The location of an active nucleus and the soft X-ray shadowing by a
  tidal tail in the ULIRG Mrk 273
  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 which dominates the far infrared luminosity. There is evidence of a
slight image extension in the 6-7 keV band, where a 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 >= 6e+21 cm-2,
consistent with the tidal tail having an edge-on orientation.
