The Panel on Theory, Computation, and Data Exploration was charged with surveying two separate branches of astronomy and astrophysics: theoretical astrophysics and data exploration. “Theoretical astrophysics,” in the convention of this report, includes both analytic theory and numerical simulation. The term “data exploration” is introduced to describe the newly emerged discipline of mining insight from large and complex astronomical databases using sophisticated modeling tools. The panel reviews the status of these two branches of astronomy and astrophysics and provides separate sets of recommendations for prioritized initiatives and policy directives.

Unlike many astronomy communities, which identify themselves by wavelength or mission, the community of theoretical and computational astrophysicists defines itself by synthetic tasks that cross disciplinary boundaries:

• Defining the frontier. The community invents concepts that create frontiers and a framework for observational discovery—new ideas about the universe—from the extremes of space-time to physics in exotic environments to the new universe of captured digital knowledge.

• Model building. It creates intelligible descriptions of physical systems with precise quantitative connections to reality, including both sophisticated simulations that incorporate a comprehensive range of physical processes and compact mathematical constructions that identify and represent the key physical effects.

• Synthesizing a world view. It knits physical science into a coherent narrative of our place in the universe, one that is accessible, interesting, and edifying to society at large. This scientific view of the universe competes in the free market of ideas; theorists tell and sell the astronomers’ story of the universe.

In these tasks, theoretical and computational astrophysicists combine leadership for and service to the larger astronomical community. Their specific activities are defined by both their core intellectual values and their interactions and collaborations outside their community. Three important themes recur in this report: