Title: The Origin of the Fermi Bubbles and Their Implications

Speaker: Professor Fulai Guo (Shanghai Astronomical Observatory, Chinese Academy of Sciences)

Time: 10:00am, Jun 9, 2023

Location: 3-402, PMO Xianlin Campus

Abstract: The Fermi bubbles are a pair of enormous gamma-ray-emitting bubbles discovered in the inner Galaxy in 2010 by the Fermi gamma-ray space telescope. Are they long-lasting or a fast evolving explosive event? What causes this structure? The Fermi bubbles may correspond to a typical galactic feedback process occurring in our own Galaxy during the past several million years. Galactic feedback is one central unsolved problem in contemporary astronomy. Furthermore, the Fermi bubbles are clearly a galactic-scale accelerator of cosmic rays, whose origin remains a century-long mystery. In this talk, I will describe our long journey to reveal the origin of the Fermi bubbles. Our recent jet-shock model could explain the X-ray, gamma-ray, and microwave observations of the Fermi bubbles, suggesting that they were produced by a pair of powerful jets emanating from the supermassive black hole at the Galactic center about 5 million years ago. We also use our Fermi bubble study to investigate the spatial density distribution of the hot circumgalactic medium in the inner Galaxy, leading to interesting implications on the origin of the newly-discovered even-larger eROSITA bubbles in our Galaxy in the X-ray band.