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Seminars

Physical processes around a black hole driven by magnetic reconnection

Speaker

Prof. Feng YUAN

Affiliation

Fudan University

Date July 11, 2025 (Friday)
Time 10:00 a.m.
Venue Room 522, 5/F, Chong Yuet Ming Physics Building, The University of Hong Kong

Abstract

In this talk, I will introduce our recent two works in which magnetic reconnection plays a key role. One is the formation and radiation of jet, another is the flares of black holes. The common key physical processe behind them is magnetic reconnection. In the first work, assuming that the nonthermal elecrons in the jet are accelerated by magnetic reconnection, we have calculated the distribution of energetic nonthermal electrons and their radiation. Taking the M87 jet as an example, we shown that the well-known BZ model of jet formation, which is a purely dynamical model, can explain various observations of jet, especially the morphology of the jet such as the elongated structure, the limb-brightening feature, and teh jet width as a function of distance. In the second work, we try to explain the flares of Sgr A*, the supermassive black hole located in the center of our Galaxy, observed by GRAVITY-VLT. Consistent with our previous theoretical prediction, we find from GRMHD numerical simulation of accretion flow that flux ropes can be formed above the accretion flow due to magnetic reconnection and the formed flux ropes will be further ejected out. Electrons will be accelerated by the reconnection and produce flares. The predicted light curve of the flare and the trajectory of the 'hot spot' are found to be well consistent with those observed by GRAVITY.

 

Anyone interested is welcome to attend.