1. Gamma-Ray Bursts: The Biggest Explosions Since the Big Bang Edo Berger

2. Talk Outline History and basic observational facts Basic Physics: compactness & baryon loading The fireball model, afterglows, and jets The progenitors of long GRBs The progenitors of short GRBs GRBs as a powerful cosmological tool

3. Cosmic Cannon: How an Exploding Star Could Fry Earth By Robert Roy Britt/Space.com

4. Gamma-Rays

5. Limited Nuclear Test Ban Treaty, 1963 … to prohibit, to prevent, and not to carry out any nuclear weapon test explosion: (a) in the atmosphere; beyond its limits, including outer space; or under water …

6. The Vela Satellites (1963-1970)

7. The First Gamma- Ray Burst

9. Uncertainty in distance by a factor of one billion Where Do GRBs Come From? (1973-1993) 135 theories, less than 100 GRBs! Short duration, intense energy: New type of supernova? Giant stellar flares? Matter/anti-matter annihilation? Neutron stars? Black holes?

11. Gamma-Ray Bursts from the Milky Way

12. The Compton Gamma-Ray Observatory

13. GRBs do not come from the disk of the Milky Way

14. The “Great Debate” (1995) “The Distance Scale to Gamma-Ray Bursts” Bohdan PaczynskiDon Lamb GalacticCosmological The Shapley–Curtis Great Debate (1920) on the “Scale of the Universe”

15. Long Short Two types of gamma-ray bursts

16. To solve the GRB mystery it is essential to: Determine accurate positions Deliver positions to observers rapidly

18. (April 30, 1996) Delivery time of ~hours Positions 100x more accurate than BATSE BeppoSAX (October 9, 2000) HETE-2

19. The Swift Satellite & Future Missions UV/Optical Telescope Burst Alert Telescope X-Ray Telescope Event rate ~100/yr Positions ~1-5” Lifetime ~2015 GLAST 8 keV - 300 GeV ~150/yr Launch 10/2007 EXIST 5-600 keV All-sky per orbit 10x Swift sensitivity ~500-1000/yr Launch >2015

20. The First Afterglow (February 28, 1997) 5 hours3 days

21. Afterglows in Visible Light

22. The Distance to Gamma-Ray Bursts Low speed (Nearby) High speed (Far away) n

23. 8 billion light-years away oxygencarbonmagnesiumhydrogen 22 sec47 sec73 sec 280 sec 450 sec

24. The Fireball Model (a mini Big Bang, or a super nuclear bomb)

25. The Compactness & Baryon Loading Problems ⇒ acceleration, thermalization ⇒ thermal GRB >10 51 erg of MeV  − rays in a few seconds (small region, c  t)  Fireball: a region optically thick due to electron-positron pair production (e 1 e 2 > m e c 2 )

26. The Compactness & Baryon Loading Problems Relativistic motion The kinetic energy of the baryons is converted to radiation via shocks - internal or external variability points to internal shocks The unavoidable baryon contamination provides a mechanism for delaying optical thinness and ensuring a high Lorentz factor required for GRB production. The new baryon loading problem is how to get only 10 -5 M  But... How do we get only 10 -5 M o in an astrophysical context?

27. Time Brightness

28. Courtesy: Tsvi Piran / Hebrew University

29. The Fireball Model Collapsar Coalescence Baryonic Magnetic Internal Shocks Magnetic instability External Shock Ε ngine  energy transport  conversion to  − rays  afterglow

31. Compact Object Mergers NS+NS BH+NS

32. Collapsing Massive Stars

34. Afterglow Physics Un-shocked ISM shocked ISM Ejecta CDFS 21  N(   -p From the afterglow we can determine the energy, density & geometry

35. Collimation (“Jets”)

38. Energy Release With jet corrections, we find a narrow distribution of gamma-ray enegy: E  ~ 1.3  10 51 erg E  iso EE  jet

39. The fraction coupled to Γ  varies widely. Quantity is the same, quality differs Energy Release

40. Soderberg et al. 2003 Wainwright, Berger & Penprase 2007, ApJ Long GRBs are Associated with Star Formation Wainwright, EB & Penprase 2007, ApJ

41. Star Nurseries

44. GRB 030329: The Rosetta Stone Saturday 3:38 am

45. GRBs result from the death of massive stars

46. Long Short Two types of gamma-ray bursts

49. LIGO

50. The Dark Ages of the Universe

52. GRB Absorption Spectroscopy Comparison to quasars: No proximity effect on galactic scales Small impact parameter In star forming regions Bright(er) [ind. of z] High(er) redshift Fade away

53. Redshift Distribution EB et al. 2005, ApJ

54. GRB 050505: z = 4.275 EB et al. 2006, ApJ log N H = 22.1  0.1 [S/H] = -1.2  0.06 Z 

55. GRB 050505: Progenitor Properties CIV extends over ~1000 km/s *  WR wind from the progenitor SiIV absorption sensitive to mass and metallicity (Leitherer & Lamers 1991)  WC Wolf-Rayet star: Z < 0.1Z  M < 25 M  * QSOs: correlation length <500 km/s (Rauch et al. 1996) EB et al. 2006, ApJ

56. GRB-DLAs EB et al. 2006, ApJ & in prep.

57. Cosmic Reionization Fan et al. 2005Gnedin et al. Neutral Fraction > 3x10 -4 ⇐

58. GRBs and Reionization Kawai et al. 2005 z = 6.295 log N H ~ 21.3 Z ~ 0.1 Z  x H < 0.6 GRBs

59. Conclusions GRBs require a source of at least  10 51 erg (similar to supernovae), but coupled to only  10 -5 solar masses Very high Lorentz factors are required The outflow is collimated in jets The progenitors of long GRBs are massive stars The progenitors of short GRBs are likely NS-NS or BH- NS binaries GRBs are a powerful cosmological tool