Work

The role of radiation pressure in accreting massive black hole binaries

Year: 2026

Type: article

Abstract: We investigate the impact of radiation pressure on the circumbinary discs surrounding accreting massive black hole binaries (MBHBs) at milli-parsec separations using 3D hyper-Lagrangian resolution hydrodynamic simulations. The circumbinary discs in our simulations evolve under an adiabatic equation of state. The gas temperature was therefore allowed to change through viscous heating, black-body cooling, and self-gravity. We made a significant decision to also include the contribution of radiation pressure in the simulations. We modelled binaries with a total mass of 10 6 M ⊙ , eccentricities of e = 0, 0.45, 0.9, and mass ratios of q = 0.7, 1. We find that the radiation pressure significantly alters the vertical and thermal structure of the disc, resulting in a geometrically thinner and therefore colder configuration. This leads to a reduced accretion rate onto the binary and suppresses cavity eccentricity growth and precession in circular equal mass binaries. The binary eccentricity remains approximately constant, while the semi-major axis decreases over time due to net negative torque regardless of the initial binary orbital parameters.

Source: Astronomy and Astrophysics

DOI: 10.1051/0004-6361/202556970

Authors: Fabiola Cocchiararo, Alessia Franchini, Alessandro Lupi, Alberto Sesana

Institutions: Istituto Nazionale di Fisica Nucleare, Sezione di Milano Bicocca, University of Milano-Bicocca, University of Milan, University of Insubria

Language: English

Topic: Astrophysical Phenomena and Observations

Subfield: Astronomy and Astrophysics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $1,865

Funders: Johns Hopkins University, European Commission, Horizon 2020 Framework Programme, European Research Council