EUSO-Balloon and EUSO-SPB are balloon borne pathfinder projects designed to val- idate the techniques of the JEM-EUSO space observatory. They are nadir pointing UV telescopes that use experimental experimental Fresnel optics to detect the ultravi- olet emission of Extensive Air Showers (EAS) induced by Ultra High Energy Cosmic Rays (UHECR) in the atmosphere. EUSO-Balloon was launched by the balloon di- vision of CNES (the french space agency) from Timmins, Ontario, Canada in 2014. Despite the success of the mission the performance of the optics was lower than what it was originally modeled and led to many doubts regarding the understanding of the optics and fresnel lenses themselves. This thesis explores three parameters proposed to explain the reduction in eciency of the system which were not simulated in the original characterization: the rounded valleys in the Fresnel lens grooves created by the tool peak radii, scratches on the surface of the lenses and the surface roughness of the fresnel lenses. These parameters were simulated and results show that they show a reduction in performance which approximates more the characterization measure- ments but still do not match exactly, leaving room for further analysis. EUSO-SPB1 is the successor of EUSO-Balloon with a launch planned in 2017 from Wanaka, New Zealand. The results of the first phase of the optics characterization campaign is pre- sented in this work. The results indicate that the optics performance is similar to that of EUSO-Balloon and require further understanding. / <p>Thesis defended in Toulouse, France as part of the SPACEMASTER programme.</p>

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第19497号 / 理博第4157号 / 新制||理||1597(附属図書館) / 32533 / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 鶴 剛, 教授 谷森 達, 准教授 成木 恵 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

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Multi-messenger astronomy is a very hot topic in the astrophysical community. A messenger is something that carries information. Different astrophysical messenger types are photons, cosmic rays, neutrinos, and gravitational waves. They all carry unique and complementary information to one another. The idea with multi-messenger astronomy is that the more different types of messengers one can obtain from the same event, the more complete the physical picture becomes. In this thesis I study the multi-messenger emission from gamma-ray bursts (GRBs), the most luminous events known in the Universe. Specifically, I study the connection of GRBs to extremely energetic particles called ultra-high-energy cosmic rays (UHECRs). UHECRs have unknown origin despite extensive research. GRBs have long been one of the best candidates for the acceleration of these particles but a firm connection is yet to be made. In Paper I and Paper II, we study the possible GRB-UHECR connection by looking at the electromagnetic radiation from electrons that would also be accelerated together with the UHECR. My conclusion is that the signal from these electrons does not match current GRB observation, disfavoring that a majority of UHECRs comes from GRBs. / ”Multi-messenger astronomy” (mångbudbärarastronomi, fri översättning) är ett väldigt aktuellt område inom astrofysiken just nu. En meddelare är någonting som bär på information. Olika meddelartyper inom astrofysiken är fotoner, kosmisk strålning, neutriner och gravitations vågor. Dessa har alla unik och olika typ av information som kompletterar varandra. Idén bakom multi-meddelare-astronomi är att ju fler olika meddelartyper vi kan upptäcka från samma event, desto mer komplett blir vår fysikaliska tolkning. I denna avhandling studerar jag multi-meddelare emission från gammablixtar (GRBs), de mest ljusstarka företeelser vi känner till i Universum. Mer specifikt, så studerar jag kopplingen mellan GRBs och ultraenergetisk kosmisk strålning (UHECRs). Ursprunget till UHECRs är fortfarande okänt trots långt pågående forskning. GRBs har länge varit en av de mest lovande accelerationskandidaterna men än så länge finns inga fasta bevis. I Paper I och Paper II studerar vi den möjliga GRB-UHECR kopplingen genom att studera den elektromagnetiska strålningen från elektronerna som även de skulle bli accelererade tillsammans med UHECRs. Min slutsats är att strålningen från elektronerna inte matchar observationer från GRBs, vilket talar emot att en majoritet av UHECRs kommer från GRBs.

京都大学 / 新制・課程博士 / 博士(理学) / 甲第24405号 / 理博第4904号 / 新制||理||1700(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 鶴 剛, 教授 井岡 邦仁, 教授 永江 知文 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

Solar wind shocks and the intracluster medium comprise hot, low-density plasmas with few Coulomb collisions. Electrons there are not fluid and so gain and exchange energy by interaction with a variety of plasma waves. We explore two mechanisms for electron energization in such plasmas. In 2D kinetic simulations of solar wind shocks with low beta (magnetic pressure greater than thermal pressure), fast-mode / oblique-whistler waves accelerate electrons in bulk via proton-scale parallel electric fields; electrons’ bulk kinetic energy then converts to heat via magnetic field-aligned electrostatic wave scattering. We show and measure the heating for 2D shocks of varying magnetic obliquity and Mach number, and we qualitatively map the mechanism’s shock parameter regime. Next, consider the intracluster medium: a high-beta plasma (thermal pressure greater than magnetic pressure) in which Megaparsec-scale motions promptly trigger nanoparsec-scale plasma waves, which in turn can scatter 1–100 MeV cosmic ray electrons. Small-scale scattering combined with large-scale motion can heat electrons, and this process is called magnetic pumping. We use 1D simulations of plasma subjected to continuous bulk compression to measure the efficiency of magnetic pumping upon cosmic ray electrons. It is speculated that magnetic pumping may help re-accelerate MeV electrons to radio-emitting energies and so help explain the origin of diffuse, MHz–GHz radio halos enshrouding some clusters of galaxies.

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