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

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 arcsec) H-band observations of this galaxy mapped the stellar kinematics and [Fe II] 1.64 μm 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 ionized and molecular gas dynamics to study the formation of the counter-rotating core and the implications for active galactic nucleus (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. Ionized gas outflows of v_out ∼ 100 km s^-1 are traced by the [Ca VIII] 2.32 μm coronal line and extend out to at least a radius of r ∼ 140 pc. The molecular gas, traced by the H₂ 2.12 μm 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 which formed the counter-rotating core was also the main mechanism providing gas for AGN fuelling.