# $\nu\texttt{bhlight}$: Radiation GRMHD for Neutrino-Driven Accretion Flows

## TL;DR

The paper introduces $
u$bhlight, a new computational scheme that models neutrino transport in general relativistic magnetohydrodynamics to better understand neutron star mergers and their associated phenomena.

## Contribution

It presents $
u$bhlight$, a novel Monte Carlo-based scheme for energy-dependent neutrino transport in 3+1D GRMHD simulations of neutron star merger accretion disks.

## Key findings

- The scheme accurately models neutrino effects in relativistic astrophysical flows.
- Tests demonstrate the scheme's effectiveness and necessity for realistic simulations.
- Sample calculations show the impact on accretion disk composition and dynamics.

## Abstract

The 2017 detection of the in-spiral and merger of two neutron stars was a landmark discovery in astrophysics. We now know that such mergers are central engines of short gamma ray bursts and sites of r-process nucleosynthesis, where the heaviest elements in our universe are formed. In the coming years, we expect many more such mergers. Modeling such systems presents a significant computational challenge along with the observational one. To meet this challenge, we present $\nu\texttt{bhlight}$, a scheme for solving general relativistic magnetohydrodynamics with energy-dependent neutrino transport in full (3+1)-dimensions, facilitated by Monte Carlo methods. We present a suite of tests demonstrating the accuracy, efficacy, and necessity of our scheme. We demonstrate the potential of our scheme by running a sample calculation in a domain of interest---the dynamics and composition of the accretion disk formed by a binary neutron star merger.