Supermassive black holes (SMBHs) may spend the majority of their lives accreting at low rates through radiatively inefficient, advection-dominated accretion flow. Therefore, low-luminosity SMBHs could greatly outnumber their more active cousins, active galactic nuclei, thus are essential for our understanding of SMBH activity cycles and their relationship to galaxy evolution. In particular, SMBHs harbored in local galaxies are found to be remarkably under-luminous. The best studied under-luminous SMBH is the closest such object to Earth, Sagittarius A*, located in the nucleus of our Milky Way galaxy. In this talk, I will discuss how I have been probing the outburst history of Sagittarius A* and how I plan to apply these techniques to SMBHs in nearby galaxies such as Andromeda. The Galactic nucleus of the Milky Way galaxy also serves as an ideal lab to probe exotic physics. I would like to introduce a new research direction of mine, to probe Galactic cosmic-rays at MeV through PeV energy scales. This research has far-reaching implications for a range of fields of study: the origin of Galactic cosmic-rays, particle acceleration mechanisms and dark matter searches, aiming to eventually answer the question whether Galactic cosmic-rays are from ordinary astrophysical sources or of more exotic origin.

BIO
Dr. Shuo Zhang is currently a postdoctoral scholar and Heising-Simons Fellow at MIT Kavli Institute for Astrophysics and Space Research. Her research focuses on observational high-energy astrophysics, including supermassive black hole accretion and feedback, the origin of Galactic cosmic-rays, and large surveys. For the past two years, Shuo has been leading a long-term multi-mission X-ray monitoring campaign of the Galactic Center supermassive black hole and its surrounding areas. Recently, Shuo initiated an original particle astrophysics project on probing Galactic cosmic-ray particles at MeV through PeV energy scales using innovative methods. Before joining MIT, Shuo obtained her Ph.D. degree in physics from Columbia University, where she held a NASA Earth and Space Science fellowship and was a key member of the NuSTAR Galactic plane survey team. Shuo received the NASA Group Achievement Awards for three times based on her contribution to the NuSTAR mission. Before that, she earned her bachelor's degree from Tsinghua University in 2010.

Host: Prof. Wei Cui