Melbourne Seminar: Ultra-High Energy Cosmic Rays: Problems and Solutions

2:00-3:00PM, Monday 23 May 2016

Level 7 Conference Room, University of Melbourne


Ultra-High Energy Cosmic Rays: Problems and Solutions

Prof Anna Uryson (Lebedev Physical Institute of Russian Academy of Sciences)

Cosmic rays are energy particles coming to the Earth from space. Particles with the highest energies, above 4·1019 eV, are called ultra-high energy cosmic rays (UHE CRs).

The main problem of ultra-high energy cosmic rays is where they come from and how they gain such high energies. A model will be presented explaining particle acceleration above 1020 eV in astrophysics objects - active galactic nuclei.  The objects include those with moderate luminosity in different energy bands.

Why particles detected have energies not higher than approximately (1-3)·1020 eV? It will be shown that besides well-known GZK-effect the reason is sources’ own restriction on the particle maximal energy. 

Ultra-high energy cosmic rays generate gamma-ray emission while propagating in extragalactic space. It will be shown that its intensity depends on characteristics of cosmic ray sources – their remoteness and initial particle energy spectra. Thus study of gamma-ray emission could be suggested as a new method to test parameters of cosmic ray sources.

Mon, 23 May 2016