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:
Report number:
  • MPA-957

Citations per year

199720042011201820250510152025
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--1.510 531.5\cdot 10~{53}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, ννˉ\nu\bar\nu-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--410 504\cdot 10~{50}erg/s. Since the 3M3\,M_{\odot} 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 γ\gamma-ray bursts at cosmological distances with an energy of the order of 10 51/(4π)10~{51}/(4\pi)erg/steradian. Analytical estimates show that the additional energy provided by the annihilation of ννˉ\nu\bar\nu pairs emitted from a possible accretion torus of 0.1M\sim 0.1\,M_{\odot} 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 10 410~{-4}--10 310~{-3}MM_\odot 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.