Dissertations / Theses on the topic 'High energy astrophysics and galactic cosmic rays'
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Gabici, Stefano. "Gamma ray astronomy and the origin of galactic cosmic rays." Habilitation à diriger des recherches, Université Paris-Diderot - Paris VII, 2011. http://tel.archives-ouvertes.fr/tel-00719791.
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Diffusive shock acceleration operating at expanding supernova remnant shells is by far the most popular model for the origin of galactic cosmic rays. Despite the general consensus received by the model, an unambiguous and conclusive proof of the supernova remnant hypothesis is still missing. In this context, the recent developments in gamma ray astronomy provide us with precious insights into the problem of the origin of galactic cosmic rays, since production of gamma rays is expected both during the acceleration of cosmic rays at supernova remnant shocks and during their subsequent propagation in the interstellar medium. In particular, the recent detection of a number of supernova remnants at TeV energies nicely fits with the model, but it still does not constitute a conclusive proof of it, mainly due to the difficulty of disentangling the hadronic and leptonic contributions to the observed gamma ray emission. The main goal of my research is to search for an unambiguous and conclusive observational test for proving (or disproving) the idea that supernova remnants are the sources of galactic cosmic rays with energies up to (at least) the cosmic ray knee. Our present comprehension of the mechanisms of particle acceleration at shocks and of the propagation of cosmic rays in turbulent magnetic fields encourages beliefs that such a conclusive test might come from future observations of supernova remnants and of the Galaxy in the almost unexplored domain of multi-TeV gamma rays.
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Szabo, Anthony Paul. "High energy emissions for astrophysical objects." Title page, contents and abstract only, 1992. http://web4.library.adelaide.edu.au/theses/09PH/09phs996.pdf.
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Brandt, Theresa J. "On High Energy Cosmic Rays from the CREAM Instrument." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1259540765.
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Sutherland, Michael. "A Method for Establishing Constraints on Galactic Magnetic Field Models Using Ultra High Energy Cosmic Rays and Results from the Data of the Pierre Auger Observatory." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1274798328.
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Grégoire, Timothée. "Search for high energy neutrinos from the Galactic plane with the ANTARES neutrino telescope." Thesis, Sorbonne Paris Cité, 2018. http://www.theses.fr/2018USPCC129/document.
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Deux analyses sont présentées dans cette thèse. Une première analyse exploite les données du télescope à neutrino ANTARES pour sonder la présence d'un flux de neutrino diffus galactique. Cette analyse se base sur un modèle récent de propagation des rayons cosmiques dans la galaxie, le modèle KRAγ. Ce modèle prédit un flux de neutrinos particulièrement élevé et proche de la sensibilité des télescopes à neutrinos actuels. Il existe deux versions de ce modèle correspondant à différentes coupures sur l'énergie des rayons cosmiques, à 5 et 50 PeV/nucléon. Une méthode de maximisation d'une fonction de vraisemblance est utilisée pour prendre en compte les caractéristiques du modèle, autant spatiales qu'en énergie. Cette analyse a également été combinée avec les données de l'expérience IceCube dans le but d'exploiter au mieux les données actuelles. Des limites ont été mises sur ce modèle rejetant la version avec une coupure à 50 PeV et limitant la version avec une coupure à 5 PeV à moins de 1,2 fois le flux prédit par le modèle. Une deuxième analyse de suivi du signal d'ondes gravitationnelles GW170817 par le télescope à neutrino ANTARES est également présentée. Le signal d'onde gravitationnelles GW170817 résulte de la coalescence d'une binaire d'étoiles à neutrons. Cette deuxième analyse a pour objectif de sonder la présence d'un flux de neutrinos provenant de cet événement en cherchant des neutrinos corrélés spatialement et temporellement. J'ai pris part à cette analyse en y ajoutant les événement de type cascade. Aucun événement n'a été détecté en corrélation, des limites ont été mises sur le flux de neutrino attenduTwo analyses are detailed in this thesis. A first analysis exploit the data of the ANTARES neutrino telescope to probe the presence of a Galactic diffuse neutrino flux. This analysis is based on a recent model of cosmic ray propagation in the Galaxy, the KRAγ model. This model predict a neutrino flux particularly high and close to the sensitivity of the current neutrino telescopes. Two versions of this model exist corresponding to different cuts in the cosmic ray energy, one at 5 PeV/nucleon and an other one at 50 PeV/nucleon. A method of maximization of a likelihood function is used in order to account for the model characteristics in energy and space. The analysis has also been combined with the data of the IceCube experiment in order to exploit all the available data. Limits have been put on this model rejecting the version of the model with the 50 PeV cut and limiting the version with the 5 PeV cut to less than 1.2 times the predicted flux.A second analysis of gravitational wave signal follow-up by the ANTARES neutrino telescope is also presented in this work. The GW170817 gravitational wave signal results from the coalescence of a binary neutron star system. This second analysis aims at probing the presence of a neutrino flux coming from this event looking for neutrino events correlated in space and time. I took part to this analysis by adding the shower-like event sample. No event has been detected in correlation, limits have been put on the expected neutrino flux
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Taylor, Andrew Martin. "The propagation of ultra high energy cosmic rays." Thesis, University of Oxford, 2007. http://ora.ox.ac.uk/objects/uuid:63572ebe-fb32-41b6-8b91-a7294db135a6.
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This thesis presents theoretical work on the propagation of ultra high energy cosmic rays, from their source to Earth. The different energy loss processes, resulting from cosmic ray interactions with the radiation fields, are addressed. The subsequent uncertainties in the energy loss rates and the effect produced on the arriving cosmic ray spectrum are highlighted. The question of the composition of ultra high energy cosmic rays remains unresolved, with the range of possibilities leading to quite different results in both the secondary fluxes of particles produced through cosmic ray energy loss interactions en route, and the arriving cosmic ray spectra at Earth. A large range of nuclear species are considered in this work, spanning the range of physically motivated nuclear types ejected from the cosmic ray source. The treatment of cosmic ray propagation is usually handled through Monte Carlo simulations due to the stochastic nature of some of the particle physics processes relevant. In this work, an analytic treatment for cosmic ray nuclei propagation is developed. The development of this method providing a deeper understanding of the main components relevant to cosmic ray nuclei propagation, and through its application, a clear insight into the contributing particle physics aspects of the Monte Carlo simulation. A flux of secondary neutrinos, produced as a consequence of cosmic ray energy loss through pion production during propagation, is also expected to be observed at Earth. This spectrum, however, is dependent on several loosely constrained factors such as the radiation field in the infrared region and cosmic ray composition. The range of possible neutrino fluxes obtainable with such uncertainties are discussed in this work. High energy cosmic ray interactions with the radiation fields present within the source may also occur, leading to cosmic ray energy loss before the cosmic ray has even managed to escape. The secondary spectra produced are investigated through the consideration of three candidate sources. A relationship between the degree of photo-disintegration in the source region and the neutrino flux produced through p γ interactions is found.
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Chadwick, Mary Paula. "Very high energy cosmic gamma rays from radio and X-ray pulsars." Thesis, Durham University, 1987. http://etheses.dur.ac.uk/6720/.
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This thesis is concerned with the detection of very high energy cosmic gamma-rays from isolated pulsars and X-ray binary sources using the atmospheric Cerenkov technique. A general introduction to gamma ray detection techniques is followed by adscription of the properties of atmospheric Cerenkov radiation and a discussion of the principles of the atmospheric Cerenkov technique. The Mark I and Mark II gamma-ray telescopes operated in Dugway, Utah by the University of Durham between 1981 and 1984 are briefly described. There follows a discussion of the results from observations at many different wavelengths of Cygnus X-3. This object was observed by the Durham group between 1981 and 1983 in Dugway Utah and also in Durham during autumn 1985. The detection in the Dugway data of the 4.8 hr X-ray period and the possible detection of a19.2 day intensity variation are considered. The discovery of a 12.59 ms pulsar in data taken on Cygnus X-3 in 1983 is described. Evidence is presented which suggests this periodicity is also present at a weaker level in earlier data and also in the data taken in Durham in 1985.Results from observations of PSR1937+21 , PSR1953+29and six radio pulsars , are presented. The design and construction of the Mark III telescope, now operating in Narrabri , N.S.W. , is described in detail. Preliminary results from observations with the Mark III telescope of three objects, LMC X-4, the Vela pulsar and CentaurusX-3, are presented, with particular reference to periodicities inherent in the sources. An observation of the supernova in the Large Magellanic Cloud is discussed. A brief discussion of the mechanisms by which V.H.E. gamma-rays may be produced in isolated pulsars and X-ray binary pulsars is given, followed by a description of the future prospects for the Mark III and Mark IV telescopes.
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Lee, Anthony A. "Application of Monte Carlo methods to some problems in high energy astrophysics /." Title page, contents and abstract only, 1993. http://web4.library.adelaide.edu.au/theses/09PH/09phl4768.pdf.
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MacRae, John Hamish Kenneth. "The detection of very high energy cosmic gamma rays using the atmospheric Cerenkov technique." Thesis, Durham University, 1985. http://etheses.dur.ac.uk/7854/.
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This thesis is concerned with the detection of very high energy cosmic gamma rays using the atmospheric Cerenkov technique. A general introduction to gamma ray detection techniques is followed by a detailed discussion of the principles of the atmospheric Cerenkov technique and the history of its use prior to this work. The design and operation of the University of Durham facility in Dugway, Utah is described in depth. Monte Carlo computer simulations have been developed to assist in both the understanding of the equipment and the analysis of the results for the Durham facility. The variation of the response of the array with zenith angle and detector threshold has been investigated and the aperture function of a single telescope calculated. The latter has been found to be a complicated function of both zenith angle and detector threshold. Computer simulations have also been developed to aid in the design of a camera to record two-dimensional Cerenkov light images from small extensive air showers, and to provide a means of testing analysis routines; these are discussed. The camera is located at the F.L. Whipple Observatory in Arizona. The techniques employed in the analysis of data recorded by the Dugway facility are discussed, and a computer package developed to aid in the routine aspects of the analysis is described. Results of observations from two sources, Cygnus X-3 and PSR0531, are presented, with particular reference to periodicities inherent in the sources and to bursts of gamma ray emission. The discussion of the results includes a review of the various models which have been proposed for Cygnus X-3.
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Morris, Chad Michael. "Detection Techniques of Radio Emission from Ultra High Energy Cosmic Rays." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1254506832.
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Burton, Ross E. "Upper Limits on the Ultra-High Energy Cosmic Ray Flux from Unresolved Sources." Case Western Reserve University School of Graduate Studies / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=case1323452264.
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LaHurd, Danielle V. "Searching for Quark Gluon Plasma Signatures in Ultra High Energy Cosmic Rays." Case Western Reserve University School of Graduate Studies / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=case1479298851843212.
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Rodrigues, Xavier. "Blazars as Sources of Neutrinos and Ultra-high-energy Cosmic Rays." Doctoral thesis, Humboldt-Universität zu Berlin, 2019. http://dx.doi.org/10.18452/20610.
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Der Ursprung ultra-hochenergetischer kosmischer Strahlung (UHECRs) ist immer noch unbekannt. Neutrinoteleskope wie IceCube messen einen Fluss hochenergetischer astrophysikalischer Neutrinos, dessen erwarteter Ursprung Wechselwirkungen kosmischer Strahlung (CR) ist. Jedoch scheinen die Ankunftsrichtungen der beobachteten Neutrinos nicht signifikant mit den Koordinaten bekannter, hochenergetischer astrophysikalischer Quellen zu korrelieren. Wir tragen zum Verständnis dieses Problems durch die Untersuchung von Blazaren, eine Klasse aktiver Galaxienkerne, bei. Motiviert durch Hinweise, dass ein Teil der UHECRs schwerer als Protonen ist, modellieren wir die Wechselwirkungen einer Population beschleunigter Kerne mit den umgebenden Photonfelder in Blazaren. Wir folgern, dass in Blazaren niedriger Luminosität beschleunigte CRs nicht effizient wechselwirken. In hellen Blazaren sind photo-hadronische Wechselwirkungen effizient, was zu starker Neutrinoproduktion und zur Entwicklung einer nuklearen Kaskade führt. Wir berechnen die Neutrinoemission der gesamten Verteilung von Blazaren, und folgern, dass eine Population niedriger Luminosität, die derzeit nicht beobachtet, aber theoretisch erwartet wird, den gesamten IceCube-Fluss bei den höchsten Energien erklären kann. Weiterhin modellieren wir den Blazar TXS 0506+056, aus dessen Richtung ein Neutrino während einer Phase erhöhter elektromagnetischer Aktivität detektiert wurde. Wir testen die Hypothese, dass ein Signal von 13+/-5 Neutrinos, die in IceCube aus der selben Richtung im Jahr 2014-15 gemessen wurden, von der selben Quelle stammt. Unser Modell kann höchstens 5 Ereignisse erklären. Schließlich untersuchen wir das erste beobachte Ereignis verschmelzender Neutronensterne, GW170817, als CR-Beschleuniger. Wir modellieren die Quelle und zeigen, dass Radio- und Röntgenmessungen strikte Beschränkungen der magnetischen Feldstärke nach sich ziehen. Wir zeigen, dass diese Quelle in der Lage ist, CRs zu emittieren.The origin of ultra-high-energy cosmic rays (UHECRs) is still unclear. Neutrino telescopes like IceCube have observed a flux of high-energy cosmic neutrinos, expected to originate in cosmic ray (CR) interactions. However, their arrival directions do not statistically correlate with the positions of known high-energy astrophysical sources. In this thesis we explore blazars, a class of active galaxies, as potential UHECR accelerators. Motivated by evidence that a fraction of the UHECRs are heavier than protons, we model the interactions of CR nuclei with the photon fields present in blazars, in order to estimate the emitted neutrino and UHECR spectrum. We conclude that in dim blazars, accelerated CRs do not interact efficiently due to the low photon density, but instead escape the source unscathed. In bright blazars, photo-hadronic interactions are more efficient, leading to abundant production of neutrinos and lighter nuclei. We use this model to quantify the neutrino emission from the entire cosmological blazar population. We conclude that low-luminosity blazars currently unobserved but expected theoretically, can explain the entire IceCube flux at the highest energies. We then focus on blazar TXS 0506+056, from whose direction a neutrino was recently detected during an electromagnetic flaring state. We test the hypothesis that a signal of 13+/-5 neutrinos observed by IceCube from the same direction in 2014-15 may have originated in the same source. Given the constraints from multi-wavelength observations, this model can explain at most 5 neutrino events. Finally, we study the remnant of the first neutron star merger ever observed, object GW170817. We model the particle interactions in the source and show that multi-wavelength observations can provide a constraint on the magnetic field strength. We estimate that this source may be an efficient CR emitter, which shows the importance of future multi-messenger observations to better constrain this source type.
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Peron, Giada [Verfasser], and Felix [Akademischer Betreuer] Aharonian. "Probing the Spatial and Spectral Distribution of Galactic Cosmic Rays with High-Energy Gamma-Rays / Giada Peron ; Betreuer: Felix Aharonian." Heidelberg : Universitätsbibliothek Heidelberg, 2021. http://d-nb.info/1225938627/34.
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Pinzke, Anders. "Gamma-Ray Emission from Galaxy Clusters : DARK MATTER AND COSMIC-RAYS." Doctoral thesis, Stockholms universitet, Fysikum, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-42453.
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The quest for the first detection of a galaxy cluster in the high energy gamma-ray regime is ongoing, and even though clusters are observed in several other wave-bands, there is still no firm detection in gamma-rays. To complement the observational efforts we estimate the gamma-ray contributions from both annihilating dark matter and cosmic-ray (CR) proton as well as CR electron induced emission. Using high-resolution simulations of galaxy clusters, we find a universal concave shaped CR proton spectrum independent of the simulated galaxy cluster. Specifically, the gamma-ray spectra from decaying neutral pions, which are produced by CR protons, dominate the cluster emission. Furthermore, based on our derived flux and luminosity functions, we identify the galaxy clusters with the brightest galaxy clusters in gamma-rays. While this emission is challenging to detect using the Fermi satellite, major observations with Cherenkov telescopes in the near future may put important constraints on the CR physics in clusters. To extend these predictions, we use a dark matter model that fits the recent electron and positron data from Fermi, PAMELA, and H.E.S.S. with remarkable precision, and make predictions about the expected gamma-ray flux from nearby clusters. In order to remain consistent with the EGRET upper limit on the gamma-ray emission from Virgo, we constrain the minimum mass of substructures for cold dark matter halos. In addition, we find comparable levels of gamma-ray emission from CR interactions and dark matter annihilations without Sommerfeld enhancement.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Accepted.
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Griffith, Nathan E. "Microwave Detection of Cosmic Rays and Multi-Messenger Analysis of the Parameters of Ultra-High Energy Astrophysical Sources." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1429799044.
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Morejon, Leonel. "New Interaction Models of Ultra-high-energy Cosmic Rays from a Nuclear Physics Approach." Doctoral thesis, Humboldt-Universität zu Berlin, 2021. http://dx.doi.org/10.18452/22585.
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Der Ursprung der ultrahochenergetischen kosmischen Strahlung (UHECRs) benötigt Modelle der photonuklearen kosmischen Strahlungsinteraktionen. In dieser Arbeit stelle ich Modelle vor, die drei Aspekte der Modellierung der Hochenergie-Astronuklearphysik verbessern: die Photomesonenproduktion durch Kerne der kosmischen Strahlung, die schwerer als Protonen sind, die Gammastrahlenemission von instabilen Kernen, die durch den Photodisintegrationsprozess der kosmischen Strahlung erzeugt werden, und die Simulation der extragalaktischen Ausbreitung von Kernen, die schwerer als Eisen sind (sogenannte superschwere Isotope). Das Photomesonenmodell ist das erste in der Literatur, das über das einfache Prinzip der Nukleonen-Superposition hinausgeht. Es liefert eine detailliertere Beschreibung der inelastischen Wirkungsquerschnitte und des emittierten Spektrums von Sekundärteilchen, einschließlich Isotopen und Pionen, die zu Photonen und Neutrinos führen. Die Auswirkungen des Modells werden in Simulationen von Gammastrahlenausbrüchen und Gezeitenstörungsereignissen gezeigt, und es beeinflusst signifikant die hochenergetische Neutrinoemission, die chemische Zusammensetzung und das Spektrum der emittierten UHECRs. Das zweite Modell beschreibt die Photoproduktion aus den De-Exzitationen und Zerfällen instabiler Kerne, die aus dem Photozerfall der kosmischen Strahlung in Wechselwirkung mit astrophysikalischen Photonen resultieren sollen. Ihre Wirkung wird am Photoemissionsspektrum des Kerns von Centaurus A veranschaulicht und mit ähnlichen Arbeiten verglichen, mit denen es Unstimmigkeiten gibt. Schließlich wird der Photodesintegration von UHECR überschweren Kernen diskutiert. Eine Wechselwirkungstabelle wird unter Verwendung von Querschnitten aus TALYS konstruiert, und die Wechselwirkungsraten werden im Zusammenhang mit der extragalaktischen Ausbreitung berechnet. Überschwere Kerne breiten sich in bestimmten Energiebereichen weiter aus als leichtere Kerne.The origin of the ultra-high-energy cosmic rays (UHECRs) is still unknown. Photonuclear interactions of cosmic rays are key to understanding this problem in a multimessenger context. Nuclear physics insights are crucial in building accurate models to interpret the data that indicates UHECR can be heavier than protons. This thesis presents models that improve three aspects of high-energy astronuclear physics modelling: photomeson production by cosmic-ray nuclei heavier than protons, gamma-ray emission from unstable nuclei created by the photodisintegration of cosmic rays, and the simulation of extragalactic propagation of nuclei heavier than iron (so-called superheavy isotopes). The photomeson model is the first in the literature to go beyond the simple principle of nucleon superposition. It provides a more accurate description of the inelastic cross sections, and the emitted spectrum of secondary particles, including isotopes and pions which lead to photons and neutrinos.The model’s impact is shown in simulations of gamma-ray bursts and tidal disruption events, and it affects significantly the high-energy neutrino emission, the chemical composition and the spectrum of the emitted UHECRs. The second model describes photoproduction from de-excitations and decay of unstable nuclei, which are expected to be produced in photo-disintegration of cosmic rays interacting with astrophysical photons. Its impact is illustrated in the photo-emission from the core of the Centaurus A and compared to similar works with which is in disagreement. This supports the need for sufficiently accurate models. Lastly, the photodisintegration of UHECR superheavy nuclei is discussed. An interaction table is produced with cross sections obtained from TALYS and the interaction rates computed in the context of extragalactic propagation. Superheavy nuclei propagate further than lighter nuclei in certain energy ranges. The models developed are publicly available as open-source software.
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Stapleton, James C. "Ultra-High Energy Cosmic Rays: Composition, Early Air Shower Interactions, and Xmax Skewness." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1431044195.
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Quinn, Sean P. "Arrival Direction Probabilities of Ultra High Energy Cosmic Rays with the Pierre Auger Observatory and Progress Toward an in-situ Cross-calibration of Auger and Telescope Array Surface Detector Stations." Case Western Reserve University School of Graduate Studies / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=case1512730856642865.
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Halliday, Robert Paul. "Electronics and Timing for the AugerPrime Upgrade and Correlation of Starburst Galaxies with Arrival Directions of Ultra High Energy Cosmic Rays." Case Western Reserve University School of Graduate Studies / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=case1553599216169462.
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Voigt, Bernhard. "Sensitivity of the IceCube detector for ultra-high energy electron-neutrino events." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2008. http://dx.doi.org/10.18452/15850.
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Zur Zeit wird das IceCube Neutrino-Teleskop am Südpol im Eis der Antarktis installiert, die Hälfte des Detektors ist bereits im Betrieb. Bei Fertigstellung im Jahr 2011 wird mehr als 1 km^3 Eis mit Photovervielfachern instrumentiert sein. IceCube bietet damit eine einzigartige Möglichkeit, die Quellen der kosmischen Strahlung mit Hilfe hochenergetischer Neutrinos zu finden. Im Rahmen dieser Arbeit wurde die Sensitivität des kompletten Icecube Detektors für den Nachweis eines diffusen Flusses von Elektronneutrinos bestimmt. Ziel war es, die Eigenschaften des Detektors für Energien oberhalb von einem PeV zu bestimmen. Besonderes Augenmerk wurde dabei auf die Simulation von elektromagnetischen Kaskaden gelegt, die in Neutrino-Nukleon-Wechselwirkungen auftreten. Da existierende Parametrisierungen die Unterdrückung der Wechselwirkungsquerschnitte durch den LPM-Effekt nicht beinhalten, wurde eine Simulation des Energieverlustes von elektromagnetischen Kaskaden für Energien oberhalb von 1 PeV entwickelt, die entsprechend modifizierte Wirkungsquerschnitte verwendet. Die Analyse, die in dieser Arbeit vorgestellt wird, nutzt die komplette Information des durch einen Photovervielfacher aufgezeichneten Ladungsverlaufes aus, die mit der Datennahme des IceCube Detektors zur Verfügung steht. Es werden neue Methoden entwickelt, um zwischen atmosphärischen Myonen-Hintergrund- und Signalereignissen von Kaskaden aus Neutrino-Nukleon-Wechselwirkungen zu unterscheiden. Die erreichbare Sensitivität innerhalb einer Laufzeit von einem Jahr ist 1.5*10^-8 E^-2 GeV/(cm^2 sr s) in einem Energiebereich von 16 TeV bis 13 PeV für den Nachweis von Elektronneutrinos eines diffusen Flusses. Eine Verbesserung von mindestens einer Größenordnung wird erwartet, wenn alle Neutrinofamilien in die Analyse einbezogen werden. Damit sollte eine Sensitivität erreicht werden, die auf dem gleichen Niveau einer diffusen Myonenanalyse liegt.IceCube is a neutrino telescope currently under construction in the glacial ice at South Pole. At the moment half of the detector is installed, when completed it will instrument 1 km^3 of ice providing a unique experimental setup to detect high energy neutrinos from astrophysical sources. In this work the sensitivity of the complete IceCube detector for a diffuse electron-neutrino flux is analyzed, with a focus on energies above 1 PeV. Emphasis is put on the correct simulation of the energy deposit of electromagnetic cascades from charged-current electron-neutrino interactions. Since existing parameterizations lack the description of suppression effects at high energies, a simulation of the energy deposit of electromagnetic cascades with energies above 1 PeV is developed, including cross sections which account for the LPM suppression of bremsstrahlung and pair creation. An attempt is made to reconstruct the direction of these elongated showers. The analysis presented here makes use of the full charge waveform recorded with the data acquisition system of the IceCube detector. It introduces new methods to discriminate efficiently between the background of atmospheric muons, including muon bundles, and cascade signal events from electron-neutrino interactions. Within one year of operation of the complete detector a sensitivity of 1.5*10^-8 E^-2 GeV/(cm^2 sr s) is reached, which is valid for a diffuse electron-neutrino flux in the energy range from 16 TeV to 13 PeV. Including all neutrino flavors in this analysis, an improvement of at least one order of magnitude is expected, reaching the anticipated performance of a diffuse muon analysis.
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Valtonen-Mattila, Nora. "High Energy gamma-ray behavior of a potential astrophysical neutrino source : The case of TXS 0506+056." Thesis, Linnéuniversitetet, Institutionen för fysik och elektroteknik (IFE), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-90569.
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Blazars are a type of Active Galaxy that emit strong astrophysical jets. The association of a HE gamma-ray flare from the blazar TXS 0506+056 to the IceCube-170922A neutrino event in 2017, opened the possibility to a link between these two events. In this thesis, we will look at the HE gamma-ray behavior of TXS 0506+056 using data obtained from the Fermi-LAT by taking into account the other set of neutrino events associated with this source from 2014-2015. We will investigate whether both neutrino events present with comparable HE gamma-ray behavior by analyzing the lightcurves and the spectra for a quiet state, the 2014-2015 period, and the flare centered around the neutrino event from 2017. The results of the analysis performed in this thesis show no strong indication of a change in the gamma-ray behaviour in these potential neutrino detections.
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Caccianiga, Lorenzo. "Cosmic-ray astronomy at the highest energies with ten years of data of the Pierre Auger observatory." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066643/document.
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L'identification des sources de rayons cosmiques d'ultra-haute énergie (au-delà de 10^18 eV) constituerait une avancée majeure aussi bien dans le domaine de l'astrophysique que dans celui de la physique des particules. La difficulté principale dans la recherche de telles sources réside dans la perte de l'information directionnelle des rayons cosmiques les moins énergétiques. En effet, leur direction est sujette à des déviations d'amplitude inversement proportionnelle à leur énergie à cause des champs magnétiques qu'il traversent lors de leur propagation jusqu'à la Terre. D'autre part, pour des énergies supérieures à 4x10^(19)eV, l'interaction des rayons cosmiques avec le fond diffus cosmologique limite l'horizon de leurs sources à l'Univers proche (200 Mpc ou moins). Cette thèse a été effectuée au sein de l’observatoire Pierre Auger, le plus grand détecteur de rayons cosmiques de haute énergie. Elle est dédiée à l'étude, la sélection, la reconstruction, ainsi qu'à l'analyse des évènements de plus haute énergie. D'autre part, les particules de plus bas numéro atomique sont plus susceptibles de garder leur direction mais la composition des rayons cosmiques est inconnue à de telles énergies. Une méthode de sélection des événements les plus similaires aux protons a été élaborée et développée dans cette thèse pour étudier la possibilité de leur utilisation pour une "astronomie protons"Identifying the sources of the ultra-high energy cosmic rays (UHECRs, above 10^{18} eV), the most energetic particles known in the universe, would be an important leap forward for both the astrophysics and particle physics knowledge. However, developing a cosmic-ray astronomy is arduous because magnetic fields, that permeate our Galaxy and the extra-Galactic space, deflect cosmic rays that may lose the directional information on their sources. This problem can be reduced by studying the highest energy end of the cosmic ray spectrum. Indeed, magnetic field deflections are inversely proportional to the cosmic ray energy. Moreover, above 4x10^{19} eV, cosmic rays interact with cosmic photon backgrounds, losing energy. This means that the sources of the highest energy cosmic rays observed on Earth can be located only in the nearby universe (200 Mpc or less). The largest detector ever built for detecting cosmic rays at such high energies is the Pierre Auger Observatory, in Argentina. It combines a 3000 km^2 surface array of water Cherenkov detectors with fluorescence telescopes to measure extensive air showers initiated by the UHECRs. This thesis was developed inside the Auger Collaboration and was devoted to study the highest energy events observed by Auger, starting from the selection and reconstruction up to the analysis of their distribution in the sky. Moreover, since the composition at these energies is unknown, we developed a method to select proton-like events, since high Z cosmic rays are too much deflected by magnetic fields to be used for cosmic-ray astronomy
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Machado, Laura Paulucci. "Matéria de quarks (strangelets) de origem astrofísica e sua detecção por experimentos terrestres." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-26112008-100951/.
Full textAbstract:
A hipótese de que a matéria estranha de quarks (um plasma composto por quarks up, down e strange em quantidades aproximadamente iguais) é estável `a pressão nula vem sendo considerada há mais de vinte anos, tanto teoricamente quanto em experimentos específicos para sua eventual detecção. Se a matéria estranha é de fato estável, então poderia haver importantes implicações para a Astrofísica. Entre as mais estimulantes destas implicações está a possibilidade de conversão da matéria nuclear ordinária em matéria estranha no interior das estrelas de nêutrons devido ás altíssimas densidades ali encontradas. Processos tais como coalescência em binárias de estrelas de nêutrons e as próprias supernovas, eventos responsáveis pelo nascimento destas estrelas, poderiam ejetar estruturas finitas de matéria estranha, chamadas strangelets (equivalentes aos núcleos), no meio interestelar. Desta forma, strangelets estariam presentes entre os primários de raios cósmicos e seriam sujeitas a processos elementares análogos aos núcleos ordinários. Nesta Tese, as strangelets são estudadas desde os prováveis sítios para sua produção astrofísica, passando por interações com a matéria do meio interestelar, ate a chegada ás imediações terrestres. Estima-se o fluxo de strangelets de baixa energia que poderia ser mantido aprisionado na magnetosfera da Terra, bem como são estudados os processos de suas interações com componentes da atmosfera, com vistas às assinaturas observacionais então resultantes. Desta forma, são determinadas as características relevantes para a identificação destes exóticos por experimentos que testam o fluxo de raios cósmicos, ajudando na melhor compreensão das propriedades da matéria nuclear em alta densidade bariônica e baixa temperatura.The strange quark matter hypothesis, which states that a plasma composed of quarks up, down and strange in roughly equal amounts is absolutely stable at zero pressure, has been studied for more than twenty years, both theoretically and during searches for its detection in specific experiments. If strange quark matter is indeed stable, then there could be important implications for the field of Astrophysics. Among the most stimulating ones is the possibility of conversion of ordinary nuclear matter in strange quark matter in the interior of neutron stars due to the extremely high densities reached in the core of these compact objects. Processes such as the merger in neutron star binaries systems and supernovae themselves, responsible for the birth of these stars, may eject lumps of strange quark matter, termed strangelets, in the interstellar medium. In this way, strangelets may be present among the cosmic ray flux and be subjected to elementary processes much in the same way as ordinary nuclei. In this Thesis, strangelets are studied from their likely astrophysical production sites, passing through the interstellar medium until they reach the Earth neighborhood. Estimates of the low energy flux of strangelets that could be trapped in the terrestrial magnetosphere are given. Also, the interaction of these particles with components in the Earth atmosphere are studied with the aim of providing better understanding of the resulting observational signatures. It allows the determination of the relevant characteristics for the identification of these exotics by experiments testing the cosmic ray flux, helping to better understand the properties of nuclear matter at high densities and low temperatures.
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Coste, Benoît. "Mesure et phénoménologie du rayonnement cosmique avec l'expérience CREAM." Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00821110.
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Le rayonnement cosmique galactique nucléaire est composé de noyaux de différentes espèces et ses sources sont encore mal identifiées. Cette méconnaissance est en partie due au caractère diffusif de la propagation des noyaux dans les champs magnétiques dont la composante turbulente supprime toute information sur la position des sources. Dans le rayonnement cosmique, on distingue les noyaux pri- maires qui sont principalement créés puis accélérés près de leurs sources des noyaux secondaires, uniquement créés par spallation des primaires plus lourds. La mesure des rapports d'abondance se- condaire sur primaire permet d'étudier les processus de propagation et donc de remonter aux méca- nisme sources du rayonnement cosmique. Cette étude apporte de plus une meilleure compréhension de l'environnement astrophysique galactique. Ce travail nécessite une très bonne connaissance des sections efficaces d'interaction du rayonnement cosmique dans le milieu interstellaire qui régissent la modification des abondances lors de la propagation. La première partie de cette thèse est dédiée à la contrainte des paramètres de propagation du rayonnement cosmique galactique via l'étude des abondances des éléments du quartet (1H,2H,3He,4He). À partir d'une nouvelle estimation des sections efficaces, une analyse statistique a permis de démontrer le potentiel de ces éléments pour contraindre les modèles de propagation du rayonnement cosmique. Ces contraintes restent cependant limitées par la précision statistique des mesures actuelles et justifient la mise en œuvre de nouvelles expériences. La deuxième partie de cette thèse est dédiée à la mesure des abondances avec l'expérience CREAM, une expérience embarquée en ballon. Cette mesure nécessite l'identification des éléments dans le dé- tecteur, le calcul des efficacités des sous-détecteurs, la déconvolution des effets dus aux erreurs sur la mesure de l'énergie ainsi que la prise en compte des effets atmosphériques. Cette analyse des données du 3ième vol de CREAM a permis une estimation des abondances des éléments bore, carbone, azote et oxygène.
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Falletti, Lola. "Étude de la région de la source non-identifiée HESS J1745-303 avec l'instrument LAT à bord du satellite Fermi." Phd thesis, Université Montpellier II - Sciences et Techniques du Languedoc, 2013. http://tel.archives-ouvertes.fr/tel-00917396.
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Le LAT est l'instrument principal du satellite Fermi et permet d'étudier le ciel en rayons gamma de 20 MeV à plus de 300 GeV. Sa sensibilité accrue a permis l'augmentation du nombre de sources détectées dans le domaine des hautes énergies. Une partie importante de celles-ci n'a pas de contrepartie connue et une étude multi-longueur d'onde est nécessaire afin de comprendre l'origine du signal observé. Dans un premier temps, cette thèse présente l'étude morphologique et spectrale détaillée de la source non-identifiée HESS J1745--303, qui a été découverte dans le domaine gamma par l'expérience H.E.S.S. en 2006 puis analysée spécifiquement dans un article de 2008, à l'aide des données du LAT. Deux sources ponctuelles situées à une localisation proche de HESS J1745--303 sont présentes dans le catalogue à deux ans de données de Fermi (2FGL) mais une analyse dédiée de cette région est néanmoins nécessaire vu sa complexité. Elle est en effet localisée à ~1° du Centre Galactique et à moins de 0.5° du pulsar de la Souris, les deux sources les plus brillantes en gamma dans cette région. Les différents processus d'émission de photons sont présentés dans un second temps. Leurs simulations permettent d'effectuer une étude approfondie de l'origine de l'émission détectée aux hautes et très hautes énergies par le LAT et par H.E.S.S. L'émission de cette source reste en effet encore énigmatique de nos jours et une étude multi-longueur d'onde est effectuée afin de contraindre les modèles d'émission.
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Ou, Ziwei. "Supernova remnants as PeVatron candidates : analysis and modeling of simulated data from the Cherenkov Telescope Array." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS421.
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L'origine du genou dans le spectre des rayons cosmiques aux énergies autour du PeV reste une question ouverte. En raison de leur budget énergétique élevé, les restes de supernovae (SNR) sont des candidats plausibles pour ces dénommés PeVatrons. Les particules chargées accélérées interagissent avec la matière environnante et produisent des pions neutres qui se désintègrent ensuite en rayons gamma de haute énergie. Ces rayons gamma, qui sont aux énergies TeV pour PeVatrons, peuvent ensuite être détectés par des télescopes Cherenkov ou d'autres observations en rayons gamma. Dans ce travail de thèse, nous étudions le potentiel du réseau de télescopes Cherenkov (CTA) à observer de tels rayons gamma. Après avoir sélectionné les candidats potentiels PeVatrons Galactiques présents dans le Data Challenge One (DC-1) de CTA, nous reconstruisons leur distribution spectrale d'énergie (SED) à l'aide du package ctools. Si des données mesurées existent à d'autres longueurs d'onde, nous les combinons aux SED simulés pour effectuer une analyse multi-longueur d'onde (MWL). Les SED sont ensuite ajustées à l’aide de différents modèles radiatifs non thermiques mis en œuvre dans le logiciel Naima, notamment de la composante pion neutre hadronique. Plusieurs résultats sont obtenus. Les paramètres spectraux reconstruits sont en bon accord avec les paramètres utilisés dans le DC-1. Les simulations donnent ainsi confiance dans le processus d'analyse des données. Parmi les SNR étudiés, certains candidats PeVatron potentiels ayant des spectres d'énergie dures sont trouvés. Il est également montré que les données MWL donnent une bonne contrainte pour la modélisation des SED et permettent de déterminer si une composante hadronique est présente dans les données. Si les données du DC-1 étaient représentatives de la réalité, nous pourrions exclure la plupart des sources en tant que PeVatrons. Des améliorations possibles des modèles spectraux d’entrée à simuler pour le prochain défi de données de CTA sont proposéesThe origin of the knee in the cosmic-ray spectrum at PeV energies is still an open question. Due to their large budget, supernova remnants (SNRs) are plausible candidates for these so-called PeVatrons. The accelerated charged particles interact with surrounding matter, produce neutral pion particles which consequently decay into high-energy gamma rays. These gamma rays, that are in TeV energies for PeVatrons, can then be detected by Cherenkov telescopes or other gamma observations. In this thesis work, we study the potential of Cherenkov Telescope Array (CTA) to observe such gamma rays. After selecting potential galactic PeVatron candidates present in the simulated Data Challenge One (DC-1) of CTA, we reconstruct their spectral energy distribution (SED) by using ctools package. In case measured data in other wavelengths exist, we combine this to the simulated SEDs to perform Multi-Wavelength (MWL) analysis. The SEDs are then fitted by using different non-thermal radiative models, including hadronic pi0 component. For the modelling we use the Naima package. Several results are obtained. The spectral parameters are reconstructed in good agreement with parameters used in DC-1. Simulations giving confidence for the data analysis process. Some potential PeVatron candidates having hard energy spectra are found among the studied SNRs. It is also shown that the MWL data gives good constrain for SED modelling and allows to determine whether a hadronic component is present in the data. If the DC-1 data were representative of reality, we could rule out most of the sources. Possible improvements in the input spectral models to be simulated for the next Data Challenge of CTA are proposed
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Plotnikov, Illya. "Ondes de choc relativistes." Phd thesis, Université de Grenoble, 2013. http://tel.archives-ouvertes.fr/tel-00961589.
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La formation et l'activité des objets compacts, tels que Trous Noirs ou étoiles à Neutrons, s'accompagne couramment d'éjection de matière ionisée sous forme de jets à la vitesse proche de celle de la lumière (vitesses relativistes). Se propageant dans le milieu environnant, par exemple Milieu Interstellaire, ces jets conduisent inéluctablement à la formation d'ondes de choc relativistes. Une forte turbulence magnétique et une population d'électrons accélérés sont requises afin de tenir compte de l'émission radiative non-thermique de ces chocs. L'approche naturelle de ce problème, décrivant de manière auto-consistante la structure du choc non-collisionnel, est celle de la physique cinétique des plasmas en régime relativiste. L'aspect essentiel de cette approche est l'étude du précurseur du choc, sous forme d'un faisceau de protons très énergétiques. Un ensemble d'instabilites plasma y prend lieu et dissipe l'energie du choc sous forme de micro-turbulence électromagnétique, électrons chauffés et particules accélérées. Ce cadre conceptuel emmène à reconsidérer le processus de transport de particules charges autour du choc. Deux études indépendantes, effectuées pendant la thèse, montrent que les lois de diffusion en aval et amont du choc se mettent sous une forme concise, en loi de puissance en fonction de l'énergie des particules et de l'intensité de la micro-turbulence magnétique. Les lois de diffusion, dérivées à l'aide des simulations Monte-Carlo et analytiquement, chiffrent l'énergie maximale des protons accélérés au choc à 10^15 eV, si le facteur de Lorentz du choc est très grand devant 1. Cette limite se situe loin de l'énergie maximale des Rayons Cosmique et rend les chocs relativistes comme accélérateurs de particules inefficaces aux énergies les plus extrêmes. Le rayonnement, issu de l'accélération des électrons, atteint plusieurs GeV et corrobore l'idée que les chocs externes des Sursauts Gamma peuvent émettre à de telles énergies. L'approche alternative de l'étude des chocs, simulations Particle-In-Cell, m'as permis d'étudier la formation, structuration et évolution des chocs modérément relativistes dans une géométrie spatiale 1D. L'auto-reformation du front d'un choc perpendiculaire, connue dans le régime non-relativiste, persiste dans le régime moyennement relativiste et exhibe un front de choc non-stationnaire. A magnétisation basse, les électrons sont préchauffés dans le pied du choc par l'instabilité de Buneman entre protons réfléchis et électrons incidents, mais leur température en aval du choc reste plus faible que celle des protons. A magnétisation croissante, l'instabilité Maser Synchrotron devient essentielle dans la structuration du front de choc, avec émission d'un fort précurseur électromagnétique a partir du front de choc. Dans ce cas les électrons se mettent en équipartition avec les protons. Ces simulations 1D ne montrent pas d'évidence d'accélération des particules et des simulations 2D (3D) sont nécessaires.
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Jones, David I. "Exploring cosmic-ray acceleration in the galactic realm." 2009. http://hdl.handle.net/2440/61076.
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Despite many years of research dedicated to elucidating the conditions in which cosmic rays (CRs) are accelerated, there is still great uncertainty about exactly how such particles are accelerated up to energies of 1 TeV (1 TeV= 10¹² eV) and well beyond. Additionally, there is also great uncertainty about the structure and amplitude of the Galactic magnetic field which necessarily has a great impact upon the movement and interaction of CRs in the Galaxy. This thesis deals with a number of ways in which Gigahertz (GHz) frequency radio continuum observations can be used with GeV–TeV γ-ray observations to explore (i) the CR spectrum and (ii) the magnetic field amplitude in the Galaxy. An accurate knowledge of the CR spectrum and amplitude of the magnetic field has important consequences for a wide range of phenomena, such as particle acceleration and even star formation within the Galaxy. We present a simple static, single-zone model of secondary electron and positron production from CR protons and heavier nuclei interacting with ambient matter. We then apply this model, assuming a local CR spectrum, to predict the synchrotron emission from two cold, dense, massive molecular cores which are relatively nearby using a prescription for the magnetic field which scales as the (approximate) square-root of the hydrogen number density. Radio continuum observations with the Australia Telescope Compact Array (ATCA) are then used to search for this emission and, due to the lack of detection, upper limits to the magnetic fields within these cores are obtained. We find that these limits are not inconsistent with the prescription used in the theoretical modeling. We also present observations of a giant molecular cloud located in the Galactic centre (GC) region, Sagittarius B2 (Sgr B2), chosen because of the expectation of a higher CR flux (than that observed at the top of the earth’s atmosphere). Based on previous work, the simple model presented in this thesis is then extended to include effects of CR diffusion into the Sgr B2 cloud parameterized by a “diffusion transport suppression” factor (and based on a molecular distribution – obtained from NH₃ spectral line emission studies – that can modeled as a three-dimensional Gaussian distribution). Our results show that the complex nature of the environment severely hampers the separation of the thermal and non-thermal emission so that no spectral, polarized or morphological evidence is found for non-thermal emission due to secondary electrons and positrons. Analysis of the radial brightness distribution from the centre of the main complex of Sgr B2 allowed us to place limits on the diffusion of GeV energy CRs into the cloud. This leads to a relative deficit of CRs at the centre of the cloud and a morphology which is reminiscent of a ‘limb-brightening’ of synchrotron emission from secondary electrons and positrons. This is in contrast to to the TeV energy γ-rays from which a good correlation with molecular matter in the GC region is observed. This is interpreted by us as evidence of the exclusion of GeV energy CRs from the densest molecular environments in this region, whilst the TeV (or higher) CRs are able to freely penetrate these regions leading to the γ-ray -molecular line emission correlation observed by the HESS telescopes. Serendipitously, observations of this region uncovered evidence of non-thermal emission from a source to the south of the main complex of emission within Sgr B2. Analysis of archival XMM-Newton X-ray observations revealed an X-ray source located approximately 20” from the non-thermal radio source whose spectrum is strongly suggestive of a SNR. The non-thermal radio spectrum, X-ray source and spectrum were then used in concert with NH3 line emission to argue that this source is a SNR of approximately 3000 years of age which had exploded in this dense region. A large gradient in the NH₃ line emission towards the X-ray source suggests that any SNR shell would expand towards this region of lower density. Analysis of higher resolution 1720 MHz ATCA data revealed a weak source whose extension is coincident with the X-ray source. Finally, the observations of the Sgr B2 region were then expanded to explore the nature of the magnetic field amplitude on large scales in the region, of which there is a two orders of- magnitude uncertainty. Based on earlier work, which showed a large (6° x 2°) region of synchrotron emission at the GC, we assembled single-dish and interferometric observations of this region. The objective of this was to explore the possibility that a ‘spectral downturn’ existed at GHz frequencies, which is due to the gradual dominance towards lower energies of the bremsstrahlung cooling rate over the synchrotron cooling rate. After the removal of appropriate background and the consideration of limitations at GeV and TeV energies, we found significant statistical evidence for a spectral break at ~ 2 GHz, which implies a magnetic field amplitude of 100 μG in a density of ~ 100 cm ⁻³. An amplitude this high, on such large scales will have a large impact on processes such as particle acceleration, star-formation and gas-dynamics in the region.http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1456598
Thesis (Ph.D.) -- University of Adelaide, School of Chemistry and Physics, 2009
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Szabo, Anthony Paul. "High energy emissions from astrophysical objects / Anthony Paul Szabo." Thesis, 1992. http://hdl.handle.net/2440/20851.
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Thomas-Albury, Justin Mark. "Extending the Energy Range of Ultra-High Energy Cosmic Ray Fluorescence Detectors." Thesis, 2020. http://hdl.handle.net/2440/130770.
Full textAbstract:
The origin, acceleration mechanisms and mass composition of ultra-high energy
cosmic rays (UHECR) are among the biggest unsolved mysteries in astrophysics.
The search is limited by the extremely low number of cosmic rays observed at
the highest energies; 1 particle per square kilometre per year. At these energies,
significant numbers of cosmic rays cannot be measured directly. Instead, extensive
air showers (EAS) produced by their interaction with the atmosphere are measured
by ground-based experiments. One such experiment, the Pierre Auger Observatory
(Auger), adopts a hybrid detection technique utilising fluorescence telescopes and
surface detector stations to measure the energy, arrival direction and chemical mass
composition of UHECRs.
The Pierre Auger Observatory (Auger) measures the depth of shower maximum
(Xmax), an observable which is sensitive to the mass composition of the primary
cosmic ray. A modified analysis chain has been developed for the study of the
chemical mass composition of UHECRs which extends the energy range of existing
analysis to both lower and higher energies. This has been achieved by relaxing
strict data selection cuts, while carefully accounting for the detector efficiency
and acceptance using Monte Carlo (MC) simulations. Furthermore, the systematic
uncertainties associated with the new analysis technique are studied and discussed
in detail. The findings of this analysis are compared with previous results from the
Pierre Auger Observatory (Auger) as well as other experiments.
A novel technique for the reconstruction of EAS using Fluorescence Detector (FD)
measurements has been developed in this thesis. The Fluorescence detector Array
of Single-pixel Telescopes (FAST) is a design concept for the next generation of
UHECR detectors which will target UHECRs above 1019.5 eV with unprecedented
sensitivity. The reconstruction algorithm has been developed in two parts: a machine
learning approach, and a top-down maximum likelihood technique. The top-down
reconstruction is based on the comparison of measured data with the output of a
sophisticated detector simulation. In a proof-of-concept study, it has been shown that
the Fluorescence detector Array of Single-pixel Telescopes (FAST) will be capable of
reconstructing EAS with acceptable resolution. The results of this thesis pave the
way for FAST to become a next-generation UHECR detector.Thesis (Ph.D.) -- University of Adelaide, School of Physical Sciences, 2020
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Whelan, Benjamin James. "A magnetic spectrometer analysis method for ultra high energy cosmic ray data." Thesis, 2012. http://hdl.handle.net/2440/72154.
Full textAbstract:
Since their discovery at the beginning of the 20th Century, cosmic rays have been the subject of much research. However, fundamental questions, such as the origin of the most energetic of these particles, await an answer. The unambiguous identification of cosmic ray sources is made difficult by the deflections that these charged particles suffer in their propagation through cosmic magnetic fields.This problem is compounded by the extremely low flux of the highest energy cosmic rays at Earth, the arrival directions of which may be expected to retain information about their point of origin. However, the advent of ultra high energy cosmic ray detectors possessing collecting areas of thousands of square kilometres, such as the Pierre Auger Observatory, means that the number of cosmic rays detected at the highest energies maybe sufficient to enable directional cosmic ray astronomy in the near future. The 'magnetic spectrometer analysis', described in this thesis, is designed for the analysis of ultra high energy cosmic ray data sets.The analysis is designed to identify energy ordering in the arrival directions of a cosmic ray data set, and reconstruct the source directions of such events. A brief history of the discovery of cosmic rays is presented in Chapter1, along with an introduction to the physics of extensive air showers and methods of detecting them. The current knowledge of the properties of the cosmic ray flux atultra high energies is reviewed in Chapter 2, and a summary of ultra high energy cosmic ray detectors, both past and present, is presented in Chapter3. The propagation of cosmic rays through magnetic fields, and the methods of measuring those fields, is briefly reviewed in Chapter 4. In addition, the Galactic magnetic field models that are used for the production of simulated cosmic ray data sets are described there. Numerical integration is employed in the generation of the simulated data sets,and the method of doing so, as well as considerations that must be made for such simulations, is described in Chapter 5. The magnetic spectrometer analysis method is introduced in Chapter 6 in addition to a discussion of related analyses found in the literature. The results of applying the magnetic spectrometer analysis to simulated cosmic ray data sets are presented in Chapter 7. Finally, the results of an application of the magnetic spectrometer analysis to real data collected by the Pierre Auger Observatory are described in Chapter 8, followed by a discussion of those results and concluding remarks.Thesis (Ph.D.) -- University of Adelaide, School of Chemistry and Physics, 2012
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Lee, Anthony A. "Application of Monte Carlo methods to some problems in high energy astrophysics / Anthony A. Lee." Thesis, 1993. http://hdl.handle.net/2440/21417.
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Petrashyk, Andrii. "Advancements in Very-High-Energy Gamma-Ray Astronomy with Applications to the Study of Cosmic Rays." Thesis, 2019. https://doi.org/10.7916/d8-9ej9-bz11.
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This work aims to contribute to the study of the origins of cosmic rays, and broadly, to the advancement of both data analysis methods and instrumentation for very-high-energy γ-ray astronomy. First, reviewing the state of γ-ray astronomy, we show how gains in sensitivity can be achieved through sophisticated data analyses and improved instrumental designs. We then develop such an improved analysis method for the Very Energetic Radiation Imaging Telescope Array System (VERITAS) by combining Image Template Method (ITM) with Boosted Decision Trees (BDT), and study its performance, attaining a 30-50% improvement in integral sensitivity over the instrument’s standard analysis. Systematic issues in spectral reconstruction that the analysis displays are resolved satisfactorily by imposing a more stringent condition on the selection of its energy threshold. We employ the newly developed analysis to measure the γ-ray energy spectrum of the starburst galaxy M82, and combining our result with a measurement from the Fermi Large Area Telescope (Fermi-LAT), we find that a single power law fits the spectrum well between 100 GeV and 10 TeV, with no evidence for a spectral break or a cutoff. We conclude that this is in line with the current understanding that M82 is not a good proton calorimeter. Finally, we detail the design, implementation, and performance of the optical alignment system of the prototypeSchwarzschild-Couder Telescope (pSCT) for the Cherenkov Telescope Array (CTA), a novel two-mirror design that addresses many shortcomings of current instruments.
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Štefánik, Stanislav. "Studium urychlování vysokoenergetických částic v extragalaktických objektech." Master's thesis, 2013. http://www.nusl.cz/ntk/nusl-330741.
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Title: Study of Cosmic-Ray Acceleration in Extragalactic Objects Author: Stanislav tefnik Department: Institute of Particle and Nuclear Physics Supervisor: RNDr. Dalibor Nosek, Dr. Abstract: This thesis deals with production processes of cosmic γ-rays in astro- physical objects and methods of their detection. Possible interactions leading to the emission of high energy γ-rays in the active galaxy Centaurus A are discussed in this context. Cherenkov Telescope Array is presented as a new experiment fo- cused on the detection of air showers initiated by cosmic γ-rays. Cherenkov light of air showers is studied in the simulations done by CORSIKA simulation tool. Method of data analysis within the framework of Cherenkov telescopes is descri- bed and performed on the dataset of the active galaxy PKS 2155-304. The results include statistical tests of γ-ray source presence and its time variability. Keywords: Cosmic rays, gamma rays, astroparticle physics, high energy astro- physics, acceleration, CTA experiment