Neutrino-pair bremsstrahlung from nucleon-nucleon scattering

Li, Yi; Liou, M. K.; Schreiber, W. M.; Gibson, Benjamin F.

doi:10.1103/physrevc.92.015504

Cited by 5 publications

(5 citation statements)

References 36 publications

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“…The general structure of the diagrams is depicted in Fig. 15, but without the gauge bosons connecting the lines in many permutations (see, e.g., [76,77] and references therein). However, in all diagrams there is a single unbroken neutrino line, so the self-energy is linear in f .…”

Section: E Nucleon-nucleon Bremsstrahlungmentioning

confidence: 99%

Neutrino quantum kinetics in compact objects

et al. 2019

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Neutrinos play a critical role of transporting energy and changing the lepton density within corecollapse supernovae and neutron star mergers. The quantum kinetic equations (QKEs) combine the effects of neutrino-matter interactions treated in classical Boltzmann transport with the neutrino flavor-changing effects treated in neutrino oscillation calculations. We present a method for extending existing neutrino interaction rates to full QKE source terms for use in numerical calculations. We demonstrate the effects of absorption and emission by nucleons and nuclei, electron scattering, electron-positron pair annihilation, nucleon-nucleon bremsstrahlung, neutrino-neutrino scattering. For the first time, we include all these collision terms self-consistently in a simulation of the full isotropic QKEs in conditions relevant to core-collapse supernovae and neutron star mergers. For our choice of parameters, the long-term evolution of the neutrino distribution function proceeds similarly with and without the oscillation term, though with measurable differences. We demonstrate that electron scattering, nucleon-nucleon bremsstrahlung processes, and four-neutrino processes dominate flavor decoherence in the protoneutron star (PNS), absorption dominates near the shock, and all of the considered processes except elastic nucleon scattering and neutrino-neutrino processes are relevant in the decoupling region. Finally, we propose an effective decoherence opacity that at most energies predicts decoherence rates to within a factor of 10 in our model PNS and within 20% outside of the PNS.

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Section: E Nucleon-nucleon Bremsstrahlungmentioning

confidence: 99%

Neutrino quantum kinetics in compact objects

et al. 2019

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“…Similar expressions can be written down for np and pp bremsstrahlung, resulting in pp ν < np ν < nn ν (see for instance [31]). The calculations show that the use of the realistic T N N matrix instead of the OPE leads to the suppression of the neutrino emissivity approximately by a factor of four [so α ex nn (T N N ) ≈ 0.2] [258,270,[278][279][280]. Note that the inclusion of additional meson exchange terms [271,278] results in a better agreement with T -matrix calculations.…”

Section: Neutrino Emission Of Nuclear Mattermentioning

confidence: 81%

“…Note that the inclusion of additional meson exchange terms [271,278] results in a better agreement with T -matrix calculations. Li et al [280] quantified the limits of applicability for the soft bremsstrahlung theorem for a certain realistic model of the nucleon interactions. They found that the approximation ( 110) is accurate within 10% up to ω ν = 60 MeV.…”

Section: Neutrino Emission Of Nuclear Mattermentioning

confidence: 99%

Reaction Rates and Transport in Neutron Stars

Schmitt

Shternin

2018

Astrophysics and Space Science Library

100

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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“…The latter modifications are quite uncertain. For instance, using the free or in-medium scattering matrix in place of the one-pion exchange matrix element leads to the reduction of the 𝑛𝑛 bremsstrahlung rate by a factor of 2-4 (e.g., Van Dalen, Dieperink & Tjon 2003;Li et al 2015). On the other hand, in the so-called 'medium-modified one-pion exchange model' (e.g., Voskresensky 2001), the bremsshtrahlung rate is predicted to be increased by a factor of 100 at densities larger than the nuclear saturation density.…”

Section: Discussionmentioning

confidence: 99%

Model-independent constraints on superfluidity from the cooling neutron star in Cassiopeia A

Shternin,

Ofengeim,

et al. 2021

Preprint

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We present a new model-independent (applicable for a broad range of equations of state) analysis of the neutrino emissivity due to triplet neutron pairing in neutron star cores. We find that the integrated neutrino luminosity of the Cooper Pair Formation (CPF) process can be written as a product of two factors. The first factor depends on the neutron star mass, radius and maximal critical temperature of neutron pairing in the core, 𝑇 𝐶𝑛max , but not on the particular superfluidity model; it can be expressed by an analytical formula valid for many nucleon equations of state. The second factor depends on the shape of the critical temperature profile within the star, the ratio of the temperature 𝑇 to 𝑇 𝐶𝑛max , but not on the maximal critical temperature itself. While this second factor depends on the superfluidity model, it obeys several model-independent constraints. This property allows one to analyse the thermal evolution of neutron stars with superfluid cores without relying on a specific model of their interiors. The constructed expressions allow us to perform a self-consistent analysis of spectral data and neutron star cooling theory. We apply these findings to the cooling neutron star in the Cassiopeia A supernova remnant using 14 sets of observations taken over 19 years. We constrain 𝑇 𝐶𝑛max to the range of (5 − 10) × 10 8 K. This value depends weakly on the equation of state and superfluidity model, and will not change much if cooling is slower than the current data suggest. We also constrain the overall efficiency of the CPF neutrino luminosity.

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Neutrino-pair bremsstrahlung from nucleon-nucleon scattering

Cited by 5 publications

References 36 publications

Neutrino quantum kinetics in compact objects

Neutrino quantum kinetics in compact objects

Reaction Rates and Transport in Neutron Stars

Model-independent constraints on superfluidity from the cooling neutron star in Cassiopeia A

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