期刊
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
卷 472, 期 1, 页码 904-918出版社
OXFORD UNIV PRESS
DOI: 10.1093/mnras/stx1987
关键词
accretion, accretion discs; dense matter; gravitational waves; hydrodynamics; neutrinos; nuclear reactions, nucleosynthesis, abundances
资金
- U.S. National Science Foundation (NSF) [AST-1333520]
- University of California Office of the President
- NSF [AST-1206097, PHY-1430152]
- Faculty of Science at the University of Alberta
- U.S. Department of Energy (DOE) Office of Nuclear Physics
- Office of Energy Research, Office of High Energy and Nuclear Physics, Divisions of Nuclear Physics, of the DOE [DE-AC02-05CH11231]
- DEO Office of Advanced Scientific Computing Research (OASCR)
- Advanced Simulation and Computing (ASC) program of the DOE's National Nuclear Security Administration (NNSA)
- Office of Science of the U.S. Department of Energy [DE-AC02-05CH11231]
- NSF under the Major Research Instrumentation (MRI) [PHY-0960291]
- Sherman Fairchild Foundation
- Yukawa Institute for Theoretical Physics
- Direct For Mathematical & Physical Scien
- Division Of Astronomical Sciences [1333520] Funding Source: National Science Foundation
- Direct For Mathematical & Physical Scien
- Division Of Physics [1430152] Funding Source: National Science Foundation
We investigate the nucleosynthesis of heavy elements in the winds ejected by accretion discs formed in neutron star mergers. We compute the element formation in disc outflows from hypermassive neutron star (HMNS) remnants of variable lifetime, including the effect of angular momentum transport in the disc evolution. We employ long-term axisymmetric hydrodynamic disc simulations to model the ejecta, and compute r-process nucleosynthesis with tracer particles using a nuclear reaction network containing similar to 8000 species. We find that the previously known strong correlation between HMNS lifetime, ejected mass and average electron fraction in the outflow is directly related to the amount of neutrino irradiation on the disc, which dominates mass ejection at early times in the form of a neutrino-driven wind. Production of lanthanides and actinides saturates at short HMNS lifetimes (less than or similar to 10 ms), with additional ejecta contributing to a blue optical kilonova component for longer-lived HMNSs. We find good agreement between the abundances from the disc outflow alone and the solar r-process distribution only for short HMNS lifetimes (less than or similar to 10 ms). For longer lifetimes, the rare-earth and third r-process peaks are significantly underproduced compared to the solar pattern, requiring additional contributions from the dynamical ejecta. The nucleosynthesis signature from a spinning black hole (BH) can only overlap with that from an HMNS of moderate lifetime (less than or similar to 60 ms). Finally, we show that angular momentum transport not only contributes with a late-time outflow component, but that it also enhances the neutrino-driven component by moving material to shallower regions of the gravitational potential, in addition to providing additional heating.
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