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(also Mastichiadis & Kazanas 2005) Spectra and Time Variability

(also Mastichiadis & Kazanas 2005) Spectra and Time Variability. Similarity of GRB/Nuclear Piles. The similarity of GRB to a “Nuclear Pile” is more than incidental: 1. They both contain lots of free energy stored in: Nuclear Binding Energy (nuclear pile)

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(also Mastichiadis & Kazanas 2005) Spectra and Time Variability

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  1. (also Mastichiadis & Kazanas 2005)Spectra and Time Variability

  2. Similarity of GRB/Nuclear Piles • The similarity of GRB to a “Nuclear Pile” is more than incidental: • 1. They both contain lots of free energy stored in: • Nuclear Binding Energy (nuclear pile) • Relativistic Protons or Magnetic Field (GRB) 2. The energy can be released explosively once certain conditions (identical in both cases) are fulfilled.

  3. There are (at least) two outstanding issues with the prompt GRB emission (Piran 2004): • A. Dissipation of the RBW free energy. Energy stored in relativistic p’s or B-field. Sweeping of ambient protons stores significant amount of energy in p’s anyway. Necessary to store energy in non-radiant form, but hard to extract when needed. • B. The presence of Epeak~0.1 – 1.0 MeV. If prompt emission is synchrotron by relativistic electrons of Loretnz factor (LF) same as shock Ep ~G4, much too strong to account for the observations.

  4. We propose a model that can resolve both these issues simultaneously. The model relies: • 1. On a radiative instability of a relativistic proton plasma with B-fields due to the internally produced sychrotron radiation. • 2. On the amplification of the instability by relativistic motion and reflection of the internally produced radiation by upstream located matter.

  5. Pg e+e- eB Bg R

  6. bG6+1 ~ 100 GeV photons bG4+1 ~ 1 MeV photons bG2+1~ 10 eV O-UV photons RBW Mirror 'Mirror' R/G2 Rel. Blast Wave

  7. bG6+1 ~ 100 GeV photons bG4+1 ~ 1 MeV photons bG2+1~ 10 eV O-UV photons RBW Mirror 'Mirror' Rel. Blast Wave

  8. We have modeled this process numerically. We assume the presence of scattering medium at R ~1016 cm and of finite radial extent. • We follow the evolution of the proton, electron and photon distribution by solving the corresponding kinetic equations. • We obtain the spectra as a function of time for the prompt GRB emission. • The time scales are given in units of the comoving blob crossing time Dco/c ~ R / G2c ~ 2 R16/G2.6 sec.

  9. The kinetic equations are solved on the RBW rest frame with pair production, synchrotron, IC losses, escape in a spherical geometry of radius R/Gand proton density n = n0G. The protons are assumed to be injected at energy Ep = mpc2G. These are the following:

  10. Spectra (Mastichiadis & Kazanas 2005)

  11. Distribution of LE indices a

  12. S=1/2, a=-3/2 The spectra of doubly scattered component (Mastichiadis & DK (2005)) S=1, a=-1 S=2, a=0

  13. 120 G 12 G 1.2 G 0.12 G

  14. Eiso of the three different spectral components as a function of B for G=400 and np=105 cm-3. x 103 denotes the relative g-ray – O-UV normalization of GRB 990123, 041219a. 1 MeV 100 GeV X103 O-UV

  15. Epeak as a function of the magnetic field B

  16. Variations • If the “mirror” is in relative motion to the RBW then the kinematic threshold is modified to b G3 G2rel ~ 2; Grel is the relative LF between the RBW and the “mirror”. • The value of Epeak is again ~ 1 MeV, however the synchrotron and IC peaks are higher and lower by G2rel than G2. • In the presence of accelerated particles the threshold condition is satisfied even for G< (2/b)1/5. This may explain the time evolution of GRB941017(Gonzalez et al. 04) • GRB flux is likely to be highly polarized (GRB 031206, Coburn & Boggs 03). • This model applicable to internal shock model (photons from downstream shell instead of “mirror”).

  17. Then ....

  18. Shock – Mirror Geometry

  19. formation region, generally not much different than the

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