Chandra Observations of Arp 220: The Nuclear Source

We present the first results from 60 ks of observations of Arp 220 using the ACIS-S instrument on Chandra. We report the detection of several sources near the galaxy's nucleus, including a point source with a hard spectrum that is coincident with the western radio nucleus B. This point source is mildly absorbed (NH ~ 3 × 1022 cm-2) and has an estimated luminosity of 4 × 1040 ergs s-1. In addition, a fainter source may coincide with the eastern nucleus A. Extended hard X-ray emission in the vicinity raises the total estimated nuclear 2-10 keV X-ray luminosity to 1.2 × 1041 ergs s-1, but we cannot rule out a hidden active galactic nucleus behind columns exceeding 5 × 1024 cm-2. We also detect a peak of soft X-ray emission to the west of the nucleus and a hard point source 2.5 kpc from the nucleus with a luminosity of 6 × 1039 ergs s-1.