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arXiv · 2509.15303

Neutron star evolution with the Bemfica-Disconzi-Noronha-Kovtun viscous hydrodynamics framework

Harry L. H. Shum·Fernando Abalos·Yago Bea·Miguel Bezares·Pau Figueras·Carlos Palenzuela
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Abstract

The recently proposed first-order viscous relativistic hydrodynamics formulation by Bemfica, Disconzi, Noronha, and Kovtun (commonly known as the BDNK formulation) has been shown to be causal, stable, strongly hyperbolic, and thus locally well-posed. It is now a viable new option for modelling out-of-equilibrium effects in fluids, and has attracted wide attention in its potential applications to astrophysical systems. In this work, we present the first non-linear numerical simulation of spherically symmetric neutron stars using the BDNK formulation under the Cowling approximation. Using a simplified equation of state, we show that stable evolutions can be constructed within a restricted parameter space up to the simulation time we explored. From these simulations, we analyse the frequency content of the quasi-normal modes and the decay rate of the fundamental mode. This analysis serves as a first step towards constructing a fully consistent model of neutron stars using the BDNK formulation.

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Harry L. H. Shum, Fernando Abalos, Yago Bea, Miguel Bezares, Pau Figueras, Carlos Palenzuela. 2025-09-18. Neutron star evolution with the Bemfica-Disconzi-Noronha-Kovtun viscous hydrodynamics framework. https://doi.org/10.1103/mthy-4119

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