# Developing Tools for Multimessenger Gravitational Wave Astronomy

## TL;DR

This paper discusses the development of open-source numerical tools, specifically the GiRaFFE code, to model electromagnetic counterparts to gravitational waves from compact binary systems, aiding multimessenger astronomy.

## Contribution

The paper introduces the GiRaFFE code for simulating force-free magnetospheres around black holes, enabling detailed studies of electromagnetic emissions in gravitational wave events.

## Key findings

- GiRaFE successfully models magnetospheres around spinning black holes.
- Strong gravitational fields and black hole spins influence jet collimation.
- Future work includes simulating black hole collisions in magnetic fields.

## Abstract

We present work in progress to craft open-sourced numerical tools that will enable the calculation of electromagnetic counterparts to gravitational waveforms: the {\tt GiRaFFE} (General Relativistic Force-Free Electrodynamics) code. {\tt GiRaFFE} numerically solves the general relativistic magnetohydrodynamics system of equations in the force-free limit, to model the magnetospheres surrounding compact binaries, in order (1) to characterize the nonlinear interaction between the source and its surrounding magnetosphere, and (2) to evaluate the electromagnetic counterparts of gravitational waves, including the production of collimated jets. We apply this code to various configurations of spinning black holes immersed in external magnetic field, in order to both test our implementation, and to explore the effect of strong gravitational field, high spins and of misalignment between the magnetic field lines an black hole spin, on the electromagnetic output and the collimation of Poynting jets. We will extend our work to collisions of black holes immersed in external magnetic field, which are prime candidates for coincident detection in both gravitational and electromagnetic spectra.