Volume 582, October 2015
|Number of page(s)||9|
|Published online||01 October 2015|
r-process nucleosynthesis in the MHD+neutrino-heated collapsar jet
1 Waseda University, Ohkubo 3-4-1, Shinjuku, 169-8555, Tokyo, Japan
2 National Astronomical Observatory of Japan, Osawa 2-21-1, Mitaka, 181-8588 Tokyo, Japan
3 Department of Astronomy, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, 113-0033 Tokyo, Japan
4 Center for Astrophysics, Department of Physics, University of Notre Dame, Notre Dame, IN 46556, USA
Received: 17 March 2015
Accepted: 23 May 2015
It has been proposed that the collapsar scenario for long-duration gamma ray bursts is a possible astrophysical site for r-process nucleosynthesis. Here we present r-process nucleosynthesis calculations based upon a model for a MHD+neutrino-heated collapsar jet. We utilize a relativistic magnetohydrodynamic model that includes ray-tracing neutrino transport to describe the development of the black hole accretion disk and the neutrino heating of the funnel region above the black hole. The late time evolution of the collapsar jet is then evolved using axisymmetric special relativistic hydrodynamics. We employ representative test particles to follow the trajectories in density, temperature, entropy, and electron fraction for material flowing from the accretion disk into the jet until they are several thousand km above the black hole. The evolution of nuclear abundances from nucleons to heavy nuclei for ejected test particle trajectories was solved in a large nuclear reaction network as temperatures fall from 9 × 109 to 3 × 108 K. We show that an r-process-like abundance distribution forms in material ejected in the collapsar jet. The possibility for a signature of collapsar r-process material to be found in metal-poor stars is discussed.
Key words: gamma-ray burst: general / stars: black holes / accretion, accretion disks / magnetohydrodynamics (MHD) / stars: abundances / stars: massive
© ESO, 2015
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