Tracing the origin of the AGN fuelling reservoir in MCG--6-30-15

TL;DR

This study investigates the origin of the counter-rotating core in galaxy MCG--6-30-15, revealing external gas inflow as the key process fueling the active galactic nucleus.

Contribution

It provides new integral field spectroscopy data showing external gas accretion as the source of the counter-rotating core and AGN fueling in MCG--6-30-15.

Findings

Counter-rotating molecular gas indicates external gas inflow.

Ionised gas outflows extend to 140 pc from the center.

External gas accretion replenishes the AGN fueling reservoir.

Abstract

The active galaxy MCG--6-30-15 has a 400 pc diameter stellar kinematically distinct core, counter-rotating with respect to the main body of the galaxy. Our previous high spatial resolution (0".1) H-band observations of this galaxy mapped the stellar kinematics and [Fe II] 1.64 {\mu}m gas dynamics though mainly restricted to the spatial region of the counter-rotating core. In this work we probe the stellar kinematics on a larger field-of-view and determine the ionised and molecular gas dynamics to study the formation of the counter-rotating core and the implications for AGN fuelling. We present integral field spectroscopy observations with SINFONI in the H and K-bands in the central 1.2 kpc and with VIMOS HR-blue in the central 4 kpc of the galaxy. Ionised gas outflows of v ~ 100 km/s are traced by the [Ca VIII] 2.32 {\mu}m coronal line and extend out to at least a radius of r ~ 140 pc. The molecular gas, traced by the H2 2.12 {\mu}m emission is also counter rotating with respect to the main body of the galaxy, indicating that the formation of the distinct core was associated with inflow of external gas into the centre of MCG--6-30-15. The molecular gas traces the available gas reservoir for AGN fuelling and is detected as close as r ~ 50 - 100 pc. External gas accretion is able to significantly replenish the fuelling reservoir suggesting that the event that formed the counter-rotating core was also the main mechanism providing gas for AGN fuelling.