Radiative Particle-in-Cell Simulations of Turbulent Comptonization in Magnetized Black-Hole Coronae

Daniel Grošelj, Hayk Hakobyan, Andrei M. Beloborodov, Lorenzo Sironi, and Alexander Philippov

Phys. Rev. Lett. 132, 085202 – Published 23 February 2024

Abstract

We report results from the first radiative particle-in-cell simulations of strong Alfvénic turbulence in plasmas of moderate optical depth. The simulations are performed in a local 3D periodic box and self-consistently follow the evolution of radiation as it interacts with a turbulent electron-positron plasma via Compton scattering. We focus on the conditions expected in magnetized coronae of accreting black holes and obtain an emission spectrum consistent with the observed hard state of Cyg X-1. Most of the turbulence power is transferred directly to the photons via bulk Comptonization, shaping the peak of the emission around 100 keV. The rest is released into nonthermal particles, which generate the MeV spectral tail. The method presented here shows promising potential for ab initio modeling of various astrophysical sources and opens a window into a new regime of kinetic plasma turbulence.

Received 26 January 2023
Revised 30 September 2023
Accepted 24 January 2024

DOI:https://doi.org/10.1103/PhysRevLett.132.085202

Physics Subject Headings (PhySH)

Space & astrophysical plasma

Accretion disk & black-hole plasma

Particle-in-cell methods

Plasma Physics

Authors & Affiliations

Daniel Grošelj ^1,2, Hayk Hakobyan ^3,4, Andrei M. Beloborodov ^4,5, Lorenzo Sironi ², and Alexander Philippov ⁶

¹Centre for mathematical Plasma Astrophysics, Department of Mathematics, KU Leuven, B-3001 Leuven, Belgium
²Department of Astronomy and Columbia Astrophysics Laboratory, Columbia University, New York, New York 10027, USA
³Computational Sciences Department, Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540, USA
⁴Department of Physics and Columbia Astrophysics Laboratory, Columbia University, New York, New York 10027, USA
⁵Max Planck Institute for Astrophysics, D-85741 Garching, Germany
⁶Department of Physics, University of Maryland, College Park, Maryland 20742, USA