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1.
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: 1202; Downloads: 0
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2.
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: 2878; Downloads: 0
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3.
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: 2709; Downloads: 0
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4.
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: 2823; Downloads: 126
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5.
TA Anisotropy Summary
K. Kawata, Jon Paul Lundquist, 2019, published scientific conference contribution

Abstract: The Telescope Array (TA) is the largest ultra-high-energy cosmic-ray (UHECR) detector in the northern hemisphere. It consists of an array of 507 surface detectors (SD) covering a total 700 km^2 and three fluorescence detector stations overlooking the SD array. In this proceedings, we summarize recent results on the search for directional anisotropy of UHECRs using the latest dataset collected by the TA SD array. We obtained hints of the anisotropy of the UHECRs in the northern sky from the various analyses.
Keywords: cosmic radiation, UHE detector, fluorescence detector, surface, Telescope Array Experiment, anisotropy, experimental results
Published in RUNG: 28.04.2020; Views: 3340; Downloads: 79
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6.
Search for Anisotropy in the Ultra High Energy Cosmic Ray Spectrum using the Telescope Array Surface Detector
R.U. Abbasi, Jon Paul Lundquist, 2017, other component parts

Abstract: The Telescope Array (TA) experiment is located in the western desert of Utah, USA, and observes ultra high energy cosmic rays (UHECRs) in the Northern hemisphere. At the highest energies, E>10~EeV, the shape of cosmic ray energy spectrum may carry an imprint of the source density distribution along the line of sight different in different directions of the sky. In this study, we search for such directional variations in the shape of the energy spectrum using events observed with the Telescope Array's surface detector. We divide the TA field of view into two nearly equal-exposure regions: the "on-source" region which we define as ±30∘ of the supergalactic plane containing mostly nearby structures, and the complementary "off-source" region where the sources are further away on average. We compare the UHECR spectra in these regions by fitting them to the broken power law and comparing the resulting parameters. We find that the off-source spectrum has an earlier break at highest energies. The chance probability to obtain such or larger difference in statistically equivalent distributions is estimated as 6.2±1.1×10−4 (3.2σ) by a Monte-Carlo simulation. The observed difference in spectra is in a reasonable quantitative agreement with a simplified model that assumes that the UHECR sources trace the galaxy distribution from the 2MRS catalogue, primary particles are protons and the magnetic deflections can be neglected.
Keywords: cosmic radiation: UHE, detector: surface, cosmic radiation: spectrum, cosmic radiation: energy spectrum, deflection: magnetic, numerical calculations: Monte Carlo, anisotropy
Published in RUNG: 27.04.2020; Views: 3186; Downloads: 98
.pdf Full text (169,05 KB)

7.
Analysis and characterization of thermal systematic effects on the PLANCK LFI data
Tanja Petrushevska, 2010, master's thesis

Abstract: The cosmic microwave background radiation discovered by Penzias and Wilson in 1965, is considered one of the most important experimental evidences in favour of the Hot Big Bang standard cosmological model. This radiation provides an image of the Universe when it was about 380,000 years old and has a blackbody spectral distribution at temperature T=2.725±0.002 K, index of thermodynamic equilibrium with the mater in epoch when it was released. The cosmic background radiation presents anisotropies at level of 10 5 which provide valuable information about the origin and the evolution of the Universe. After the discovery of background radiation, tens of experiments have been performed to measure this radiation and its anisotropies. In 1992 the COBE satellite revolutionized cosmology by detecting temperature anisotropies for the first time. Launched on May 14, 2009, Planck is a European Space Agency mission designed to measure the CMB anisotropies with an accuracy set by fundamental astrophysical limits. To do this, Planck is imaging the whole sky with an unprecedented combination of sensitivity ( ΔT/T~2*10^-6), angular resolution (to 5’), and 9 frequency coverage (30 857 GHz). To reach these ambitious requirements, Planck uses an active cryogenic thermal system which cools the instruments to 0.1 K. The high sensitivity of the instrument and the cryogenic system makes the thermal systematic effects study of crucial importance to the scientific success. The thesis is divided into six chapters: 1. Chapter 1 explains the properties of the cosmic background radiation and its anisotropies; 2. Chapter 2 presents a short overview of the various experiments dedicated to the study of cosmic background radiation; 3. Chapter 3 describes the Planck mission, its instruments and its goals, in particular the Low Frequency Instrument (LFI) and its thermal structure; Chapter 4 discusses the analysis of the LFI thermal stability. This work was carried out in the Physics department at the University of Trieste, at the LFI Data Processing Centre located at INAF (Instituto Nazionale di AstroFisica) - OATS (Astronomical Observatory of Trieste); Chapter 5 presents the results of this analysis; in Chapter 6 conclusions are drawn and proposals for future work are discussed.
Keywords: Cosmic background radiation, CMB, Planck, satellite mission
Published in RUNG: 24.01.2018; Views: 3393; Downloads: 109
.pdf Full text (23,33 MB)

8.
FERMI-LAT OBSERVATIONS OF HIGH-ENERGY γ-RAY EMISSION TOWARD THE GALACTIC CENTER
Gabrijela Zaharijas, B. L. Winer, 2016, original scientific article

Abstract: The Fermi Large Area Telescope (LAT) has provided the most detailed view to date of the emission toward the Galactic center (GC) in high-energy γ-rays. This paper describes the analysis of data taken during the first 62 months of the mission in the energy range 1–100 GeV from a 15° × 15° region about the direction of the GC. Specialized interstellar emission models (IEMs) are constructed to enable the separation of the γ-ray emissions produced by cosmic ray particles interacting with the interstellar gas and radiation fields in the Milky Way into that from the inner ∼1 kpc surrounding the GC, and that from the rest of the Galaxy. A catalog of point sources for the 15° × 15° region is self-consistently constructed using these IEMs: the First Fermi-LAT Inner Galaxy Point Source Catalog (1FIG). The spatial locations, fluxes, and spectral properties of the 1FIG sources are presented, and compared with γ-ray point sources over the same region taken from existing catalogs. After subtracting the interstellar emission and point-source contributions a residual is found. If templates that peak toward the GC are used to model the positive residual the agreement with the data improves, but none of the additional templates tried account for all of its spatial structure. The spectrum of the positive residual modeled with these templates has a strong dependence on the choice of IEM.
Keywords: cosmic rays – Galaxy: center – gamma-rays: general – gamma-rays: ISM – radiation mechanisms: non-thermal
Published in RUNG: 02.03.2016; Views: 5507; Downloads: 293
.pdf Full text (6,36 MB)

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