Issue |
A&A
Volume 496, Number 2, March III 2009
|
|
---|---|---|
Page(s) | 381 - 387 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361:200810488 | |
Published online | 20 January 2009 |
A forming, dust-enshrouded disk at z = 0.43: the first example of a massive, late-type spiral rebuilt after a major merger?
1
Laboratoire Galaxies Étoiles Physique et Instrumentation, Observatoire de Paris, 5 place Jules Janssen, 92195 Meudon, France e-mail: francois.hammer@obspm.fr
2
Laboratoire d'Astrophysique de Marseille, Observatoire Astronomique de Marseille Provence, Technopole de l'Étoile, Site de Chateau-Gombert, 38 rue Frédéric Joliot-Curie, 13388 Marseille Cedex 13, France
3
ESO, Karl-Schwarzschild-Strasse 2, 85748 Garching bei Munchen, Germany
4
Institut d'Astrophysique de Paris, France
Received:
1
July
2008
Accepted:
27
November
2008
By combining Ultra Deep Field imagery from HST/ACS with kinematics
from VLT/GIRAFFE, we derive a physical model of distant galaxies
in a way similar to that achievable for nearby galaxies.
A significant part of the evolution in the density of cosmic
star formation is related to the rapid evolution of both luminous IR galaxies (LIRGs)
and Luminous Compact galaxies: here we study the properties of a
distant, compact galaxy, J033245.11-274724.0, which is also a
LIRG. Given the photometric and spectrophotometric accuracies of data of
all wavelengths, we can decompose the galaxy into sub-components
and correct them for reddening. Combination of deep imagery and
kinematics provides a reasonable physical model of the galaxy.
The galaxy is dominated by a dust-enshrouded disk revealed by UDF imagery.
The disk radius is half
that of the Milky Way and the galaxy forms stars at a rate of 20
/yr. Morphology and kinematics show that both gas and stars
spiral inwards rapidly to feed the disk and the
central regions. A combined system of a bar and two nonrotating
spiral arms regulates the material accretion, induces high
velocity dispersions, with σ larger than 100 km s-1 and
redistributes the angular momentum. The detailed physical
properties of J033245.11-274724.0 resemble the expectations of
modeling the merger of two equal-mass, gaseous-rich galaxies, 0.5 Gyr
after the merger. They cannot be reproduced by any combination of
intrinsic disk perturbations alone, given the absence of any
significant outflow mechanisms. In its later evolution,
J033245.11-274724.0 could become a massive, late-type spiral that evolves to become part of
the Tully-Fisher relation, with an angular momentum induced mostly
by the orbital angular-momentum of the merger.
Key words: galaxies: formation / galaxies: spiral / Galaxy: kinematics and dynamics
© ESO, 2009
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