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Černé díry pod vlivem silných zdrojů gravitace / Black holes under the influence of strong sources of gravitationKotlařík, Petr January 2019 (has links)
In this thesis we study a deformation of a black-hole spacetime due to another strong sources of gravity. Keeping within static and axially symmetric metrics, we consider a binary of Schwarzschild black holes held apart from each other by a repulsive effect of an Appell ring. After verifying that such a system can rest in static equilibrium (without any supporting struts), we compute its several basic geometric characteristics and we plot simple invariants determined by the metric functions (especially lapse, or, equivalently, potential) and by their first and second derivatives (gravitational acceleration and Kretschmann scalar). Then we extend the analysis below the black-hole horizon and inspect the behaviour of the scalars inside. The geometry turns out to be deformed in a non-trivial way, we even find regions of negative Kretschmann scalar in some cases. In the second part, we present a summary of the perturbative solution describing a slowly rotating system of a black hole surrounded by a thin finite circular disc, and an analysis of equatorial circular geodesics in such a spacetime. 1
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Multidimensional multiscale dynamics of high-energy astrophysical flowsCouch, Sean Michael 23 November 2010 (has links)
Astrophysical flows have an enormous dynamic range of relevant length scales. The physics occurring on the smallest scales often influences the physics of the largest scales, and vice versa. I present a detailed study of the multiscale and multidimensional behavior of three high-energy astrophysical flows: jet-driven supernovae, massive black hole accretion, and current-driven instabilities in gamma-ray burst external shocks. Both theory and observations of core-collapse supernovae indicate these events are not spherically-symmetric; however, the observations are often modeled assuming a spherically-symmetric explosion. I present an in-depth exploration of the effects of aspherical explosions on the observational characteristics of supernovae. This is accomplished in large part by high-resolution, multidimensional numerical simulations of jet-driven supernovae. The existence of supermassive black holes in the centers of most large galaxies is a well-established fact in observational astronomy. How such black holes came to be so massive, however, is not well established. In this work, I discuss the implications of radiative feedback and multidimensional behavior on black hole accretion. I show that the accretion rate is drastically reduced relative to the Eddington rate, making it unlikely that stellar mass black holes could grow to supermassive black holes in less than a Hubble time. Finally, I discuss a mechanism by which magnetic field strength could be enhanced behind a gamma-ray burst external shock. This mechanism relies on a current-driven instability that would cause reorganization of the pre-shock plasma into clumps. Once shocked, these clumps generate vorticity in the post-shock plasma and ultimately enhance the magnetic energy via a relativistic dynamo process. / text
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Applications of strong gravitational lensing: utilizing nature’s telescope for the study of intermediate to high redshift galaxiesBandara, H. M. Kaushala T. 12 December 2012 (has links)
This dissertation presents a detailed analysis of the galaxy-scale strong gravitational lenses discovered by the Sloan Lens ACS (SLACS) survey, with the aim of providing new insight into the processes that affect the evolution of galaxies at intermediate and high redshift. First, we present evidence for a relationship between the supermassive black hole mass and the total gravitational mass of the host galaxy, by utilizing the fact that gravitational lensing allows us to accurately measure the inner mass density profile of early-type lens galaxies and their total masses within an aperture. These results confirm that the properties of the bulge component of early-type galaxies and the resulting supermassive black hole are fundamentally regulated by the properties of the dark matter halo. We then utilize the lensing magnification for a detailed study of the photometric properties (luminosity, size and shape) of SLACS background sources and determine the evolution of the disk galaxy luminosity-size relation since z ~ 1. A comparison of the observed SLACS luminosity-size relation to theoretical simulations provides strong evidence for mass-dependent evolution of disk galaxies since z ~ 1. Furthermore, a comparison of the SLACS luminosity-size relation to that of a non-lensing, broad-band imaging survey shows that one can probe a galaxy population that is ~ 2 magnitudes deeper by utilizing the lensing magnification. We continue the detailed study of SLACS background sources by combining the lensing magnification with diffraction-limited integral field spectroscopy to derive two-dimensional kinematic, star formation rate and metallicity distributions of gravitationally lensed galaxies at z > 0.78. Integral field spectroscopic observations of the Hα emission line properties of a SLACS source galaxy (SDSS J0252+0039), at z = 0.98, show that the lensing magnification and adaptive optics advantages can be effectively combined to derive spatially resolved kinematics and star formation rates of compact, sub-luminous galaxies. Finally, we summarize the results of this dissertation and discuss how the powerful advantages of strong gravitational lensing can be utilized to address various questions about galaxy evolution through upcoming surveys and new telescope facilities. / Graduate
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Buried AGNs in Advanced Mergers: Mid-infrared Color Selection as a Dual AGN Candidate FinderSatyapal, Shobita, Secrest, Nathan J., Ricci, Claudio, Ellison, Sara L., Rothberg, Barry, Blecha, Laura, Constantin, Anca, Gliozzi, Mario, McNulty, Paul, Ferguson, Jason 23 October 2017 (has links)
A direct consequence of hierarchical galaxy formation is the existence of dual supermassive black holes, which may be preferentially triggered as active galactic nuclei (AGNs) during galaxy mergers. Despite decades of searching, however, dual AGNs are extremely rare, and most have been discovered serendipitously. Using the all-sky WISE survey, we identified a population of over 100 morphologically identified interacting galaxies or mergers that display red mid-infrared colors often associated in extragalactic sources with powerful AGNs. The vast majority of these advanced mergers are optically classified as star-forming galaxies, which suggests that they may represent an obscured population of AGNs that cannot be found through optical studies. In this work, we present Chandra/ACIS observations and near-infrared spectra with the Large Binocular Telescope of six advanced mergers with projected pair separations less than similar to 10 kpc. The combined X-ray, near-infrared, and mid-infrared properties of these mergers provide confirmation that four out of the six mergers host at least one AGN, with four of the mergers possibly hosting dual AGNs with projected separations less than similar to 10 kpc, despite showing no firm evidence for AGNs based on optical spectroscopic studies. Our results demonstrate that (1) optical studies miss a significant fraction of single and dual AGNs in advanced mergers, and (2) mid-infrared pre-selection is extremely effective in identifying dual AGN candidates in late-stage mergers. Our multi-wavelength observations suggest that the buried AGNs in these mergers are highly absorbed, with intrinsic column densities in excess of similar to N-H > 10(24) cm(-2), consistent with hydrodynamic simulations.
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Chaos v polích deformovaných černých děr / Chaos in deformed black-hole fieldsWitzany, Vojtěch January 2015 (has links)
The consequences of two key approximations of accretion-disc physics near black holes are studied in this thesis. First, the question of effective ``pseudo-Newtonian" potentials mimicking a black hole is investigated both through numerical simulations and analytical means, and second, the neglect of additional gravitating matter near accreted-upon black holes and its consequences are put to test. After some broader discussion of integrability, resonance and chaos, a general "pseudo-Newtonian" limit for geodesic motion is derived, and applied for the case of null geodesics near a glowing toroid and for time-like geodesics in the Kerr metric. Afterwards, a new Newtonian gravitational potential for non- singular toroids is proposed and its usefulness for the so-called Weyl space-times is discussed. Finally, a new pseudo-Newtonian potential is introduced and applied alongside already known potentials in models of free test particle motion in the field of a black hole with a disc or ring, in complete analogy with previous exact-relativistic studies, and the previous conclusion of chaos in disc/ring-hole models is confirmed. Overall, the pseudo-Newtonian framework is able to reproduce a number of key features of the original systems with notable differences arising only as a consequence of extremely strong or...
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New methods for probing black-hole space-time based on infalling gas clouds / 落下ガス雲に基づいたブラックホール時空の新検証法Moriyama, Kotaro 26 March 2018 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第20919号 / 理博第4371号 / 新制||理||1627(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 嶺重 慎, 准教授 前田 啓一, 教授 太田 耕司 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM
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Investigating Disk-Jet Structure around Supermassive Black Hole through Polarization Images / 偏光画像から探る、超大質量ブラックホール付近の円盤―ジェット構造Tsunetoe, Yuh 23 March 2023 (has links)
京都大学 / 新制・課程博士 / 博士(理学) / 甲第24417号 / 理博第4916号 / 新制||理||1702(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 嶺重 慎, 教授 前田 啓一, 教授 太田 耕司 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM
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Study of Supermassive Black Hole and Galaxy Coevolution in X-ray selected Active Galactic Nuclei Based on Multiwavelength Spectral Energy Distribution Analysis / 多波長スペクトル解析で探るX線で検出された活動銀河核における超大質量ブラックホールと銀河の共進化Setoguchi, Kenta 25 March 2024 (has links)
京都大学 / 新制・課程博士 / 博士(理学) / 甲第25117号 / 理博第5024号 / 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 上田 佳宏, 准教授 岩室 史英, 教授 前田 啓一 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM
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Multiwavelength Study of the Black Hole X-ray Binary MAXI J1820+070 in the Rebrightening Phase / 多波長観測で探る再増光期におけるブラックホールX線連星 MAXI J1820+070の研究Yoshitake, Tomohiro 25 March 2024 (has links)
京都大学 / 新制・課程博士 / 博士(理学) / 甲第25120号 / 理博第5027号 / 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 上田 佳宏, 准教授 野上 大作, 教授 前田 啓一 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM
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Comprehensive Multiwavelength Studies of Local Ultra-/Luminous Infrared Galaxies and Implications on the Mechanism of Supermassive Black Hole-Galaxy Coevolution / 近傍超/高光度赤外線銀河の包括的な多波長研究と超大質量ブラックホールと銀河の共進化機構への示唆Yamada, Satoshi 23 March 2022 (has links)
京都大学 / 新制・課程博士 / 博士(理学) / 甲第23707号 / 理博第4797号 / 新制||理||1687(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)准教授 上田 佳宏, 教授 嶺重 慎, 准教授 岩室 史英 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM
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