1. Multi-messenger astrophysics with the Pierre Auger ObservatoryMassimo Mastrodicasa, Andrej Filipčič, Jon Paul Lundquist, Shima Ujjani Shivashankara, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, Lukas Zehrer, 2022, objavljeni znanstveni prispevek na konferenci Opis: The Pierre Auger Observatory is sensitive to ultra-high energy neutral particles, such as photons, neutrinos, and neutrons, and can take part in Multi-Messenger searches in collaboration with other observatories. Photons and neutrinos are searched by exploiting the design of the Pierre Auger Observatory and profiting from the different properties of the induced showers caused by different particles. Diffuse and point source fluxes of photons and neutrinos are searched for. Furthermore, photon and neutrino follow-ups of the gravitational wave events observed by the LIGO/Virgo Collaboration are conducted. The Pierre Auger Observatory is also used to search for neutrons from point-like sources. In contrast to photons and neutrinos, neutrons induce air showers that cannot be distinguished from those produced by protons. For this reason, the search for neutrons from a given source is performed by searching for an excess of air showers from the corresponding direction. All these searches have resulted in stringent upper limits on the corresponding fluxes of the considered particles, allowing, together with the results obtained by other experiments, to shed some light on the most energetic phenomena of our Universe. An overview of the Multi-Messenger activities carried out within the Pierre Auger Collaboration is presented.
Ključne besede: ultra-high-energy cosmic rays, UHE photons, UHE neutrinos, UHE neutrons, Pierre Auger Observatory, multi-messenger astrophysical studies
Objavljeno v RUNG: 04.10.2024; Ogledov: 135; Prenosov: 0
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2. Ultrahigh-Energy multi-messengers at the Pierre Auger ObservatoryFrancisco Pedreira, Andrej Filipčič, Gašper Kukec Mezec, Ahmed Saleh, Samo Stanič, Marta Trini, Serguei Vorobiov, Lili Yang, Danilo Zavrtanik, Marko Zavrtanik, Lukas Zehrer, 2019, objavljeni znanstveni prispevek na konferenci Opis: The study of correlations between observations of different messengers from extreme sources of the Universe has emerged as an outstanding way to make progress in astrophysics. The Pierre Auger Observatory is capable of significant contributions as an ultra-high energy particle detector, particularly through its capability to search for inclined showers produced by neutrinos. We describe the neutrino searches made with
the Observatory with particular emphasis on the recent results following the detections of
gravitational waves from binary mergers with Advanced LIGO and VIRGO, leading to competitive limits.
Ključne besede: ultra-high-energy (UHE) cosmic rays (CRs), Pierre Auger Observatory, UHE neutrinos, multi-messenger astrophysics
Objavljeno v RUNG: 11.10.2023; Ogledov: 1958; Prenosov: 7
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3. TA SD analysis for inclined air showersK. Takahashi, Jon Paul Lundquist, 2023, objavljeni znanstveni prispevek na konferenci Opis: The origin of UHECRs is an open question which is complicated due to not very well-known deflections of the charged particles in Galactic and intergalactic magnetic fields. Finding the EeV neutrinos from astronomical sources will be a key to solve the problem of the origin. EeV neutrinos are expected to produce extensive air showers which are observable by the current operational air shower arrays. To search for neutrino-induced showers, it is important to increase both the interaction probability and background rejection power in the analysis of the inclined showers. We study a reconstruction method of the Telescope Array surface detector (TA SD) data for the neutrino-induced inclined air showers. The prime target is to improve the angular resolution for the astronomical objects. In this contribution, we present the detail of analysis method, angular resolution and total exposure of TA SD for neutrinos from the astronomical objects as a function of the declination.
Ključne besede: Telescope Array, indirect detection, surface detection, ground array, ultra-high energy, cosmic rays, inclined showers, neutrinos
Objavljeno v RUNG: 09.10.2023; Ogledov: 1654; Prenosov: 6
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4. Telescope Array Combined Fit to Cosmic Ray Spectrum and CompositionD. Bergman, Jon Paul Lundquist, 2022, objavljeni znanstveni prispevek na konferenci Opis: We present the result of fits of an astrophysical model of UHECR sources to the energy spectrum measured using the Telescope Array (TA) surface detectors and the composition data measured by TA fluorescence detectors in stereo mode. The astrophysical model consists of identical sources, uniformly distributed with a density which evolves with age, where groups of nuclei with varying fractions are accelerated producing a power law source with a rigidity-dependent cutoff. The model includes the propagation effects of photo-pion production, photo-nuclear disintegration and general energy loss from universal expansion. Comparison of model data with detector data in both the energy and the Xmax distributions is done via a forward-folding description of detector effects. A prediction of the cosmogenic neutrino flux at Earth resulting from the cosmic rays produced in the model with these fit values is also presented. The predicted flux is considerably higher than other similar fits to Auger data have previously predicted.
Ključne besede: Telescope Array, indirect detection, stereo detection, fluorescence detection, ultra-high energy, cosmic rays, energy spectrum, composition, combined fit, cosmogenic neutrinos, multimessenger
Objavljeno v RUNG: 02.10.2023; Ogledov: 1475; Prenosov: 6
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5. Science with the Global Cosmic-ray Observatory (GCOS)Rafael Alves Batista, M. Ahlers, Pedro Assis, Markus Gottfried Battisti, J. A. Bellido, S. Bhatnagar, K. Bismark, Teresa Bister, Martina Boháčová, Serguei Vorobiov, 2023, objavljeni znanstveni prispevek na konferenci Opis: The Global Cosmic-ray Observatory (GCOS) is a proposed large-scale observatory for studying
ultra-high-energy cosmic particles, including ultra-high-energy cosmic rays (UHECRs), photons,
and neutrinos. Its primary goal is to characterise the properties of the highest-energy particles in
Nature with unprecedented accuracy, and to identify their elusive sources. With an aperture at least a ten-fold larger than existing observatories, this next-generation facility should start operating after 2030, when present-day detectors will gradually cease their activities. Here we briefly review the scientific case motivating GCOS. We present the status of the project, preliminary ideas for its design, and some estimates of its capabilities.
Ključne besede: ultra-high-energy cosmic rays, UHE photons, UHE neutrinos, the Global Cosmic-ray Observatory project
Objavljeno v RUNG: 27.09.2023; Ogledov: 1841; Prenosov: 6
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6. Sensitivity of the Cherenkov Telescope Array to the gamma-ray emission from neutrino sources detected by IceCubeOlga Sergijenko, Saptashwa Bhattacharyya, Judit Pérez Romero, Samo Stanič, Veronika Vodeb, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, Miha Živec, 2023, objavljeni znanstveni prispevek na konferenci Opis: Gamma-ray observations of the astrophysical neutrino sources are fundamentally important for understanding the underlying neutrino production mechanism. We investigate the Cherenkov Telescope Array (CTA) ability to detect the very-high-energy (VHE) gamma-ray counterparts to the neutrino-emitting Active Galaxies. The CTA performance under different configurations and array layouts is computed based on the neutrino and gamma-ray simulations of steady and transient types of sources, assuming that the neutrino events are detected with the IceCube neutrino telescope. The CTA detection probability is calculated for both CTA sites taking into account the visibility constraints. We find that, under optimal observing conditions, CTA could observe the VHE gamma-ray emission from at least 3 neutrino events per year.
Ključne besede: Cherenkov Telescope Array, IceCube neutrino telescope, neutrinos, neutrino sources
Objavljeno v RUNG: 26.09.2023; Ogledov: 1768; Prenosov: 8
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7. Sensitivity of the Cherenkov Telescope Array to emission from the gamma-ray counterparts of neutrino eventsOlga Sergijenko, Saptashwa Bhattacharyya, Barbara MARČUN, Judit Pérez Romero, Samo Stanič, Veronika Vodeb, Serguei Vorobiov, Gabrijela Zaharijas, Marko Zavrtanik, Danilo Zavrtanik, Miha Živec, 2021, objavljeni znanstveni prispevek na konferenci Opis: We investigate the possibility of detection of the VHE gamma-ray counterparts to the neutrino astrophysical sources within the Neutrino Target of Opportunity (NToO) program of CTA using the populations simulated by the FIRESONG software to resemble the di˙use astrophysical neutrino flux measured by IceCube. We derive the detection probability for di˙erent zenith angles and geomagnetic field configurations. The di˙erence in detectability of sources between CTA-North and CTA-South for the average geomagnetic field is not substantial. We investigate the e˙ect of a higher night-sky background and the preliminary CTA Alpha layout on the detection probability.
Ključne besede: Cherenkov Telescope Array, VHE gamma-rays, neutrinos, Ice Cube, FIRESONG
Objavljeno v RUNG: 19.09.2023; Ogledov: 1316; Prenosov: 9
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8. Multi-messenger studies with the Pierre Auger ObservatoryLukas Zehrer, Andrej Filipčič, Gašper Kukec Mezek, Jon Paul Lundquist, Samo Stanič, Marta Trini, Serguei Vorobiov, Marko Zavrtanik, Danilo Zavrtanik, 2021, objavljeni znanstveni prispevek na konferenci Opis: Over the past decade the multi-messenger astrophysics has emerged as a distinct discipline,
providing unique insights into the properties of high-energy phenomena in the Universe. The
Pierre Auger Observatory, located in Malargüe, Argentina, is the world’s largest cosmic ray
detector sensitive to photons, neutrinos, and hadrons at ultra-high energies. Using its data, stringent
limits on photon and neutrino fluxes at EeV energies have been obtained. The collaboration uses
the excellent angular resolution and the neutrino identification capabilities of the Observatory
for follow-up studies of events detected in gravitational waves or other messengers, through
cooperation with global multi-messenger networks. We present a science motivation together
with an overview of the multi-messenger capabilities and results of the Pierre Auger Observatory.
Ključne besede: high-energy cosmic phenomena, multi-messenger astrophysical studies, cosmic rays, gamma-rays, neutrinos, Pierre Auger Observatory
Objavljeno v RUNG: 06.05.2022; Ogledov: 2125; Prenosov: 0
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9. Experimental bounds on sterile-active neutrino mixing anglesMihael Petač, 2015, magistrsko delo Opis: Despite the success of the Standard Model in the last few decades, we know it is not complete. There is strong motivation for assuming the existence of additional heavy neutral leptons, which can account for active neutrino masses and possibly also have cosmological implications. In this work I consider the Standard Model with two neutral lepton singlets (sterile neutrinos) with degenerated masses in the range 20MeV - 2GeV. The constraints on the active-sterile neutrino mixing angles are evaluated based on recent neutrino oscillations data. Using these constraints the bounds from accelerator experiments are reanalyzed for the case of the considered model. Finally, the results are compared with cosmological constraints coming from Big Bang nucleosynthesis and the nMSM resonant leptogenesis.
Ključne besede: Sterile neutrinos, Neutrino mixing, See-saw, High-Energy Physics - Phenomenology, High-Energy Physics - Experiments
Objavljeno v RUNG: 01.10.2021; Ogledov: 2432; Prenosov: 52
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10. Extrapolating FR-0 radio galaxy source properties from propagation of multi-messenger ultra-high energy cosmic raysJon Paul Lundquist, Lukas Merten, Serguei Vorobiov, Margot Boughelilba, Anita Reimer, Paolo Da Vela, Fabrizio Tavecchio, Giacomo Bonnoli, Chiara Righi, 2021, objavljeni znanstveni prispevek na konferenci Opis: Recently, it has been shown that relatively low luminosity Fanaroff-Riley type 0 (FR-0) radio galaxies are a good candidate source class for a predominant fraction of cosmic rays (CR) accelerated to ultra-high energies (UHE, E>10[sup]18 eV). FR-0s can potentially provide a significant fraction
of the UHECR energy density as they are much more numerous in the local universe than more energetic radio galaxies such as FR-1s or FR-2s (up to a factor of ∼5 with z≤0.05 compared to
FR-1s).
In the present work, UHECR mass composition and energy spectra at the FR-0 sources are estimated by fitting simulation results to the published Pierre Auger Observatory data. This fitting is done using a simulated isotropic sky distribution extrapolated from the measured FR-0 galaxy properties and propagating CRs in plausible extragalactic magnetic field configurations using the CRPropa3 framework. In addition, we present estimates of the fluxes of secondary photons and neutrinos created in UHECR interactions with cosmic photon backgrounds during
CR propagation. With this approach, we aim to investigate the properties of the sources with the help of observational multi-messenger data.
Ključne besede: jetted active galaxies, FR-0 radiogalaxies, ultra-high energy cosmic rays, extragalactic magnetic fields, UHECR propagation, UHECR interactions, cosmogenic photons, cosmogenic neutrinos
Objavljeno v RUNG: 16.08.2021; Ogledov: 2578; Prenosov: 5
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