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If deconfined quark matter exists inside compact stars, the primary cooling mechanism is neutrino radiation via the direct Urca processes d->u+e+antinu_e and u+e->d+nu_e. Below a critical temperature, T_c, quark matter forms a colour…

Nuclear Theory · Physics 2010-03-04 Prashanth Jaikumar , Craig D. Roberts , Armen Sedrakian

Modelling of crust heating and cooling across multiple accretion outbursts of the low mass X-ray binary MXB 1659-29 indicates that the neutrino luminosity of the neutron star core is consistent with direct Urca reactions occurring in $\sim…

High Energy Astrophysical Phenomena · Physics 2022-10-21 Melissa Mendes , Farrukh J. Fattoyev , Andrew Cumming , Charles Gale

We discuss the effect of compression on Urca shells in the ocean and crust of accreting neutron stars, especially in superbursting sources. We find that Urca shells may be deviated from chemical equilibrium in neutron stars which accrete at…

High Energy Astrophysical Phenomena · Physics 2017-06-15 Wei-Hua Wang , Xi Huang , Xiao-Ping Zheng

We study the heat capacity and neutrino emission reactions (direct and modified Urca processes, nucleon-nucleon bremsstrahlung, Cooper pairing of nucleons) in matter of supranuclear density of the neutron star cores with superfluid neutrons…

Astrophysics · Physics 2011-02-16 D. G. Yakovlev , K. P. Levenfish , Yu. A. Shibanov

The density dependence of the symmetry energy in relativistic mean-field models with density dependent couplings is discussed in terms of the possible opening of nucleonic direct Urca processes inside neutron stars, which induce a very…

Nuclear Theory · Physics 2024-11-27 Olfa Boukari , Tuhin Malik , Aziz Rabhi , Constança Providência

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

A brief review is given of neutrino emission processes in dense matter, with particular emphasis on recent developments. These include direct Urca processes for nucleons and hyperons, which can give rise to rapid energy loss from the…

Astrophysics · Physics 2016-08-30 C. J. Pethick , Vesteinn Thorsson

The bulk viscosity of the neutron star matter due to the direct Urca processes involving nucleons, electrons and muons is studied taking into account possible superfluidity of nucleons in the neutron star cores. The cases of singlet-state…

Astrophysics · Physics 2009-05-13 P. Haensel , K. P. Levenfish , D. G. Yakovlev

Using a model for the equation of state and composition of dense matter and the magnitude of singlet proton superconductivity and triplet neutron superfluidity, we perform the first simultaneous fit of neutron star masses and radii…

Nuclear Theory · Physics 2019-11-13 Spencer Beloin , Sophia Han , Andrew W. Steiner , Khorgolkhuu Odbadrakh

We study non-linear effects of radiative viscosity of $npe$ matter in neutron stars for both direct Urca process and modified Urca process, and find that non-linear effects will decrease the ratio of radiative viscosity to bulk viscosity…

High Energy Astrophysical Phenomena · Physics 2014-11-20 Shu-Hua Yang , Xiao-Ping Zheng , Chun-Mei Pi

The neutron excess at the time of explosion provides a powerful discriminant among models of Type Ia supernovae. Recent calculations of the carbon simmering phase in single degenerate progenitors have disagreed about the final neutron…

High Energy Astrophysical Phenomena · Physics 2017-12-27 Josiah Schwab , Héctor Martínez-Rodríguez , Anthony L. Piro , Carles Badenes

The remnant of neutron star mergers is dense in neutrinos. By employing inputs from one hydrodynamical simulation of a binary neutron star merger remnant with a black hole of $3\ M_\odot$ in the center, dimensionless spin parameter $0.8$…

High Energy Astrophysical Phenomena · Physics 2018-01-03 Meng-Ru Wu , Irene Tamborra , Oliver Just , Hans-Thomas Janka

We use the field theoretical model to perform relativistic calculations of neutrino energy losses caused by the direct Urca processes on nucleons in the degenerate baryon matter. By our analysis, the direct neutron decay in the superdense…

High Energy Physics - Phenomenology · Physics 2009-11-07 L. B. Leinson

The symmetry energy of nucleonic matter is usually assumed to be quadratic in the isospin density. While this may be justified at sub-saturation densities, there is no need to enforce this restriction at super-saturation densities. The…

Nuclear Theory · Physics 2007-05-23 Andrew W. Steiner

In the present work we apply non extensive statistics to obtain equations of state suitable to describe stellar matter and verify its effects on microscopic and macroscopic quantities. Two snapshots of the star evolution are considered and…

Nuclear Theory · Physics 2015-12-02 Débora P. Menezes , Airton Deppman , Eugenio Megías , Luis B. Castro

In nuclear matter at neutron-star densities and temperatures, Cooper pairing leads to the formation of a gap in the nucleon excitation spectra resulting in exponentially strong Boltzmann suppression of many transport coefficients. Previous…

Nuclear Theory · Physics 2017-01-17 Mark G. Alford , Kamal Pangeni

Neutron stars cooling after sustained accretion outbursts provide unique information about the neutron star crust and underlying dense matter. Comparisons between astronomical observations of these cooling transients and model calculations…

High Energy Astrophysical Phenomena · Physics 2019-09-11 Sudhanva Lalit , Zach Meisel , Edward F. Brown

We study neutrino emission from direct Urca processes in pion condensed quark matter. In compact stars with high baryon density, the emission is dominated by the gapless modes of the pion condensation which leads to an enhanced emissivity.…

High Energy Physics - Phenomenology · Physics 2008-11-26 Xuguang Huang , Qun Wang , Pengfei Zhuang

We study the cooling of isolated neutron stars, employing different nuclear equations of state with or without active direct Urca process, and investigate the interplay with the nuclear pairing gaps. We find that a consistent description of…

High Energy Astrophysical Phenomena · Physics 2024-06-12 H. C. Das , Jin-Biao Wei , G. F. Burgio , H. -J. Schulze

This work aims to analyze how hyperons affect neutrino radiation properties in nucleonic direct URCA processes, expecting to provide useful references for finding evidence of the existence of hyperons in astronomical observations. This…

Nuclear Theory · Physics 2026-01-08 Yan Xu , Yufu Shen , Qi Yuan , Xiulin Huang , Yibo Wang