GRDzhadzha: A code for evolving relativistic matter on analytic metric backgrounds

TL;DR

GRDzhadzha is an open-source simulation code that models relativistic matter on analytic curved spacetimes, offering efficiency improvements by leveraging analytical metrics instead of full numerical relativity.

Contribution

It introduces a novel code that combines analytical metric backgrounds with relativistic matter simulations, reducing computational resources needed.

Findings

Efficient simulations of matter in black hole spacetimes.

Applicable to dark matter environments with small matter density.

Demonstrated successful applications of the code.

Abstract

GRDzhadzha is an open-source code for relativistic simulations of matter fields on curved spacetimes that admit an analytic description (e.g. stationary black holes). It is based on the publicly available 3+1D numerical relativity code GRChombo. Such a description is valid where the density of the matter is small compared to the curvature scale of the spacetime, which is the case for many physical scenarios - for example, dark matter environments. The approach offers significant savings on memory and speed compared to running full numerical relativity simulations, since the metric variables and their derivatives are calculated analytically, and therefore are not evolved or stored on the grid. This brief paper introduces the code and gives details of some applications for which it has already been used.