Posts Tagged ‘gamma ray bursts’

Did An 8th Century Gamma Ray Burst Irradiate The Earth?

January 24, 2013 Leave a comment

A nearby short duration gamma-ray burst may be the cause of an intense blast of high-energy radiation that hit the Earth in the 8th century, according to new research led by astronomers Valeri Hambaryan and Ralph Neuhӓuser. The two scientists, based at the Astrophysics Institute of the University of Jena in Germany, publish their results in the journal Monthly Notices of the Royal Astronomical Society.

In 2012 scientist Fusa Miyake announced the detection of high levels of the isotope Carbon-14 and Beryllium-10 in tree rings formed in 775 CE, suggesting that a burst of radiation struck the Earth in the year 774 or 775. Carbon-14 and Beryllium-10 form when radiation from space collides with nitrogen atoms, which then decay to these heavier forms of carbon and beryllium. The earlier research ruled out the nearby explosion of a massive star (a supernova) as nothing was recorded in observations at the time and no remnant has been found.

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Galaxy’s Gamma-Ray Flares Erupted Far From Its Black Hole

January 15, 2013 Leave a comment

In 2011, a months-long blast of energy launched by an enormous black hole almost 11 billion years ago swept past Earth. Using a combination of data from NASA’s Fermi Gamma-ray Space Telescope and the National Science Foundation’s Very Long Baseline Array (VLBA), the world’s largest radio telescope, astronomers have zeroed in on the source of this ancient outburst.

Theorists expect gamma-ray outbursts occur only in close proximity to a galaxy’s central black hole, the powerhouse ultimately responsible for the activity. A few rare observations suggested this is not the case. The 2011 flares from a galaxy known as 4C +71.07 now give astronomers the clearest and most distant evidence that the theory still needs some work. The gamma-ray emission originated about 70 light-years away from the galaxy’s central black hole.

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X-ray Vision Can Reveal The Moment Of Birth Of Violent Supernovae

December 12, 2012 Leave a comment

GRB 080913, a distant supernova detected by Swift. Credit: NASA/Swift/Stefan Immler

GRB 080913, a distant supernova detected by Swift. Credit: NASA/Swift/Stefan Immler

A team of astronomers led by the University of Leicester has uncovered new evidence that suggests that X-ray detectors in space could be the first to witness new supernovae that signal the death of massive stars. Astronomers have measured an excess of X-ray radiation in the first few minutes of collapsing massive stars, which may be the signature of the supernova shock wave first escaping from the star.

The findings have come as a surprise to Dr Rhaana Starling, of the University of Leicester Department of Physics and Astronomy, whose research is published in the Monthly Notices of the Royal Astronomical Society, published by Oxford University Press.

Dr Starling said: “The most massive stars can be tens to a hundred times larger than the Sun. When one of these giants runs out of hydrogen gas it collapses catastrophically and explodes as a supernova, blowing off its outer layers which enrich the Universe. But this is no ordinary supernova; in the explosion narrowly confined streams of material are forced out of the poles of the star at almost the speed of light. These so-called relativistic jets give rise to brief flashes of energetic gamma-radiation called gamma-ray bursts, which are picked up by monitoring instruments in Space, that in turn alert astronomers.”

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Spacetime: A Smoother Brew Than We Knew

August 23, 2012 Leave a comment

Spacetime may be less like beer and more like sipping whiskey. Or so an intergalactic photo finish would suggest.

Physicist Robert Nemiroff of Michigan Technological University reached this heady conclusion after studying the tracings of three photons of differing wavelengths that had been recorded by NASA’s Fermi Gamma-ray Space Telescope in May 2009.

The photons originated about 7 billion light years away from Earth in one of three pulses from a gamma-ray burst and arrived at the orbiting telescope just one millisecond apart, in a virtual tie

“Gamma-ray bursts can tell us some very interesting things about the universe,” Nemiroff said. In this case, those three photons recorded by the Fermi telescope suggest that spacetime may not be not as bubbly as some scientists think.

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Astrophysicist Chryssa Kouveliotou Wins 2012 Heineman Prize

January 30, 2012 Leave a comment

The American Institute of Physics (AIP) and the American Astronomical Society (AAS) are pleased to announce that renowned astrophysicist Chryssa Kouveliotou, Ph.D., has been selected as the 2012 recipient of the Dannie Heineman Prize for Astrophysics, which is given annually to recognize outstanding work in the field.

Her citation reads: “For her extensive accomplishments and discoveries in the areas of gamma ray bursts and their afterglows, soft gamma repeaters, and magnetars. Particularly notable are Dr. Kouveliotou’s abilities to create collaborations and her effectiveness and insights in using multiwavelength observations.”

The award will be presented at the American Astronomical Society’s 221st Meeting, January 2013, in Long Beach, Calif., at which Kouveliotou will give a plenary lecture.

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