Near-infrared dust and line emission from the central region of Mrk 1066: constraints from Gemini NIFS

Abstract

We present integral field spectroscopy of the inner 350 pc of the Mrk1066 obtained with Gemini NIFS at a spatial resolution of 35 pc. This high spatial resolution allowed us to observe, for the first time in this galaxy, an unresolved dust concentration with mass 0.014 M_Sun, which may be part of the dusty torus. The emission-line fluxes are elongated in PA=135/315deg in agreement with the [OIII] and radio images and, except for the H lines, are brighter to the north-west than to the south-east. The H emission is stronger to the south-east, where we find a large region of star-formation. The strong correlation between the radio emission and the highest emission-line fluxes indicates that the radio jet plays a fundamental role at these intensity levels. The H2 flux is more uniformly distributed and has an excitation temperature of 2100 K. Its origin appears to be circumnuclear gas heated by X-rays from the AGN. The [FeII] emission also is consistent with X-ray heating, but with additional emission due to excitation by shocks in the radio jet. The coronal-line emission of [CaVIII] and [SIX] are unresolved by our observations indicating a distribution within 18pc from the nucleus. The reddening ranges from E(B-V) ~ 0 to E(B-V) ~ 1.7 with the highest values defining a S-shaped structure along PA ~ 135/315deg. The emission-line ratios are Seyfert-like within the ionization cone indicating that the line emission is powered by the central active nucleus in these locations. Low ionization regions are observed away from the ionization cone, and may be powered by the diffuse radiation field which filters through the ionization cone walls. Two regions at 0.5 arcsec south-east and at 1 arcsec north-west of the nucleus show starburst-like line ratios, attributed to additional emission from star forming regions.