Gamma-Ray Bursts: Relativistic shells or central engines?

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In many models of Gamma-Ray Bursts (GRBs) relativistic shells are responsible for the overall envelope of emission. The authors use kinematics and symmetry to calculate the time history and spectral evolution expected from a relativistic shell including effects from intrinsic variations in the shell`s intensity and spectra. They find that the decay phase of an envelope is produced by photons delayed by the shell`s curvature. These delayed photons are produced by regions that are off-axis such that the spectra evolve according to a universal function ({proportional_to} T{sup {minus}1}) regardless of intrinsic variations in the rest frame of the shell. They ... continued below

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7 p.

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Fenimore, E.E. & Summer, M.C. August 1, 1997.

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In many models of Gamma-Ray Bursts (GRBs) relativistic shells are responsible for the overall envelope of emission. The authors use kinematics and symmetry to calculate the time history and spectral evolution expected from a relativistic shell including effects from intrinsic variations in the shell`s intensity and spectra. They find that the decay phase of an envelope is produced by photons delayed by the shell`s curvature. These delayed photons are produced by regions that are off-axis such that the spectra evolve according to a universal function ({proportional_to} T{sup {minus}1}) regardless of intrinsic variations in the rest frame of the shell. They compare these predictions to the overall envelope of emission of GRBs. The observed spectra evolve faster ({approximately} T{sup {minus}3}). Intrinsic variations cannot make the spectra evolve that fast, which adds strength to the shell symmetry problem: models, in particular, the external shock model, that involve relativistic shells must either confine the material to narrow pencil beams, be very inefficient, or break the local spherical symmetry so that the shell acts like a parallel slab. In the case of the internal shock models involving winds (i.e., central engines), it will probably be easier to break the local spherical symmetry, but the none must postulate nearly continuous energy generation at 10{sup 51} erg s{sup {minus}1} lasting up to hundreds of seconds at the central site.

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7 p.

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OSTI as DE97008181

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  • All-sky x-ray observations in the next decade workshop, Tokyo (Japan), Mar 1997

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  • Other: DE97008181
  • Report No.: LA-UR--97-1675
  • Report No.: CONF-9703111--1
  • Grant Number: W-7405-ENG-36
  • Office of Scientific & Technical Information Report Number: 515644
  • Archival Resource Key: ark:/67531/metadc692779

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  • August 1, 1997

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  • Aug. 14, 2015, 8:43 a.m.

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  • April 21, 2016, 9:50 p.m.

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Fenimore, E.E. & Summer, M.C. Gamma-Ray Bursts: Relativistic shells or central engines?, article, August 1, 1997; New Mexico. (digital.library.unt.edu/ark:/67531/metadc692779/: accessed November 22, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.