A MAGNHIFFIC cold-gas filament fuelling the nuclear activity of NGC 3100

Abstract

MAGNHIFFIC (MeerKAT AGN HI Feeding & Feedback Investigation close-by) leverages on sensitive MeerKAT 21-cm and VLT Survey Telescope (VST) observations of nearby Active Galactic Nuclei (AGN) to study feeding and feedback from the circum-nuclear ($\lesssim 1$ kpc) to the circum-galactic scales ($\gtrsim 10$ kpc). In nearby ($D\sim 38$~Mpc) radio galaxy NGC 3100, these observations reveal, for the very first time, a starless filament of neutral atomic hydrogen ($M_{\mathrm{H}\mathtt{I}}\sim 3.4\times 10^8{\mathrm{M}}_{\odot }$) extending from its outskirts ($\sim 340$ kpc) down to its innermost kiloparsecs. The kinematical properties of the filament show it likely formed by gas stripped from dwarf galaxy MKT095931-312323, flying by NGC 3100 $\gtrsim 0.5$ Gyr ago. The filament appears to replenish the cold-gas reservoir of NGC 3100's circum-nuclear disk traced by archival ${}^{12}$CO images as well as by HI absorption. The kinematics of the HI absorption and of the ${}^{12}$CO(3--2) show that, in the very centre, the jets are currently stirring the multi-phase gas while dense clouds may still fall into the SMBH. The coexistence of a surviving cold reservoir, compact inner atomic/molecular clouds, and localised jet-driven heating indicates that AGN feeding and feedback operate simultaneously rather than as separate evolutionary phases.

arXiv comment12 pages, 7 figures. Accepted for publication in Astronomy & Astrophysics