Nuclear correlations and neutrino emissivity from the neutron branch of the modified Urca process

Niri, A. Dehghan; Moshfegh, H. R.; Haensel, P.

doi:10.1103/physrevc.93.045806

Cited by 14 publications

(18 citation statements)

References 48 publications

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“…The rescattering diagrams effectively are included in Refs. [10,11] via the pair correlation functions. The results of these authors are not dramatically far from the standard results of Ref.…”

Section: Resultsmentioning

confidence: 99%

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In-medium enhancement of the modified Urca neutrino reaction rates

2018

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We calculate modified Urca neutrino emission rates in the dense nuclear matter in neutron star cores. We find that these rates are strongly enhanced in the beta-stable matter in regions of the core close to the direct Urca process threshold. This enhancement can be tracked to the use of the in-medium nucleon spectrum in the virtual nucleon propagator. We describe the in-medium nucleon scattering in the non-relativistic Bruckner-Hartree-Fock framework taking into account two-body as well as the effective threebody forces, although the proposed enhancement does not rely on a particular way of the nucleon interaction treatment. Finally we suggest a simple approximate expression for the emissivity of the neutron branch of the modified Urca process that can be used in the neutron stars cooling simulations with any nucleon equation of state of dense matter.

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Section: Resultsmentioning

confidence: 99%

“…[9] estimated the effect of the replacement of the free one-pion exchange interaction with the in-medium T -matrix and found some reduction of the emissivity. Recent study [10] employed independent pair approximation extending Ref. [11].…”

Section: Introductionmentioning

confidence: 99%

In-medium enhancement of the modified Urca neutrino reaction rates

2018

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“…On the one hand, the direct Urca onset and its neutrino emissivity are artificially moderated, which ought to be handled properly in a consistent and more physical manner; similarly, many-body corrections to the emissivity of modified Urca [80] are to be in-corporated in the simulations. On the other hand, superfluid gaps in a generic Gaussian form are completely phenomenological, ignoring sophisticated adjustments necessary for some realistic models.…”

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confidence: 99%

Cooling of neutron stars in soft x-ray transients

Steiner

2017

Phys. Rev. C

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Thermal states of neutron stars in soft X-ray transients (SXRTs) are thought to be determined by "deep crustal heating" in the accreted matter that drives the quiescent luminosity and cooling via emission of photons and neutrinos from the interior. In this study, we assume a global thermal steady-state of the transient system and calculate the heating curves (quiescent surface luminosity as a function of mean accretion rate) predicted from theoretical models, taking into account variations in the equations of state, superfluidity gaps, thickness of the light element layer and a phenomenological description of the direct Urca threshold. We further provide a statistical analysis on the uncertainties in these parameters, and compare the overall results with observations of several SXRTs, in particular the two sources containing the coldest (SAX J1808.4-3658) and the hottest (Aql X-1) neutron stars. Interpretation of the observational data indicates that the direct Urca process is required for the most massive stars and also suggests small superfluid gaps.

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“…[281], the expected reduction is about 1/4 with respect to the OPE result and the use of the in-medium T -matrix leads to further reduction by an additional factor of 0.6 − 0.9. In the recent work by Dehghan Niri et al [285], the in-medium modified Urca emissivity was calculated starting from the correlated nucleon pair states (see also Refs. [286,287]).…”

Section: Neutrino Emission Of Nuclear Mattermentioning

confidence: 99%

Reaction Rates and Transport in Neutron Stars

Schmitt

Shternin

2018

Astrophysics and Space Science Library

122

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Understanding signals from neutron stars requires knowledge about the transport inside the star. We review the transport properties and the underlying reaction rates of dense hadronic and quark matter in the crust and the core of neutron stars and point out open problems and future directions. arXiv:1711.06520v3 [astro-ph.HE] 29 Oct 2018 65 References 66 I. INTRODUCTION A. ContextTransport describes how conserved quantities such as energy, momentum, particle number, or electric charge are transferred from one region to another. Such a transfer occurs if the system is out of equilibrium, for instance through a temperature gradient or a non-uniform chemical composition. Different theoretical methods are used to understand transport, depending on how far the system is away from its equilibrium state. If the system is close to equilibrium locally and perturbations are on large scales in space and time, hydrodynamics is a powerful technique. Further away from equilibrium other techniques are required, for example kinetic theory, which can also be used to provide the transport coefficients needed in the hydrodynamic equations. In any case, transport is determined by interactions on a microscopic level, and it is the resulting transport properties that we are concerned with in this review.Signals from neutron stars are sensitive to equilibrium properties such as the equation of state but also, to a large extent, to transport properties -here, by neutron stars we mean all objects with a radius of about 10 km and a mass of about 1-2 solar masses, including the possibilities of hybrid stars, which have a quark matter core, and pure quark stars. Therefore, understanding transport is crucial to interpret astrophysical observations, and, turning the argument around, we can use astrophysical observations to improve our understanding of transport in dense matter and thus ultimately our understanding of the microscopic interactions.Transport properties are most commonly computed from particle collisions. (Although, in strongly coupled systems, the picture of well-defined particles scattering off each other has to be taken with care.) These can be scattering processes in which energy and momentum is exchanged without changing the chemical composition of the system, or these can be flavor-changing processes from the electroweak interaction. Understanding transport thus amounts to understanding the rates of these processes, as a function of temperature and density. Electroweak processes are well understood, but large uncertainties arise if the strong interaction is involved in a reaction that contributes to transport. Therefore, approximations such as weak-coupling techniques or one-pion exchange for nucleon-nucleon collisions are being used, and efforts in current research aim at improving these approximations.In a neutron star, most of the particles involved in these processes are fermions: electrons, muons, neutrinos, neutrons, protons, hyperons, and quarks. Since the Fermi momenta of these fermions are typically much larger tha...

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Nuclear correlations and neutrino emissivity from the neutron branch of the modified Urca process

Cited by 14 publications

References 48 publications

In-medium enhancement of the modified Urca neutrino reaction rates

In-medium enhancement of the modified Urca neutrino reaction rates

Cooling of neutron stars in soft x-ray transients

Reaction Rates and Transport in Neutron Stars

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