Gray two-moment neutrino transport: Comprehensive tests and improvements for supernova simulations

¹ The Oskar Klein Centre, Department of Astronomy Stockholm University, AlbaNova, 106 91 Stockholm, Sweden
e-mail: haakon.andresen@astro.su.se
² Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824, USA
³ Department of Computational Mathematics, Science, and Engineering, Michigan State University, East Lansing, MI 48824, USA
⁴ Facility for Rare Isotope Beams, Michigan State University, East Lansing, MI 48824, USA

Received: 28 February 2024
Accepted: 10 April 2024

Abstract

Aims. In this work we extended an energy-integrated neutrino transport method to facilitate efficient, yet precise, modeling of compact astrophysical objects. We particularly focus on core-collapse supernovae.

Methods. We implemented a gray neutrino-transport framework from the literature into FLASH and performed a detailed evaluation of its accuracy in core-collapse supernova simulations. Based on comparisons with results from simulations using energy-dependent neutrino transport, we incorporated several improvements to the original scheme.

Results. Our analysis shows that our gray neutrino transport method successfully reproduces key aspects from more complex energy-dependent transport across a variety of progenitors and equations of state. We find both qualitative and reasonable quantitative agreement with multi-group M1 transport simulations. However, the gray scheme tends to slightly favor shock revival. In terms of gravitational wave and neutrino signals, there is a good alignment with the energy-dependent transport, although we find 15–30% discrepancies in the average energy and luminosity of heavy-lepton neutrinos. Simulations using the gray transport are around four times faster than those using energy-dependent transport.