J/A+A/711/A169 Ks-band images of 18 Seyfert galaxies (Mackensen+, 2026)
Adaptive optics imaging of the nuclei of Seyfert 2 galaxies:
An unexpectedly high incidence of nuclear stellar rings.
Mackensen N., Heidt J., Pozo Nunez F.
<Astron. Astrophys. 711, A169 (2026)>
=2026A&A...711A.169M 2026A&A...711A.169M (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, Seyfert ; Active gal. nuclei ; Infrared
Keywords: instrumentation: adaptive optics - methods: data analysis -
galaxies: active - galaxies: nuclei - galaxies: Seyfert
Abstract:
The high-resolution imaging of active galactic nuclei on
sub-kiloparsec scales offers an important avenue for investigating
their fueling. Observations in the near-infrared are especially
valuable as they minimize the absorption by dust. However, the
inferred nuclear morphology may depend on the method used to analyze
the images.
The aim of this study is to assess whether ground-based
adaptive-optics observations of the cores of Seyfert 2 galaxies in the
Ks-band provide advantages over HST observations at shorter
wavelengths (V- and H-band). We also investigate whether a dedicated
two-dimensional analysis is preferable to a one-dimensional approach.
A sample of 18 Seyfert 2 galaxies was observed with the adaptive
optics system in the Ks-band at the Large Binocular Telescope and
compared to archival HST V- or H-band images. The analysis included
two-dimensional modeling via GALFIT and the use of the unsharp masking
technique.
The results obtained in different filters are mutually consistent,
indicating no clear advantage of using a redder filter. Using GALFIT
and unsharp-masking in concert is preferable, as the two methods
provide complementary strengths.
We identify nuclear stellar rings in 8 of the 18 galaxies in our
sample (44±12%. This fraction is significantly higher than reported
in previous studies, and about a factor of two higher than found in
the most complete atlas of nuclear rings. The radii, size
distribution, and inferred masses of the detected nuclear rings are
similar to those observed in non-active galaxies. Low-luminosity
active nuclei seem to have little, if any, impact on the formation and
evolution of nuclear rings.
The high incidence of nuclear stellar rings was unexpected and
warrants further investigation. It can be tested using the large
number of suitable archival HST images available. If confirmed, it
would imply that nuclear stellar rings are considerably more common
than previously recognized.
Description:
This data release provides fully reduced and stacked Ks-band images of
the central 21" of a sample of 18 Seyfert galaxies. The AO-assisted
data were taken with LUCI/LBT and are suitable for morphological
studies. Spatial sampling is 0.015 arcsec per pixel.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 126 18 List of fits images
fits/* . 18 Individual fits images
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- Name Galaxy name
9- 17 F9.5 deg RAdeg Right Ascension of center (J2000)
18- 26 F9.5 deg DEdeg Declination of center (J2000)
28- 31 I4 --- Nx Number of pixels along X-axis
33- 36 I4 --- Ny Number of pixels along Y-axis
38- 47 A10 "datime" Obs.date Observation date
49- 52 I4 Kibyte size Size of FITS file
54- 65 A12 --- FileName Name of FITS file, in subdirectory fits
67-126 A60 --- Title Title of the FITS file
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Acknowledgements:
From Jochen Heidt, jheidt(at)lsw.uni-heidelberg.de
Based on AO-assisted observations with the LUCI instruments at the
Large Binocular Telescope
License: CC-BY-4.0
(End) Patricia Vannier [CDS] 04-Jun-2026