GRB a New Tool for the Study of the Universe Expansion

1. GRB a New Tool for the Study of the Universe Expansion Guido Barbiellini and Francesco Longo University and INFN, Trieste In collaboration with A.Celotti and Z.Bosnjak (SISSA) Venice 24th February 2005 XI International Workshop on "Neutrino Telescopes"

2. Outline • Introduction • GRB phenomenology • Prompt Emission and Afterglow • GRB standard fireball model • GRB engine • Energetics and Collimation • Source models • The fireworks model • Spectral Energy correlations • Peak Energy vs Total energy correlations • Reproducing the BATSE fluence distribution • GRB environment • SN & GRB connection • The Compton tail • Recent experimental evidences

3. CGRO-BATSE (1991-2000) CGRO/BATSE (25 keV÷10 MeV)

4. Gamma-Ray Bursts Temporal behaviour Spectral shape Spatial distribution

5. BeppoSAX and the Afterglows • Good Angular resolution (< arcmin) • Observation of the X-Afterglow Costa et al. (1997) • Optical Afterglow (HST, Keck) • Direct observation of the host galaxies • Distance determination Kippen et al. (1998) Djorgoski et al. (2000)

6. The Fireball Model Cartoon by Piran (1999)

7. GRB progenitors GRB020813 (credits to CXO/NASA)

8. Afterglow Observations Harrison et al (1999) Achromatic Break Woosley (2001)

9. Jet and Energy Requirements Frail et al. (2001)

10. Jet and Energy Requirements Bloom et al. (2003)

11. Collapsar model Woosley (1993) • Very massive star that collapses in a rapidly spinning BH. • Identification with SN explosion.

12. B field Vacuum Breakdown Blandford & Znajek (1977) Brown et al. (2000) Barbiellini & Longo (2001) Barbiellini, Celotti & Longo (2003) Blandford-Znajek mechanism

13. Vacuum Breakdown The GRB energy emission is attributed to an high magnetic field that breaks down the vacuum around the BH and gives origin to a e fireball. Polar cap BH vacuum breakdown Pair production rate Figure from Heyl 2001

14. Two phase expansion The first phase of the evolution occurs close to the engine and is responsible of energizing and collimating the shells. It ends when the external magnetic field cannot balance the radiation pressure. • Phase 1 (acceleration and collimation) ends when: • Assuming a dependence of the B field: this happens at • Parallel stream with • Internal “temperature”

15. Two phase expansion • Phase 2 (adiabatic expansion) ends at the radius: • Fireball matter dominated: • R2 estimation • Fireball adiabatic expansion The second phase of the evolution is a radiation dominated expansion.

16. Jet Angle estimation The fireball evolution is hypothized in analogy with the in-flight decay of an elementary particle. • Lorentz factors • Opening angle • Result: Figure from Landau-Lifšits (1976)

17. Energy Angle relationship The observed angular distribution of the fireball Lorentz factor is expected to be anisotropic. Predicted Energy-Angle relation

18. Spectral Energy correlations Amati et al. (2002) Ghirlanda et al. (2004)

19. GRB for Cosmology Ghirlanda et al. (2004)

20. GRB for Cosmology Ghirlanda et al. 2005

21. Testing the correlations (Band and Preece 2005)

22. GRB fluence distribution GRB RATESFR Madau & Pozzetti 2000 FLUENCE DISTRIBUTION USING AMATI RELATION By random extraction of Epeak (Preece et al. 2000) and GRB redshift for a sample of GRBs we reproduce bright GRB fluence distribution. Bosnjak et al. (2004)

23. Testing the correlations Bosnjak et al. astro-ph/0502185

24. Testing the correlations Bosnjak et al. astro-ph/0502185

25. Testing the correlations Ghirlanda et al. astro-ph/0502186

26. SN- GRB connection SN evidence SN 1998bw - GRB 980425 chance coincidence O(10-4) (Galama et al. 98)

27. GRB 030329: the “smoking gun”? (Matheson et al. 2003)

28. Bright and Dim GRB Q = cts/peak cts (Connaughton 2002) • BRIGHT GRB  DIM GRB

29. GRB tails • Connaughton (2002), ApJ 567, 1028 • Search for Post Burst emission in prompt GRB energy band • Looking for high energy afterglow (overlapping with prompt emission) for constraining Internal/External Shock Model • Sum of Background Subtracted Burst Light Curves • Tails out to hundreds of seconds decaying as temporal power law  = 0.6  0.1 • Common feature for long GRB • Not related to presence of low energy afterglow

30. GRB tails Sum of 400 long GRB bkg subtracted peak alligned curve Connaughton 2002

31. GRB tails Dim Bursts Bright Bursts Connaughton 2002

32. Bright and Dim Bursts • 3 equally populated classes • Bright bursts • Peak counts >1.5 cm-2 s-1 • Mean Fluence 1.5  10-5erg cm-2 • Dim bursts • peak counts < 0.75 cm-2 s-1 • Mean fluence 1.3  10-6erg cm-2 • Mean fluence ratio = 11

33. Bright and Dim GRB Q = cts/peak cts • BRIGHT GRB  DIM GRB

34. The Compton Tail Barbiellini et al. (2004) MNRAS 350, L5

35. The Compton tail • “Prompt” luminosity • Compton “Reprocessed” luminosity • “Q” ratio

36. Bright and Dim Bursts • Bright bursts (tail at 800 s) • Peak counts >1.5 cm-2 s-1 • Mean Fluence 1.5  10-5erg cm-2 • Q = 4.0  0.8 10-4 (5 ) fit over PL •  = 1.3 • Dim bursts (tail at 300s) • peak counts < 0.75cm-2 s-1 • Mean fluence 1.3  10-6erg cm-2 • Q = 5.6  1.4 10-3 (4 ) fit over PL •  =2.8 • Mean fluence ratio = 11 • “Compton” correction • Corrected fluence ratio = 2.8 (z or Epeak?) R = 1015 cm R ~ R  ~ 0.1

37. Recent evidences GRB 011121 Piro et al. (2005)

38. Recent evidences GRB 011121 Piro et al. (2005)

39. Effect of Attenuation Epeak Preliminary Ep ~ Eg0.7 Ep ~ Eg Tau = 1.5 +- 0.5 Caution: scaling fluence and Epeak Egamma

40. Effects on Hubble Plots Preliminary Luminosity distance Reducing the scatter Redshift

41. Effects on Hubble Plots Luminosity distance Preliminary Redshift

42. Cosmology with GRB requires: Spectral Epeak determination Measurement of Jet Opening Angle Evaluation of environment material Waiting for Swift results Conclusions