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). 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 Late 1960s ->detected bursts of gamma-rays Several years -> gamma-ray bursts are coming from space Several years -> gamma-ray bursts are coming from space They publicized the discovery in 1973. They publicized the discovery in 1973.

6. Vela Satellites 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. The Vela 5A Satellite

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

9. GRB Distribution detected by BATSE

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

12. Theoretical Explanation Come from unusually powerful supernovae 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. 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 A supernova that forms a black hole->more matter into smaller region->more energy Hypernova Hypernova

13. Suggestions A lot of literature related to GRB A lot of literature related to GRB http://imagine.gsfc.nasa.gov/docs/science/kno w_l1/grbs.html http://imagine.gsfc.nasa.gov/docs/science/kno w_l1/grbs.html

14. GRB Clip http://imagine.gsfc.nasa.gov/Videos/news/GR Bstar2.mov http://imagine.gsfc.nasa.gov/Videos/news/GR Bstar2.mov

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