Jh. Knapen et al., RESOLVED STRUCTURE IN THE NUCLEAR REGION OF THE ULTRALUMINOUS INFRARED GALAXY MARKARIAN-273, The Astrophysical journal, 490(1), 1997, pp. 29
We have studied the core morphology of the ultraluminous infrared gala
xy Mrk 273 by combining a high- resolution adaptive optics near-infrar
ed image with an optical image from the Hubble Space Telescope and int
erferometric radio continuum data, all at spatial resolutions of 150 m
as or better. The near-infrared image reveals that the nucleus has two
main components, both of which have radio counterparts. The strongest
component (N) shows very similar extended structure in the radio and
near-infrared. It has a hat radio spectrum and is resolved into a doub
le-lobed structure (Ne; Nw), with a separation of 90 +/- 5 mas (70 pc)
. A similar structure is detected in the near-infrared. We identify th
is component as the location of the active nucleus. The second compone
nt (SW), strong in the near-infrared but relatively weak in the radio,
is located similar to 1 '' to the southwest. We interpret this as an
obscured starburst region associated with the merger. The radio contin
uum images show a third, strong, component (SE) that has previously be
en interpreted as a second nucleus. However it shows no associated opt
ical or near-infrared emission, which suggests that it is in fact a ba
ckground source.