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High-resolution calculations of merging neutron stars - III. Gamma-ray bursts

Rosswog, S.; Ramirez-Ruiz, E. and Davies, Melvyn B LU (2003) In Monthly Notices of the Royal Astronomical Society 345. p.1077-1090
Abstract
Recent three-dimensional, high-resolution simulations of neutron star coalescences are analysed to assess whether short gamma-ray bursts (GRBs) could originate from such encounters. The two most popular modes of energy extraction - namely the annihilation of and magnetohydrodynamic processes - are explored in order to investigate their viability in launching GRBs. We find that annihilation can provide the necessary stresses to drive a highly relativistic expansion. However, unless the outflow is beamed into less than 1 per cent of the solid angle, this mechanism may fail to explain the apparent isotropized energies implied for short GRBs at cosmological distances. We argue that the energetic, neutrino-driven wind that accompanies the... (More)
Recent three-dimensional, high-resolution simulations of neutron star coalescences are analysed to assess whether short gamma-ray bursts (GRBs) could originate from such encounters. The two most popular modes of energy extraction - namely the annihilation of and magnetohydrodynamic processes - are explored in order to investigate their viability in launching GRBs. We find that annihilation can provide the necessary stresses to drive a highly relativistic expansion. However, unless the outflow is beamed into less than 1 per cent of the solid angle, this mechanism may fail to explain the apparent isotropized energies implied for short GRBs at cosmological distances. We argue that the energetic, neutrino-driven wind that accompanies the merger event will have enough pressure to provide adequate collimation to the -annihilation-driven jet, thereby comfortably satisfying constraints on event rate and apparent luminosity. We also assess magnetic mechanisms to transform the available energy into a GRB. If the central object does not collapse immediately into a black hole, it will be convective and it is expected to act as an effective large scale dynamo, amplifying the seed magnetic fields to a few times 1017 G within a small fraction of a second. The associated spindown time-scale is 0.2 s, coinciding with the typical duration of a short GRB. The efficiencies of the various assessed magnetic processes are high enough to produce isotropized luminosities in excess of 1052 erg s-1 even without beaming. (Less)
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author
publishing date
type
Contribution to journal
publication status
published
subject
keywords
dense matter - hydrodynamics - neutrinos - methods: numerical - stars: neutron - gamma-rays: bursts
in
Monthly Notices of the Royal Astronomical Society
volume
345
pages
1077 - 1090
publisher
Wiley-Blackwell
external identifiers
  • scopus:0242425047
ISSN
1365-2966
DOI
10.1046/j.1365-2966.2003.07032.x
language
English
LU publication?
no
id
e3e25e86-e68a-4ee2-921d-8cc85b0fa85c (old id 768132)
date added to LUP
2007-12-18 12:28:10
date last changed
2017-07-09 04:42:24
@article{e3e25e86-e68a-4ee2-921d-8cc85b0fa85c,
  abstract     = {Recent three-dimensional, high-resolution simulations of neutron star coalescences are analysed to assess whether short gamma-ray bursts (GRBs) could originate from such encounters. The two most popular modes of energy extraction - namely the annihilation of and magnetohydrodynamic processes - are explored in order to investigate their viability in launching GRBs. We find that annihilation can provide the necessary stresses to drive a highly relativistic expansion. However, unless the outflow is beamed into less than 1 per cent of the solid angle, this mechanism may fail to explain the apparent isotropized energies implied for short GRBs at cosmological distances. We argue that the energetic, neutrino-driven wind that accompanies the merger event will have enough pressure to provide adequate collimation to the -annihilation-driven jet, thereby comfortably satisfying constraints on event rate and apparent luminosity. We also assess magnetic mechanisms to transform the available energy into a GRB. If the central object does not collapse immediately into a black hole, it will be convective and it is expected to act as an effective large scale dynamo, amplifying the seed magnetic fields to a few times 1017 G within a small fraction of a second. The associated spindown time-scale is 0.2 s, coinciding with the typical duration of a short GRB. The efficiencies of the various assessed magnetic processes are high enough to produce isotropized luminosities in excess of 1052 erg s-1 even without beaming.},
  author       = {Rosswog, S. and Ramirez-Ruiz, E. and Davies, Melvyn B},
  issn         = {1365-2966},
  keyword      = {dense matter - hydrodynamics - neutrinos - methods: numerical - stars: neutron - gamma-rays: bursts},
  language     = {eng},
  pages        = {1077--1090},
  publisher    = {Wiley-Blackwell},
  series       = {Monthly Notices of the Royal Astronomical Society},
  title        = {High-resolution calculations of merging neutron stars - III. Gamma-ray bursts},
  url          = {http://dx.doi.org/10.1046/j.1365-2966.2003.07032.x},
  volume       = {345},
  year         = {2003},
}