-regulating the activity of Fornax A, in agreement with CCA simulations. To date, this is one of the most in-depth probes of such a mechanism, paving the way to apply these precise diagnostics to a larger sample of nearby AGN hosts and their multi-phase ISM.