The influence of extragalactic magnetic fields on the propagation of cosmic rays from Centaurus A

The motion of different chemical composition of ultra high energy cosmic rays in the galactic magnetic fields with taking into account the extragalactic magnetic field was considered. The ultra high energy events registered by the AUGER observatory in the sky region near Centaurus A were investigated. It is shown that in the case when the extragalactic magnetic field is taken into account some of these events could originate from Centaurus A, but it leads to expanding of sky region of possible source localization

Cosmic Ray Extremely Distributed Observatory: a global network of detectors to probe contemporary physics mysteries

In the past few years, cosmic-rays beyond the GZK cut-off ($E > 5 \times 10^{19}$ eV) have been detected by leading collaborations such as Pierre Auger Observatory. Such observations raise many questions as to how such energies can be reached and what source can possibly produce them. Although at lower energies, mechanisms such as Fermi acceleration in supernovae front shocks seem to be favored, top-down scenarios have been proposed to explain the existence of ultra-high energy cosmic-rays: the decay of super-massive long-lived particles produced in the early Universe may yield to a flux of ultra-high energy photons. Such photons might be presently generating so called super-preshowers, an extended cosmic-ray shower with a spatial distribution that can be as wide as the Earth diameter. The Cosmic Ray Extremely Distributed Observatory (CREDO) mission is to find such events by means of a network of detectors spread around the globe. CREDO's strategy is to connect existing detectors and create a worldwide network of cosmic-ray observatories. Moreover, citizen-science constitutes an important pillar of our approach. By helping our algorithms to recognize detection patterns and by using smartphones as individual cosmic-ray detectors, non-scientists can participate in scientific discoveries and help unravel some of the deepest mysteries in physics.Comment: excited QCD Conference, CREDO Collaboration, 7 pages, 3 figure

Search for ultra-high energy photons through preshower effect with gamma-ray telescopes: Study of CTA-North efficiency

Indexación ScopusAs ultra-high energy photons (EeV and beyond) propagate from their sources of production to Earth, radiation-matter interactions can occur, leading to an effective screening of the incident flux. In this energy domain, photons can undergo e+/e− pair production when interacting with the surrounding geomagnetic field, which in turn can produce a cascade of electromagnetic particles called preshower. Such cascade can initiate air showers in the Earth's atmosphere that gamma-ray telescopes, such as the next-generation gamma-ray observatory Cherenkov Telescope Array, can detect through Cherenkov emission. In this paper, we study the feasibility of detecting such phenomenon using Monte-Carlo simulations of nearly horizontal air showers for the example of the La Palma site of the Cherenkov Telescope Array. We investigate the efficiency of multivariate analysis in correctly identifying preshower events initiated by 40 EeV photons and cosmic ray dominated background simulated in the energy range 10 TeV – 10 EeV. The effective areas for such kind of events are also investigated and event rate predictions related to different ultra-high energy photons production models are presented. While the expected number of preshowers from diffuse emission of UHE photons for 30 hours of observation is estimated around 3.3×10−5 based on the upper limits put by the Pierre Auger Observatory, this value is at the level of 2.7×10−4 (5.7×10−5) when considering the upper limits of the Pierre Auger Observatory (Telescope Array) on UHE photon point sources. However, UHE photon emission may undergo possible ”boosting” due to gamma-ray burst, increasing the expected number of preshower events up to 0.17 and yielding a minimum required flux of ~ 0.2 km−2yr−1 to obtain one preshower event, which is about a factor 10 higher than upper limits put by the Pierre Auger Observatory and Telescope Array (0.034 and 0.019 km−2yr−1, respectively). © 2020https://www-sciencedirect-com.recursosbiblioteca.unab.cl/science/article/pii/S092765052030061X?via%3Dihu