The Galaxy Activity-Interaction Connection. 2. Radio Observations
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIGHT CENTER
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As the second part of an ongoing investigation into the triggering of nuclear radio emission in inter acting galaxies, we present the results of a Very Large Array snapshot survey of southern interacting galaxies at 6 and 20 cm. The purpose of the survey was to search for and classify the nature of radio emission in a set of advanced-interaction disk galaxies which we had previously imaged optically. There were 42 interacting systems in our sample as well as 10 control systems, none of which had been previously detected by the Parkes surveys. Maps of the radio emission are presented and discussed. The radio properties of the galaxies are compared with their optical and infrared properties to determine the nature of the radio emission. We find that the radio emission in all our interacting galaxies can be attributed to processes associated with a burst of star formation caused by the galaxy interaction. In a specific case 0558-33, we quantitatively confirm earlier models of a starburst, but using radio observations to estimate the number of supernova remnants rather than optical spectra and broadband observations. In no case did we find clear evidence for a buried active nucleus. Further high resolution observations are needed however to better assess the contribution from any compact, weak active nuclei. Despite the obvious interaction these galaxies have undergone, none have developed into powerful radio sources, even though many of the most powerful radio sources are themselves the likely products of galaxy-galaxy interactions. We briefly discuss the implications for the triggering of nuclear activity.
- Atomic and Molecular Physics and Spectroscopy
- Radiofrequency Wave Propagation