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

Abstract

In a complete sample of local 14-195 keV selected 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, 8 AGNs and 5 inactive galaxies. The stellar velocity fields show a disk-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 disk structure, and 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.

Stellar populations in local AGNs: evidence for enhanced star formation in the inner 100pc

“…A similar result has already been found by Lin et al (2018), who analyzed eight AGNs and five control galaxies. Having detected a nuclear stellar light excess in their AGNs compared to their control sample, which they attributed to a younger stellar population, they also did not detect a significant change in their stellar 𝜎 in this region.…”

Ionized outflows in local luminous AGN: what are the real densities and outflow rates?

“…And the ability to compare the results to a matched sample of inactive galaxies has been essential in many of the studies so far, including the analysis presented here. These studies include the following: the physical properties of, and extinction to, the broad-line region (BLR;Schnorr-Müller et al 2016b); the respective roles of host galaxy and environment in fuelling AGN (Davies et al 2017); the molecular gas content and depletion time on kiloparsec scales (Rosario et al 2018); the nuclear stellar population and kinematics (Lin et al 2018); the black hole masses and location in the M BH -σ * plane (Caglar et al 2020); and the nuclear star formation histories (Burtscher et al, in preparation).…”

The multiphase gas structure and kinematics in the circumnuclear region of NGC 5728

“…Telluric correction and flux calibration were carried out using B-type stars. Finally, we also corrected for differential atmospheric refraction, a wavelength dependent spatial offset due to the atmosphere, using a custom procedure described in Lin et al (2018).…”