Welcome to my home page. I am a Professor in the Department of Astronomy and Director of the Joint Space Science Institute (JSI) at the University of Maryland, College Park. My research interests lie in the astrophysics of black holes (both stellar and supermassive), the physics of relativistic jets, and the properties and evolution of intracluster and intergalactic plasma. Please explore these pages to find out about me, my research group and my teaching activities.