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The Macrophysics and Microphysics of Cosmic Rays

Event Details

Event Dates: 

Monday, October 15, 2012 - 10:00am

Speaker Name(s): 

Ellen Zweibel

Speaker Affiliation(s): 

University of Wisconsin
Seminar Type/Subject

Event Details & Abstract: 

One hundred years ago, Viktor Hess showed that an extraterrestrial, and probably extrasolar, source of ionizing radiation impinges on the atmosphere of the Earth. Over the next few decades it was established that these "cosmic rays" are not photons but charged particles, that their propagation through interstellar space is regulated by a pervasive Galactic magnetic field, and that their energy density is in rough equipartition with the thermal, turbulent, and magnetic energy densities of the interstellar medium. I will describe how cosmic rays couple dynamically to their environments, despite being virtually collisionless, some consequences of the coupling, and some uncertainties in the standard picture.