Coalescing neutron stars: A Step towards physical models. 2. Neutrino emission, neutron tori, and gamma-ray bursts
Jun, 1996
35 pages
Published in:
- Astron.Astrophys. 319 (1997) 122-153
e-Print:
- astro-ph/9606181 [astro-ph]
Report number:
- MPA-957
View in:
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Abstract: (arXiv)
Three-dimensional hydrodynamical, Newtonian calculations of the coalescence of equal-mass binary neutron stars are performed, including a physical high-density equation of state and a treatment of the neutrino emission of the heated matter. The total neutrino luminosity climbs to a maximum value of 1--erg/s of which 90--95\% originate from the toroidal gas cloud surrounding the very dense core formed after the merging. When the neutrino luminosities are highest, -annihilation deposits about 0.2--0.3\% of the emitted neutrino energy in the immediate neighborhood of the merger, and the maximum integral energy deposition rate is 3--erg/s. Since the core of the merged object will most likely collapse into a black hole within milliseconds, the energy that can be pumped into a pair-photon fireball is insufficient by a factor of about 1000 to explain -ray bursts at cosmological distances with an energy of the order of erg/steradian. Analytical estimates show that the additional energy provided by the annihilation of pairs emitted from a possible accretion torus of around the central black hole is still more than a factor of 10 too small, unless focussing of the fireball into a jet-like expansion plays an important role. About -- of material lost during the neutron star merging and swept out from the system in a neutrino-driven wind might be a site for nucleosythesis. Aspects of a possible r-processing in these ejecta are discussed.References(129)
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