I was born in Annapolis, Maryland in 1958. My family lived in Severna Park, Maryland until early 1965 when we moved to Salina, Kansas. Our family consisted of my parents, Bernard and Jeanne Hawley, my brothers Jim and Steve, my sister Diane, and assorted cats. My interest in astronomy was stoked by my fascination with the 1960s era space programme. Isaac Asimov’s essays, especially those on cosmology, black holes and space, were also influential. My older brother Steve served as a role model. His abiding interest in astronomy led him eventually to a PhD in astronomy and a career as a space shuttle astronaut.

I graduated from Salina Central High School in 1976 and attended Haverford College in Pennsylvania where I majored in astronomy and physics. My senior thesis project was computational; I modelled the nuclear reactions of the helium-burning shell of a red giant star. Sometime in my senior year I attended a seminar on accretion disks, then a novel subject. I was struck by the comment that no one knew the nature or strength of the internal stress that drove accretion, but that ignorance could be reduced to a single parameter, “alpha.” This was my introduction to the fundamental problem in accretion.

After graduation in 1980, I joined the graduate programme at the University of Illinois. My PhD adviser Larry Smarr, a pioneer in numerical relativity, inspired me to pursue the numerical simulation of gas dynamics around black holes as a thesis topic.

I completed my PhD in 1984 and went to the California Institute of Technology as a Bantrell Prize Fellow. Among other things, I studied a global disk instability discovered by John Papaloizou and James Pringle. I collaborated with members of the theoretical astrophysics group in a way that combined simulation and analysis. This synergy provided new insight into the fundamental nature of the instability, and found a previously unknown type of orbiting equilibrium. This set the pattern for future work.

During my postdoctoral years I attended a conference on general relativity where I met a graduate student named Katherine Holcomb, who was presenting work on general relativistic simulations of non-isotropic cosmologies. She was eventually to become my wife; conferences can inspire one in new and rewarding directions.

I joined the faculty at the University of Virginia in the fall of 1987. My experience at Caltech had impressed upon me the power of wedding numerical simulation with analysis. Steve Balbus, with his keen understanding of fluid dynamics and formidable mathematical skill, was the ideal collaborator. By 1990, Steve and I had started to consider the nature of waves in a magnetized disk. Steve’s earlier experience with cooling flows of gas in galaxy clusters had impressed upon him that magnetic fields can change the linear properties of a gas in significant ways. As it turned out, this was especially true in a disk, where magnetic fields prove to be unstable to the magneto-rotational instability, or MRI. When Steve showed me his first results, my response was simple: “That’s very important.” I immediately ran a short simulation of vertical magnetic fields in a disk. A plot from that first simulation showed the development of kinks in the initially smooth field lines. Steve kept that plot on his office wall for many years.

A demonstration that the MRI led to turbulence and stress required three-dimensional simulations. Steve, Charles Gammie and I published the first turbulent “shearing box” simulations in 1995. The shearing box approximation has proven to be a valuable tool; it has since been used for a wide range of problems in a variety of astrophysical contexts.

In 2003 I returned to general relativistic simulations when my postdoc Jean-Pierre De Villiers and I developed a new GR-MHD code. Over the last decade I have collaborated with Julian Krolik (Johns Hopkins University) on global simulations of disks and jets. GR-MHD disk simulations are now widely used to investigate increasingly detailed issues of stress distribution, emission, and jet formation. The theory community seems to be moving rapidly toward fulfilling the dream of first-principle disk models.

In 2006 I was asked to be the Chair of the Department of Astronomy. In 2012 I was appointed the Associate Dean for the Sciences in the College of Arts and Sciences. While administration is not nearly as much fun as computational theoretical astrophysics, I have gained a considerably broader perspective into the academy and the wide range of scientific disciplines contained within.

Looking back at my education and career, one thing stands out: the interactions with insightful individuals who influenced my thinking along constructive new paths. I was fortunate to participate in the tremendous growth of computational astrophysics. I was even more fortunate to work with collaborators whose unique skills, knowledge and ability could complement my own so well.



23 September 2013   Hong Kong