The Black Hole and its Flaring Activity at the Center of the Galaxy

lundi 1 déc. 2025, 11:00 → 12:00 Europe/Paris

200/0-Auditorium - Auditorium P. Lehmann (IJCLab)

v1_ijclab_paris.pdf

11:00 → 12:00 The Black Hole and its Flaring Activity at the Center of the Galaxy

Precise measurements taken at radio and infrared wavelengths over the last two decades have led to the conclusion that a 4.2 million solar mass black hole lies at the center of the Galaxy. These measurements are consistent with the predictions of the Einstein's general theory of relativity. I will present highlights of recent James Web Space telescope observations to study the flaring activity of the black hole. The variability of the black hole probes the process of the accretion flow at a distance of few Schwarzschild radius. These observations indicate that the flux of Sgr A* is fluctuating constantly with multiple synchrotron flares per day. I will argue that two distinct populations of particles produce bright and faint synchrotron variable emission. As for the origin of the infrared flares, a number of recent simulations suggest that flares are ejected plasmoids from the accretion disk due to reconnection of the magnetic field lines. Time permitting, I will also discuss the origin of X-ray flares from Sgr A*.

Orateur: Farhad Yusef-Zadeh (Northwestern University)