domingo, 23 de octubre de 2011

Astronomy - Black Hole Secrets… Water Vapor Gives Clues To Star Formation

Artist's Concept of Water Vapor in Black Hole Disk - Credit: Leiden University
A eye-opening discovery has been made by an international team of scientists led by astronomer Paul van der Werf (Leiden University, The Netherlands). They have discovered a black hole in the early Universe located about 12 billion light years away that’s surrounded by a nearly impenetrable disk of gas and dust. The halo isn’t the surprise, however… but the presence of star formation in dense water vapor is.
Using the sensitive radio telescopes of IRAM (Institut de Radioastronomie Millimétrique) at the Plateau de Bure in the French Alps, the team was searching for the signs of water vapor around a quasar – a distant galaxy which gathers its luminosity from the growth of a black hole which weighs in at hundreds of millions times more mass than Sol.
“Water in cosmic clouds is normally frozen to ice, but the ice can be evaporated by the strong radiation of the quasar or of young stars. Therefore we decided to search for water vapor in this object.” says van der Werf. “It is located so far away that we are looking back in time, to an era where the Universe was only 10% of its present age. This is one of the first searches ever conducted to find water in the early Universe.”
A shocking revelation? Not really. Water vapor has been discovered before. In this instance, however, the water amounted to about 1,000 trillion times the volume found on Earth. What’s more… it’s forming stars. It’s a dense disk, so thick that light barely escapes, and star propagation is rapid.
“Water molecules are sensitive to infrared radiation, so we could use the water vapor detected as a cosmic infrared light meter. With this method we found that essentially all radiation is locked up in the gas disk surrounding the black hole.” team member Marco Spaans (University of Groningen, The Netherlands) explains. “This trapped radiation is so intense that it will build up enormous pressure and eventually blow away the gas and dust clouds surrounding the black hole.”
These findings add a new complexity to our understanding of black holes and the galaxies which hold them. Team member Alicia Berciano Alba (ASTRON, The Netherlands) says: “There is a mysterious relation between the masses of black holes in the centers of galaxies and the masses of the galaxies themselves, as if the formation of both is regulated by the same process. Our results show that these opaque gas disks, which will be ultimately blown away by the intense pressure of the trapped radiation, probably play a key role in this process.” IRAM director Pierre Cox, co-author of the paper, adds: “This discovery opens new possibilities for studying galaxies in the early Universe, using water molecules that probe regions closest to the central black hole, that are otherwise difficult to explore.”
Keep on going, because the IRAM team is up to the task and continuing to look for other sources of water vapor in the early Universe!
Source: Universe Today

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