Extreme host galaxy growth in powerful early-epoch radio galaxies. (arXiv:1209.0324v1 [astro-ph.CO]):
During the first half of the universe's age, a heyday of star-formation must
have occurred because many massive galaxies are in place after that epoch in
cosmic history. Our observations with the revolutionary Herschel Space
Observatory reveal vigorous optically obscured star-formation in the
ultra-massive hosts of many powerful high-redshift 3C quasars and radio
galaxies. This symbiotic occurrence of star-formation and black hole driven
activity is in marked contrast to recent results dealing with Herschel
observations of X-ray selected active galaxies. Three archetypal radio
galaxies, at redshifts 1.132,1.575, and 2.474 are presented here, with inferred
star-formation rates of hundreds of solar masses per year. A series of
spectacular coeval AGN/starburst events may have formed these ultra-massive
galaxies and their massive central black holes during their relatively short
lifetimes.
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