The Persistent Mystery of the Highest Energy Cosmic Ray – Corbin Covault

Date: Thu. February 17th, 2011, 4:15 pm-5:15 pm
Location: Rockefeller 301

One of the longest-standing mysteries of fundamental astrophysics is the origin and nature of the highest energy cosmic rays. These particles are the most energetic in the universe, arriving to the Earth from all directions in outer space. When these particles strike the earth’s atmosphere, they produce extensive air showers made of billions of secondary particles. The Pierre Auger Observatory has been designed and built to directly confront this mystery by making extensive measurements of air showers from these cosmic rays. After several years of operation, results from Auger have revealed key properties of the cosmic rays in terms of their energies, arrival directions, and composition. Some of these results have been long-anticipated, while other results are quite contrary to conventional expectations. In this talk, I will summarize the recent results from Auger, which taken together provide a new understanding of cosmic rays even as the mystery of their origin remains unresolved. Apparently solving this mystery will require expanding our present paradigm for how such particles might be created and propagated. In this sense, explaining the results from Auger will require either `new physics’ or `new astrophysics’ — or both.