Simulation of merging galaxies and Chandra image of central blackholes in mergers
Credit: X-ray: NASA/CXC/IoA/D.Alexander et al.; Illustration: CXC/M.Weiss

The Growing Years

Active galaxies are those possessing an actively feeding central, supermassive black hole. The black hole swallows matter from its immediate vicinity and produces all sorts of energetic phenomena, like powerful radio jets and X-rays and Gamma-rays. We see many more active galaxies in the past than we do at present, suggesting there was an era when black hole activity turned on, but when was it? An observation, shown in the inset above, may help answer this question. The inset image, obtained in the Deep Field North Survey by the Chandra X-ray Observatory, shows two active black holes in close proximity (separated only by about 70,000 light years). Observations with the James Clerk Maxwell submillimeter telescope on Mauna Kea in Hawaii showed that these black holes are contained in two galaxies which are merging. The illustration shows how this merger might appear. The merger of these galaxies produces a burst of star formation, and may help feed the black holes. These observations suggest that this onset of black hole activity happened about 10 to 12 billion years ago.

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Page Author: Dr. Michael F. Corcoran
Last modified Friday, 20-Apr-2012 15:11:22 EDT