Computational Astrophysics

Introduction
O and Wolf-Rayet (WR) stars are some of the most massive and powerful stars in the universe. These stars have been detected in non-thermal radiation in the radio and TeV gamma-rays as well as possibly in X-rays. Currently it has been shown that WR stars emitting non-thermal radiation are most likely colliding wind binaries^[1]. It has also been shown that in 1-D Hydro simulations that it is difficult to explain the non-thermal emission from O-stars as being from a single star^[2]. However it is known that additional instabilities and shocks develop in multiple dimensions, plus simulations must be done to accurately model the Diffusive Shock Acceleration (DSA) process that the particles (electrons and protons) producing the non-thermal radiation undergo^[3].

Our Simulations
To address these issues we are developing a 2-D Magnetohydrodynamic (MHD) code that includes DSA with losses. This code will be the merger of two previously successful codes AstroBEAR and CGMV^[4] and will for the first time (to our knowledge) be able to model self-consistently the acceleration of particles via DSA and its feedback on the MHD flows in multiple dimensions (see Multidimensional DSA for more details). Once this code is completed we will run a suite of simulations that will model the cosmic ray acceleration in winds from single O and WR stars and for colliding wind binaries. Using these simulations we will produce synthetic observations of these objects and address the concerns of the community about these interesting objects.

References

^[1]Dougherty, S. M. & Williams, P. M., 2000, Monthly Notices of the Royal Astronomical Society, 319, 1005 (ADS Link)
^[2]van Loo S., Runacres M. C., & Blomme R., 2006, Astronomy & Astrophysics, 452, 1011 (ADS Link)
^[3]Pittard, J. M. & Dougherty, S. M., 2006, Monthly Notices of the Royal Astronomical Society, 372, 801 (ADS Link)
^[4]Jones, T. W. & Kang, H. 2005, Astroparticle Physics, 24, 75 (ADS Link)