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Related papers: Second-Order Transport Coefficients in Neutron Sta…

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We compute first and second-order bulk-viscous transport properties due to weak-interaction processes in $npe$ matter in the neutrino transparent regime. The transport coefficients characterize the out-of-beta-equilibrium pressure…

Nuclear Theory · Physics 2023-12-18 Yumu Yang , Mauricio Hippert , Enrico Speranza , Jorge Noronha

We investigate the weak-interaction-driven bulk-viscous transport properties of $npe$ matter in the neutrino transparent regime. Previous works assumed that the induced bulk viscosity correction to pressure, near beta equilibrium, is linear…

Nuclear Theory · Physics 2023-12-20 Yumu Yang , Mauricio Hippert , Enrico Speranza , Jorge Noronha

The early post-merger phase of a binary neutron-star coalescence is shaped by characteristic rotational velocities as well as violent density oscillations and offers the possibility to constrain the properties of neutron star matter by…

General Relativity and Quantum Cosmology · Physics 2025-03-10 Michail Chabanov , Luciano Rezzolla

In nuclear matter in isolated neutron stars, the flavor content (e.g., proton fraction) is subject to weak interactions, establishing flavor ($\beta$-)equilibrium. However, there can be deviations from this equilibrium during the merger of…

High Energy Astrophysical Phenomena · Physics 2024-09-04 Elias R. Most , Alexander Haber , Steven P. Harris , Ziyuan Zhang , Mark G. Alford , Jorge Noronha

After an introduction to the QCD phase diagram, the nuclear equations of state, and neutron star mergers, I discuss three projects related to transport and nuclear matter in neutron star mergers. The first is the nature of beta equilibrium…

Nuclear Theory · Physics 2021-11-24 Steven P. Harris

The dissipative properties of relativistic strongly interacting nuclear matter significantly influence the damping of stellar oscillations and density fluctuations during compact star mergers. In this work, we derive the evolution equation…

High Energy Physics - Phenomenology · Physics 2026-02-18 José Luis Hernandez , Cristina Manuel , Saga Säppi , Laura Tolos

Hydrodynamic simulations of neutron star mergers rely on the clear separation between the strong-interaction, weak-interaction, and hydrodynamic timescales. In this effective framework, weak Urca interactions are typically the slowest…

High Energy Astrophysical Phenomena · Physics 2026-03-17 Jamie M. Karthein , Maneesha Sushama Pradeep , Rachel Steinhorst

Inferring the properties of dense matter is one of the most exciting prospects from the measurement of gravitational waves from neutron star mergers. However, it will require reliable numerical simulations that incorporate viscous…

General Relativity and Quantum Cosmology · Physics 2018-01-31 Mark G. Alford , Luke Bovard , Matthias Hanauske , Luciano Rezzolla , Kai Schwenzer

Binary neutron star mergers play an important role in nuclear astrophysics: their gravitational wave and electromagnetic signals carry information about the equation of state of cold matter above nuclear saturation density, and they may be…

High Energy Astrophysical Phenomena · Physics 2024-09-24 Francois Foucart , Patrick Chi-Kit Cheong , Matthew D. Duez , Lawrence E. Kidder , Harald P. Pfeiffer , Mark A. Scheel

We study the importance of hydrodynamic effects on the evolution of coalescing binary neutron stars. Using an approximate energy functional constructed from equilibrium solutions for polytropic binary configurations, we incorporate…

Astrophysics · Physics 2009-10-22 D. Lai , F. A. Rasio , S. L. Shapiro

Neutron stars offer the opportunity to study the behaviour of matter at densities and temperatures inaccessible to terrestrial experiments. Gravitational-wave observations of binary neutron star coalescences can constrain the neutron-star…

High Energy Astrophysical Phenomena · Physics 2021-01-14 Francisco Hernandez-Vivanco , Paul D. Lasky , Eric Thrane , Rory Smith , Debarati Chatterjee , Sarmistha Banik , Theo Motta , Anthony Thomas

We study the impact of finite-temperature effects in numerical-relativity simulations of binary neutron star mergers with microphysical equations of state and neutrino transport in which we vary the effective nucleon masses in a controlled…

High Energy Astrophysical Phenomena · Physics 2023-08-01 Jacob Fields , Aviral Prakash , Matteo Breschi , David Radice , Sebastiano Bernuzzi , André da Silva Schneider

Recent studies invoke a unified description of different neutron star observables using metamodels, which parametrize the Equation of State (EoS) of neutron star matter close to nuclear saturation density in terms of few nuclear parameters.…

High Energy Physics - Phenomenology · Physics 2026-03-26 José Luis Hernández , Cristina Manuel , Laura Tolos

Recent nonmagnetized studies of binary neutron star mergers have indicated the possibility of identifying equation of state features, such as a phase transition or a quark-hadron crossover, based on the frequency shift of the main peak in…

General Relativity and Quantum Cosmology · Physics 2024-11-05 Antonios Tsokaros , Jamie Bamber , Milton Ruiz , Stuart L. Shapiro

Employing a simplified version of the Israel-Stewart formalism of general-relativistic shear-viscous hydrodynamics, we explore the evolution of a remnant massive neutron star of binary neutron star merger and pay special attention to the…

High Energy Astrophysical Phenomena · Physics 2017-08-02 Masaru Shibata , Kenta Kiuchi

In this paper we present a computation of the rates of strangeness-changing processes and the resultant bulk viscosity in matter at the densities and temperatures typical of neutron star mergers. To deal with the high temperature in this…

Nuclear Theory · Physics 2021-05-05 Mark G. Alford , Alexander Haber

Determining the equation of state of matter at nuclear density and hence the structure of neutron stars has been a riddle for decades. We show how the imminent detection of gravitational waves from merging neutron star binaries can be used…

General Relativity and Quantum Cosmology · Physics 2014-09-05 Kentaro Takami , Luciano Rezzolla , Luca Baiotti

Neutrino interactions play a central role in transport and flavor evolution in the ejecta of binary neutron star mergers. Simulations suggest that neutron star mergers may produce magnetic fields as strong as $10^{17}$ G, but computational…

High Energy Astrophysical Phenomena · Physics 2026-04-10 Mia Kumamoto , Catherine Welch

We consider transport properties of the hypernuclear matter in neutron star cores. In particular, we calculate the thermal conductivity, the shear viscosity, and the momentum transfer rates for np$\Sigma^{-}\Lambda e\mu$ composition of…

High Energy Astrophysical Phenomena · Physics 2021-06-24 Peter Shternin , Isaac Vidaña

We calculate the coefficient of bulk viscosity by considering the non-leptonic weak interactions in the cores of hybrid stars with both hyperons and quarks. We first determine the dependence of the production rate of neutrons on the…

Astrophysics · Physics 2009-11-11 Nana Pan , Xiaoping Zheng , Jiarong Li
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