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Session 50 - Active Galaxies.
Display session, Tuesday, January 16
North Banquet Hall, Convention Center
Recent 18cm VLBA images of the ultraluminous IR galaxies UGC5101 and NGC7469 are presented. In combination with 15GHz and 22GHz VLA A-array images of these two objects, we have spatial information on all scales down to about 6 milliarcseconds. The VLBA images show several bright knots of emission which are generally slightly resolved, and an overall structure which is quasi-linear, with total extent about 45 pc. In addition, there is diffuse emission to the SE in UGC5101 which can be identified with a shoulder of emission seen in the 0.1 arcsecond resolution VLA images. This forms the start of a ridgeline of emission that can be traced out to over 1 arcsecond, and the overall structure of the source is therefore suggestive of a curved jet morphology. Based on energetic arguments, the resolved knots argue against a supernova interpretation of the parsec-scale emission in luminous IR galaxies, and at least in UGC5101, the overall structure suggests that a major portion of the radio emission from this galaxy is AGN-related.
