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Title: The r-PROCESS IN THE NEUTRINO-DRIVEN WIND FROM A BLACK-HOLE TORUS

Abstract

We examine r-process nucleosynthesis in the neutrino-driven wind from the thick accretion disk (or 'torus') around a black hole. Such systems are expected as remnants of binary neutron star or neutron star-black hole mergers. We consider a simplified, analytic, time-dependent evolution model of a 3 M{sub Sun} central black hole surrounded by a neutrino emitting accretion torus with 90 km radius, which serves as basis for computing spherically symmetric neutrino-driven wind solutions. We find that ejecta with modest entropies ({approx}30 per nucleon in units of the Boltzmann constant) and moderate expansion timescales ({approx}100 ms) dominate in the mass outflow. The mass-integrated nucleosynthetic abundances are in good agreement with the solar system r-process abundance distribution if a minimal value of the electron fraction at the charged-particle freezeout, Y{sub e,min} {approx} 0.2, is achieved. In the case of Y{sub e,min} {approx} 0.3, the production of r-elements beyond A {approx} 130 does not reach to the third peak but could still be important for an explanation of the abundance signatures in r-process deficient stars in the early Galaxy. The total mass of the ejected r-process nuclei is estimated to be {approx}1 Multiplication-Sign 10{sup -3} M{sub Sun }. If our model was representative, thismore » demands a Galactic event rate of {approx}2 Multiplication-Sign 10{sup -4} yr{sup -1} for black-hole-torus winds from merger remnants to be the dominant source of the r-process elements. Our result thus suggests that black-hole-torus winds from compact binary mergers have the potential to be a major, but probably not the dominant, production site of r-process elements.« less

Authors:
 [1];  [2]
  1. Technische Universitaet Muenchen, Excellence Cluster Universe, Boltzmannstr. 2, D-85748 Garching (Germany)
  2. Max-Planck-Institut fuer Astrophysik, Karl-Schwarzschild-Str. 1, D-85748 Garching (Germany)
Publication Date:
OSTI Identifier:
22011658
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 746; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABUNDANCE; ACCRETION DISKS; BLACK HOLES; CHARGED PARTICLES; GALACTIC EVOLUTION; GALAXIES; NEUTRINOS; NEUTRON STARS; NEUTRONS; NUCLEOSYNTHESIS; R PROCESS; SOLAR SYSTEM; STELLAR WINDS; TIME DEPENDENCE

Citation Formats

Wanajo, Shinya, and Janka, Hans-Thomas. The r-PROCESS IN THE NEUTRINO-DRIVEN WIND FROM A BLACK-HOLE TORUS. United States: N. p., 2012. Web. doi:10.1088/0004-637X/746/2/180.
Wanajo, Shinya, & Janka, Hans-Thomas. The r-PROCESS IN THE NEUTRINO-DRIVEN WIND FROM A BLACK-HOLE TORUS. United States. https://doi.org/10.1088/0004-637X/746/2/180
Wanajo, Shinya, and Janka, Hans-Thomas. 2012. "The r-PROCESS IN THE NEUTRINO-DRIVEN WIND FROM A BLACK-HOLE TORUS". United States. https://doi.org/10.1088/0004-637X/746/2/180.
@article{osti_22011658,
title = {The r-PROCESS IN THE NEUTRINO-DRIVEN WIND FROM A BLACK-HOLE TORUS},
author = {Wanajo, Shinya and Janka, Hans-Thomas},
abstractNote = {We examine r-process nucleosynthesis in the neutrino-driven wind from the thick accretion disk (or 'torus') around a black hole. Such systems are expected as remnants of binary neutron star or neutron star-black hole mergers. We consider a simplified, analytic, time-dependent evolution model of a 3 M{sub Sun} central black hole surrounded by a neutrino emitting accretion torus with 90 km radius, which serves as basis for computing spherically symmetric neutrino-driven wind solutions. We find that ejecta with modest entropies ({approx}30 per nucleon in units of the Boltzmann constant) and moderate expansion timescales ({approx}100 ms) dominate in the mass outflow. The mass-integrated nucleosynthetic abundances are in good agreement with the solar system r-process abundance distribution if a minimal value of the electron fraction at the charged-particle freezeout, Y{sub e,min} {approx} 0.2, is achieved. In the case of Y{sub e,min} {approx} 0.3, the production of r-elements beyond A {approx} 130 does not reach to the third peak but could still be important for an explanation of the abundance signatures in r-process deficient stars in the early Galaxy. The total mass of the ejected r-process nuclei is estimated to be {approx}1 Multiplication-Sign 10{sup -3} M{sub Sun }. If our model was representative, this demands a Galactic event rate of {approx}2 Multiplication-Sign 10{sup -4} yr{sup -1} for black-hole-torus winds from merger remnants to be the dominant source of the r-process elements. Our result thus suggests that black-hole-torus winds from compact binary mergers have the potential to be a major, but probably not the dominant, production site of r-process elements.},
doi = {10.1088/0004-637X/746/2/180},
url = {https://www.osti.gov/biblio/22011658}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 746,
place = {United States},
year = {Mon Feb 20 00:00:00 EST 2012},
month = {Mon Feb 20 00:00:00 EST 2012}
}