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Gamma-ray Bursts

Gamma-ray Bursts. Presentation by Aung Sis Naing. A little bit about gamma-rays. How do you make gamma-rays?. What is GRB ?. are short-lived bursts of gamma-ray photons last from a few milliseconds to several minutes shine hundreds of times brighter than a typical supernova

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Gamma-ray Bursts

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  1. Gamma-ray Bursts Presentation by Aung Sis Naing

  2. A little bit about gamma-rays

  3. How do you make gamma-rays?

  4. What is GRB ? • are short-lived bursts of gamma-ray photons • last from a few milliseconds to several minutes • shine hundreds of times brighter than a typical supernova • they are (briefly) the brightest source of cosmic gamma-ray photons in the observable universe

  5. History • In the early 1960s, the United States began launching a series of top-secret satellites designed to look for gamma rays emitted by nuclear bomb tests (on the look out for Soviet nuclear testing in violation of the atmospheric nuclear test ban treaty). • Late 1960s ->detected bursts of gamma-rays • Several years -> gamma-ray bursts are coming from space • They publicized the discovery in 1973.

  6. Launched by the US Air Force to verify the Nuclear Test Ban Treaty of 1963. Sensitive to Gamma-Rays No test ban violations were identified, but mysterious flashes of gamma-rays were detected outside the solar system. Vela Satellites The Vela 5A Satellite

  7. Mystery • Origin unknown -> Astronomers didn’t know if these bursts originated at the edge of our solar system, somewhere in our Milky Way Galaxy, or very far away. • Most astronomers assumed that GRB’S, like X-ray bursts, came from explosive events associated with neutron stars.

  8. NASA launched Compton in 1991. Carried an array of 8 detectors Could determine the direction of a gamma-ray burst within about 1 deg. Recorded about 1 per day Even distribution across the sky ->ruled out the possibility that they come from anywhere in the Milky Way Galaxy. Compton Gamma-Ray Observatory

  9. GRB Distribution detected by BATSE

  10. X-ray afterglow detected by an Italian satellite in 1997 Visual afterglow Very bright Afterglow

  11. Theoretical Explanation • Come from unusually powerful supernovae • An ordinary supernova that forms a neutron star does not release enough energy to power the luminosity of the brightest GRB’S. • A supernova that forms a black hole->more matter into smaller region->more energy • Hypernova

  12. Suggestions • A lot of literature related to GRB • http://imagine.gsfc.nasa.gov/docs/science/know_l1/grbs.html

  13. GRB Clip • http://imagine.gsfc.nasa.gov/Videos/news/GRBstar2.mov

  14. Thank you! • Special Thanks to Online resources and The Cosmic Perspective by Bennett, et al. • Q & A

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