LLAMA: nuclear stellar properties of Swift-BAT AGN and matched inactive galaxies

In a complete sample of local 14–195 keV selected active galactic nuclei (AGNs) and inactive
galaxies, matched by their host galaxy properties, we study the spatially resolved stellar
kinematics and luminosity distributions at near-infrared wavelengths on scales of 10–150 pc,
using SINFONI on the VLT. In this paper, we present the first half of the sample, which
comprises 13 galaxies, eight AGNs and five inactive galaxies. The stellar velocity fields show
a disc-like rotating pattern, for which the kinematic position angle is in agreement with the
photometric position angle obtained from large scale images. For this set of galaxies, the stellar
surface brightness of the inactive galaxy sample is generally comparable to the matched sample
of AGN, but extends to lower surface brightness. After removal of the bulge contribution, we
find a nuclear stellar light excess with an extended nuclear disc structure, which exhibits
a size-luminosity relation. While we expect the excess luminosity to be associated with a
dynamically cooler young stellar population, we do not typically see a matching drop in
dispersion. This may be because these galaxies have pseudo-bulges in which the intrinsic
dispersion increases towards the centre. And although the young stars may have an impact in
the observed kinematics, their fraction is too small to dominate over the bulge and compensate
the increase in dispersion at small radii, so no dispersion drop is seen. Finally, we find no
evidence for a difference in the stellar kinematics and nuclear stellar luminosity excess between
these active and inactive galaxies.