21. Searches for ultra-high-energy photons with the Pierre Auger ObservatoryNicolás González, Andrej Filipčič, Jon Paul Lundquist, Shima Ujjani Shivashankara, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, 2025, published scientific conference contribution Abstract: Ultra-high-energy (UHE, E≳10[sup]17 eV) photons are expected to originate from the interaction of UHE cosmic rays with background radiation fields, as well as from more exotic processes like the decay of hypothetical super-heavy dark matter particles. UHE photons produced at cosmic-ray sources are key ingredients for enhancing our multimessenger understanding of the cosmic-ray acceleration and transient phenomena. Pierre Auger Observatory, designed to investigate UHE cosmic rays, offers unparalleled sensitivity to UHE photons. In this contribution, we present recent results of photon searches above 10[sup]16.7 eV obtained with data collected prior to the upgrade of the Observatory. Additionally, we discuss directional and follow-up searches conducted in coincidence with gravitational wave events detected by LIGO/Virgo, highlighting the role of the Observatory in advancing multi-messenger astronomy at the highest energies.
Keywords: ultra-high-energy cosmic rays, Pierre Auger Observatory, UHE photon search, diffuse photon flux
Published in RUNG: 24.03.2025; Views: 172; Downloads: 6
 Full text (2,04 MB)
This document has many files! More... |
22. The Pierre Auger Observatory and physics beyond the standard modelR. Aloisio, Andrej Filipčič, Jon Paul Lundquist, Shima Ujjani Shivashankara, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, 2025, published scientific conference contribution Abstract: The Pierre Auger Observatory, the world’s largest cosmic ray detector, plays a pivotal role in exploring the frontiers of physics beyond the standard model of particle physics. By the observation of ultra-high energy cosmic rays, Auger provides critical insights into two major scenarios: super heavy dark matter and Lorentz invariance violation. Super heavy dark matter, hypothesized to originate in the early universe, offers a compelling explanation for the dark matter problem and is constrained by Auger through searches for photons and neutrinos resulting from its decay. Lorentz invariance violations, motivated by quantum gravity theories implying deviations from fundamental symmetries, are probed by Auger through alterations of the particle dispersion relation and the energy thresholds of their interactions with astrophysical photons backgrounds.
Keywords: ultra-high-energy cosmic rays, Pierre Auger Observatory, UHE neutrinos, UHE photons
Published in RUNG: 24.03.2025; Views: 200; Downloads: 4
Full text (2,72 MB)
This document has many files! More... |
23. Large-scale cosmic-ray anisotropies measured by the Pierre Auger ObservatoryEsteban Roulet, Andrej Filipčič, Jon Paul Lundquist, Shima Ujjani Shivashankara, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, 2025, published scientific conference contribution Abstract: An update of the measurements of large-scale anisotropies in the arrival directions of ultra high-energy cosmic rays detected at the Pierre Auger Observatory is presented. The established dipolar anisotropy in right ascension has now reached a significance of 6.8σ when considering all energies above 8 EeV and 5.7 σ when only considering energies between 8 and 16 EeV. The 3D dipole amplitude and direction are reconstructed in four different energy bins above 4 EeV. At energies above 8 EeV it points more than 100∘ away from the Galactic centre, providing evidence that the anisotropy observed is of extragalactic origin. An analysis allowing for both dipolar and quadrupolar anisotropies finds qualitatively similar dipole components and no significant quadrupole components. The results for the angular power spectrum are shown, demonstrating that no other statistically significant multipoles are present. The equatorial dipole components are presented down to 0.03 EeV using a trigger which has been optimized for low energies. We find no significant departures from isotropic expectations below 8 EeV, although below 2 EeV the phases appear to be consistently aligned with the right ascension of the Galactic centre. Finally, model predictions based on source emission scenarios obtained in the combined fit of spectrum and composition data above 0.6 EeV are discussed and compared with observations.
Keywords: ultra-high-energy cosmic rays, Pierre Auger Observatory, large scale anisotropies
Published in RUNG: 24.03.2025; Views: 177; Downloads: 4
Full text (2,76 MB)
This document has many files! More... |
24. Astrophysical models to interpret the Pierre Auger Observatory dataJuan Manuel González, Andrej Filipčič, Jon Paul Lundquist, Shima Ujjani Shivashankara, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, 2025, published scientific conference contribution Abstract: The Pierre Auger Observatory has measured the spectrum of ultra-high-energy cosmic rays with unprecedented precision, as well as the distribution of the depths of the maximum of the shower development in the atmosphere, which provide a reliable estimator of the mass composition. The measurements above 10[sup]17.8 eV can be interpreted assuming two populations of uniformly distributed sources, one with a soft spectrum dominating the flux below few EeV, and another one with a very hard spectrum dominating above that energy. When considering the presence of intense extragalactic magnetic fields between our Galaxy and the closest sources and a high-energy population with low spatial density, a magnetic horizon appears, suppressing the cosmic ray's flux at low-energies, which could explain the very hard spectrum observed at Earth. The distribution of arrival directions, which at energies above 32 EeV shows indications of a correlation with a population of starburst galaxies or the radio galaxy Centaurus A (Cen A), are also important to constrain the sources. It is shown that adding a fractional contribution from these sources of about 20% on top of an homogeneous background leads to an improvement of the model likelihood.
Keywords: ultra-high-energy cosmic rays, UHECR energy spectrum, UHECR mass composition, UHECR anisotropies, UHECR propagation, UHECR data interpretation, extragalactic magnetic fields, starburst galaxies, Centaurus A, Pierre Auger Observatory
Published in RUNG: 24.03.2025; Views: 172; Downloads: 6
Full text (790,55 KB)
This document has many files! More... |
25. The flux of UHECRs along the supergalactic plane using Pierre Auger Observatory dataArmando Di Matteo, Andrej Filipčič, Jon Paul Lundquist, Shima Ujjani Shivashankara, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, 2025, published scientific conference contribution Abstract: We use the latest dataset from the surface detector array of the Pierre Auger Observatory, with events detected up to 31 December 2022 and a total exposure of 135,000 km² sr yr, to search for possible excesses in the flux of the most energetic cosmic rays on an intermediate angular scale (top-hat radius 27°, based on our previous results) from regions along the supergalactic plane. We find no indication for any such excesses other than the previously reported one in the Centaurus region, with a post-trial significance around 3σ, which we find extends down to lower energies than previously studied. In particular, the field of view of our dataset overlaps both regions in the northern celestial hemisphere from which excesses of events have been reported by the Telescope Array. With our integral exposures over these regions comparable to the Telescope Array ones, we find no indication of any flux excesses from there, with event counts in good agreement with the expectations from an isotropic distribution.
Keywords: ultra-high-energy cosmic rays, Pierre Auger Observatory, anisotropies, Centaurus region
Published in RUNG: 24.03.2025; Views: 199; Downloads: 5
Full text (5,88 MB)
This document has many files! More... |
26. Multi-messenger insights into ultra-high-energy cosmic rays from FR0 radio galaxies : emission spectrum, composition, and secondary photons and neutrinosJon Paul Lundquist, Serguei Vorobiov, Lukas Merten, Anita Reimer, Margot Boughelilba, Paolo Da Vela, Fabrizio Tavecchio, Giacomo Bonnoli, Chiara Righi, 2025, published scientific conference contribution Abstract: Despite their low individual luminosity, Fanaroff-Riley Type 0 (FR0) radio galaxies have emerged as potentially significant contributors to the observed flux of ultra-high-energy cosmic rays (UHECRs, E≥10 EeV) due to their substantial prevalence in the local universe. Outnumbering more powerful FR radio galaxies by approximately fivefold within redshifts of z≤0.05, FR0s may contribute a considerable fraction of the total UHECR energy density. The presented comprehensive study employs CRPropa3 simulations to estimate the mass composition and energy spectra of UHECRs emitted by FR0 galaxies. These simulations, which integrate extrapolated FR0 properties and various configurations of intergalactic magnetic fields (both random and structured), are compared to recent data from the Pierre Auger Observatory using three extensive air-shower models. By fitting the simulated spectral indices, rigidity cutoffs, and elemental fractions to Auger’s observed energy spectrum and ⟨lnA⟩ composition, we probe the contribution of FR0 sources to the UHECR flux. Furthermore, we predict the secondary photon and neutrino fluxes resulting from UHECR interactions with cosmic photon backgrounds and compare these results with current upper limits and theoretical models. This multi-messenger approach provides valuable insights into the role of low-luminosity FR0 radio galaxies within the UHECR landscape.
Keywords: ultra-high-energy cosmic rays, energy spectrum, mass composition, Fanaroff-Riley type 0
Published in RUNG: 24.03.2025; Views: 190; Downloads: 8
Full text (5,94 MB)
This document has many files! More... |
27. Theoretical and experimental studies of thermal parameters of annealed polybutyl methacrylate-siloxane protective coatings by means of nondestructive photothermal radiometry and photothermal beam deflection methodsŁukasz Chrobak, Mirosław Maliński, Dorota Korte, Sylwia Janta-Lipińska, 2025, original scientific article Keywords: nondestructive testing, photothermal radiometry, photothermal beam deflection spectroscopy, PBMA-siloxane thin coatings, thermal parameters
Published in RUNG: 21.03.2025; Views: 183; Downloads: 4
Full text (1,47 MB)
This document has many files! More... |
28. One of those things is not like the others: non-uniformity of theme vowel classes in Slovenian : lecture at the CRISSP TCC Seminar, CRISSP, KU Leuven, Brussels, Belgium,20. 3. 2025Petra Mišmaš, 2025, invited lecture at foreign university Keywords: Slovenian, derivational affix, theme vowel, secondary imperfectives, unaccusative
Published in RUNG: 21.03.2025; Views: 168; Downloads: 2
 Link to file
This document has many files! More... |
29. |
30. Transboundary particulate matter, photo-oxidants, acidifying and eutrophying components : status report 1/2024Hilde Fagerli, Anna Benedictow, Lewis Blake, Willem Van Caspel, Bruce Rolstad Denby, Michael Gauss, Jan Eiof Jonson, Heiko Klein, Gunnar Felix Lange, Griša Močnik, 2024, final research report Keywords: Convention on long-range transboundary air pollution, CLRTAP, EMEP, reports
Published in RUNG: 20.03.2025; Views: 230; Downloads: 1
Link to file
This document has many files! More... |
