Recent results from the Pierre Auger Observatory

In this paper some recent results from the Pierre Auger Collaboration are presented. These are the measurement of the energy spectrum of cosmic rays over a wide range of energies ($10^{17.5}$ to above $10^{20}$ eV), studies of the cosmic-ray mass composition with the fluorescence and surface detector of the Observatory, the observation of a large-scale anisotropy in the arrival direction of cosmic rays above 8 x $10^{18}$ eV and indications of anisotropy at intermediate angular scales above 4 x $10^{19}$ eV. The astrophysical implications of the spectrum and composition results are also discussed. Finally the progress of the upgrade of the Observatory, AugerPrime is presented.Comment: 20th International Symposium on Very High Energy Cosmic Ray Interactions (ISVHECRI 2018

Cosmogenic neutrinos and gamma-rays and the redshift evolution of UHECR sources

If ultra-high-energy cosmic rays (UHECRs) have extragalactic origins, as is widely assumed to be the case at least for the majority of cosmic rays with energies above a few EeV, secondary neutrinos and photons can be expected to be produced during the propagation of UHECRs through intergalactic space via interactions with cosmic background photons. The fluxes of such secondary particles are strongly dependent on the redshift evolution of the emissivity (number density times luminosity) of UHECR sources. We show how cosmic rays, neutrinos, and gamma rays can potentially provide complementary information about UHECR source evolution.Comment: 6 pages, 3 figures; published in the proceedings of the Neutrino Oscillation Workshop, 4-11 September 2016, Otranto, Ital

Testing hadronic and photo-hadronic interactions as responsible for UHECR and neutrino fluxes from Starburst Galaxies

We test the hypothesis of starburst galaxies as sources of ultra-high energy cosmic rays and high-energy neutrinos. The computation of interactions of ultra-high energy cosmic rays in the starburst environment as well as in the propagation to the Earth is made using a modified version of the Monte Carlo code {\it SimProp}, where hadronic processes in the environment of sources are implemented for the first time. Taking into account a star-formation-rate distribution of sources, the fluxes of ultra-high energy cosmic rays and high-energy neutrinos are computed and compared with observations, and the explored parameter space for the source characteristics is discussed. We find that, depending on the density of the gas in the source environment, spallation reactions could exceed theoutcome in neutrinos from photo-hadronic interactions in the source environment and in the extra-galactic space.Comment: 10 pages, 9 figures, comments are welcom

UHECR: raggi cosmici di energia ultra elevata

Lo studio dei raggi cosmici di energia ultra elevata (UHE, E > 10^18 eV) permette di aprire uno spiraglio nella comprensione della loro origine. A queste energie, infatti, l'Universo non è trasparente ai raggi cosmici, nel loro percorso dalle sorgenti fino a Terra, a causa del fondo cosmico di fotoni che lo pervade. Mostreremo, con argomenti di base, come è possibile trattare la propagazione di questi raggi cosmici, qual è la fisica particellare e nucleare coinvolta e, infine, come lo studio combinato delle osservabili a Terra (in particolare, spettro di energia e composizione) permette di inferire le caratteristiche delle sorgenti di raggi cosmici

UHECR: raggi cosmici di energia ultra elevata

Lo studio dei raggi cosmici di energia ultra elevata (UHE, E > 10^18 eV) permette di aprire uno spiraglio nella comprensione della loro origine. A queste energie, infatti, l'Universo non è trasparente ai raggi cosmici, nel loro percorso dalle sorgenti fino a Terra, a causa del fondo cosmico di fotoni che lo pervade. Mostreremo, con argomenti di base, come è possibile trattare la propagazione di questi raggi cosmici, qual è la fisica particellare e nucleare coinvolta e, infine, come lo studio combinato delle osservabili a Terra (in particolare, spettro di energia e composizione) permette di inferire le caratteristiche delle sorgenti di raggi cosmici

Measurement of the cosmic ray spectrum above 4×10184{\times}10^{18} eV using inclined events detected with the Pierre Auger Observatory

A measurement of the cosmic-ray spectrum for energies exceeding $4{\times}10^{18}$ eV is presented, which is based on the analysis of showers with zenith angles greater than $60^{\circ}$ detected with the Pierre Auger Observatory between 1 January 2004 and 31 December 2013. The measured spectrum confirms a flux suppression at the highest energies. Above $5.3{\times}10^{18}$ eV, the "ankle", the flux can be described by a power law $E^{-\gamma}$ with index $\gamma=2.70 \pm 0.02 \,\text{(stat)} \pm 0.1\,\text{(sys)}$ followed by a smooth suppression region. For the energy ($E_\text{s}$) at which the spectral flux has fallen to one-half of its extrapolated value in the absence of suppression, we find $E_\text{s}=(5.12\pm0.25\,\text{(stat)}^{+1.0}_{-1.2}\,\text{(sys)}){\times}10^{19}$ eV.Comment: Replaced with published version. Added journal reference and DO