Over the past two decades, precise measurements have established that a 4.2-million-solar-mass black hole, Sgr A*, resides at the center of our Galaxy, in agreement with predictions from Einstein’s general theory of relativity. Current flaring activity from Sgr A* offers a unique probe of accretion processes near the event horizon, within a few Schwarzschild radii, and is considered a fundamental property of emission from the accretion disk. While the origin of these flares, spanning radio to X-ray wavelengths, remains debated, recent simulations suggest that magnetic reconnection events may drive them. On larger scales, the Galactic center hosts a population of synchrotron-emitting filaments within the inner few hundred parsecs, coinciding with regions of elevated diffuse cosmic-ray flux. These structures reveal the extreme conditions in the nucleus of our Galaxy. I will present highlights from recent multi-wavelength observations of Sgr A* with JWST, NuSTAR, and VLA (2023–2024) and propose a unified physical framework for variable emission across radio to X-ray bands. Additionally, using statistical properties derived from MeerKAT data, I will argue that the Galactic center filaments provide the earliest evidence of Sgr A*’s past energetic outburst approximately 10 million years ago.
The Present and Past Activity of Sgr A*
Lundi 16 mars 2026
de
11:00 à
12:00
Amphithéâtre, bâtiment 18 Evry Schatzman - Campus de Meudon, Observatoire de Paris-PSL
