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TOPIC: Gamma-ray bursts

Blobrana

L

Posts: 131433

Date: Jun 8 22:51 2009

'Dark' Gamma-ray Bursts	Permalink

Keck Study Sheds New Light on 'Dark' Gamma-ray Bursts Gamma-ray bursts are the universe's biggest explosions, capable of producing so much light that ground-based telescopes easily detect it billions of light-years away. Yet, for more than a decade, astronomers have puzzled over the nature of so-called dark bursts, which produce gamma rays and X-rays but little or no visible light. They make up roughly half of the bursts detected by NASA's Swift satellite since its 2004 launch. At the American Astronomical Society meeting in Pasadena, California, an international team of astronomers today reported surprising new insight into dark bursts. The study finds that most occur in normal galaxies detectable by large, ground-based optical telescopes. Read more __________________

Blobrana

L

Posts: 131433

Date: Jun 8 17:02 2009

Gamma-ray bursts	Permalink

Fog lifted on 'dark' gamma-ray bursts, mysterious counterparts to bursts with an afterglow Study shows most 'dark' bursts are normal bursts occurring in dusty regions of galaxies Gamma-ray bursts, with their ability to pierce through gas and dust to shine brightly across the universe, are revealing areas of intense star formation and stellar death where astronomers have been unable to look - the dusty corners of otherwise dust-free galaxies. The conclusion comes from a survey of "dark" gamma-ray bursts - bright in gamma- and X-ray emissions, but with little or no visible light - reported today (Monday, June 8) at a meeting of the American Astronomical Society in Pasadena, Calif., by astronomers from the University of California, Berkeley, and institutions around the world. "Our study provides compelling evidence that a large fraction of star formation in the universe is hidden by dust in galaxies that do not appear otherwise dusty" - Joshua Bloom, associate professor of astronomy at UC Berkeley and senior author of the study. Star formation occurs in dense clouds that quickly fill with dust as the most massive stars rapidly age and explode, spewing newly created elements into the interstellar medium to seed new star formation. Hence, astronomers presume that a large amount of star formation is occurring in dust-filled galaxies, although actually measuring how much dust this process has built up in the most distant galaxies has proved extremely challenging. University of California - Berkeley -- Edited by Blobrana on Monday 8th of June 2009 06:01:12 PM __________________

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