Improved neutrino-nucleon interactions in dense and hot matter for numerical simulations

Abstract

Neutrinos play an important role in compact star astrophysics: neutrino-heating is one of the main ingredients in core-collapse supernovae, neutrino-matter interactions determine the composition of matter in binary neutron star mergers and have among others a strong impact on conditions for heavy element nucleosynthesis and neutron star cooling is dominated by neutrino emission except for very old stars. Many works in the last decades have shown that in dense matter medium effects considerably change the neutrino-matter interaction rates, whereas many astrophysical simulations use analytic approximations which are often far from reproducing more complete calculations. In this work we present a scheme which allows to incorporate improved rates for charged current interactions, into simulations and show as an example some results for core-collapse supernovae, where a noticeable difference is found in the location of the neutrinospheres of the low-energy neutrinos in the early post-bounce phase.

Finite-temperature infinite matter with effective-field-theory-inspired energy-density functionals

“…The possibility of using these EFT-inspired functionals for describing finite-temperature properties of neutron matter opens new and promising horizons for computations and modeling in scenarios of astrophysical interest. The description of the low-density regime of matter has indeed revealed itself to be extremely important, to properly evaluate a broad spectrum of observables of astrophysical relevance, such as the heat capacity, the thermal conductivity, the neutrino emission, as well as for a precise determination of the crust-core transition point and the related crustal moment of inertia [72][73][74][75][76][77][78][79].…”

Proto-neutron star evolution with improved charged-current neutrino–nucleon interactions

“…Starting with the progenitor model s15 from Woosley et al (2002), we run the spherically-symmetric version of the CCSN code CoCoNuT (Dimmelmeier et al 2005), using the "Fast Multigroup Transport" (FMT) scheme for neutrino transport (Müller & Janka 2015), with the same method as in Oertel et al (2020). Each model has been computed such that the EoS and the neutrino interactions are consistent with the PNS cooling simulation.…”

“…(anti-)neutrino energy independent, correction factors to the mean field expressions have been implemented. As discussed in Oertel et al (2020), the importance of RPA correlations is energy dependent and a density and temperature dependent shift in reaction thresholds is induced. The full physics can thus not be included into a grey factor.…”

“…Some of these improvements are modifying the analytical rates by several orders of magnitude, such that it became a priority to perform CCSN and PNS evolution simulations with state of the art neutrino interactions in order to test them against previous simulations and predict the emitted neutrino signal. In Oertel et al (2020) a first step has been made in this direction, electron (anti)-neutrino opacities from charged current neutrino nucleon interactions are computed including mean field corrections, optionally RPA correlations and include the full phase space integration. As reactions, electron and positron capture, neutron and proton decay as well as their inverse processes have been considered.…”

“…An interpolation scheme has been developed which allows to provide the obtained opacity data with the full dependence on neutrino energy Eν , baryon number density nB, temperature T and electron fraction Ye, with tables of interpolation coefficients publicly available via the ComPOSE data base 1 (Typel et al 2015). The feasibility of CCSN simulations employing these opacities with only a minor excess in computation time compared with analytical rates has been demonstrated in Oertel et al (2020). In the present work we perform a step further by using those rates in a simulation of PNS evolution.…”