Resolved Structure in the Nuclear Region of the Ultraluminous Infrared Galaxy Markarian 273

November 1997 • 1997ApJ...490L..29K

Authors • Knapen, J. H. • Laine, S. • Yates, J. A. • Robinson, A. • Richards, A. M. S. • Doyon, R. • Nadeau, D.

Abstract • We have studied the core morphology of the ultraluminous infrared galaxy Mrk 273 by combining a high-resolution adaptive optics near-infrared image with an optical image from the Hubble Space Telescope and interferometric radio continuum data, all at spatial resolutions of 150 mas 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 flat radio spectrum and is resolved into a double-lobed structure (Ne; Nw), with a separation of 90+/-5 mas (70 pc). A similar structure is detected in the near-infrared. We identify this component as the location of the active nucleus. The second component (SW), strong in the near-infrared but relatively weak in the radio, is located ~1" to the southwest. We interpret this as an obscured starburst region associated with the merger. The radio continuum images show a third, strong, component (SE) that has previously been interpreted as a second nucleus. However, it shows no associated optical or near-infrared emission, which suggests that it is in fact a background source.

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Seppo Laine

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