Energy spectrum of cosmic rays measured using the Pierre Auger Observatory

Abstract

We present the energy spectrum of cosmic rays measured at the Pierre Auger Observatory from 6 × 10 15 eV up to the most extreme energies where the accumulated exposure reaches about 80 000 km 2 sr yr. The wide energy range is covered with five different data sets: events detected by the surface detector (with separate reconstruction methods for zenith angles below and above 60 • ), those collected by a denser array, a set of hybrid events simultaneously recorded by the surface and fluorescence detectors, and those events in which the signal is dominated by Cherenkov light registered by the high-elevation telescopes. In this contribution, we report updates of the analysis techniques and present the spectrum obtained by combining the five different measurements. Spectral features occurring in the wide energy range covered by the Observatory are discussed.

Ultra-High-Energy Cosmic Rays: The Intersection of the Cosmic and Energy Frontiers

“…The SD-750 has a detection efficiency of approximately 100% for events with θ < 40 • and E ≥ 10 17 eV, and has been used to measure the energy spectrum of cosmic rays down to the so-called second-knee [48]. The SD-433 will extend the full efficiency further to 10 16.6 eV [49], while preliminary studies using the HEAT FD to detect the air Cherenkov emissions from showers reach down to 10 15.8 eV, below the so-called low-energy ankle [66]. As for arrival directions, the SD-750 has been used to extend the measurements of the right ascension (RA) modulation down to 1/32 nd EeV [67].…”

“…2.6, the spectrum measurements performed at the Auger and TA observatories extend to lower energies, allowing for the coverage of almost the entire energy range in which CRs are studied through the detection of extensive air showers. The lowest energies are attained by analyzing the events dominated by Cherenkov light detected with special fluorescence telescopes that point at high elevation angles [72,66]. For the SD-based measurements, the energy threshold is lowered using denser arrays of SD stations nested in the main array.…”

“…Figure 2.6: Recent measurements of the all-particle flux from the TA[108], IceCube[82], Pierre Auger[33,48,66], Yakutsk[109], KASCADE-Grande[110], and TUNKA[111] experiments, which define the spectral features in the UHE region, are shown. Those with upgrades specifically described in this white paper are shown in color.…”

Constraining ultra-high-energy cosmic ray composition through cross-correlations

“…where eV = 100 EeV, respectively. These are the number of events we can expect to have for a full-sky observatory with statistics comparable with current experimental facilities [27,28]. For each E cut we compute the corresponding attenuation and define five logarithmic bins as described in subsection 2.2 for the deflections, analogously to the UHECR kernel Equation 2.8.…”

Cosmic Ray Indirect Rapporteur Report (37th ICRC )

“…An updated energy spectrum using 10 years of FD data, Figure 6, was shown by TA [65]. The Auger energy spectrum was extended down in energy to 6 PeV, Figure 7, using observations by the HEAT telescopes of Cherenkov dominated events [66]. Efforts to use surface detectors for mass composition are continuing.…”