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A. Bialecki (Harvard University), C. Lonsdale (MIT Haystack Observatory), P. Diamond, H. Thrall (Jodrell Bank Observatory, UK)
When two galaxies merge together their interaction can produce significant activity in the form of star formation, supernova explosions, and even possibly the development of supermassive black holes and quasars. By far the closest and most easily observable example of an intergalactic merger is Arp 220, an ultra luminous infrared galaxy (ULIRG) only 76 megaparsecs away. By observing Arp 220 at 18cm wavelength using global VLBI techniques, high-resolution measurements of hydroxyl absorption and maser emission have been made.
We present the data analysis techniques and results for observations of the 1667 and 1665 MHz hydroxyl (OH) transitions in the two merging nuclei of Arp 220. In particular, we examine the OH emission and absorption associated with the ~50 unresolved continuum point sources present in the nuclei, which are presumed to be radio supernovae (RSN). We find that the inverted gas responsible for the OH maser emission at these sky locations is most plausibly local to and physically associated with the RSN, rather than in a distant and diffuse foreground screen as was originally thought. Considerations for future observations are also explored.
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Bulletin of the American Astronomical Society, 37 #4
© 2005. The American Astronomical Soceity.