Theoretical Astrophysics
Faculty:
Chatzopoulos - (Supernovae, stellar evolution, computational astrophysics)
Frank (Emeritus)- (Accretion, binary stars, binary evolution, mergers)
Tohline (Emeritus) – (Star formation, hydrodynamics of gravity wave sources)
The focal points for the theoretical astrophysics group are the hydrodynamics of binary and single stars, compact objects (black holes, neutron stars, and white dwarfs) and their accretion disks at violent and dynamical phases of their evolution (tidal disruptions, mergers, flares, star formation, and supernova explosions). Typical goals of our research include understanding the main physical processes taking place during these events and the calculation of observable outcomes such as multi-wavelength light curves from a variety of energy generation mechanisms, nuclear reactions and chemical abundances, and gravitational wave signatures of potential sources for LIGO and LISA. The hydrodynamics is run using local supercomputers such as SuperMIKE-II, and other machines available through LONI and XSEDE.
Chatzopoulos is interested in late stages of the evolution of massive stars and core collapse supernovae and in particular the puzzles presented by a class of super-luminous supernovae. He is investigating the role of exotic mechanisms such as pair instability and magneto-rotational energy injection by a newly-born magnetar. These studies require multi-physics, multi-dimensional hydrodynamics, stellar evolution and radiation transport calculations.
Frank's research interests focus on accretion and mergers in interacting binary stars including compact objects, binary white dwarfs, cataclysmic binaries containing an accreting white dwarf, and X-ray binaries involving an accreting neutron star or a black hole. These investigations consist of modeling the hydrodynamics of the accretion flow and the properties of the observed radiation. The ultimate goal of this research program is to understand the origin and evolution of binaries containing compact objects and the birth and structure of exotic stellar objects born of binary mergers.
Tohline and his former students have invested a great deal of time developing nontrivial computational algorithms to simulate fully three-dimensional, self-gravitating, compressible fluid flows and to visualize the results of these flows, which often can be quite complex. Postdoctoral researcher Dominic Marcello (CCT), building on these earlier algorithms, has developed Octo-Tiger, an accurate hydrodynamic code with adaptive mesh refinement, ideally suited to model mass transfer and mergers in close binary stars.