151. Sensitivity of the Cherenkov Telescope Array to TeV photon emission from the Large Magellanic CloudA. Acharyya, R. Adam, Saptashwa Bhattacharyya, Samo Stanič, Veronika Vodeb, Serguei Vorobiov, Gabrijela Zaharijas, Danilo Zavrtanik, Marko Zavrtanik, Miha Živec, 2023, original scientific article Abstract: A deep survey of the Large Magellanic Cloud at ∼ 0.1−100 TeV photon energies with the Cherenkov Telescope Array is planned.
We assess the detection prospects based on a model for the emission of the galaxy, comprising the four known TeV emitters,
mock populations of sources, and interstellar emission on galactic scales. We also assess the detectability of 30 Doradus and SN 1987A, and the constraints that can be derived on the nature of dark matter. The survey will allow for fine spectral studies of N 157B, N 132D, LMC P3, and 30 Doradus C, and half a dozen other sources should be revealed, mainly pulsar-powered
objects. The remnant from SN 1987A could be detected if it produces cosmic-ray nuclei with a flat power-law spectrum at high energies, or with a steeper index 2.3−2.4 pending a flux increase by a factor > 3−4 over ∼ 2015−2035. Large-scale interstellar emission remains mostly out of reach of the survey if its > 10 GeV spectrum has a soft photon index ∼ 2.7, but degree-scale 0.1 − 10 TeV pion-decay emission could be detected if the cosmic-ray spectrum hardens above >100 GeV. The 30 Doradus star-forming region is detectable if acceleration efficiency is on the order of 1 − 10% of the mechanical luminosity and diffusion is suppressed by two orders of magnitude within < 100 pc. Finally, the survey could probe the canonical velocity-averaged cross section for self-annihilation of weakly interacting massive particles for cuspy Navarro-Frenk-White profiles.
Keywords: very-high energy (VHE) gamma-rays, Cherenkov Telescope Array Observatory, Large Magellanic Cloud, pulsar wind nebulas, galaxiesstar-forming regions, cosmic rays, dark matter
Published in RUNG: 02.06.2023; Views: 1017; Downloads: 1
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152. Time-of-flight photoconductivity investigation of high charge carrier mobility in ▫$Ti_3C_2T_x$▫ MXenes thin-filmJurij Urbančič, Erika Tomsic, Manisha Chhikara, Nadiia Pastukhova, Vadym Tkachuk, Alex Dixon, Andraž Mavrič, Payam Hashemi, Davood Sabaghi, Ali Shaygan Nia, Gvido Bratina, Egon Pavlica, 2023, original scientific article Abstract: Charge transport through a randomly oriented multilayered network of two-dimensional (2D) Ti3C2Tx (where Tx is the surface termination and corresponds to O, OH and F) was studied using time-of-flight photoconductivity (TOFP) method, which is highly sensitive to the distribution of charge carrier velocities. We prepared samples comprising Ti3C2Tx with thickness of 12 nm or 6-monolayers. MXene flakes of size up to 16 μm were randomly deposited on the surface by spin-coating from water solution. Using TOFP, we have measured electron mobility that reached values up to 279 cm2/Vs and increase with electric-field in a Poole-Frenkel manner. These values are approximately 50 times higher than previously reported field-effect mobility. Interestingly, our zero-electric-field extrapolate approaches electron mobility measured using terahertz absorption method, which represents intra-flake transport. Our data suggest that macroscopic charge transport is governed by two distinct mechanisms. The high mobility values are characteristic for the intra-flake charge transport via the manifold of delocalized states. On the other hand, the observed Poole-Frenkel dependence of charge carrier mobility on the electric field is typical for the disordered materials and suggest the existence of an important contribution of inter-flake hopping to the overall charge transport.
Keywords: charge transport, multilayered network, flakes, time-of-flight photoconductivity, MXene exfoliation, high-mobility solution-cast thin-film, semiconducting MXene
Published in RUNG: 31.03.2023; Views: 1141; Downloads: 4
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153. Limits to gauge coupling in the dark sector set by the nonobservation of instanton-induced decay of super-heavy dark matter in the Pierre Auger Observatory dataP. Abreu, Andrej Filipčič, Jon Paul Lundquist, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, Lukas Zehrer, 2023, original scientific article Keywords: ultra-high energy cosmic rays, UHE photon flux upper limits, super-heavy dark matter models, instantons, Pierre Auger Observatory
Published in RUNG: 09.02.2023; Views: 1026; Downloads: 0
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154. Cosmological implications of photon-flux upper limits at ultrahigh energies in scenarios of Planckian-interacting massive particles for dark matterP. Abreu, Andrej Filipčič, Jon Paul Lundquist, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, Lukas Zehrer, 2023, original scientific article Keywords: ultra-high energy, cosmic rays, Pierre Auger Observatory, UHE photon flux upper limits, super-heavy dark matter models
Published in RUNG: 09.02.2023; Views: 1115; Downloads: 0
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155. A catalog of the highest-energy cosmic rays recorded during Phase I of operation of the Pierre Auger ObservatoryA. Abdul Halim, Andrej Filipčič, Jon Paul Lundquist, Shima Ujjani Shivashankara, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, 2023, original scientific article Abstract: A catalog containing details of the highest-energy cosmic rays recorded through the detection of extensive air
showers at the Pierre Auger Observatory is presented with the aim of opening the data to detailed examination.
Descriptions of the 100 showers created by the highest-energy particles recorded between 2004 January 1 and 2020
December 31 are given for cosmic rays that have energies in the range 78–166 EeV. Details are also given on a
further nine very energetic events that have been used in the calibration procedure adopted to determine the energy
of each primary. A sky plot of the arrival directions of the most energetic particles is shown. No interpretations of
the data are offered.
Keywords: ultra-high-energy cosmic rays, cosmic ray air showers, experimental data, catalogs, Pierre Auger Observatory
Published in RUNG: 09.02.2023; Views: 1149; Downloads: 16
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156. Searches for Ultra-High-Energy Photons at the Pierre Auger ObservatoryP. Abreu, Andrej Filipčič, Jon Paul Lundquist, Shima Ujjani Shivashankara, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, Lukas Zehrer, 2022, review article Abstract: The Pierre Auger Observatory, being the largest air-shower experiment in the world, offers an unprecedented exposure to neutral particles at the highest energies. Since the start of data taking more than 18 years ago, various searches for ultra-high-energy (UHE, E > 10[sup]17 eV) photons have been performed: either for a diffuse flux of UHE photons, for point sources of UHE photons or for UHE photons associated with
transient events like gravitational wave events. In the present paper, we summarize these searches and review
the current results obtained using the wealth of data collected by the Pierre Auger Observatory.
Keywords: photons, ultra-high energies, air showers, Pierre Auger Observatory, upper limits, transients
Published in RUNG: 03.01.2023; Views: 1253; Downloads: 0
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157. Recent results from the Pierre Auger ObservatorySerguei Vorobiov, 2022, published scientific conference contribution abstract (invited lecture) Abstract: 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 sq.km per year above 10[sup]19 eV) UHECR events is obtained by the Pierre Auger Observatory, a large area (~3000 sq.km) 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.
Keywords: ultra-high-energy cosmic rays, Pierre Auger Observatory, UHECR mass composition, energy spectrum, anisotropies, AugerPrime upgrade
Published in RUNG: 23.12.2022; Views: 1333; Downloads: 7
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158. Investigation of the effective transmittance of Mach-Zehnder interferometer in the multi-longitudinal-mode high-spectral-resolution lidarFei Gao, Fengjia Gao, Xiao Yang, Gaipan Li, Li Wang, Meng Wang, Dengxin Hua, Griša Močnik, Samo Stanič, 2022, original scientific article Abstract: Effective transmittance is an important parameter of Mach-Zehnder interferometer in the retrieval of aerosol optical properties using the multi-longitudinal-mode high-spectral-resolution lidar, which is a function of the complex degree of coherence. In this paper, we retrieve the parameter of the complex degree of coherence for the multi-longitudinal-mode laser from the theoretical analysis, optical simulation and experimental measurements, which are 0.726, 0.678 and 0.453 using the Mach-Zehnder interferometer with the optimal optical path difference of two times of laser optical cavity length (∼1000 mm) and under the light illumination of the high power Nd:YAG laser with the mode number of 101 and mode interval of 300 MHz under the condition of laser linewidth of 1 cm−1 (30 GHz). The preliminary measurement results of aerosol optical properties using the constructing multi-longitudinal-mode high-spectral-resolution lidar show that the difference of the complex degree of coherence retrieved from the presented methods results in the relative error of 40% in the aerosol backscattering coefficient with thin cloud layer and 90% with the presence of dense aerosol layer.
Keywords: effective transmittance, Mach-Zehnder interferometer, Multi-logitudinal-mode laser, High-spectral-resolution lidar
Published in RUNG: 20.09.2022; Views: 1408; Downloads: 0
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160. 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, published scientific conference contribution Abstract: 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.
Keywords: high-energy cosmic phenomena, multi-messenger astrophysical studies, cosmic rays, gamma-rays, neutrinos, Pierre Auger Observatory
Published in RUNG: 06.05.2022; Views: 1462; Downloads: 0
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