GRB Puzzles

1. GRB Puzzles The Baryon Purity Puzzle: Why is the energy spend on gamma rays and not on expanding matter? Why is  what it is? The photon entropy puzzle: Why Gamma Rays at 100 to 1000 KeV? Why not fewer photons at higher energy, or more photons at lower energy?

2. dM/dt scales as Ln5/3+… (Duncan, Shapiro, and Wasserman 1986, Woosley and coworkers 1996)….. ….but nearly linearly with Le+e- (Levinson and Eichler 1993): Assume standing baryonic rarefaction wave at critical point: Then dM/dt = area x critical density x sound velocity ~ 1031 L519/8 g/s TOO MUCH!

3. Possible answer to the Baryon Purity question: All or nothing principle: Something must prevent baryons from emerging. (e.g. event horizon, bare strange surface, NS gravity) This makes GRB particularly interesting. Perhaps they confirm Schwarzschild event horizons. Neutron stars, strange stars might not need accretion disk but black holeMUST have accretion disk, and accretion disk must generate a baryonic wind

4. CONSEQUENCE OF ALL OR NOTHING PRINCIPLE: ANY BARYONS IN GRB FIREBALL MUST HAVE ENTERED THROUGH THE SIDES e.g. from exterior baryonic wind, walls of host star…. They typically do so after the fireball is already at high G, with violent consequences.

5. How? Possible answers: Neutron leakage Photon drag of walls Why Gamma Rays at 100 to 1000 KeV?

6. Possible Answers Why Gamma Rays at 100 to 1000 KeV?

7. Possible Answers Why Gamma Rays at 100 to 1000 KeV? Photosphere established by pair annihilation (Eichler and Levinson, 1999)

8. Neutron Leakage into Baryon-Pure Fireball 1012 cm 1011 cm Neutrons crossing B lines Baryonpure jet High 

9. Collisional Avalanche Neutrons converted to protons + neutrons + pairs + neutrinos. This happens quickly, near the walls. n n n n trigger Typical p for emergent protons is about 2 # neutrons that diffuse across is of order (area/cross section)x(r/mfp)1/2 roughly 1050

10. Collisional Avalanche Neutron and ex-neutron mist Nn about A/about 1049A12 n n n n Neutron free streaming boundary Nn about A/

11. So what is G? 1) Pure Compton drag of pick-up ex-neutron gives G = [(3/4)(L/Ledd)(Rs/R) +Go]1/3 (L/Ledd) about 1012 to 14 , (Rs/R) about 10-6 So G or order 102 to 108/3 2) Gyration in Poynting flux gives naive estimate of [1051 ergs/ 1049 Nnmc2]1/2 ~300 but significant transverse gradients and subsequent acceleration

12. 3) Constrained Compton drag of walls: G about or less than 1/sinc, where c is the angular size of the photon production region as seen at the point of last scattering …. G of order 102 ? c

13. GRB Polarization by IC (Eichler and Levinson 2003) High polarization at Thin pencil beam Hollow cone on the cone

14. Probability of observing polarization > P, homogeneous distribution, Euclidian geometry,

15. Compton Sailing e,p WALL s = 1 / sin  In frame of sail, ’/2 

18. Intensity Polarization

20. Ring-shaped Source

21. The index k depends on details of detectability D D prop to k

22. Dependence on Source Geometry point source disk ring

23. Dependence on Beaming Factor Azimuthal overlap

24. Given geometry, dependence on  Compton sailing state

25. Polarization from scattering by geometrically THICK annulus

26. Eiso- peak correlation (Amati et al 2002, Atteia et al 2003) Eiso proportional to peak2

27. Off-axis Viewing as Grand Eiso- peak Correlate Viewer outside annulus annulus Pencil beam 

28. Inside annulus

30. XRF’s GRB’s 10 KeV 1 MeV

31. Reflection to Large Angles and GRB 980425

32. dVmax/dcosq (Eichler and Levinson, 1999) GRB 980425 type events can be normal GRB, but expected to be rarely observed, because of small Vmax, despite large solid angle.

33. Note that • GRB 980425 did not have any significant flux above the pair production threshold. Scattered photons would not have pair produced with unscattered ones, even at large scattering angles • Scattering material is at r>30 lightseconds, and probably propagated from source. It has an edge. • Obscuration of scattered photons is not a necessary consequence of any assumptions of the model .

34. Distinguishing features of model: 1)Violentbaryon loading allows extremely hard non-thermal spectra (even harder than shock acceleration). Multiscale baryon loading allows recycling of collisional byproducts, allowing extremely efficient UHE neutrino emission.

35. Distinguishing features of model: 1)Violentbaryon loading allows extremely hard non-thermal spectra (even harder than shock acceleration). Multiscale baryon loading allows recycling of collisional byproducts, allowing extremely efficient UHE neutrino emission 2)Scattering off baryon-rich walls can account for GRB980425 and similar ones as scattered photons into off-axis viewing angle

36. Distinguishing features of model: 1)Violentbaryon loading allows extremely hard non-thermal spectra (even harder than shock acceleration). Multiscale baryon loading allows recycling of collisional byproducts, allowing extremely efficient UHE neutrino emission 2)Scattering off baryon-rich walls can account for GRB980425 and similar ones as scattered photons into off-axis viewing angle 3) Positive polarization –intensity correlation expected if walls “sail” on Compton pressure. (Compton upscattering predicts negative correlation.)

37. Distinguishing features of model: 1)Violentbaryon loading allows extremely hard non-thermal spectra (even harder than shock acceleration). Multiscale baryon loading allows recycling of collisional byproducts, allowing extremely efficient UHE neutrino emission 2)Scattering off baryon-rich walls can account for GRB980425 and similar ones as scattered photons into off-axis viewing angle 3) Positive polarization –intensity correlation expected if walls “sail” on Compton pressure. (Compton upscattering predicts negative correlation.) 4)Annular geometry can account for X-ray flashes and Amati et. al Eiso –npeak correlation

38. 5?) Matter kinetic energy significant only because of baryon seeding. Baryon seeding increases with GRB duration t5/2. Afterglow efficiency may be an increasing function of duration. But we are not sure yet.