When do Black Holes Become Active? The Case of the Strangely-Shaped Galaxy Mrk 273

The Hubble image above shows a strange galaxy, known as Mrk 273. The odd shape - including the infrared bright center and the long tail extending into space for 130 thousand light-years - is strongly indicative of a merger between galaxies. Near-infrared observations have revealed a nucleus with multiple components, but for years the details