The location of an active nucleus and a shadow of a tidal tail in the ULIRG Mrk 273
Veilleux, S.; Sanders, D. B.; Surace, J. A.; Armus, L.; Iwasawa, K.; Komossa, S.; Evans, A. S.; Howell, J. H.; Mazzarella, J. M.; U, Vivian; Teng, S. H.; Petric, A.
Spain, United States, Germany
Abstract
Analysis of data from the Chandra X-ray Observatory for the double nucleus ULIRG Mrk 273 reveals an absorbed hard X-ray source coincident with the southwest nucleus, implying that this unresolved, near-infrared source is where an active nucleus resides, while the northern nuclear region contains a powerful starburst that dominates the far infrared luminosity. There is evidence of a slight image extension in the 6-7 keV band, where an Fe K line is present, towards the northern nucleus. A large-scale, diffuse emission nebula detected in soft X-rays contains a dark lane that spatially coincides with a high surface-brightness tidal tail extending ~50 arcsec (40 kpc) to the south. The soft X-ray source is likely located behind the tidal tail, which absorbs X-ray photons along the line of sight. The estimated column density of cold gas in the tidal tail responsible for shadowing the soft X-rays is NH ≥ 6 × 1021 cm -2, consistent with the tidal tail having an edge-on orientation.