Features of the Energy Spectrum of Cosmic Rays above 2.5 x 10(18) eV Using the Pierre Auger Observatory
2020
Abstract
We report a measurement of the energy spectrum of cosmic rays above 2.5 x 10(18) eV based on 215 030 events. New results are presented: at about 1.3 x 10(19) eV, the spectral index changes from 2.51 +/- 0.03(stat) +/- 0.05(syst) to 3.05 +/- 0.05(stat) +/- 0.10(syst), evolving to 5.1 +/- 0.3(stat) +/- 0.1(syst) beyond 5 x 10(19) eV, while no significant dependence of spectral features on the declination is seen in the accessible range.
These features of the spectrum can be reproduced in models with energy-dependent mass composition. The energy density in cosmic rays above 5 x 10(18) eV is [5.66 +/- 0.03(stat) +/- 1.40(syst)] x 10(53) erg Mpc(-3).