Keynote Presentation

Black Hole Accretion: Answers and Questions

Author(s): John Hawley (University of Virginia)

Presenter: John Hawley (University of Virginia)

It is now over four decades since the papers of Shakura & Sunyev (1973), and Novikov & Thorne (1973) laid out the basic theory of black hole accretion. While providing a basic framework for understanding the accretion process, this work left unanswered several fundamental questions, such the origin and nature of the internal disk stress, and how are outflows launched. Since then a plethora of observations have posed additional questions related to jet launching, time dependent behavior, and the nature of the different thermodynamic and spectroscopic states in accretion systems. Theoretical advances have been providing answers, but the answers themselves often lead to new questions. This talk will review some of these answers and questions, and discuss how future investigations may shed further light on the nature of black hole accretion.