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Published November 1, 2015 | Submitted + Published
Journal Article Open

Monte Carlo Neutrino Transport Through Remnant Disks from Neutron Star Mergers

Abstract

We present Sedonu, a new open source, steady-state, special relativistic Monte Carlo (MC) neutrino transport code, available at bitbucket.org/srichers/sedonu. The code calculates the energy- and angle-dependent neutrino distribution function on fluid backgrounds of any number of spatial dimensions, calculates the rates of change of fluid internal energy and electron fraction, and solves for the equilibrium fluid temperature and electron fraction. We apply this method to snapshots from two-dimensional simulations of accretion disks left behind by binary neutron star mergers, varying the input physics and comparing to the results obtained with a leakage scheme for the cases of a central black hole and a central hypermassive neutron star. Neutrinos are guided away from the densest regions of the disk and escape preferentially around 45° from the equatorial plane. Neutrino heating is strengthened by MC transport a few scale heights above the disk midplane near the innermost stable circular orbit, potentially leading to a stronger neutrino-driven wind. Neutrino cooling in the dense midplane of the disk is stronger when using MC transport, leading to a globally higher cooling rate by a factor of a few and a larger leptonization rate by an order of magnitude. We calculate neutrino pair annihilation rates and estimate that an energy of 2.8 × 10^(46) erg is deposited within 45° of the symmetry axis over 300 ms when a central BH is present. Similarly, 1.9 × 10^(48) erg is deposited over 3 s when an HMNS sits at the center, but neither estimate is likely to be sufficient to drive a gamma-ray burst jet.

Additional Information

© 2015. The American Astronomical Society. Received 2015 July 13. Accepted 2015 September 14. Published 2015 October 26. We thank A. Burrows, M. Duez, F. Foucart, L. Roberts, J. Lippuner, E. Murchikova, and T. Urbatsch for helpful discussions and Rollin Thomas for an interface to the Lua library. SR is supported by a DOE Computational Science Graduate Fellowship under grant number DE-FG02-97ER25308. S.R. and C.D.O. acknowledge support by the National Science Foundation under awards AST-1205732, AST-1333520, and PHY-1151197, by the Sherman Fairchild Foundation, and by the Los Alamos National Laboratory Institute for Geophysics, Planetary Physics and Signatures. E.O. acknowledges support from NASA through Hubble Fellowship grant #51344.001-A awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555. R.F. acknowledges support from the University of California Office of the President, and from NSF award AST-1206097. This research used computing and storage resources (repo m2058) provided by the National Energy Research Scientific Computing Center (NERSC), which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. Parts of the computations were also performed on the Caltech compute cluster Zwicky (NSF MRI-R2 award PHY-0960291), on the NSF XSEDE network under allocation TG-PHY100033, and on NSF/NCSA Blue Waters under NSF PRAC award ACI-1440083.

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Published - Richers_2015.pdf

Submitted - 1507.03606v1.pdf

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Additional details

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August 20, 2023
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October 23, 2023