1. 9 May 2013: New Moon Image: May 2012 annular eclipse, Monument Valley AZ

2. GRB 130427 4 hour long burst seen by Fermi z=0.34

3. AST101 The Biggest Explosions Since the Big Bang

4. 1967: A Mystery Unfolds Vela 5b

5. A Century of Gamma Ray Bursts, R. Nemiroff, 1994

6. Clues Large energy release Fast energy release Only high energy photons seen

8. Possibilities Include… Asteroids or comets falling onto neutron stars neutron starquakes neutron star novae stellar flares black holes white holes active galactic nuclei collisions of cosmic strings strange matter supernovae

9. More Clues

10. Isotropic distribution on the sky: They can be faint and close (within a few hundred light years). They can be associated with the halo of the galaxy. They can be bright and very far away.

11. Isotropy High degree of isotropy means They can not originate in the Galaxy They must be cosmological Energies exceed 10 51 ergs

12. The Problem Gamma rays do not focus well Localization by timing 5-10 degree positions Compton Gamma Ray Observatory

13. The Solution Beppo-SAX: Satellite per Astronomia X (1996-2002) Combined burst detector with X-ray imager

14. z=0.8

15. Irregular galaxy, z=3.4

16. GRB 980425 coincident with sn 1998 bw galaxy is ESO 184-G82, distance = 100 MLy

17. GRB 011121 optical decay

18. What are the GRBs? Peculiar type Ic supernovae (collapse of a massive star) Collisions/mergers between neutron stars There is about 1/day in the universe, or 1/200 Myr/galaxy

19. What are the GRBs? And… some are terrestrial – probably associated with lightning and/or the red sprites and blue jets.

20. Why the GRBs are Important They are the brightest things in the universe They are standard candles for the youngest, most distant parts of the universe They can be deadly