University of Maryland
Atlantic Building, Room 2400 4:30 PM Monday, February 6, 2017
Coffee, Tea & Snacks 4:15-4:30 PM

Vladimir Ptuskin
IZMIRAN, Moscow, Russia

Inverse Problem for Transport of Ultra-High Energy Cosmic Raysin Expanding Universe

The origin of ultra-high energy extragalactic cosmic rays is discussed. The propagation of nuclei with energies more than 10^18 eV in expanding Universe filled with the background electromagnetic radiation is considered. The source spectrum of extragalactic cosmic rays for protons and nuclei up to Iron is determined from the observed at the Earth spectrum of particles as the solution of inverse problem of transport of ultrarelativistic nuclei. The method of regularization of this mathematically incorrect problem is employed. The data of the Auger experiment on cosmic-ray energy spectrum, the mean logarithm of mass number and it's dispersion are used. The found energy spectra of sources are very hard and strongly depend on the composition of accelerated nuclei.