20
February 2003
Astronomy: The active in active galaxies
A consensus 'unification' model is emerging to explain the structure of active galactic nuclei (AGNs), the most powerful objects in the Universe. High-resolution interferometry of the hydroxyl 'megamaser' galaxy Mrk231 gives a clear picture of the structures at its centre, and is consistent with some of the basic assumptions of the unification model. The detected hydroxyl and radio-continuum emissions reveal an edge-on dusty torus, blocking most of the emissions from the AGN from our view. A torus of this type is predicted for AGNs as a result of the nature of the central engine, thought to be a black hole pulling in a swirling disk of material.
Investigation of the obscuring circumnuclear torus in
the active galaxy Mrk231
HANS-RAINER KLÖCKNER,
WILLEM A. BAAN & MICHAEL A. GARRETT
Nature 421, 821–823
(2003); doi:10.1038/nature01381
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