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The UHECR-FR0 Radio Galaxy Connection: A Multi-Messenger Study of Energy Spectra/Composition Emission and Intergalactic Magnetic Field Propagation
Jon Paul Lundquist, Lukas Merten, Serguei Vorobiov, Margot Boughelilba, Anita Reimer, Paolo Da Vela, Fabrizio Tavecchio, Giacomo Bonnoli, Chiara Righi, 2023, objavljeni znanstveni prispevek na konferenci

Opis: This study investigates low luminosity Fanaroff-Riley Type 0 (FR0) radio galaxies as a potentially significant source of ultra-high energy cosmic rays (UHECRs). Due to their much higher prevalence in the local universe compared to more powerful radio galaxies (about five times more than FR-1s), FR0s may provide a substantial fraction of the total UHECR energy density. To determine the nucleon composition and energy spectrum of UHECRs emitted by FR0 sources, simulation results from CRPropa3 are fit to Pierre Auger Observatory data. The resulting emission spectral indices, rigidity cutoffs, and nucleon fractions are compared to recent Auger results. The FR0 simulations include the approximately isotropic distribution of FR0 galaxies and various intergalactic magnetic field configurations (including random and structured fields) and predict the fluxes of secondary photons and neutrinos produced during UHECR propagation through cosmic photon backgrounds. This comprehensive simulation allows for investigating the properties of the FR0 sources using observational multi-messenger data.
Ključne besede: ultra-high energy cosmic rays (UHECRs), UHECR propagation, CRPropa, active galactic nuclei (AGN), jetted AGN, FR0 radio galaxies, Pierre Auger Observatory, UHECR energy spectrum, UHECR mass composition
Objavljeno v RUNG: 24.08.2023; Ogledov: 186; Prenosov: 2
.pdf Celotno besedilo (1,12 MB)
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Constraining the sources of ultra-high-energy cosmic rays across and above the ankle with the spectrum and composition data measured at the Pierre Auger Observatory
A. Abdul Halim, Andrej Filipčič, Jon Paul Lundquist, Shima Ujjani Shivashankara, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, 2023, izvirni znanstveni članek

Opis: In this work we present the interpretation of the energy spectrum and mass composition data as measured by the Pierre Auger Collaboration above 6 × 10[sup]17 eV. We use an astrophysical model with two extragalactic source populations to model the hardening of the cosmic-ray flux at around 5 × 10[sup]18 eV (the so-called "ankle" feature) as a transition between these two components. We find our data to be well reproduced if sources above the ankle emit a mixed composition with a hard spectrum and a low rigidity cutoff. The component below the ankle is required to have a very soft spectrum and a mix of protons and intermediate-mass nuclei. The origin of this intermediate-mass component is not well constrained and it could originate from either Galactic or extragalactic sources. To the aim of evaluating our capability to constrain astrophysical models, we discuss the impact on the fit results of the main experimental systematic uncertainties and of the assumptions about quantities affecting the air shower development as well as the propagation and redshift distribution of injected ultra-high-energy cosmic rays (UHECRs).
Ključne besede: ultra-high-energy cosmic rays (UHECRs), Pierre Auger Observatory, extensive air showers, UHECR propagation, UHECR energy spectrum, UHECR mass composition
Objavljeno v RUNG: 18.08.2023; Ogledov: 177; Prenosov: 3
.pdf Celotno besedilo (2,39 MB)
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Recent results from the Pierre Auger Observatory
Serguei Vorobiov, 2022, objavljeni povzetek znanstvenega prispevka na konferenci (vabljeno predavanje)

Opis: Ultra-high-energy cosmic rays (UHECRs) are mostly protons and heavier nuclei arriving on Earth from space and producing particle cascades in the atmosphere, ”extensive air showers”. As of today, the most precise and high-statistics data set of the rare (≤ 1 particle per per year above 10[sup]19 eV) UHECR events is obtained by the Pierre Auger Observatory, a large area (~3000 hybrid detector in Argentina. The Auger Observatory determines the arrival directions and energies of the primary UHECR particles and provides constraints for their masses. In this talk, I will present and discuss the recent results, including the detailed measurements of the cosmic-ray energy spectrum features, the study of the anisotropies in the UHECR arrival directions at large and intermediate angular scales, the multi-messenger searches, and the inferred cosmic-ray mass composition. Finally, the progress of the current upgrade of the Observatory, "AugerPrime" which is aimed at improving the sensitivity to the mass composition of ultra-high-energy cosmic rays, will be presented.
Ključne besede: ultra-high-energy cosmic rays, Pierre Auger Observatory, UHECR mass composition, energy spectrum, anisotropies, AugerPrime upgrade
Objavljeno v RUNG: 23.12.2022; Ogledov: 784; Prenosov: 6
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Mass composition of cosmic rays with energies from 10^17.2 eV to 10^20 eV using surface and fluorescence detectors of the Pierre Auger Observatory
Gašper Kukec Mezek, 2018, objavljeni znanstveni prispevek na konferenci

Opis: Ultra-high-energy cosmic rays (UHECRs) are highly energetic particles with EeV energies, exceeding the capabilities of man-made colliders. They hold information on extreme astrophysical processes that create them and the medium they traverse on their way towards Earth. However, their mass composition at such energies is still unclear, because data interpretation depends on our choice of high energy hadronic interaction models. With its hybrid detection method, the Pierre Auger Observatory has the possibility to detect extensive air showers with an array of surface water-Cherenkov stations (SD) and fluorescence telescopes (FD). We present recent mass composition results from the Pierre Auger Collaboration using observational parameters from SD and FD measurements. Using the full dataset of the Pierre Auger Observatory, implications on composition can be made for energies above 10^17.2 eV.
Ključne besede: astroparticle physics, ultra-high energy cosmic rays, extensive air showers, mass composition, Pierre Auger Observatory, fluorescence telescopes, water-Cherenkov stations
Objavljeno v RUNG: 24.05.2019; Ogledov: 2917; Prenosov: 108
.pdf Celotno besedilo (573,00 KB)

Mass composition of ultra-high energy cosmic rays at the Pierre Auger Observatory
Gašper Kukec Mezek, 2019, doktorska disertacija

Opis: Cosmic rays with energies above 10^18 eV, usually referred to as ultra-high energy cosmic rays (UHECR), have been a mystery from the moment they have been discovered. Although we have now more information on their extragalactic origin, their direct sources still remain hidden due to deviations caused by galactic magnetic fields. Another mystery, apart from their production sites, is their nature. Their mass composition, still uncertain at these energies, would give us a better understanding on their production, acceleration, propagation and capacity to produce extensive air showers in the Earth's atmosphere. Mass composition studies of UHECR try to determine their nature from the difference in development of their extensive air showers. In this work, observational parameters from the hybrid detection system of the Pierre Auger Observatory are used in a multivariate analysis to obtain the mass composition of UHECR. The multivariate analysis (MVA) approach combines a number of mass composition sensitive variables and tries to improve the separation between different UHECR particle masses. Simulated distributions of different primary particles are fitted to measured observable distributions in order to determine individual elemental fractions of the composition. When including observables from the surface detector, we find a discrepancy in the estimated mass composition between a mixed simulation sample and the Pierre Auger data. Our analysis results from the Pierre Auger data are to a great degree independent on hadronic interaction models. Although they differ at higher primary masses, the different models are more consistent, when combining fractions of oxygen and iron. Compared to previously published results, the systematic uncertainty from hadronic interaction models is roughly four times smaller. Our analysis reports a predominantly heavy composition of UHECR, with more than a 50% fraction of oxygen and iron at low energies. The composition is then becoming heavier with increasing energy, with a fraction of oxygen and iron above 80% at the highest energies.
Ključne besede: astroparticle physics, ultra-high energy cosmic rays, extensive air showers, mass composition, Pierre Auger Observatory, machine learning, multivariate analysis
Objavljeno v RUNG: 03.04.2019; Ogledov: 4266; Prenosov: 171
.pdf Celotno besedilo (17,53 MB)

Results from the Pierre Auger Observatory
Ivan De Mitri, Andrej Filipčič, Samo Stanič, Darko Veberič, Danilo Zavrtanik, Marko Zavrtanik, 2015, objavljeni znanstveni prispevek na konferenci

Ključne besede: Pierre Auger Observatory, Ultra High Energy Cosmic Rays (UHECR), UHECR energy spectrum, UHECR mass composition
Objavljeno v RUNG: 27.06.2017; Ogledov: 3583; Prenosov: 0
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