Black holes at all scales - From stellar binaries to galactic centers

Charlista: Prof. Ileyk El Mellah. Departamento de Física - Universidad de Santiago de Chile

Resumen: Long thought to be theoretical chimeras, black holes (BHs) are now routinely studied through the twofold interaction they maintain with their surroundings: they accrete plasma and power relativistic jets. BHs provide us with a unique environment to test physics in the strong gravitational, magnetic and radiative field limits. The discovery of merging BHs in 2015 has ushered in a hunt for their progenitors. For now, massive stellar binaries are the most likely progenitors but our limited understanding of mass transfer from the star to the BH hampers our capacity to draw robust conclusions. On the other hand, the EHT observations since 2019 have highlighted the major role played by large scale magnetic fields around accreting BHs.

In this talk, I will highlight the role played by multi-physics simulations in bridging the gap between scales, from the companion star all the way to the very vicinity of the BH, where the curvature of spacetime manifests. At the orbital scale, magneto-hydrodynamic simulations enable us to study how the BH accretes a fraction of the tremendous amount of mass lost by the star through a radiation driven wind. In the dilute, hot and highly magnetized plasma immediately surrounding the accreting black hole, global plasma simulations describe how electrons are accelerated up to relativistic speeds through magnetic reconnection (see illustrating figure). I will discuss the implications of these results on the long term evolution of massive stellar binaries, and on the observational properties of accreting stellar-mass and supermassive BHs.