Although cosmic rays were discovered almost a century ago the details of where and how they are accelerated and how they propagate to us remain somewhat mysterious. Acceleration can occur in many cosmic sources, including spinning, magnetized neutron stars, massive black holes, gamma ray bursts, shock waves expanding from supernova explosions, and even similar but larger shocks surrounding clusters of galaxies. The field is being revitalized by recent discoveries, and by greatly improved measurements of the spectra and composition of cosmic rays. This project is a theoretical investigation of cosmic particle acceleration mechanisms spanning several sites and responding to recent observations. It will explore the mechanism known as unipolar induction, and analyze in detail how particles can acquire energy and momentum in very small steps, such as in the vicinity of shock fronts. Qualitatively new types of magnetic reconnection and relativistic shock fronts will be studied using both simple analysis and more detailed simulations. The results should help to explain recent surprising observations of cosmic sources, throughout the seventy octave electromagnetic spectrum and beyond.
These problems have been only partially understood despite a century of attention, and tackling them both observationally and through simulation will require quite sophisticated tools. The work links broadly to the study of solar weather, and of magnetic and inertial fusion, topics of strong public interest and societal concern. A student will receive valuable training in plasma astrophysics, which is a good preparation for many other fields.
