Bulk Viscosity of Relativistic npeμ Matter in Neutron-Star Mergers
- Washington University, St. Louis, MO (United States); Washington University in St. Louis
- National Academy of Sciences, Byurakan (Armenia); Yerevan State University (Armenia)
- Frankfurt Institute for Advanced Studies (Germany); University of Wrocław (Poland)
We discuss the bulk viscosity of hot and dense npeμ matter arising from weak-interaction direct Urca processes. We consider two regimes of interest: (a) the neutrino-transparent regime with T ≤ Ttr (Ttr ≃ 5 ÷ 10 MeV is the neutrino-trapping temperature); and (b) the neutrino-trapped regime with T ≥ Ttr. Nuclear matter is modeled in relativistic density functional approach with density-dependent parametrization DDME2. The maximum of the bulk viscosity is achieved at temperatures T ≃ 5 ÷ 6 MeV in the neutrino-transparent regime, then it drops rapidly at higher temperatures where neutrino-trapping occurs. As an astrophysical application, we estimate the damping timescales of density oscillations by the bulk viscosity in neutron star mergers and find that, e.g., at the oscillation frequency f = 10 kHz, the damping will be very efficient at temperatures 4 ≤ T ≤ 7 MeV where the bulk viscosity might affect the evolution of the post-merger object.
- Research Organization:
- Washington University in St. Louis, MO (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Nuclear Physics (NP); Deutsche Forschungsgemeinschaft; Polish NCN
- Grant/Contract Number:
- FG02-05ER41375
- OSTI ID:
- 2008328
- Journal Information:
- Particles, Journal Name: Particles Journal Issue: 3 Vol. 5; ISSN 2571-712X
- Publisher:
- MDPICopyright Statement
- Country of Publication:
- United States
- Language:
- English
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