Neutrino Cooling of Neutron Stars: Medium Effects

Abstract

Abstract. This review demonstrates that the neutrino emission from the dense hadronic component in neutron stars is subject to strong modifications due to collective effects in nuclear matter. With the most important in-medium processes incorporated in the cooling code an overall agreement with available soft X ray data can be easily achieved. With these findings so called "standard" and "non-standard" cooling scenarios are replaced by one general "nuclear medium cooling scenario" which relates slow and rapid neutron star coolings to the star masses (interior densities). In-medium effects play an important role also in the early hot stage of the neutron star evolution by decreasing the neutrino opacity for less massive and increasing it for more massive neutron stars. A formalism for the calculation of the neutrino radiation from nuclear matter is presented that treats on equal footing one-nucleon and multiple-nucleon processes as well as reactions with resonance bosons and condensates. The cooling history of neutron stars with quark cores is also discussed.

Neutron Stars—Cooling and Transport

“…Neutrino emissivity Q ν may be strongly modified by in-medium (collective) effects at the high densities of neutron stars (see Voskresensky 2001, for a review). For instance, these effects may result in renormalization of electroweak interaction parameters.…”

The role of medium modifications for neutrino-pair processes from nucleon-nucleon bremsstrahlung

“…Based on the Fermi-liquid model, explicit expressions for (a) and (b) have been derived in Voskresensky (2001). In the latter article it has also been shown that for the medium modifications of D π the most important contribution to the charged current processes (modified Urca) originates from neutrino reactions of intermediate nucleon-loops coupled to the π for ρ ρ 0 /2.…”

“…A more general approach to study medium modifications for weak processes that involve N N interactions is the Fermi-liquid theory of Migdal (1978) and Migdal et al (1990) (see also Voskresensky, 2001, and references therein). It assumes that the nucleons are only slightly excited above their Fermi sea such that all the processes occur in a narrow vicinity of the Fermi surface and that the vertices of the processes are dressed by N N correlations.…”

“…Following Senatorov & Voskresensky (1987) and Voskresensky (2001) the current article provides a MVOPE density-dependent parametrization, i.e. for the medium modification of the πN N -vertex, for applications in simulations of core-collapse supernovae.…”

“…the right panel of Fig. (1) in Voskresensky, 2001) with neutrino-pair emission from intermediate nucleon-loops. Such additional medium modifications may become relevant during the late-time cooling at the transition from neutrino diffusion to freely streaming, when the PNS core temperature decreases below T ∼ 1 MeV such that neutrinos are escaping from densities also in excess of ρ 0 .…”