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TwitterA&A 490, 77-86 (2008)
DOI: 10.1051/0004-6361:200809909
LABOCA observations of nearby, active galaxies
A. Weiß, A. Kovács, R. Güsten, K. M. Menten, F. Schuller, G. Siringo, and E. KreysaMax-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
e-mail: aweiss@mpifr-bonn.mpg.de
Received 4 April 2008 / Accepted 17 August 2008
Abstract
We present large scale 870 
m maps of the nearby starburst galaxies NGC 253 and NGC 4945 as well as the
nearest giant elliptical radio galaxy Centaurus A (NGC 5128) obtained with the newly commissioned Large Apex Bolometer
Camera (LABOCA) operated at the Atacama Pathfinder Experiment telescope. Our continuum images reveal for the first time
the distribution of cold dust at a angular resolution of 20'' across the entire optical disks of NGC 253 and NGC 4945
out to a radial distance of 10' (7.5 kpc). In NGC 5128 our LABOCA image also shows, for the first time at submillimeter
wavelengths, the synchrotron emission associated with the radio jet and the inner radio lobes. From an analysis of
the 870 m emission in conjunction with ISO-LWS, IRAS and long wavelengths radio data we find temperatures for the
cold dust in the disks of all three galaxies of 17-20 K, comparable to the dust temperatures in the disk of the Milky Way.
The total gas mass in the three galaxies is determined to be 2.1, 4.2 and 2.8 
for NGC 253,
NGC 4945 and NGC 5128, respectively. The mass of the warmer (30-40 K) gas associated with the central starburst regions
in NGC 253 and NGC 4945 only accounts for ~
of the total gas mass. A detailed comparison between the gas masses
derived from the dust continuum and the integrated CO(1-0) intensity in NGC 253 suggests that changes of the CO luminosity
to molecular
mass conversion factor are mainly driven by a metallicity gradient and only to a lesser degree by variations of the CO excitation.
An analysis of the synchrotron spectrum in the northern radio lobe of NGC 5128 shows that the synchrotron emission from radio to
the ultraviolet (UV) wavelengths is well described by a broken power law and that the break frequency is a function of the distance
from the radio core as expected for aging electrons. We derive an outflow speed of
~0.5 c at a distance of 2.6 kpc from the center, consistent with the speed derived in the vicinity of the nucleus.
Key words: galaxies: starburst -- galaxies: ISM -- galaxies: jets -- ISM: dust, extinction -- radio continuum: ISM -- infrared: ISM
© ESO 2008