A&A Supplement Ser., Vol. 124, September 1997, 533-557
Received October 18; accepted December 16, 1996
P.-A. Duc 
- I.F. Mirabel 
- J. Maza 
Send offprint request: pduc@eso.org
ESO, Karl-Schwarzschild-Str. 2,
D-85748 Garching bei München, Germany -
Service d'Astrophysique, CEA/DSM/DAPNIA, C.E. Saclay,
91191 Gif-sur-Yvette Cedex, France
Depto. Astronomia,
Univ. de Chile, Casilla 36-D, Santiago, Chile
We have carried out
an optical and infrared study of 24 ultraluminous infrared galaxies in
the southern hemisphere (SULIRGs). This flux limited, complete
sample, has been extracted from the redshift survey of IRAS galaxies compiled
by Strauss et al. (1992). It includes systems with a 60 
m IRAS flux
greater than 3 Jy and a far-infrared luminosity
greater than 
(H0= 75 km s-1 Mpc-1). With the ESO New Technology Telescope,
we have obtained high resolution optical images in the R band of all SULIRGs, and with the ESO/MPI 2.2-meter telescope, near
infrared J, H and K images for
most of them. Low and high resolution spectra have been taken with the 4-meter
telescope of the Cerro Tololo
Inter-American Observatory. The nature and morphology of all objects are consistent with
the wide-spread idea that most, if not all, galaxies with an extreme
far-infrared luminosity are close interacting or merging systems.
The galaxies that appear as isolated and devoid of tidal
features exhibit several isophotal distortions in their main body. However
three cases are more ambiguous. They are indeed interacting systems, but
their companions are at a distance greater than 40 kpc.
We find in the SULIRG sample a significant proportion of objects having
AGN like spectra:
, including one Seyfert 1 galaxy.
keywords: galaxies: active -- galaxies: interactions -- infrared: galaxies