| Issue |
A&A
Volume 468, Number 3, June IV 2007
Extended baselines for the IRAM Plateau de Bure interferometer: First results
|
|
|---|---|---|
| Page(s) | 937 - 950 | |
| Section | Extragalactic astronomy | |
| DOI | https://doi.org/10.1051/0004-6361:20066673 | |
| Published online | 24 April 2007 | |
Morphological evolution of z ~ 1 galaxies from deep K-band AO imaging in the COSMOS deep field *,**,***
1
LESIA-Paris Observatory, 5 place Jules Janssen, 92195 Meudon, France e-mail: marc.huertas@obspm.fr
2
IAA-C/ Camino Bajo de Huétor, 50-18008 Granada, Spain
3
Laboratoire d'Astrophysique de Toulouse-Tarbes, CNRS-UMR 5572 and Université Paul Sabatier Toulouse III, 14 avenue Belin, 31400 Toulouse, France
4
LAM-Marseille Observatory, Traverse du Siphon, Les trois Lucs, BP 8, 13376 Marseille Cedex 12, France
Received:
31
October
2006
Accepted:
13
March
2007
Context.We present the results of an imaging program of
distant galaxies (
) at high spatial resolution (~
)
aiming at studying their morphological evolution. We observed 7 fields of 
with the NACO Adaptive Optics system (VLT)
in Ks (
m) band with typical 
guide stars and 3 h integration time per field. Observed fields are selected within
the COSMOS survey area, in which multi-wavelength photometric and
spectroscopic observations are ongoing. High angular-resolution K-band data
have the advantage of probing old stellar
populations in the rest-frame, enabling a determination of galaxy morphological
types unaffected by recent star formation, which are more closely linked to the
underlying mass than classical optical morphology studies (HST).
Adaptive optics on ground based telescopes is the only method today for obtaining
such a high resolution in the K-band, but it suffers from limitations since only small fields are observable and long integration times are necessary.
Aims.In this paper we show that reliable results can be obtained and establish a first basis for larger observing programs.
Methods.We analyze the morphologies by means of B/D (bulge/disk) decomposition
with GIM2D and C-A (concentration-asymmetry) estimators for 79
galaxies with magnitudes between 
and classify
them into three main morphological types (late type, early type and
irregulars). Automated and objective classification allows precise
error estimation. Simulations and comparisons with seeing-limited
(CFHT/Megacam) and space (HST/ACS) data are carried out to
evaluate the accuracy of adaptive optics-based observations for
morphological purposes.
Results.We obtain the first estimate of the distribution
of galaxy types at redshift 
as measured from the near
infrared at high spatial resolution. We show that galaxy parameters
(disk scale length, bulge effective radius, and bulge fraction) can
be estimated with a random error lower than 
for the bulge
fraction up to 
(
) and that classification into the
three main morphological types can be done up to 
(
)
with at least 70% of the identifications correct. We used the known photometric redshifts to obtain a redshift distribution over 2 redshift bins (
, 
) for each morphological type.
Key words: galaxies: fundamental parameters / galaxies: high-redshift / galaxies: evolution / instrumentation: adaptive optics
Based on ESO observations at the VLT. Programmes P73.A-0814A and P75.A-0569A and 175.A-0839 (zCOSMOS).
Based on observations obtained with MegaPrime/MegaCam, a joint project of the CFHT and CEA/DAPNIA, at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council (NRC) of Canada, the Institut National des Science de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii. This work is based in part on data products produced at TERAPIX and the Canadian Astronomy Data Centre as part of the Canada-France-Hawaii Telescope Legacy Survey, a collaborative project of the NRC and CNRS.
© ESO, 2007
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