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1.
An overview of the ASKOS campaign in Cabo Verde
Eleni Marinou, Peristera Paschou, Ioanna Tsikoudi, Alexandra Tsekeri, Vasiliki Daskalopoulou, Dimitra Kouklaki, Nikos Siomos, Vasileios Spanakis-Misirlis, Kalliopi Artemis Voudouri, Griša Močnik, Jesús Yus-Díez, 2023, published scientific conference contribution

Abstract: In the framework of the ESA-NASA Joint Aeolus Tropical Atlantic Campaign (JATAC), the ASKOS experiment was implemented during the summer and autumn of 2021 and 2022. ASKOS comprised roughly 9 weeks of measurements in the Saharan dust outflow towards the North Atlantic, with operations conducted from the Cabo Verde Islands. Through its unprecedented dataset of synergistic measurements in the region, ASKOS will allow for the calibration and validation of the aerosol/cloud product from Aeolus and the preparation of the terrain for EarthCARE cal/val activities. Moreover, ASKOS marks a turning point in our ability to study Saharan dust properties and the processes affecting its atmospheric transport, as well as the link to other components of the Earth’s system, such as the effect of dust particles on cloud formation over the Eastern Atlantic and the effect of large and giant particles on radiation. This is possible through the synergy of diverse observations acquired during the experiment, which include intense 24/7 ground-based aerosol, cloud, wind, and radiation remote sensing measurements, and UAV-based aerosol in situ measurements within the Saharan air layer, up to 5.3 km altitude, offering particle size-distributions up to 40 μm as well as sample collection for mineralogical analysis. We provide an outline of the novel measurements along with the main scientific objectives of ASKOS. The campaign data will be publicly available by September of 2023 through the EVDC portal (ESA Validation Data Center).
Keywords: experimental campaign, remote sensing, lidar, radar, radiosondes, radiation, desert dust
Published in RUNG: 25.09.2023; Views: 997; Downloads: 5
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MINOT: Modeling the intracluster medium (non-)thermal content and observable prediction tools
Rémi Adam, Hazal Gosku, A. Leingärtner-Goth, Steffano Ettori, R. Gnatyk, B. Hnatyk, Moritz Hütten, Judit Pérez Romero, Miguel Sánchez-Conde, Olga Sergijenko, original scientific article

Abstract: In the past decade, the observations of diffuse radio synchrotron emission toward galaxy clusters revealed cosmic-ray (CR) electrons and magnetic fields on megaparsec scales. However, their origin remains poorly understood to date, and several models have been discussed in the literature. CR protons are also expected to accumulate during the formation of clusters and probably contribute to the production of these high-energy electrons. In order to understand the physics of CRs in clusters, combining of observations at various wavelengths is particularly relevant. The exploitation of such data requires using a self-consistent approach including both the thermal and the nonthermal components, so that it is capable of predicting observables associated with the multiwavelength probes at play, in particular in the radio, millimeter, X-ray, and γ-ray bands. We develop and describe such a self-consistent modeling framework, called MINOT (modeling the intracluster medium (non-)thermal content and observable prediction tools) and make this tool available to the community. MINOT models the intracluster diffuse components of a cluster (thermal and nonthermal) as spherically symmetric. It therefore focuses on CRs associated with radio halos. The spectral properties of the cluster CRs are also modeled using various possible approaches. All the thermodynamic properties of a cluster can be computed self-consistently, and the particle physics interactions at play are processed using a framework based on the Naima software. The multiwavelength observables (spectra, profiles, flux, and images) are computed based on the relevant physical process, according to the cluster location (sky and redshift), and based on the sampling defined by the user. With a standard personal computer, the computing time for most cases is far shorter than one second and it can reach about one second for the most complex models. This makes MINOT suitable for instance for Monte Carlo analyses. We describe the implementation of MINOT and how to use it. We also discuss the different assumptions and approximations that are involved and provide various examples regarding the production of output products at different wavelengths. As an illustration, we model the clusters Abell 1795, Abell 2142, and Abell 2255 and compare the MINOT predictions to literature data. While MINOT was originally build to simulate and model data in the γ-ray band, it can be used to model the cluster thermal and nonthermal physical processes for a wide variety of datasets in the radio, millimeter, X-ray, and γ-ray bands, as well as the neutrino emission.
Keywords: galaxy clusters, intracluster medium, cosmic rays, radiation mechanisms, numerical methods
Published in RUNG: 27.01.2023; Views: 1076; Downloads: 0
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Monitoring of chemical processes at the atomic level by X-ray absorption spectrometry using extremely bright synchrotron radiation sources
Iztok Arčon, unpublished invited conference lecture

Abstract: X-ray absorption spectroscopy (XAS) is a powerful tool for characterisation of local structure and chemical state of selected elements in different new functional materials and biological or environmental samples. The XAS spectroscopy is based on extremely bright synchrotron radiation X-rays sources, which allow precise characterisation of bulk, nanostructured or highly diluted samples. The rapid development of extremely bright synchrotron sources of X-ray and ultraviolet light in recent years has opened new possibilities for research of matter at the atomic or molecular level, indispensable in the development of new functional nanostructured materials with desired properties. The lecture will present the possibilities offered by X-ray absorption spectroscopy with synchrotron light for ex-situ and in-situ or operando characterization of various functional porous and other nanomaterials before, after and during their operation. With the operando micro-XANES and EXAFS methods it is possible to track changes in the valence states and local structures of selected elements in different energy storage materials or in various (photo)catalysts, during chemical reactions under controlled reaction conditions, thus gaining insight into the dynamic functional properties and reaction mechanisms of these materials. New synchrotron light sources also opened the possibility of combining X-ray absorption or emission spectroscopy and microscopy with a resolution of up to a few tens of nanometres, crucial for analysis of environmental and biological samples on sub-cellular level, to understand the mechanisms of uptake, transport, accumulation, and complexation of metal cations on subcellular level in various plant tissues or accumulation in environment, to develop effective remediation approaches.
Keywords: X-ray absorption spectroscopy, EXAFS, XANES, synchrotron radiation sources, operando
Published in RUNG: 15.12.2021; Views: 2002; Downloads: 0
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6.
Scrutinizing FR 0 radio galaxies as ultra-high-energy cosmic ray source candidates
Lukas Merten, Margot Boughelilba, Anita Reimer, Paolo Da Vela, Serguei Vorobiov, Fabrizio Tavecchio, Giacomo Bonnoli, Jon Paul Lundquist, Chiara Righi, 2021, original scientific article

Abstract: Fanaroff-Riley (FR) 0 radio galaxies compose a new class of radio galaxies, which are usually weaker but much more numerous than the well-established class of FR 1 and FR 2 galaxies. The latter classes have been proposed as sources of the ultra-high-energy cosmic rays (UHECRs) with energies reaching up to eV. Based on this conjecture, the possibility of UHECR acceleration and survival in an FR 0 source environment is examined in this work. In doing so, an average spectral energy distribution (SED) based on data from the FR 0 catalog (FR0CAT) is compiled. The resulting photon fields are used as targets for UHECRs, which suffer from electromagnetic pair production, photo-disintegration, photo-meson production losses, and synchrotron radiation. Multiple mechanisms are discussed to assess the UHECR acceleration probability, including Fermi-I order and gradual shear accelerations, and particle escape from the source region. This work shows that in a hybrid scenario, combining Fermi and shear accelerations, FR 0 galaxies can contribute to the observed UHECR flux, as long as where shear acceleration starts to dominate over escape. Even in less optimistic scenarios, FR 0s can be expected to contribute to the cosmic-ray flux between the knee and the ankle. Our results are relatively robust with respect to the realized magnetic turbulence model and the speed of the accelerating shocks.
Keywords: acceleration of particles, nonthermal radiation mechanisms, jets, active galaxies, cosmic rays
Published in RUNG: 05.02.2021; Views: 2725; Downloads: 0
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7.
Search for large-scale anisotropy on arrival directions of ultra-high-energy cosmic rays observed with the telescope array experiment
R. U. Abbasi, Mitsuhiro Abe, T. Abu-Zayyad, M. Allen, R. Azuma, E. Barcikowski, J. W. Belz, Douglas R. Bergman, S. A. Blake, Jon Paul Lundquist, 2020, original scientific article

Abstract: Motivated by the detection of a significant dipole structure in the arrival directions of ultra-high-energy cosmic rays above 8 EeV reported by the Pierre Auger Observatory (Auger), we search for a large-scale anisotropy using data collected with the surface detector array of the Telescope Array Experiment (TA). With 11 yr of TA data, a dipole structure in a projection of the R.A. is fitted with an amplitude of 3.3% ± 1.9% and a phase of 131° ± 33°. The corresponding 99% confidence-level upper limit on the amplitude is 7.3%. At the current level of statistics, the fitted result is compatible with both an isotropic distribution and the dipole structure reported by Auger.
Keywords: cosmic rays, ultra-high-energy cosmic radiation, cosmic ray sources, cosmic ray showers, cosmic ray detectors, cosmic ray astronomy, extragalactic astronomy
Published in RUNG: 05.02.2021; Views: 2539; Downloads: 0
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8.
Evidence for a supergalactic structure of magnetic deflection multiplets of ultra-high-energy cosmic rays
R. U. Abbasi, Mitsuhiro Abe, T. Abu-Zayyad, M. Allen, R. Azuma, E. Barcikowski, J. W. Belz, Douglas R. Bergman, S. A. Blake, Jon Paul Lundquist, 2020, original scientific article

Abstract: Evidence for a large-scale supergalactic cosmic-ray multiplet (arrival directions correlated with energy) structure is reported for ultra-high-energy cosmic-ray (UHECR) energies above 1019 eV using 7 years of data from the Telescope Array (TA) surface detector and updated to 10 years. Previous energy–position correlation studies have made assumptions regarding magnetic field shapes and strength, and UHECR composition. Here the assumption tested is that, because the supergalactic plane is a fit to the average matter density of the local large-scale structure, UHECR sources and intervening extragalactic magnetic fields are correlated with this plane. This supergalactic deflection hypothesis is tested by the entire field-of-view (FOV) behavior of the strength of intermediate-scale energy–angle correlations. These multiplets are measured in spherical cap section bins (wedges) of the FOV to account for coherent and random magnetic fields. The structure found is consistent with supergalactic deflection, the previously published energy spectrum anisotropy results of the TA (the Hotspot and Coldspot), and toy-model simulations of a supergalactic magnetic sheet. The seven year data posttrial significance of this supergalactic structure of multiplets appearing by chance, on an isotropic sky, is found by Monte Carlo simulation to be 4.2σ. The 10 years of data posttrial significance is 4.1σ. Furthermore, the starburst galaxy M82 is shown to be a possible source of the TA Hotspot, and an estimate of the supergalactic magnetic field using UHECR measurements is presented.
Keywords: extragalactic magnetic fields, ultra-high-energy cosmic radiation, cosmic rays, high energy astrophysics, astrophysical magnetism, cosmic ray astronomy, cosmic ray sources
Published in RUNG: 05.02.2021; Views: 2657; Downloads: 126
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The bursts of high energy events observed by the telescope array surface detector
R.U. Abbasi, Jon Paul Lundquist, 2017, original scientific article

Abstract: The Telescope Array (TA) experiment is designed to detect air showers induced by ultra high energy cosmic rays. The TA ground Surface particle Detector (TASD) observed several short-time bursts of air shower like events. These bursts are not likely due to chance coincidence between single shower events. The expectation of chance coincidence is less than 10^-4 for five-year's observation. We checked the correlation between these bursts of events and lightning data, and found evidence for correlations in timing and position. Some features of the burst events are similar to those of a normal cosmic ray air shower, and some are not. On this paper, we report the observed bursts of air shower like events and their correlation with lightning.
Keywords: High energy radiation, Lightning, Terrestrial gamma-ray flash
Published in RUNG: 30.04.2020; Views: 2739; Downloads: 0
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