Issue |
A&A
Volume 458, Number 2, November I 2006
|
|
---|---|---|
Page(s) | 385 - 396 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361:20065504 | |
Published online | 12 September 2006 |
Galaxy morphology and evolution from SWAN adaptive optics imaging
1
INAF - Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy e-mail: gcresci@arcetri.astro.it
2
Max-Planck-Institut für extraterrestrische Physik, Postfach 1312, 85741 Garching, Germany
3
Jansky Fellow, National Radio Astronomy Observatory
4
Department of Astronomy, University of Maryland, College Park, MD 20742-2421, USA
5
CNR-Istituto di Radioastronomia, Largo E. Fermi 5, 50125 Firenze, Italy
6
Department of Astronomy, Kyoto University, Kitashirakawa, Kyoto 606-8502, Japan
7
Institute of Astronomy, School of Science, University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015, Japan
Received:
26
April
2006
Accepted:
7
July
2006
We present the results from adaptive optics (AO) assisted
imaging in the Ks band of an area of for
SWAN (Survey of a Wide Area with NACO). We derive the high resolution
near-IR morphology of ∼400 galaxies up to
in
the first 21 SWAN fields around bright guide stars, carefully taking into
account the survey selection effects and using an accurate treatment of the
anisoplanatic AO PSF. The detected galaxies are sorted into two morphological
classes according to their Sérsic index. The extracted morphological
properties and number counts of the galaxies are compared with the predictions
of different galaxy formation and evolution models, both for the whole galaxy
population and separately for late-type and early-type galaxies. This is one
of the first times such a comparison has been done in the near-IR, as AO observations
and accurate PSF modeling are needed to obtain reliable morphological
classification of faint field galaxies at these wavelengths.
For early-type galaxies we find that a pure luminosity evolution model,
without evidence for relevant number and size evolution, better reproduces the observed
properties of our Ks-selected sample than current semi-analytic models
based on the
hierarchical picture of galaxy formation. In particular, we find that the observed
flattening of elliptical galaxy counts at
is quantitatively in
good agreement with the prediction of the pure luminosity evolution model that was
calculated prior to the observation.
For late-type galaxies, while both models are able to reproduce the number counts,
we find some hints of a possible size growth.
These results demonstrate the unique power of AO
observations to derive high resolution details of faint galaxies' morphology
in the near-IR and drive studies of galaxy evolution.
Key words: Galaxy: fundamental parameters / galaxies: statistics / infrared: galaxies / instrumentation: adaptive optics
© ESO, 2006
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