Feeding versus feedback in AGN from near-infrared IFU observations : the case of Mrk 766

Abstract

We have mapped the emission-line flux distributions and ratios as well as the gaseous kinematics of the inner 450 pc radius of the type 1 Seyfert galaxy Mrk 766 using integral field near-infrared J- and Kl-band spectra obtained with the Gemini Near Infrared Integral Field Spectrograph at a spatial resolution of 60 pc and velocity resolution of 40 kms-ˡ. Emission-line flux distributions in ionized and molecular gas extend up to≈300 pc from the nucleus. Coronal [S IX] λ1.2523 μm line emission is resolved, being extended up to 150 pc from the nucleus. At the highest flux levels, the [Fe II] λ1.257 μm line emission is most extended to the south-east, where a radio jet has been observed. The emission-line ratios [Fe II] λ1.2570 μm/Paβ and H2λ2.1218 μm/Brγ show a mixture of Starburst and Seyfert excitation; the Seyfert excitation dominates at the nucleus, to the north-west and in an arc-shaped region between 0.2 and 0.6 arcsec to the south-east at the location of the radio jet. A contribution from shocks at this location is supported by enhanced [Fe II]/[P II] line ratios and increased [Fe II] velocity dispersion. The gas velocity field is dominated by rotation that is more compact for H2 than for Paβ, indicating that the molecular gas has a colder kinematics and is located in the galaxy plane. There is about 103 Mʘ of hot H2, implying ≈109 Mʘ of cold molecular gas. At the location of the radio jet, we observe an increase in the [Fe II] velocity dispersion (150 km s-ˡ), as well as both blueshift and redshifts in the channel maps, supporting the presence of an outflow there. The ionized gas mass outflow rate is estimated to be ≈10 Mʘ yr-ˡ, and the power of the outflow ≈0.08 Lbol.