Simulations of recoiling black holes: adaptive mesh refinement and radiative transfer

TL;DR

This paper introduces a new numerical code that combines adaptive mesh refinement and radiative transfer to simulate matter behavior around black holes, validated through various accretion scenarios and applied to a recoiling black hole post-merger, producing detailed electromagnetic emission predictions.

Contribution

The paper presents a novel computational framework integrating advanced hydrodynamics, AMR, and radiative transfer for modeling black hole accretion and recoil events, enabling accurate, self-consistent emission predictions.

Findings

Validated the code with stationary accretion flows in 2D and 3D.

Produced first ray-traced images of shocked fluid around recoiling black holes.

Generated light-curves from general-relativistic radiation transport simulations.

Abstract

(Abridged) We here continue our effort to model the behaviour of matter when orbiting or accreting onto a generic black hole by developing a new numerical code employing advanced techniques geared solve the equations of in general-relativistic hydrodynamics. The new code employs a number of high-resolution shock-capturing Riemann-solvers and reconstruction algorithms, exploiting the enhanced accuracy and the reduced computational cost of AMR techniques. In addition, the code makes use of sophisticated ray-tracing libraries that, coupled with general-relativistic radiation-transfer calculations, allow us to compute accurately the electromagnetic emissions from such accretion flows. We validate the new code by presenting an extensive series of stationary accretion flows either in spherical or axial symmetry and performed either in 2D or 3D. In addition, we consider the highly nonlinear scenario of a recoiling black hole produced in the merger of a supermassive black hole binary interacting with the surrounding circumbinary disc. In this way we can present, for the first time, ray-traced images of the shocked fluid and the light-curve resulting from consistent general-relativistic radiation-transport calculations from this process. The work presented here lays the ground for the development of a generic computational infrastructure employing AMR techniques to deal accurately and self-consistently with accretion flows onto compact objects. In addition to the accurate handling of the matter, we provide a self-consistent electromagnetic emission from these scenarios by solving the associated radiative-transfer problem. While magnetic fields are presently excluded from our analysis, the tools presented here can have a number of applications to study accretion flows onto black holes or neutron stars.