261. Very high-energy gamma-ray signature of ultrahigh-energy cosmic-ray acceleration in Centaurus AJagdish Joshi, Marlui Miranda, Lili Yang, Soebur Razzaque, 2017, published scientific conference contribution abstract Abstract: The association of at least a dozen ultrahigh-energy cosmic-ray (UHECR) events with energy 54 EeV or higher detected by the Pierre Auger Observatory from the direction of Centaurus-A, the nearest radio galaxy, supports the scenario of UHECR acceleration in the jets of radio galaxies. Multiwavelength observations of Centaurus-A suggest that the inner jet is likely the site for particle acceleration, which emits in X-ray to very high-energy (VHE) gamma-ray. We model broadband spectral energy distribution with emission from shock-accelerated electrons and protons in a combined synchrotron-self-Compton and photo-hadronic scenario. The UHECR flux from Centaurus-A, required to explain Pierre Auger data, successfully explains observed VHE gamma rays as photo-hadronic emission. Keywords: Centaurus A, gamma ray, cosmic rays Published in RUNG: 17.01.2018; Views: 3293; Downloads: 0 This document has many files! More... |
262. Astroparticle studies at the Pierre Auger ObservatoryLili Yang, invited lecture at foreign university Abstract: The Pierre Auger Observatory (PAO), the world’s largest cosmic ray detector combines a large surface detector (SD) with an air fluorescence detector (FD). It is designed to observe extensive air showers (EAS) of billions of secondary particles induced by the UHECRs in the earths’ atmosphere. The “hybrid” design (i.e., detected simultaneously by SD and FD) provides wealth of information about shower development and excellent event reconstruction. Together with observations of UHECRs, the Surface Detector (SD) of the PAO is sensitive to UHE neutrinos through the observation of deeply initiated inclined down-going showers produced by neutrino interactions in the atmosphere, which method has been well established. On the other hand, high-energy photons can also be discriminated from background of charged cosmic rays based on their characters of the shower front. In this talk, I will give a review on recent results from PAO and introduce the ultra-high energy multi-messenger studies from PAO. Keywords: Pierre Auger Observatory, cosmic rays, ultra-high energy Published in RUNG: 17.01.2018; Views: 3822; Downloads: 0 This document has many files! More... |
263. Search for Physics beyond the Standard Model with the CRESST Experiment2017, master's thesis Abstract: In spite of the successes of observational astro- and particle physics and cosmology very much of the universe remains unknown. The Standard Model of particle physics is a theory describing the electromagnetic, weak, and strong nuclear interactions, as well as classifying all the subatomic particles known. But there is overwhelming evidence, that all the known particles, the ordinary (baryonic) matter, the building blocks of planets, stars and ourselves, only make up about 4.9% of the energy content of the universe. The standard model of cosmology (CDM) indicates that the total mass-energy of the universe contains beside the 4.9% ordinary matter two other components: 26.8% dark matter and 68.3% dark energy. The accelerating expansion of the Universe is the result of the effect of the dark energy with its most simple form given by a cosmological constant in Einstein's Equation. Dark matter is an unidentified type of matter that is not accounted for by dark energy and neutrinos and is generally believed to be a non-relativistic, charge neutral and non-baryonic new form of matter. Although dark matter has not been directly observed yet, its existence and properties are inferred from its gravitational effects such as the motions of visible matter, gravitational lensing, its influence on the universe's large-scale structure, and its effects in the cosmic microwave background. Thus the search for Dark Matter is the search for physics beyond the standard model. Although the nature of dark matter is yet unknown, its presence is crucial to understanding the future of the universe. The CRESST experiment is searching for direct evidence in the form of a nuclear recoil induced on a scintillating CaWO4 crystal by a dark matter particle, and is installed and taking data underground at Laboratory Nazionali del Gran Sasso (LNGS) in Italy. While both, dark energy and dark matter, have not been detected directly, a class of dark matter particles that interact only via gravity and the weak force, referred to asWeakly Interacting Massive Particles (WIMPs), has been established as the leading candidate among the dark matter community. For this thesis a special model of dark matter was studied, namely the dark photon. This thesis provides a detailed description of the calculation of the 90% upper limit on the dark photon kinetic mixing based on data from the second phase of the CRESST experiment. The analysis was carried out in a frequentist approach based on the (unbinned) maximum-likelihood method and likelihood ratios. To make a statement about the calculated result and its quality, the used algorithm had to be tested, what was done with Monte Carlo simulations (pseudo data). Keywords: astro physics, particle physics, cosmology, universe, Standard Model of particle physics, standard model of cosmology, matter, ordinary matter, dark matter, dark energy, accelerating expansion of the Universe, non-baryonic, new form of matter, gravitational lensing, cosmic microwave background, search for physics beyond the standard model, CRESST experiment, direct detection, CaWO4 crystal, underground laboratory, Laboratory Nazionali del Gran Sasso, Weakly Interacting Massive Particles, WIMP, dark photon, 90% upper limit, upper limit, kinetic mixing, frequentist approach, unbinned, maximum likelihood Published in RUNG: 13.10.2017; Views: 4632; Downloads: 0 This document has many files! More... |
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265. Results from the Pierre Auger ObservatoryIvan De Mitri, Andrej Filipčič, Samo Stanič, Darko Veberič, Danilo Zavrtanik, Marko Zavrtanik, 2015, published scientific conference contribution Keywords: Pierre Auger Observatory, Ultra High Energy Cosmic Rays (UHECR), UHECR energy spectrum, UHECR mass composition Published in RUNG: 27.06.2017; Views: 4222; Downloads: 0 This document has many files! More... |
266. Multi-resolution anisotropy studies of ultrahigh-energy cosmic rays detected at the Pierre Auger ObservatoryA. Aab, Andrej Filipčič, Gašper Kukec Mezek, Ahmed Saleh, Samo Stanič, Marta Trini, Darko Veberič, Serguei Vorobiov, Lili Yang, Danilo Zavrtanik, Marko Zavrtanik, 2017, original scientific article Keywords: Pierre Auger Observatory, ultra-high energy cosmic rays (UHECR), UHECR anisotropies, angular power spectrum, needlet wavelet analysis Published in RUNG: 23.06.2017; Views: 4201; Downloads: 0 This document has many files! More... |
267. Astroparticles at the High Energy Frontier: Results from the Pierre Auger ObservatoryGonzalo Parente, Andrej Filipčič, Ahmed Saleh, Samo Stanič, Darko Veberič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, 2014, published scientific conference contribution Keywords: Pierre Auger Observatory, ultra-high energy cosmic rays (UHECR), UHECR energy spectrum, mass composition, anisotropies Published in RUNG: 20.06.2017; Views: 4975; Downloads: 0 This document has many files! More... |
268. Auger HighlightsAntonella Castellina, Andrej Filipčič, Gašper Kukec Mezek, Ahmed Saleh, Samo Stanič, Marta Trini, Darko Veberič, Serguei Vorobiov, Lili Yang, Danilo Zavrtanik, Marko Zavrtanik, 2014, published scientific conference contribution Keywords: Pierre Auger Observatory, ultra high energy cosmic rays (UHECR), UHECR hybrid detection technique, UHECR energy spectrum, UHECR mass composition, UHECR arrival directions Published in RUNG: 20.06.2017; Views: 5237; Downloads: 395 Full text (861,47 KB) |
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270. Search for photons with energies above 10^18 eV using the hybrid detector of the Pierre Auger ObservatoryA. Aab, Andrej Filipčič, Gašper Kukec Mezek, Ahmed Saleh, Samo Stanič, Marta Trini, Darko Veberič, Serguei Vorobiov, Lili Yang, Danilo Zavrtanik, Marko Zavrtanik, 2017, original scientific article Keywords: ultra high energy (UHE) cosmic rays, cosmic ray experiments, Pierre Auger Observatory, UHE photon search Published in RUNG: 13.04.2017; Views: 4136; Downloads: 0 This document has many files! More... |