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Scientists have spied in a young galaxy located more than 12 billion light-years away the simultaneous occurrence of central supermassive black hole growth and new star formation. The findings, published online today by the journal Science, provide clues as to how galaxies formed in the early universe.
In 2000, astronomers discovered a correlation between a galaxy's total stellar mass and the mass of its central black hole. Ever since, researchers have been trying to establish a link between black hole formation and the growth of a galaxy itself. The evidence so far, however, has been pretty circumstantial. Now an international team of astronomers led by Chris Carilli of the National Radio Astronomy Observatory (NRAO) in Socorro, NM, has found a more direct link. The researchers exploited a so-called gravitational lens, in which the immense gravity of massive objects in space bends light and acts like a giant magnifying glass, to study the quasar known as PSS J2322+1944. "What we needed wasn't just any old gravitational lens, but a nearly-perfect alignment of the distant quasar, mid-distance galaxy, and Earth--and that's what we got," says team member Geraint Lewis of the University of Sydney in Australia.
This lens allowed the team to get a detailed view of PSS J2322+1944's central black hole, which was surrounded by a star-forming disk 13,000 light-years in diameter. According to the report, the disk could churn out stars equivalent to 900 solar masses each year. This rate of activity, Carilli notes, is between 100 and 1,000 times more active than star formation in our own galaxy. Remarks team member Pierrre Cox of the Institute for Space Astrophysics of the University of Paris, "This new observation gives strong support to the idea that large numbers of stars were forming in young galaxies at the same time that their central black holes were pulling in additional mass."