190 research outputs found
In-medium enhancement of the modified Urca neutrino reaction rates
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 three-body 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 n-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.Comment: 8 pages, 3 figures; accepted for publication in PLB. In v.2 misprint
in eq.(9) corrected and discussion of cooling curves expande
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