Philosophiae Doctor - PhD / Observations of galaxies at di↵erent wavelengths have shaped our understanding of their formation and evolution through time. The commonly derived parameters, such as stellar mass and star formation rate (SFR), rely on the assumption that the radiation received is exclusively generated by the stars within the galaxy. This assumption is true for pure star-forming (SF) galaxies, but not in the presence of an active galactic nucleus (AGN). AGNs are structures that also radiate in the full electromagnetic spectrum, inducing additional flux to that emitted by stars. Their small sizes in comparison to the host galaxy (⌧1 %) generally make them invisible in galaxy images. AGNs come in many variations making the most powerful (e.g., quasi-stellar objects) easily identifiable, whereas others with much weaker signatures can be hidden in the total emission from the host. Therefore it is imperative to find accurate methods to separate and study the properties of AGNs versus pure SF galaxies.

No description available.

Cette thèse présente les résultats d'une étude du milieu interstellaire local basée sur les mesures de rougissement dû aux poussières (excès de couleur E(B-V)), de l'émission thermique des poussières à 353 GHz (épaisseur optique des grains tau353), du rayonnement diffus γ produit par l'interaction des rayons cosmiques avec le gaz, de l'émission free-free du gaz ionisé et des raies d'émissions des atomes HI et des molécules CO. Ces traceurs permettent de sonder la quantité totale de gaz ainsi que celle dans les différentes phases du milieu interstellaire. L'objectif de cette étude est de tester la capacité de ces traceurs à estimer les quantités de gaz, de chercher des effets d'environnement et de comparer les tendances observées aux prédictions des modèles théoriques. Nous avons étudié plus particulièrement la région de l'anticentre galactique. L'information sur la vitesse du gaz apportée par les raies d'émission HI et CO a été utilisée pour séparer dans l'espace position-vitesse six complexes de nuages locaux et pour les séparer de l'arrière-plan galactique. Ces complexes incluent les nuages bien connus de Taurus-Auriga, California et Perseus / This thesis presents the results of a study of the local interstellar medium based on several tracers: the dust reddening (color excess E(B-V), the dust thermal emission of dust at 353 GHz (optical thickness of the grains tau353), the diffuse γ-ray emission produced by the interaction of cosmic rays with gas, the free-free emission of the ionized gas and the emission lines of HI atoms and CO molecules. These tracers probe the total quantity of gas as well as the quantity of gas in the different phases of the interstellar medium. The main objectives of this study are to test the capability of these tracers to estimate gas quantities, to search for environmental effects and to compare observed trends with the predictions of theoretical models.We have studied more specifically the region of the Galactic anticenter. The information on the velocity of the gas provided by the HI and CO emission lines was used to separate six local cloud complexes in the longitude-latitude-velocity and to separate them from the Galactic background. These complexes include the well-known clouds of Taurus-Auriga, California and Perseus

Active galactic nuclei (AGN) ubiquitously show outflows. It is now widely recognized that these outflows are key components in the evolution of super-massive black holes and their host galaxies. As important as these outflows are, we still lack sufficient understanding of their structure and energetics. The majority of the work presented in this thesis involved photoionization modeling of AGN outflows along with analysis of density diagnostics in order to determine the distances and energetics of observed outflows. The main findings of these analyses are that 1) outflows are often at distances of hundreds to thousands of parsecs from the central supermassive black hole and 2) quasars outflows can be sufficiently powerful to provide feedback in galactic evolution scenarios. We also find in some cases that the recombination timescales of metal ions are long compared with the flux variability timescales. The large distances we find provide a challenge to current outflow models. For example, these outflows cannot be connected with an accretion disk surrounding the supermassive black hole as assumed in some models. Furthermore, the outflows may be out of equilibrium as we find in Mrk 509. In this case, a thorough understanding of time-dependent photoionization effects is necessary. In this thesis, I include early steps toward understanding time-dependent photoionization as well as ionization studies of accretion disk winds. The main results of these theoretical studies is that 1) the appearance of multiple ionization components in an outflow can be an artifact of the incorrect assumption that the outflow is in ionization equilibrium and 2) the shielding gas required in accretion-disk-wind models should have a clear signature in UV spectra, but none has been observed to date. / Ph. D.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第18080号 / 理博第3958号 / 新制||理||1570(附属図書館) / 30938 / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)准教授 上田 佳宏, 准教授 岩室 史英, 教授 長田 哲也 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第20898号 / 理博第4350号 / 新制||理||1624(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 田中 貴浩, 准教授 樽家 篤史, 教授 川合 光 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

No description available.

The Earth’s upper atmosphere is suffused by radiation caused primarily by a bombardment of Cosmic Rays, as a result of which it is hazardous for human beings as well as sensitive electronic equipment on board flight vehicles. A series of ground based as well as airborne experiments were performed using Polylactic Acid (PLA), Acrylonitrile-Butadiene-Styrene (ABS) and High Impact Polystyrene (HIPS), in order to investigate the applicability of polymers that can meet today’s needs for lightweight, multifunctional, and cost efficiency in radiation shielding of electronic equipment. It was found that PLA at 8 mm thickness has an effectiveness of 66% against gamma radiation (i.e., it blocked 66% of the gamma radiation). Therefore, it was decided to proceed with a high altitude balloon experiment with an 8 mm thickness of PLA. The shield was demonstrated to be reasonably effective in attenuating radiation from cosmic rays.

<p>Astrophysical jets are collimated streams of magnetized plasma launched from compact objects, such as neutron stars or black holes. These jets, powered by the accretion of surrounding gas onto the compact object, can accelerate particles to extreme energies and produce powerful radiation.</p> <p><br></p> <p>In this report, I investigate energy dissipation and particle acceleration in two key regions in jets: (i) external shocks which form where jets interact with ambient gas and (ii) internally in the jet where particles are likely to be energized through the process of magnetic reconnection.</p> <p><br></p> <p>First, I explore inverse Compton scatterings of electrons accelerated at the external shock as a candidate for the high energy emissions from gamma-ray burst afterglows. I consider two sources of seed photons for scattering: synchrotron photons from the blast wave (synchrotron self-Compton) and photon fields external to the shock (external Compton) from the star-forming region in the host galaxy. I develop an analytical model to predict the high-energy spectra from these blasts and reproduce the observed spectra and lightcurves of GRB~190114C. The model implies that inverse Compton can dominate the sub-TeV/TeV emission in this event.</p> <p><br></p> <p>Second, I study the particle acceleration mechanism of magnetic reconnection internally in astrophysical jets. I employ particle-in-cell (PIC) simulations of 3D relativistic magnetic reconnection. My analysis reveals a novel acceleration mechanism that only operates in 3D that results in faster particle acceleration. Unlike in 2D simulations where particles are trapped in the reconnected plasma and stop being accelerated, a fraction of particles in 3D can escape from this region (along the third direction) and be further accelerated. The escaped particles are characterized by a harder energy spectrum with a higher cutoff compared to those found in previous studies. Based on the PIC simulation findings, I build an analytical model for the particle kinetics, which divides particles into two groups --- one undergoing fast energization in the reconnection upstream region and the other residing in the reconnected plasma without energy change. The model predicts a power-law spectra for both groups of particles. PIC simulations reveal a universal magnetization-independent spectra with $dN/d\gamma\propto \gamma^{-2}$ for the overall particle population. The results demonstrate that relativistic reconnection in jets may be a promising mechanism for generating Ultra-High-energy Cosmic Rays. </p>

Simulation and game content includes the levels, models, textures, items, and other objects encountered and possessed by players during the game. In most modern video games and simulation software, the set of content shipped with the product is static and unchanging, or at best, randomized within a narrow set of parameters. However, ideally, if game content could be constantly and automatically renewed, players would remain engaged longer in the evolving stream of content. This dissertation introduces three novel technologies that together realize this ambition. (1) The first, NEAT Particles, is an evolutionary method to enable users to quickly and easily create complex particle effects through a simple interactive evolutionary computation (IEC) interface. That way, particle effects become an evolvable class of content, which is exploited in the remainder of the dissertation. In particular, (2) a new algorithm called content-generating NeuroEvolution of Augmenting Topologies (cgNEAT) is introduced that automatically generates graphical and game content while the game is played, based on the past preferences of the players. Through cgNEAT, the game platform on its own can generate novel content that is designed to satisfy its players. Finally, (3) the Galactic Arms Race (GAR) multiplayer online video game is constructed to demonstrate these techniques working on a real online gaming platform. In GAR, which was made available to the public and playable online, players pilot space ships and fight enemies to acquire unique particle system weapons that are automatically evolved by the cgNEAT algorithm. The resulting study shows that cgNEAT indeed enables players to discover a wide variety of appealing content that is not only novel, but also based on and extended from previous content that they preferred in the past. The implication is that with cgNEAT it is now possible to create applications that generate their own content to satisfy users, potentially significantly reducing the cost of content creation and considerably increasing entertainment value with a constant stream of evolving content.