首页

What powers the hard, non-thermal X-rays from accreting black holes has been a longstanding mystery. In this talk, I will address the underlying question of what energizes the plasma of the Comptonizing “corona” against the strong inverse Compton cooling losses with first-principle particle-in-cell simulations of magnetic reconnection subject to radiative cooling losses in magnetized electron-positron and electron-ion plasmas. We find that the electrons are swiftly cooled to non-relativistic temperatures, yet they engage in Comptonization through their stochastic trans-relativistic bulk motions. I will also show—using global resistive general relativistic magnetohydrodynamic simulations of accreting black holes—that the black hole jet sheath is laden with current sheets and is a site of efficient dissipation of electromagnetic power (comparable to accretion power) through processes such as magnetic reconnection and turbulence. The distribution of bulk energy of the radially outflowing plasma along the jet sheath resembles a Maxwellian distribution with an 'effective bulk temperature' of a few 100 keV, and this site could be a candidate for the Comptonizing corona.

Host: Xinyu Li