Theoretical and Computational Astrophysics

Robert Fisher

Gaurav Khanna

For more information see http://gravity.phy.umassd.edu/

http://www.wired.com/wiredscience/2009/08/visualizations/8/ (This simulation of a Type Ia supernova event, recently completed by Prof. Robert Fisher, in collaboration with colleagues from the University of Chicago and Argonne National Laboratory, was recently honored by the Department of Energy as one of ten of this year's best scientific visualizations at its annual Scientific Discovery through Advanced Computing (SciDAC) conference in June.)

Thanks to the monumental advances in parallel supercomputers over the past decade, astrophysicists can now directly simulate important astrophysical phenomena in fully three-dimensional calculations, including such key physical processes as turbulence, self-gravity, radiative transfer, and nuclear burning. These advances in computing come at the same time as a powerful new generation of observational instruments are emerging across the entire spectrum -- including SCUBA-2, CARMA, SMA, ALMA, Spitzer, SOFIA, LMT, James Webb, and Chandra. As the result of this tremendous progress, physicists are now at an exciting point in time where we can now begin to answer a number of fundamental, long-standing astrophysical questions by directly comparing computer simulation against observation.

Prof. Fisher's research has focused on two endpoints of stellar evolution -- star formation and supernovae, as well as on theevolution -- star formation and supernovae, as well as on the fundamental physics of turbulent fluids. In the context of star formation, outstanding questions include : How is turbulence within star-forming giant molecular clouds (GMCs) generated and sustained? What sets the stellar initial mass function (IMF)? What sets the rate at which stars are formed? How do complex molecules form in the extraordinarily cold background temperatures of molecular clouds? How are brown dwarfs formed? How are binary stars formed? In the context of supernovae, these questions include : How does a Chandrasekhar-mass white dwarf first ignite and initiate a subsonic deflagration front that becomes a type Ia supernova? What is the nature of turbulent deflagration within Ia supernovae? Does the deflagration front transition into a supersonic detonation, and if so, how? What is the origin of the Phillips relation, and is it possible to obtain an even-tighter relation using first principles simulations of Ia supernovae, and thereby provide even tighter constraints on the properties of dark energy?

Prof. Fisher's research, in collaboration with graduate and undergraduate University of Massachusetts Dartmouth students and colleagues from other institutions, has made fundamental advances on a number of these questions through the combined use of theory and simulation.

 Last Updated On: 9/1/08