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J. N. Daniel, T. Tajima (U. Texas at Austin)
Gamma-ray bursts now have been identified as cosmological objects with very high energy density, most likely provided by a collision of two neutron stars. The extremely hot electron-positron-baryon plasma exploding upon this collision is regarded as a source of intense gamma-ray emission. However, many gamma-ray bursts exhibit significant high energy components far from the thermal spectrum. Although ordinary acoustic shocks are capable of heating, they are unable to accelerate particles comprising high energy components. Upon the collision of two neutron stars with sufficient magnetic fields, transverse Alfvén shocks carry an equally large amount of energy. The electron-positron plasma of this event allows the mode-conversion of these Alfvén shocks into intense EM pulses, which are capable of accelerating electrons and positrons into high energies. A computational model of this mode conversion process provides photon spectra not inconsistent with observation, which follow a multiple power law with log-log slopes of approximately -1, before a ''knee" in the spectrum.
The author(s) of this abstract have provided an email address for comments about the abstract: daniel@ziggy.ph.utexas.edu