Validating Binary Neutron Star Simulations with Insights from GW170817 and GW190425*

Binary neutron star mergers are key to understanding extreme physics, the origins of gamma-ray bursts, fast radio bursts and heavy elements. With limited observations, we rely on numerical relativity simulations for advancing our knowledge. However, accurately modeling BNS collisions require ongoing refinement due to complex multi-physics, numerical methods, and high-performance computing.

Existing simulations show similarities in convergence properties and dynamics, but differ in predictions like merger timing and gravitational wave characteristics. This leads us to compare results obtained by various codes simulating the real-world events GW170817 and GW190425. We collect simulations results and compare them, focusing on four sets of indicators: initial conditions, collision time, gravitational wave and matter output and remnant fate. If we find significant differences between the results, we investigate the sources of disagreement, which  allow us to identify the role played by the numerical and analytical methods implemented. Our aim is to distinguish what are the numerical differences affecting these simulations.

This study is vital for future gravitational wave astronomy, considering the upcoming generation of GW observatories are promising a surge in BNS systems detections. Our work will enhance simulation reliability, paving the way for significant astronomical discoveries and improved gravitational wave templates.