To see the other types of publications on this topic, follow the link: Supermassive Black Hole.
Dissertations / Theses on the topic 'Supermassive Black Hole'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Supermassive Black Hole.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Vika, Marina. "Supermassive black holes : the local supermassive black hole mass function." Thesis, University of St Andrews, 2012. http://hdl.handle.net/10023/2553.
Full textAbstract:
Over recent years there has been an increase of the number of secure supermassive black hole (SMBH) detections. These SMBH measurements have lead astronomers to establish well defined empirical relationships between the SMBH mass and some of the properties of the host galaxy. The number of galaxies with SMBH mass measurements is currently limited to about 100. One approach of expanding the study of the SMBH is to use the empirical relations for estimating M[subscript(bh)] for larger samples of galaxies. The investigation of the SMBH population (or SMBH mass function) for large sample of galaxies in the nearby universe has helped to constrain the SMBH and the galaxy evolution. Previous estimates of the SMBH mass function at low redshift were produced mainly by combining the measurements of the galaxy luminosity or velocity function with one of the SMBH scaling relations. In the first part of the thesis I will present an independent construction of the nearby supermassive black hole mass function by applying the optical M[subscript(bh)]–L relation onto the Millennium Galaxy Catalogue (MGC). Additionally, in the second part I will provide photometric analysis of all UKIDSS galaxies for which SMBH masses have been measured. I will derive composite profiles of brightness, ellipticity and position angles of each galaxy. I will show that the Sérsic function fits the brightness profile of the majority of the elliptical galaxies and the bulge of disk galaxies and I will provide alternative multi-component fits when necessary. Then these photometric parameters will be used for constructing the M[subscript(bh)]–L relation in the near-IR and to investigate the M[subscript(bh)]–n relation. In the third part I will construct the near-IR SMBH mass function for the Galaxy and Mass Assembly (GAMA) survey. For this purpose I will apply the newly derived M[subscript(bh)]–L relation onto an elliptical subsample of K-band images. The advantage of this SMBH mass function is that during the M[subscript(bh)]–L construction I used the same quality images and techniques used on the GAMA survey. Apart from the M[subscript(bh)]–L relation, the M[subscript(bh)]–sigma relation was used as an alternative approach for a subsample of galaxies for which the velocity dispersions were available. Furthermore, I employed both local SMBH mass functions (MGC & GAMA) for estimating the SMBH mass density at redshift zero and accounted for the dependence of the total SMBH density on the look-back time by comparing with semi-analytic SMBH mass functions. Finally, from the SMBH mass density I estimated the baryon fraction that is locked into SMBHs.
2
Hobbs, Alexander Paul. "Supermassive black hole feeding in galactic nuclei." Thesis, University of Leicester, 2011. http://hdl.handle.net/2381/8997.
Full textAbstract:
In this thesis we present numerical and analytical models of supermassive black hole (SMBH) feeding, via deposition of gas, in galactic nuclei. Through simulations, we consider the environment of galactic centres, starting at sub-parsec scales within our own Milky Way, and moving upwards in scale and outwards in generality to scales of hundreds of parsecs in typical galaxies and finally to dark matter halos within which galaxies reside. We find that the stellar features observed in our own Galactic centre are likely explained by a collision between two molecular clouds at a distance of a few parsecs from the central black hole, Sgr A*. The amount of gas transported to small radii is large, occurring on a timescale close to dynamical. The disordered nature of the flow leads to the formation of a gaseous disc around Sgr A* that in some cases remains small-scale, undergoing complex, time-varying evolution in its orientation. Such a disc would efficiently feed the SMBH, if replenished from larger scales. We develop a model for ballistic accretion onto an SMBH at the centre of a typical galaxy, from scales of ~ hundreds of parsecs. We invoke turbulence in the gas, assumed to be driven by feedback from supernovae, as the means to create such a flow. The accretion mode is again dominated, soon after the initial turbulent kick, by the dynamical timescale for the gas in the angular momentum loss-cone, resulting in an accretion rate at or near Eddington, >~ 1Mסּ yr−1. At the largest scale, we critically evaluate the current state-of-the-art prescription for SMBH growth in cosmological simulations, finding that in general it lacks a physically consistent basis. We propose an alternative, motivated by our analytical estimates and numerical simulations, that is based on the free-fall time.
3
Trump, Jonathan Russell. "Supermassive Black Hole Activity in the Cosmic Evolution Survey." Diss., The University of Arizona, 2010. http://hdl.handle.net/10150/194982.
Full textAbstract:
I investigate active supermassive black holes, also called active galactic nuclei (AGNs). My tool for this work is the Cosmic Evolution Survey (COSMOS), a deep multiwavelength survey over 2 deg² of the sky. I describe the COSMOS AGN optical spectroscopy campaign, and present the largest AGN sample to date with full multiwavelength (radio, IR, optical, UV and X-ray) spectral energy distributions. Studying the COSMOS AGN sample reveals a unified model for supermassive black hole activity based on accretion rate, as shown by the following main results. (1) Classically “obscured” (Type 2) AGNs are more prevalent at higher redshifts and lower luminosities, suggesting that these objects accrete through low-level stochastic disk feeding by their hosts. (2) The prescence of broad emission lines in an AGN requires a minimum accretion rate (L/L(Edd) > 0.01). Broad-line (Type 1) AGNs in COSMOS span a large range of accretion rates (0.01 < L/L(Edd) < 1), in contrast to results from previous, shallower surveys, and broad-line AGNs become more optically luminous as accretion rate increases. (3) Lineless, “optically dull” AGNs have very different SEDs than broad-line and narrow-line AGNs, with comparatively brighter X-ray emission, redder optical continua, no infrared hot dust, and stronger radio emission. While up to 2/3 of optically dull AGNs may be “normal” AGNs diluted by extranuclear host galaxy light, at least 1/3 are best described as unobscured, intrinsically weak AGNs. (4) At low accretion rates, material accreting onto an AGN changes from a thin disk to an advection-dominated flow near the black hole, resulting in very different observed properties: the broad-line region disappears, radio jets become more important, and the hot dust signature changes. In contrast to previous unification models, observations indicate that most of the narrow-line and lineless AGNs in COSMOS are best described as weakly accreting AGNs. We conclude by noting a few predictions and observational tests to further investigate our model of AGN unification by accretion rate.
4
Koushiappas, Savvas Michael. "From supermassive black holes to supersymmetric dark matter." Connect to this title online, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1085673923.
Full textAbstract:
Thesis (Ph. D.)--Ohio State University, 2004.Title from first page of PDF file. Document formatted into pages; contains xxi, 172 p.; also includes graphics (some col.) Includes bibliographical references (p. 162-172). Available online via OhioLINK's ETD Center
5
Buchner, Johannes. "On the obscuration of the growing supermassive black hole population." Diss., Ludwig-Maximilians-Universität München, 2015. http://nbn-resolving.de/urn:nbn:de:bvb:19-181878.
Full textAbstract:
Aktive Galaxienkerne (AGN) werden durch das Wachstum super-schwere schwarze Löcher, die im Zentrum jeder massiven Galaxie sitzen, betrieben. Da enge Korrelationen ihrer Massen zu Eigenschaften der elliptischen Galaxienkomponente beobachtet werden, und durch ihre extreme Leuchtkraft ist es naheliegend, dass AGN einen wichtigen Baustein von Galaxien bilden. Der erste Schritt, AGN zu verstehen ist es, ihre Häufigkeit zu ermitteln, sowie die Leuchtkraft der Population. Dieses Unterfangen wird dadurch erschwert, dass die meisten AGN von Gas und Staub umgeben sind. Selbst im energiereichen Röntgenbereich, der in dieser Arbeit verwendet wird, wird die intrinsische Strahlung durch Absorption um mehrere Größenordnung verringert.
Die vorliegenden Doktorarbeit untersucht zuerst die Eigenschaften dieser Wolken, im speziellen ihre Geometrie, Säulendichteverteilung und ihr Verhältnis zur Leuchtkraft des AGN. Dazu werden ∼ 300 AGN von der längst-beobachteten Röntgenregion, der Chandra Deep Field South Kampagne verwendet. Eine neue Bayesische Methode zur Spektralanalyse wurde entwickelt, um verschiedene physikalisch motivierte Modelle für den Aufbau der Wolken zu vergleichen. Das Röntgenspektrum reagiert, hauptsächlich dank Compton-Streuung, auf die Gesamtbedeckung der Quelle durch das Gas. Eine detaillierte Analyse zeigt, dass die Wolken mit einer Torus (“Donut”) Form konsistent sind, und sowohl vollständige Bedeckung als auch eine Scheiben-artige Konfiguration ausgeschlossen werden können. Außerdem ist eine weiteren Komponente höherer Dichte notwendig um zusätzlich beobachtete Compton-Reflektion zu erklären. Dies deutet auf eine strukturierte Formation
hin, wie etwa ein Torus mit einem Dichtegradienten.
Die Untersuchung der gesamten AGN-Population inklusive der AGN mit hohen Säulendichten, verlangt eine große Stichprobe mit einem genauen Verständnis für die Stichprobenverzerrung, sowie fortgeschrittene statistische Inferenzmethoden. Diese Arbeit baut auf eine ∼ 2000 AGN große Stichprobe die durch Röntgenemission detektiert wurde, bestehend aus mehrschichtigen Kampagnen aus den CDFS, AEGIS-XD, COSMOS and XMM-XXL Regionen. Die Röntgenspektren wurden im Detail mit einem physikalischen Spektralmodell analysiert, um die intrinsische Leuchtkraft, Rotverschiebung, sowie Säulendichte (N_H) für jedes Objekt zu erhalten, inklusive der Messunsicherheit. Außerdem wurden in dieser Arbeit neue statistische Methoden entwickelt um die richtige Assoziation zu optischen/infraroten Objekten zu finden, und um die Unsicherheiten durch Objekte ohne Pendant, der Rotverschiebungsmessung, sowie der Poissonfehler des Röntgenspektrums in alle Ergebnisse einzubinden.
Einen weiteren wichtigen Beitrag bildet eine Bayesische, nicht-parametrische Methode um die unverzerrte Dichte von AGN in kosmologischen Volumen als Funktion von intrinsischer Leuchtkraft, Rotverschiebung und Säulendichte (N H ) der verbergenden Wolken zu rekonstruieren. Obwohl in dieser Methode lediglich Glattheit verwendet wird, kann dieser Ansatz dieselben Formen der Leuchtkraftverteilung sowie ihre Entwicklung rekonstruieren, die sonst oft in emprischen Modellen verwendet werden, jedoch ohne diese apriori anzunehmen. Im Großen und Ganzen kann die Leuchtkraftverteilung, in allen Rotverschiebungsschalen, als Potenzgesetz mit einem Umbruchspunkt beschrieben werden.
Sowohl die Normalisation als auch der Leuchtkraftumbruchspunkt entwickeln sich über den Lauf des Universums, allerdings zeigen die Daten keine Belege für eine Veränderung der Form der Verteilung. Dies deutet darauf hin, im Gegensatz zu Aussagen vorherigen Studien, dass der Rückkopplungsmechanismus zwischen AGN und beherbergender Galaxie immer gleich funktioniert, und sich nur die Anzahl und Größe der wachsenden Systeme verändert. Die nicht-parametrische Rekonstruktionsmethode verwendet keine Annahmen darüber wie sich z.B. die Häufigkeiten von Säulendichte des verdeckenden Gases mit Leuchtkraft oder Rotverschiebung verändert. Dies erlaubt sehr robuste Schlüsse über den Anteil der
verdeckten AGN (N_H > 10^22 cm −2 ), die 77 +4 −5 % der Population ausmachen sowie den Anteil der Compton-dicken AGN (38 +8 −7 %), die sich hinter enormen Säulendichten (N_H > 10^24 cm −2 ) verbergen. Insbesondere dass der letztere Anteil bestimmt werden konnte, lässt endlich Schlüsse darauf zu, wieviel AGN “verdeckt” wachsen. Außerdem suggeriert es, dass der Torus einen großen Teil des AGN verdeckt. Basierend auf der Leuchtkraft der gesamten AGN Population wurde die Masse, die über den Lauf der Zeit in schwarzen Löchern gesperrt wurde, geschätzt, und die Massendichte der supermassereichen schwarzen Löcher im heutigen Universum vorhergesagt.
Die Rekonstruktion bringt außerdem zu Tage, dass der Anteil der verdeckten AGN (insbesondere der Compton-dünnen AGN) eine negative Leuchtkraftabhängigkeit aufweist, und dass sich diese Abhängigkeit über die Geschichte des Universums entwickelt hat. Dieses Resultat wird in dieser Arbeit im Zusammenhang mit bestehenden Modellen interpretiert und ist möglicherweise ein Nebeneffekt eines nicht-hierarchischen Wachstums von AGN.Active Galactic Nuclei (AGN) are powered by the growth of super-massive black holes (SMBHs), which can be found at the centre of every massive galaxy. Due to tight scaling relationships of their masses with properties of their host spheroidal components, as well as the massive energy output AGN release, they are thought to play an important role in the formation and evolution of galaxies. The first step to understanding AGN is to determine their prevalence in the Universe, as well as the luminosity output of their entire population. This enterprise is hampered by the fact that most AGN are obscured by thick layers of gas and dust, making them difficult to detect. Even in the energetic X-ray wavelengths employed in this work, the intrinsic radiation of obscured AGN is suppressed by multiple orders of magnitude. In this work I first study the properties of this obscurer, specifically its geometry, column density distribution and its relation to the AGN luminosity. For this, ∼ 300 AGN from the deepest X-ray field to date, the Chandra Deep Field South survey, are used. I apply a novel Bayesian spectral analysis methodology to distinguish between several physically motivated models for the obscurer. The X-ray spectrum is, mainly due to Compton scattering, sensitive to the covering fraction of the obscurer. A detailed spectral analysis shows that the obscurer is consistent with a torus (“donut”) shape, but complete covering as well as disk-like configurations can be excluded. Furthermore, a high-density component is necessary to explain additional observed Compton-reflection beyond that expected from the line-of-sight obscuration, indicating a structured obscurer such as a torus with a density gradient. The study of the population of AGN requires a large sample with detailed understanding of the selection effect and sophisticated inference techniques. A X-ray selected sample of ∼ 2000 AGN from a multi-tiered survey including the CDFS, AEGIS-XD, COSMOS and XMM-XXL fields is analysed in detail. Through Bayesian spectral analysis with a physical model, the intrinsic luminosity, redshift and column density (N H ) is obtained for each source, including their uncertainties. This thesis also develops advanced statistical methodology for choosing the correct counterpart, and propagates the uncertainty from missing counterparts, redshift estimation as well as the Poisson noise from X-ray spectra into all final results. Another important new contribution is a Bayesian non-parametric technique to reconstruct the unbiased number density of AGN in cosmological volumes as a function of intrinsic luminosity, redshift and column density (N_H). Despite only assuming smoothness, this approach is capable of reproducing the shapes commonly assumed for the luminosity function and its evolution, without assuming them a priori. Overall, the luminosity function appears to be consistent with a double powerlaw at all redshifts studied. Both the normalisation and break luminosity evolve over time, while there is no evidence that the shape changes. This indicates that contrary to previous claims, the feedback mechanism works the same across the history of the Universe, but only the number and luminosity scale of the accreting systems changes. The non-parametric reconstruction allows the study of the fraction of obscured AGN up to the Compton-thick regime in a very robust way, i.e. without assuming a luminosity or redshift-dependent behaviour a priori. About 77 +4 −5 % of AGN are obscured (N_H > 10^22 cm −2), while 38 +8 −7 % belong to the heavily obscured, elusive Compton-thick class (N_H > 10^24 cm −2). The latter fraction in particular finally constrains the importance of obscured growth phases in the life of accreting SMBHs. Based on the total luminosity output of the AGN population, the mass locked into black holes over cosmic time is estimated, and the mass density of relic SMBHs in the local Universe is predicted, and matches local estimates. The large fraction of obscured AGN suggests that the obscuring torus must have a large angular extent. The non-parametric reconstruction also finds and characterises a negative luminosity dependence for the fraction of obscured AGN, in particular those that are Compton-thin, which are less prevalent at high luminosities. Additionally, this luminosity dependence appears to evolve with redshift. These findings are discussed in the context of existing models and it is concluded that the observed evolution may be to first order a side-effect of a anti-hierarchical growth of super-massive black holes.
6
OROFINO, Maria Carmela. "Black Hole Accretion in Primordial Galaxies." Doctoral thesis, Scuola Normale Superiore, 2020. http://hdl.handle.net/11384/97654.
Full textAbstract:
Supermassive black holes (SMBHs) with masses up to 1010M⊙ are thought to power the emission from quasars and Active Galactic Nuclei. Surprisingly, these extremely massive, compact objects are already in place within the first billion years from the Big Bang, or redshift z ≥ 6. In addition, a tight relation between the stellar and central black hole mass in galaxies has been established locally. The SMBH origin, evolution and relation to the host galaxy are key open problems in modern cosmology and astrophysics. They are the main subject of this Thesis.
As far as the origin is concerned, the most natural idea considers SMBHs as the end-product of accretion and merging on black hole remnants of massive stars. We have examined this possibility showing that this hypothesis entails several theoretical difficulties. To this aim, we have followed the accretion history of a 100M⊙ stellar BH hosted by a typical z = 10 galaxy down to z = 6. We analysed the growth under different conditions linked to the galaxy geometry and BH orbital parameters. We conclude that in all cases, the BH mass can increase at most by 30%, thus making stellar seeds unsuitable to explain the observed masses of SMBH. As a by-product of the study, we have estimated the cumulative X- ray emission from an early BH population and the total energy released in the intergalactic medium. Given the above low accretion rates, we conclude that the X-ray emission from accreting BHs is negligible with respect to that provided by X-ray binaries in the same galaxy. Although sub-dominant, the X-ray preheating of the intergalactic medium by early BHs might have left a specific signature, potentially detectable with SKA, on the HI 21cm line power spectrum.
The above results forced us to look for alternative SMBH formation processes. Thus, we explored the scenario in which SMBHs grow by merging of more mas- sive seeds, directly formed through non-stellar channels. These theoretically pre- dicted, massive (104 − 106M⊙) “direct collapse” seeds provide a head-start of the SMBH build-up and overcome the inefficient stellar BH accretion. Lacking an observational confirmation of the existence of these putative SMBH progeni- tors, we first assessed whether these ancestors can be detected by the Chandra X-ray Observatory, and used the upper limits provided by current observations to constrain theoretical model parameters. For this purpose, we exploit a semi- analytical model to predict the number density of progenitors of a z = 6.4 SMBH, their accretion and the amount of obscuring material in their host galaxies. For each ancestor we computed its X-ray spectrum accounting for interstellar absorp- tion and compared it with current observations. Faint progenitors are found to be luminous enough to be detected in the X-ray band of current surveys. Even accounting for a maximum obscuration effect, the number of detectable BHs is reduced at most by a factor of 2. In our simulated sample, observations of faint quasars are mainly limited by their very low active fraction (about 1%), which is the result of short, super-critical growth episodes. We suggest that to detect high-z SMBHs progenitors, large area surveys with shallower sensitivities, such as COSMOS Legacy and XMM-LSS+XXL, are to be preferred with respect to deep surveys probing smaller fields, such as Chandra Deep Field South.
The models discussed so far imply that massive black holes (≈ 108M⊙) must be present also in galaxies routinely observed in the Epoch of Reionization, such as the so-called Lyman Break Galaxies (LBG) at z > 6. This is an important point because the presence of a (faint) AGN in these systems might substantially alter their physical and observable properties. We addressed this question by combining our semi-analytical model with tight constraints from the 7 Ms Chan- dra survey, and the known high-z SMBH population. Depending on the fraction of early halos planted with a BH direct collapse seed, the model suggests two possible scenarios: (a) if a maximal seeding occurs, massive BH in LBGs mostly grow by merging and must accrete at a low Eddington ratio not to exceed the ex- perimental X-ray luminosity upper bound; (b) if the seeding is inefficient, direct accretion dominates and massive BH emission in LBGs must be heavily obscured. Scenario (a) poses extremely challenging, and possibly unphysical, requirements on seeds formation. Scenario (b) entails testable implications on the physical properties of LBGs involving far-infrared luminosity, emission lines, and presence of outflows that we discuss in detail.
7
Denney, Kelly D. "Black Hole Masses in Active Galactic Nuclei." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1274716921.
Full text
8
Garrido, Goicovic Felipe [Verfasser], and Volker [Akademischer Betreuer] Springel. "Infalling clouds onto supermassive black hole binaries / Felipe Garrido Goicovic ; Betreuer: Volker Springel." Heidelberg : Universitätsbibliothek Heidelberg, 2017. http://d-nb.info/1178010031/34.
Full text
9
Juneau, Stephanie. "Connecting Galaxy and Supermassive Black Hole Growth During the Last 8 Billion Years." Diss., The University of Arizona, 2011. http://hdl.handle.net/10150/202989.
Full textAbstract:
It has become increasingly clear that a complete picture of galaxy evolution requires a better understanding of the role of Active Galactic Nuclei (AGN). In particular, they could be responsible for regulating star formation and galaxy growth via feedback processes. There are also competing views about the main modes of stellar growth and supermassive black hole growth in galaxies that need to be resolved. With high infrared luminosities (thus star formation rates) and a frequent occurrence of AGN, galaxies selected in the far-infrared wavebands form an ideal sample to search for a connection between AGN and star formation. The first part of this thesis contains a detailed analysis of the molecular gas properties of nearby infrared luminous and ultraluminous infrared galaxies (LIRGs and ULIRGs). We find that the enhanced molecular gas density in the most IR-luminous systems can be explained by major galaxy mergers, and that AGN are more likely to reside in higher-density systems. While the frequent concurrence of AGN and galaxy mergers in ULIRGs was already established, this work provides a coherent framework that explains trends observed with five molecular gas tracers with a broad range of critical densities, and a comparison with simulations that reproduce observed molecular line ratios without invoking AGN-induced chemistry. The second part of the thesis presents an analysis of the AGN content of intermediate redshift galaxies (0.3
10
Araya, Salvo Claudia Lorena. "Discovery of an Active Supermassive Black Hole in the Bulge-less Galaxy NGC 4561." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1335977333.
Full text
11
Buchner, Johannes [Verfasser], and Kirpal [Akademischer Betreuer] Nandra. "On the obscuration of the growing supermassive black hole population / Johannes Buchner. Betreuer: Kirpal Nandra." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2015. http://d-nb.info/1070762989/34.
Full text
12
Hornstein, Seth David. "A search for and characterization of the infrared emission from our galaxy's supermassive black hole." Diss., Restricted to subscribing institutions, 2007. http://proquest.umi.com/pqdweb?did=1317344071&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
Full text
13
Anglés-Alcázar, Daniel, Romeel Davé, Claude-André Faucher-Giguère, Feryal Özel, and Philip F. Hopkins. "Gravitational torque-driven black hole growth and feedback in cosmological simulations." OXFORD UNIV PRESS, 2017. http://hdl.handle.net/10150/622943.
Full textAbstract:
We investigate black hole-host galaxy scaling relations in cosmological simulations with a self-consistent black hole growth and feedback model. Our sub-grid accretion model captures the key scalings governing angular momentum transport by gravitational torques from galactic scales down to parsec scales, while our kinetic feedback implementation enables the injection of outflows with properties chosen to match observed nuclear outflows (star formation-driven winds are not included to isolate the effects of black hole feedback). We show that 'quasar mode' feedback can have a large impact on the thermal properties of the intergalactic medium and the growth of galaxies and massive black holes for kinetic feedback efficiencies as low as 0.1 per cent relative to the bolometric luminosity. None the less, our simulations indicate that the black hole-host scaling relations are only weakly dependent on the effects of black hole feedback on galactic scales, since black hole feedback suppresses the growth of galaxies and massive black holes by a similar amount. In contrast, the rate at which gravitational torques feed the central black hole relative to the host galaxy star formation rate governs the slope and normalization of the black hole-host correlations. Our results suggest that a common gas supply regulated by gravitational torques is the primary driver of the observed co-evolution of black holes and galaxies.
14
Mezcua, Pallerola Mar [Verfasser], Andreas [Akademischer Betreuer] Eckart, and Anton [Akademischer Betreuer] Zensus. "Supermassive binary black hole systems in active galaxies / Mar Mezcua Pallerola. Gutachter: Andreas Eckart ; Anton Zensus." Köln : Universitäts- und Stadtbibliothek Köln, 2011. http://d-nb.info/1038111919/34.
Full text
15
Levine, Robyn. "Simulating the growth of a disk galaxy and its supermassive black hole in a cosmological context." Connect to online resource, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3315831.
Full text
16
Takeo, Eishun. "Super-Eddington accretion onto seed black holes in the early Universe." Doctoral thesis, Kyoto University, 2020. http://hdl.handle.net/2433/253087.
Full textAbstract:
京都大学0048
新制・課程博士
博士(理学)
甲第22251号
理博第4565号
新制||理||1655(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 長田 哲也
学位規則第4条第1項該当
Doctor of Science
Kyoto University
DFAM
17
Tanimoto, Atsushi. "Development of Monte Carlo Based X-Ray Clumpy Torus Model and Its Applications to Nearby Obscured Active Galactic Nuclei." Kyoto University, 2020. http://hdl.handle.net/2433/253088.
Full text
18
Rujopakarn, W., K. Nyland, G. H. Rieke, G. Barro, D. Elbaz, R. J. Ivison, P. Jagannathan, J. D. Silverman, V. Smolčić, and T. Wang. "Cospatial Star Formation and Supermassive Black Hole Growth in z ∼ 3 Galaxies: Evidence for In Situ Co-evolution." IOP PUBLISHING LTD, 2018. http://hdl.handle.net/10150/627111.
Full textAbstract:
We present a sub-kiloparsec localization of the sites of supermassive black hole (SMBH) growth in three active galactic nuclei (AGNs) at z similar to 3 in relation to the regions of intense star formation in their hosts. These AGNs are selected from Karl G. Jansky Very Large Array (VLA) and Atacama Large Millimeter/submillimeter Array (ALMA) observations in the Hubble Ultra-Deep Field and COSMOS, with the centimetric radio emission tracing both star formation and AGN, and the sub/millimeter emission by dust tracing nearly pure star formation. We require radio emission to be >= 5 x more luminous than the level associated with the sub/millimeter star formation to ensure that the radio emission is AGN-dominated, thereby allowing localization of the AGN and star formation independently. In all three galaxies, the AGNs are located within the compact regions of gas-rich, heavily obscured, intense nuclear star formation, with R-e = 0.4-1.1 kpc and average star formation rates of similar or equal to 100-1200 M(circle dot)yr(-1). If the current episode of star formation continues at such a rate over the stellar mass doubling time of their hosts, similar or equal to 0.2 Gyr, the newly formed stellar mass will be of the order of 10(11)M(circle dot). within the central kiloparsec region, concurrently and cospatially with significant growth of the SMBH. This is consistent with a picture of in situ galactic bulge and SMBH formation. This work demonstrates the unique complementarity of VLA and ALMA observations to unambiguously pinpoint the locations of AGNs and star formation down to similar or equal to 30 mas, corresponding to; 230 pc at z = 3.
19
Rosado, González Pablo Antonio [Verfasser]. "Gravitational wave background from compact objects and a new search for supermassive black hole binaries / Pablo Antonio Rosado González." Hannover : Technische Informationsbibliothek und Universitätsbibliothek Hannover (TIB), 2013. http://d-nb.info/1047352435/34.
Full text
20
Parsa, Marzieh [Verfasser], Andreas [Gutachter] Eckart, and J. Anton [Gutachter] Zensus. "Stellar Motion Near the Supermassive Black Hole in the Galactic Center / Marzieh Parsa ; Gutachter: Andreas Eckart, J. Anton Zensus." Köln : Universitäts- und Stadtbibliothek Köln, 2017. http://d-nb.info/1156712599/34.
Full text
21
Savić, Đorđe. "Measuring black hole masses in active galactic nuclei using the polarization of broad emission lines." Thesis, Strasbourg, 2019. http://www.theses.fr/2019STRAE034.
Full textAbstract:
Les trous noirs supermassifs (SMBH) se trouvent au coeur de presque toutes les galaxies massives dans l’Univers. La plupart sont en sommeil, mais lorsqu’il y a assez de gaz à proximité, ils entrent dans une phase active et forment ce qu’on appelle un noyau actif de galaxie (AGN). Ils ont alors un effet profond sur l'évolution de la galaxie hôte et jouent un rôle important sur leur environnement. La mesure fiable de la masse des SMBH est donc une tâche importante dans l'astronomie moderne. À cette fin, Afanasiev et Popovic (2015) ont récemment proposé une méthode qui utilise la rotation de l'angle de position du plan de polarisation sur le profil en fréquence des raies d'émission larges afin de tracer le mouvement Keplerien et de déterminer la masse du SMBH. Le but de la thèse est d'explorer théoriquement les possibilités de cette méthode. Pour ce faire, nous avons dans une première partie effectué de nombreuses simulations de transfert radiatif pour la modélisation de la diffusion équatoriale dans AGN à l'aide du code STOKES. Nous avons inclus les mouvements complexes présents dans le système sous forme d’accrétion et d’éjection, et nous avons également comparé nos résultats aux observations. Notre travail est important car nous avons démontré dans quelles circonstances cette méthode peut être utilisée pour mesurer la masse du trou noir de manière indépendante. La deuxième partie de ce travail consiste à prédire la polarisation des raies larges au cas où les AGN seraient alimentés par des trous noirs binaires supermassifs (SMBBH). Nous avons traité quatre cas différents avec des binaires de trous noirs séparés de moins d’un parsec, et modélisé à nouveau la diffusion équatoriale. Nous avons obtenu une signature de polarisation unique sur les raies larges. Nous avons montré que la spectropolarimétrie pouvait constituer un outil puissant et une première étape pour la recherche de SMBBH dans les futurs levés spectropolarimétriques systématiquesSupermassive black holes (SMBHs) reside in the heart of nearly every massive galaxy in the Universe. Most of them lie dormant, but when the nearby gas is abundant, it will enter an active phase and form an active galactic nucleus (AGN). When in their active phase, SMBHs have a profound effect on the host galaxy evolution and play an important role in shaping their environment. Reliable SMBH mass measuring is therefore an important task in modern astronomy. For that purpose, a method has been recently proposed by Afanasiev & Popovic (2015) that uses the rotation of the polarization plane position angle across the broad emission line profile in order to trace the Keplerian motion and determine the SMBH mass. The goal of the thesis is to theoretically explore the possibilities of this method. In order to do that, we performed numerous radiative transfer simulations for modeling equatorial scattering in AGNs using the code STOKES. We included complex motions present in the system in the form of inflows and outflows, and we also compared our results with observations. We have demonstrated under which circumstances this method can be used to measure the SMBH mass in a new independent way. The second part of this work involves predicting the broad lines polarization when AGNs are powered by supermassive binary black holes (SMBBHs). We treated four different cases with sub-pc SMBBHs, and again modeled equatorial scattering. We obtained a unique polarization signature across the broad lines. We have shown that spectropolarimetry could be a powerful tool and a first step for searching SMBBHs in the future systematic spectropolarimetric surveys
22
Mossoux, Emmanuelle. "Multiwavelength study of the flaring activity of the supermassive black hole Sgr A* at the center of the Milky Way." Thesis, Strasbourg, 2016. http://www.theses.fr/2016STRAE044/document.
Full textAbstract:
Sgr A*, le trou noir supermassif le plus proche de nous, émet une luminosité quiescente très faible ainsi que des éruptions en infrarouge proche (NIR), rayons X et radio. Cette thèse a pour but d'étudier l'effet du passage de DSO/G2 près de Sgr A* sur les éruptions. J'ai utilisé et amélioré trois méthodes pour l'étude en rayons X : les blocs Bayésiens en deux passes pour détecter les éruptions avec une certaine probabilité, le lissage des courbes de lumières pour diminuer le bruit de Poisson et la méthode de Monte Carlo par chaînes de Markov pour l'ajustement des spectres des éruptions. J'ai contraint les paramètres physiques de la source pour une des 3 éruptions détectées en rayons X en 2011 et pour 3 éruptions détectées en rayons X et NIR durant la campagne multi-longueurs d'onde de février-avril 2014. L'activité en rayons X et NIR de février-avril 2014 correspond à celle observée avant le passage de DSO/G2 près de Sgr A*. J'ai calculé le taux d'éruption intrinsèque en rayons X de Sgr A* en 1999-2015 et détecté une plus faible activité à partir du 28 octobre 2013. L'énergie stockée pendant cette période peut expliquer la plus forte activité observée du 30 août au 9 septembre 2014Sgr A*, the closest supermassive black hole, is an extremely low luminosity black hole emitting flares in near-infrared (NIR), X-rays and radio. The goal of this Ph.D. is to study the impact of the pericenter passage of the Dusty S-cluster Object DSO/G2 close to Sgr A* on the flaring activity. I used and improved three methods for the study in X-rays: the two-steps Bayesian blocks method to detect flares with a given false detection probability, the light curve smoothing to reduce the Poisson noise and the Monte Carlo Markov chains method for the fitting of the flare spectra. I constrained the physical parameters of the flaring region for one of the three X-ray flares detected in 2011 and for three NIR/X-ray flares detected during the 2014 Feb.-Apr. multiwavelength campaign. The X-ray and NIR activity during the 2014 Feb.-Apr. is not different from those observed before the DSO/G2 pericenter passage. I computed the intrinsic flaring rate in X-rays from Sgr A* in 1999-2015 and I detected a smaller flaring activity beginning on 2013 Oct. 28. The energy saved during this time period could explain the largest activity observed from 2014 Aug. 30 to Sept. 9
23
Bustamante, Jaramillo Sebastian [Verfasser], and Volker [Akademischer Betreuer] Springel. "Modelling supermassive black hole spins and the metallicity evolution of merging galaxies in a cosmological context / Sebastian Bustamante Jaramillo ; Betreuer: Volker Springel." Heidelberg : Universitätsbibliothek Heidelberg, 2019. http://d-nb.info/1192373103/34.
Full text
24
Klein, Fabian [Verfasser], and Rainer [Akademischer Betreuer] Spurzem. "Simulations of an accretion disk surrounding a supermassive black hole and its interaction with a nuclear star cluster / Fabian Klein ; Betreuer: Rainer Spurzem." Heidelberg : Universitätsbibliothek Heidelberg, 2018. http://d-nb.info/1177149672/34.
Full text
25
Rocha, João Pedro Mendes. "Numerical study of the tidal disruption of stors by the supermassive black note Sgr A* in the Galactic Center." Doctoral thesis, Universidade de Évora, 2019. http://hdl.handle.net/10174/25799.
Full textAbstract:
A Super Massive Black Hole (SMBH) with a mass of 4 106M⊙ lurks in the center of the Milky Way
known as Sagittarius A* (Sgr A*). Its presence affects both the Galactic Center (GC) interstellar gas, of
which the central molecular zone is an example, as well as the stellar system in which it resides.
A direct effect of the presence of Sgr A* is the capture of objects, in particular stars, leaving a trace of
of X-ray (soft and hard) and gamma-ray emissions. A secondary effect is the origin and powering of the
Fermi Bubbles, large superbubbles extending 8 kpc above and below the GC. Their energetic content (1055
erg) points towards an origin due to the tidal disruption of stars that end up being captured into an orbit
around the black hole. Such captures release up to 1053 erg of energy, which, at a rate of 1 capture every
105 years is enough to energize the Fermi Bubbles.
Two paramount issues require a detailed attention: (i) what is the amount of energy released in a Tidal
Disruption Event (TDE) that is available to power the black hole’s surrounding medium, and thus, the
Fermi Bubbles and (ii) how is the energy injected into the Fermi Bubbles. This thesis deals with the first
point of this quest and looks into the second issue.
When a star is scattered from its trajectory and enters in a fatal orbit onto the SMBH, the tidal forces
of the black hole overcome the star’s self-gravity disrupting it partially or completely. A fate that depends
on the strength of the encounter, which is determined by the proximity of the star to the black hole.
Therefore, in order to understand the evolution of the captured star and the energy that is released during
the process, a parametric study of the evolution of TDEs, its dependence on the penetration parameter and
of their orbit (parabolic and elliptic) was carried out using smoothed particle hydrodynamics simulations.
The main results of this work concern the passage of the star at pericentre and the effects on the stellar
structure due to the tidal forces of the SMBH. One of such effects caused by these forces is known as the
pancake phase as the star acquires a stretched shape during its passage at pericentre. Immediately after
this passage the star will develop two tidal tails of debris (gas that is removed from the stellar surface) that
can evolve into a narrow stream of gas and the tail faced on to the black hole will fall on a steady rate
of accretion onto the compact object. The penetration parameter defines how deep the star falls onto the
black hole and the amount of energy that is released by the star. TDEs that result from parabolic orbits
represent the cases where larger amounts of energy is released for the surrounding medium in the galactic
center and can contribute potentially to power up the Fermi Bubbles; RESUMO: estrelas pelo Buraco Negro Super Massivo Sgr A*
no Cento Galáctico
Um Buraco Negro Super Massivo (SMBH) com uma massa de ~4 x 106M⊙ reside no centro da Via
Láctea e é conhecido como Sagittarius A* (Sgr A*). A sua presença afecta tanto o gás interestelar do
centro galáctico, do qual a Zona Molecular Central é um exemplo, assim como o sistema estelar no qual
se inclui.
Um efeito directo da presença de Sgr A* é a captura de objectos, em particular estrelas, deixando
vestígios de emissões de raios X e de raios gama. Um efeito secundário é a origem e energização das
Bolhas de Fermi, superbolhas gigantes com cerca de 8 kpc que se estendem acima e abaixo do centro
galáctico. O seu conteúdo energético (1055 erg) aponta no sentido da origem se dever a eventos de
disrupção de estrelas que são capturadas numa órbita em torno do buraco negro. Estas capturas podem
libertar até 1053 erg de energia que, á razão de uma captura a cada 105 anos poderá ser suficiente para
energizar as Bolhas de Fermi.
Duas questões da maior importância exigem atenção detalhada: (i) qual a quantidade de energia
libertada num evento de disrupção de uma estrela que fica disponível para alimentar o meio circundante
ao buraco negro, e assim, das Bolhas de Fermi e (ii) como é injectada a energia nas Bolhas de Fermi. Esta
tese trabalha na primeira questão e lança a atenção sobre a segunda questão.
Quando uma estrela é dispersada da sua trajectória e entra numa órbita fatal em direcção ao SMBH, as
forças de maré gravitacional do buraco negro sobrepõem-se á autogravidade da estrela, promovendo a sua
disrupção parcial ou total. Este destino depende da força com que o encontro ocorre e é determinado pela
proximidade da estrela ao buraco negro. Assim e para compreender a evolução da estrela capturada e a
energia que é libertada durante este processo, foi realizado um estudo paramétrico da evolução de eventos
de disrupção de estrelas, da sua dependência do parâmetro de penetração e das suas órbitas (parabólicas
e elípticas) usando simulações hidrodinâmicas de partículas.
Os resultados mais importantes obtidos neste trabalho são relativos á passagem da estrela no pericentro
e os efeitos na estrutura estelar devido ás forças por efeito de maré gravitacional do SMBH. Um desses
efeitos devido a estas forças é conhecido como a fase da panqueca uma vez que a estrela adquire uma
forma achatada durante a sua passagem pelo pericentro. Imediatamente após esta passagem a estrela
desenvolve duas estrias de detritos (gás que é removido da superfície da estrela) que evoluem para um
longo e estreito sulco de gás e a estria voltada para o buraco negro será atraída numa taxa de acreção estável para o objecto compacto. O parâmetro de penetração define a profundidade com que a estrela é
atraída para o buraco negro e a quantidade de energia que esta liberta.
Os eventos de disrupção de estrelas em órbitas parabólicas libertam mais energia para o meio circundante
no centro galáctico e podem contribuir potencialmente para alimentar as Bolhas de Fermi.
26
Trupia, Denise. "Variability of quasars at the dawn of Universe." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/22212/.
Full textAbstract:
I buchi neri supermassicci sono onnipresenti al centro della maggior parte delle galassie. Se si verificano eventi di accrescimento, il materiale che cade nel BH si riscalda e diventa molto luminoso: questi oggetti sono chiamati nuclei galattici attivi. A causa della loro elevata luminosità, gli AGN possono essere studiati anche se molto distanti.
Un grande enigma dell’astrofisica moderna deriva dalla presenza di buchi neri supermassicci completamente formati ad altissimo redshift (z>6). Questo fatto implica che alcuni di questi oggetti erano simili a quelli che osserviamo al giorno d’oggi quando l’Universo aveva meno di 1 miliardo di anni. Come si sono formati e che tipo di meccanismo ha agito sulla loro crescita in così poco tempo?
Per aumentare la sua massa, l’accrescimento di gas deve aver proceduto quasi continuamente vicino al limite di Eddington. Rompendo la condizione di equilibrio tra la forza di gravità e la pressione di radiazione, ci si potrebbe aspettare una variabilità più pronunciata nell’accrescimento dei quasar con il redshift più alto, quindi nella loro luminosità.
La maggior parte dei quasar attualmente noti a z≈6 sono stati scoperti grazie a survey profonde e su larga scala. Ad oggi, a distanza di 20 anni dalle prime rilevazioni, siamo in grado di ricercare qualsiasi indicazione di variabilità anche per quasar ad alto redshift. In questo lavoro di tesi, utilizzando il Telescopio Cassini da 152 cm di Loiano, ho osservato un piccolo campione di quasar luminosi con magnitudine ≈18−20 nella banda z a redshift z>5.5. Dopo la riduzione e l’analisi dei dati, ho ottenuto la magnitudine delle sorgenti osservate per confrontarle con i risultati di SDSS, Pan-STARRS e DECaLS. Come risultato, ho riscontrato una diversità nel comportamento di queste sorgenti: alcuni oggetti non mostrano evidenza di variabilità, mentre per altri sembra esserci un andamento consistente nell’aumento o diminuzione del flusso osservato rispetto alle osservazioni con le altre survey
27
Schulze, Andreas. "Demographics of supermassive black holes." Phd thesis, Universität Potsdam, 2011. http://opus.kobv.de/ubp/volltexte/2011/5446/.
Full textAbstract:
Supermassive black holes are a fundamental component of the universe in general and of galaxies in particular. Almost every massive galaxy harbours a supermassive black hole (SMBH) in its center. Furthermore, there is a close connection between the growth of the SMBH and the evolution of its host galaxy, manifested in the relationship between the mass of the black hole and various properties of the galaxy's spheroid component, like its stellar velocity dispersion, luminosity or mass. Understanding this relationship and the growth of SMBHs is essential for our picture of galaxy formation and evolution. In this thesis, I make several contributions to improve our knowledge on the census of SMBHs and on the coevolution of black holes and galaxies.
The first route I follow on this road is to obtain a complete census of the black hole population and its properties. Here, I focus particularly on active black holes, observable as Active Galactic Nuclei (AGN) or quasars. These are found in large surveys of the sky. In this thesis, I use one of these surveys, the Hamburg/ESO survey (HES), to study the AGN population in the local volume (z~0). The demographics of AGN are traditionally represented by the AGN luminosity function, the distribution function of AGN at a given luminosity. I determined the local (z<0.3) optical luminosity function of so-called type 1 AGN, based on the broad band B_J magnitudes and AGN broad Halpha emission line luminosities, free of contamination from the host galaxy. I combined this result with fainter data from the Sloan Digital Sky Survey (SDSS) and constructed the best current optical AGN luminosity function at z~0. The comparison of the luminosity function with higher redshifts supports the current notion of 'AGN downsizing', i.e. the space density of the most luminous AGN peaks at higher redshifts and the space density of less luminous AGN peaks at lower redshifts.
However, the AGN luminosity function does not reveal the full picture of active black hole demographics. This requires knowledge of the physical quantities, foremost the black hole mass and the accretion rate of the black hole, and the respective distribution functions, the active black hole mass function and the Eddington ratio distribution function. I developed a method for an unbiased estimate of these two distribution functions, employing a maximum likelihood technique and fully account for the selection function. I used this method to determine the active black hole mass function and the Eddington ratio distribution function for the local universe from the HES. I found a wide intrinsic distribution of black hole accretion rates and black hole masses. The comparison of the local active black hole mass function with the local total black hole mass function reveals evidence for 'AGN downsizing', in the sense that in the local universe the most massive black holes are in a less active stage then lower mass black holes.
The second route I follow is a study of redshift evolution in the black hole-galaxy relations. While theoretical models can in general explain the existence of these relations, their redshift evolution puts strong constraints on these models. Observational studies on the black hole-galaxy relations naturally suffer from selection effects. These can potentially bias the conclusions inferred from the observations, if they are not taken into account. I investigated the issue of selection effects on type 1 AGN samples in detail and discuss various sources of bias, e.g. an AGN luminosity bias, an active fraction bias and an AGN evolution bias. If the selection function of the observational sample and the underlying distribution functions are known, it is possible to correct for this bias. I present a fitting method to obtain an unbiased estimate of the intrinsic black hole-galaxy relations from samples that are affected by selection effects.
Third, I try to improve our census of dormant black holes and the determination of their masses. One of the most important techniques to determine the black hole mass in quiescent galaxies is via stellar dynamical modeling. This method employs photometric and kinematic observations of the galaxy and infers the gravitational potential from the stellar orbits. This method can reveal the presence of the black hole and give its mass, if the sphere of the black hole's gravitational influence is spatially resolved. However, usually the presence of a dark matter halo is ignored in the dynamical modeling, potentially causing a bias on the determined black hole mass. I ran dynamical models for a sample of 12 galaxies, including a dark matter halo. For galaxies for which the black hole's sphere of influence is not well resolved, I found that the black hole mass is systematically underestimated when the dark matter halo is ignored, while there is almost no effect for galaxies with well resolved sphere of influence.Supermassereiche Schwarze Löcher sind ein fundamentaler Bestandteil unseres Universims im Allgemeinen, und von Galaxien im Besonderen. Fast jede massereiche Galaxie beherbergt ein supermassereiches Schwarzes Loch in seinem Zentrum. Außerdem existiert eine enge Beziehung zwischen dem Wachstum des Schwarzen Loches und der Entwicklung seiner umgebenden Galaxie. Diese zeigt sich besonders in der engen Beziehung zwischen der Masse eines Schwarzen Loches und den Eigenschaften der sphäroidalen Komponente der Galaxie, beispielsweise seiner stellaren Geschwindigkeitsdispersion, seiner Leuchtkraft und seiner Masse. Diese Beziehung erklären zu können, sowie das Wachstum von Schwarzen Löchern zu verstehen, liefert einen wichtigen Beitrag zu unserem Bild der Entstehung und Entwicklung von Galaxien. In dieser Arbeit steuere ich verschiedene Beiträge dazu bei unser Verständnis des Vorkommens Schwarzer Löcher und der Beziehung zu ihren Galaxien zu verbessern. Zunächst versuche ich ein vollständiges Bild der Anzahl und Eigenschaften Schwarzer Löcher zu erhalten. Dazu beschränke ich mich auf aktive Schwarze Löcher, wie man sie im Universum als Aktive Galaxienkerne (AGN) in großen Himmelsdurchmusterungen finden kann. Ich benutze eine solche Durchmusterung, das Hamburg/ESO Survey (HES), um die AGN Population im lokalen Universum zu studieren. Dazu habe ich die optische Leuchtkraftfunktion von AGN bestimmt. Diese habe ich mit anderen Ergebnissen leuchtschwächerer AGN kombiniert um die bisher beste AGN Leuchtkraftfunktion im lokalen Universum zu erhalten. Der Vergleich mit Ergebnissen bei höherer kosmischer Rotverschiebung bestätigt unser Bild des sogenannten "AGN downsizing". Dies sagt aus, dass leuchtkräftige AGN bei hoher Rotverschiebung am häufigsten vorkommen, während leuchtschwache AGN bei niedriger Rotverschiebung am häufigsten sind. Allerdings verrät uns die AGN Leuchtkraftfunktion allein noch nicht das ganze Bild der Demographie Schwarzer Löcher. Vielmehr sind wir an den zugrunde liegenden Eigenschaften, vor allem der Masse und der Akkretionsrate der Schwarzen Löcher, sowie deren statistischen Verteilungsfunktionen, interessiert. Ich habe eine Methode entwickelt um diese beiden Verteilungsfunktionen zu bestimmen, basierend auf der Maximum-Likelihood-Methode. Ich habe diese Methode benutzt um die aktive Massenfunktion Schwarzer Löcher, sowie die Verteilungsfunktion ihrer Akkretionsraten für das lokale Universum aus dem HES zu bestimmen. Sowohl die Akkretionsraten, als auch die Massen der Schwarzen Löcher zeigen intrinsisch eine breite Verteilung, im Gegensatz zur schmaleren beobachtbaren Verteilung. Der Vergleich der aktiven Massenfunktion mit der gesamten Massenfunktion Schwarzer Löcher zeigt ebenfalls Hinweise auf "AGN downsizing". Als nächstes habe ich mich mit Untersuchungen zur zeitlichen Entwicklung in den Beziehungen zwischen Schwarzem Loch und Galaxie beschäftigt. Diese kann helfen unser theoretisches Veständnis der physikalischen Vorgänge zu verbessern. Beobachtungen sind immer auch Auswahleffekten unterworfen. Diese können die Schlussfolgerungen aus den Beobachtungen zur Entwicklung in den Beziehungen beeinflussen, wenn sie nicht entsprechend berücksichtigt werden. Ich habe den Einfluss von Auswahleffekten auf AGN Stichproben im Detail untersucht, und verschiedende möchgliche Einflussquellen identifiziert, die die Beziehung verfälschen können. Wenn die Auswahlkriterien der Stichprobe, sowie die zugrunde liegenden Verteilungen bekannt sind, so ist es möglich für die Auswahleffekte zu korrigieren. Ich habe eine Methode entwickelt, mit der man die intrinsische Beziehung zwischem Schwarzem Loch und Galaxie aus den Beobachtungen rekonstruieren kann. Schließlich habe ich mich auch inaktiven Schwarzen Löchern und der Bestimmung ihrer Massen gewidmet. Eine der wichtigsten Methoden die Masse Schwarzer Löcher in normalen Galaxien zu bestimmen ist stellardynamische Modellierung. Diese Methode benutzt photometrische und kinematische Beobachtungen, und rekonstruiert daraus das Gravitationspotenzial aus der Analyse stellarer Orbits. Bisher wurde in diesen Modellen allerdings der Einfluss des Halos aus Dunkler Materie vernachlässigt. Dieser kann aber die Bestimmung der Masse des Schwarzen Loches beeinflussen. Ich habe 12 Galaxien mit Hilfe stellardynamischer Modellierung untersucht und dabei auch den Einfluss des Halos aus Dunkler Materie berücksichtigt. Für Galaxien bei denen der Einflussbereich des Schwarzen Loches nicht sehr gut räumlich aufgelöst war, wird die Masse des Schwarzen Loches systematisch unterschätzt, wenn der Dunkle Materie Halo nicht berücksichtigt wird. Auf der anderen Seite ist der Einfluss gering, wenn die Beobachtungen diesen Einflussbereich gut auflösen können.
28
Habouzit, Mélanie. "Formation of supermassive black holes." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066360/document.
Full textAbstract:
Des trous noirs supermassifs (TNs) de plusieurs millions de masses solaires occupent le centre de la plupart des galaxies proches. La découverte du TN Sagittarius A* au centre de notre galaxie, La Voie lactée, l'a confirmé. Pour autant, certaines galaxies semblent dépourvues de TNs (par exemple NGC205, M33), ou alors ne posséder un TN que de quelques milliers de masses solaires. D'autre part, des TNs dans leur forme la plus lumineuse, appelés quasars, dont la luminosité est plus importante que des centaines de fois celle d'une galaxie toute entière, ont été observés à très grand décalage spectral, lorsque l'Univers n'était alors âgé que d'un milliard d'années. Les modèles de formation des TNs doivent expliquer à la fois l'existence des TNs de faibles masses observés aujourd'hui dans les galaxies de faibles masses, mais aussi leur prodigieux homologues quasars dans l'Univers jeune. La formation des TNs pose encore de nos jours de nombreuses questions: comment se forment les TNs au début de l'histoire de l'Univers? Quelle est leur masse initiale? Quelle est la masse minimale d'une galaxie pour posséder un TN? Pour répondre à ces questions et pour étudier la formation des TNs dans le contexte de l'évolution des galaxies, nous avons utilisé des simulations hydrodynamiques cosmologiques, qui offrent l'avantage de suivre l'évolution temporelle de nombreux processus comme la formation stellaire, l'enrichissement en métaux, les mécanismes de rétroactions des TNs et des supernovae. J'ai particulièrement dirigé mes recherches sur les trois principaux modèles de formation des TNs à partir du reliquat des premières étoiles, d'amas d'étoiles, ou encore par effondrement directSupermassive black holes (BHs) harboured in the center of galaxies have been confirmed with the discovery of Sagittarius A* in the center of our galaxy, the Milky Way. Recent surveys indicate that BHs of millions of solar masses are common in most local galaxies, but also that some local galaxies could be lacking BHs (e.g. NGC205, M33), or at least hosting low-mass BHs of few thousands solar masses. Conversely, massive BHs under their most luminous form are called quasars, and their luminosity can be up to hundred times the luminosity of an entire galaxy. We observe these quasars in the very early Universe, less than a billion years after the Big Bang. BH formation models therefore need to explain both the low-mass BHs that are observed in low-mass galaxies today, but also the prodigious quasars we see in the early Universe.BH formation is still puzzling today, and many questions need to be addressed: How are BHs created in the early Universe? What is their initial mass? How many BHs grow efficiently? What is the occurrence of BH formation in high redshift galaxies? What is the minimum galaxy mass to host a BH? We have used cosmological hydrodynamical simulations to capture BH formation in the context of galaxy formation and evolution. Simulations offer the advantage of following in time the evolution of galaxies, and the processes related to them, such as star formation, metal enrichment, feedback of supernovae and BHs. We have particularly focused our studies on the three main BH formation models: Pop III remnant, stellar cluster, and direct collapse models
29
Atkinson, John William. "Demography of supermassive black holes." Thesis, University of Hertfordshire, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.397769.
Full text
30
Peißker, Florian [Verfasser], Andreas [Gutachter] Eckart, and J. Anton [Gutachter] Zensus. "Tracing the Dusty S-cluster Object on its orbit around the supermassive black hole in our galaxy. Near infrared observations with sinfoni at the Very Large Telescope / Florian Peißker ; Gutachter: Andreas Eckart, J. Anton Zensus." Köln : Universitäts- und Stadtbibliothek Köln, 2018. http://d-nb.info/1165772787/34.
Full text
31
Liu, Siming. "Accretion processes around supermassive black holes." Diss., The University of Arizona, 2002. http://hdl.handle.net/10150/289825.
Full textAbstract:
Active Galactic Nuclei (AGNs) are believed to be powered by accretion onto supermassive black holes (BHs). With the development in high resolution observations over a broad frequency range, it is now tenable to study the corresponding physical processes in detail. We find that the emission from the closest supermassive BH candidate, Sagittarius A*, a compact radio source presumably accreting from stellar winds prevailing at the Galactic Center, can be explained as due to a quasi-spherical accretion flow, which circularizes to form a small magnetized accretion disk near the BH's event horizon. The mm/sub-mm and X-ray emissions are produced via thermal synchrotron processes and their self-Comptonization, respectively, in the inner ten Schwarzschild radii of the resultant Keplerian structure. The cm radio emission, however, appears to be produced by non-thermal synchrotron processes in the circularization zone. The recently detected X-ray flare seems to indicate a transient enhancement of mass accretion rate through the inner accretion disk. The 106-day cycle seen at 2.0 cm and 1.3 cm, on the other hand, suggests that the disk is precessing around a spinning BH, whose spin may be determined by timing observation of Sgr A* at mm/sub-mm wavelengths. Our tentative observational result is consistent with this magnetized disk model. The supermassive BH M31*, a compact radio source in the nucleus of M31, has many features in common with Sgr A*, yet their differences are significant. We show that the accretion model being developed for Sgr A* comprises two branches of solutions, distinguished by the relative importance of cooling compared to compressional heating at the capture radius. Sgr A* is presumably a 'hot' BH. While M31* seems to be a member of the 'cold' BH family. The study of the nuclei in radio galaxies reveals many new characteristics of the large scale accretion flows. In NGC 4261, we show that a turbulence-dominated disk, illuminated by its AGN, can not only account for the observed sub-parsec scale radio gap in the core, but also produce the optical broad lines emitted from the region. However, the prominent radio jets distinguish such BHs from those in the compact radio sources. The relativistic jets are probably driven by the action of supermassive, fast spinning BHs. Our study on NGC 6251* indicates that the initial ejection of matter can be associated with the thermal expansion of the accreted gas, which is heated by a spinning BH near its even horizon.
32
Clavel, Maïca. "Activité du trou noir supermassif au centre de la Galaxie." Thesis, Paris 11, 2014. http://www.theses.fr/2014PA112170/document.
Full textAbstract:
Le centre de la Galaxie abrite un trou noir supermassif, Sagittarius A*. Sa proximité en fait un laboratoire privilégié pour étudier les phénomènes d’accrétion à l’œuvre autour des trous noirs et contraindre le cycle d’activité de ces astres. Sgr A* est actuellement extrêmement peu lumineux et malgré des sursauts d’activité quotidiens sa luminosité demeure au moins huit ordres de grandeur en dessous de sa luminosité d’Eddington. Cet objet est ainsi l’un des trous noirs supermassifs connus les moins lumineux. Les mécanismes radiatifs à l’origine des variations quotidiennes observées ne sont pas clairement identifiés. Nous présentons les résultats d’une campagne d’observation multi-longueurs d’onde visant à mesurer le spectre de ces événements simultanément en rayons X et en infrarouge proche, à l’aide de l’observatoire XMM-Newton et de l’instrument VLT/NACO. Les données infrarouges obtenues grâce à la technique de spectro-imagerie en bande large ont permis d’étudier la variabilité du spectre de Sgr A* en infrarouge. Les incertitudes liées aux erreurs systématiques sont encore importantes mais les premiers tests réalisés semblent indiquer que l’indice spectral pourrait dépendre de la luminosité du trou noir. Sur des échelles de temps plus grandes, nous montrons également que Sgr A* n’a pas toujours été aussi peu actif. Des traces de son activité passée sont en effet visibles dans la matière moléculaire directement autour du trou noir, notamment sous la forme d’un rayonnement réfléchi visible dans la raie de fluorescence du fer à 6.4 keV. Nous avons réalisé une étude complète et systématique des variations de cette émission détectée dans la zone moléculaire centrale en utilisant les observatoires Chandra et XMM-Newton. Nos résultats confirment que Sgr A* a connu des sursauts intenses au cours des derniers siècles, au moins six ordre de grandeur en dessus de la luminosité actuelle. En particulier, nous avons mis en évidence, pour la première fois, la présence de deux événements transitoires distincts de relativement courte durée, probablement liés à des événements catastrophiques. Ces résultats constituent une première étape pour relier l’activité de ce trou noir spécifique aux autres noyaux de galaxie présents dans l’UniversSagittarius A⋆ is the supermassive black hole at the Galactic center. Due to its proximity, this specimen is an excellent laboratory to study the accretion processes occurring around black holes and to constrain the duty cycle of these objects. Sgr A* is currently extremely faint and despite the detection of daily flares, its luminosity remains at least eight orders of magnitude below its Eddington luminosity, making this specimen one of the least luminous known supermassive black holes. The radiative processes responsible for the daily variations of its luminosity have not been clearly identified yet. We present the results of a multi-wavelength campaign observing Sgr A* simultaneously in X-rays and in the near-infrared, using the XMM-Newton observatory and the VLT/NACO instrument. We studied the spectral variability of Sgr A* using the infrared data we obtained through a spectro-imaging technique. Uncertainties linked to the systematic errors are still large but the first tests applied seem to show that the spectral index of Sgr A* could depend on the black hole luminosity. On longer timescales, we demonstrate that Sgr A* experienced a higher level of activity in the recent past. Indeed, echoes of its past activity can be detected in the molecular material surrounding the black hole. They are traced by a strong signal in the iron fluorescence line at 6.4 keV. We achieved a complete and systematic study of this variable emission detected from the central molecular zone, using Chandra and XMM-Newton observatories. Our results confirm that Sgr A* experienced intense flares in the past few centuries, with a luminosity at least six orders of magnitude higher than its current one. In particular, we highlight for the first time the existence of two distinct transient events of relatively short duration, which are probably due to catastrophic events. These results are the first step needed to include Sgr A*’s activity into a broader understanding of the galactic nuclei
33
Babic, Ana. "The Cosmological Evolution of Supermassive Black Holes." Thesis, University of Oxford, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.487136.
Full textAbstract:
It is now thought that all massive galaxies contain supermassive (> 106 M0 ) black holes. A model relating the history of supermassive black hole growth and the history of dark matter halo assembly is presented. It is based on the Press-Schechter formalism, and an analytic expression for the mean rate of mass accretion onto dark matter haloes. A simple assumption that the time scale' of the black hole growth is the same as the time scale for the host halo growth leads to a prediction for the mean Eddington ratio (>'Edd = LboI/LEdd) , that is a strong function of the cosmic epoch. Observational consequences of the model are investigated in the optical and X-ray bands. Good agreement between the model and the observations is found, if the relation between the dark matter halo mass and the black hole mass is allowed to evolve with redshift. The required additional evolution depends on the method for obtaining the black hole mass function, but in both investigated cases is mild, compared to some of the observational and theoretical reports in the literature. The model for the supermassive black hole gro~th is simple, yet it is able to account for a large portion of the observed active galactic nuclei (AGN) evolution. Motivated by the model's prediction that the Eddington ratio averaged over the population of haloes evolves strongly with epoch, Eddington ratios for a sample of hard X-ray selected AGN in the Chandra Deep Field South are investigated. The epoch (z < 1) and the luminosity range (L2-1O keY = 1041 - 1045 erg s-l) of the sample probe the AGN population implicated in AGN 'cosmic downsizing'. The results indicate a differen~ picture than the one previously inferred from optically-selected samples: the AGN responsible for the observed downsizing are powered by average-sized black holes (MBH rv 108 M0 ), typically radiating at low Eddington ratios (>'Edd rv 0.01). This finding, together with the fact that high-redshift, higher luminosity AGN are typically found radiating close to the Eddington limit, indicates that diminishing accretion rates play an important role in the observed AGN downsizing.
34
Nixon, Christopher James. "Chaotic accretion and merging supermassive black holes." Thesis, University of Leicester, 2012. http://hdl.handle.net/2381/11034.
Full textAbstract:
The main driver of the work in this thesis is the idea of chaotic accretion in galaxy centres. Most research in this area focuses on orderly or coherent accretion where supermassive black holes or supermassive black hole binaries are fed with gas always possessing the same sense of angular momentum. If instead gas flows in galaxies are chaotic, feeding occurs through randomly oriented depositions of gas. Previous works show that this chaotic mode of feeding can explain some astrophysical phenomena, such as the lack of correlation between host galaxy structure and the direction of jets. It has also been shown that by keeping the black hole spin low this feeding mechanism can grow supermassive black holes from stellar mass seeds. In this thesis I show that it also alleviates the ‘final parsec problem’ by facilitating the merger of two supermassive black holes, and the growth of supermassive black holes through rapid accretion. I also develop the intriguing possibility of breaking a warped disc into two or more distinct planes.
35
Melia, F., and T. M. McClintock. "Supermassive black holes in the early Universe." The Royal Society, 2015. http://hdl.handle.net/10150/614765.
Full textAbstract:
The recent discovery of the ultraluminous quasar SDSS J010013.02+280225.8 at
redshift 6.3 has exacerbated the time compression problem implied by the appearance
of supermassive black holes only $\sim 900$ Myr after the big bang, and only $\sim
500$ Myr beyond the formation of Pop II and III stars. Aside from heralding the
onset of cosmic reionization, these first and second generation stars could have
reasonably produced the $\sim 5-20\;M_\odot$ seeds that eventually grew into $z\sim
6-7$ quasars. But this process would have taken $\sim 900$ Myr, a timeline that
appears to be at odds with the predictions of $\Lambda$CDM without an anomalously
high accretion rate, or some exotic creation of $\sim 10^5\;M_\odot$ seeds. There
is no evidence of either of these happening in the local universe. In this paper,
we show that a much simpler, more elegant solution to the supermassive
black hole anomaly is instead to view this process using the age-redshift relation
predicted by the $R_{\rm h}=ct$ Universe, an FRW cosmology with zero active mass.
In this context, cosmic reionization lasted from $t\sim 883$ Myr to $\sim 2$ Gyr
($6\lesssim z\lesssim 15$), so $\sim 5-20\;M_\odot$ black hole seeds formed
shortly after reionization had begun, would have evolved into $\sim 10^{10}\;
M_\odot$ quasars by $z\sim 6-7$ simply via the standard Eddington-limited
accretion rate. The consistency of these observations with the age-redshift
relationship predicted by $R_{\rm h}=ct$ supports the existence of dark
energy; but not in the form of a cosmological constant.
36
Yi, Qiang. "The cosmological evolution of supermassive black holes." Thesis, University of Oxford, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.559791.
Full textAbstract:
In this thesis we investigate selection effects in astrophysical observations. We demonstrate that the determination of the quasar black hole mass function and Eddington ratio distribution via observations are biased. By modelling the quasar selection function and the black hole mass measurement process we show that one is able to infer the true distribution of physical quantities from observations. We present the intrinsic accretion rates of AGN, the intrinsic accretion rates and the black hole mass function for optically selected quasars up to redshift of two. The results show that the Eddington limit continues to be a real physical limit to black hole accretion. We present a new upper limit of black hole masses from the inferred intrinsic black hole mass function and demonstrate the need of a mass dependent accretion rate in accordance with down sizing. Finally we investigate correlations between radio luminosity and observed black hole mass for optically selected quasars. We first show that mixing of fiat and steep spectrum quasars leads to results that are dependent on the observing frequency, and therefore should be treated with caution. We demonstrate that beaming of the radio core together with an orientation dependent optical selection effect can give rise to a bimodal distribution in the radio luminosities of optically selected quasars.
37
Khan, Abid, Vasileios Paschalidis, Milton Ruiz, and Stuart L. Shapiro. "Disks around merging binary black holes: From GW150914 to supermassive black holes." AMER PHYSICAL SOC, 2018. http://hdl.handle.net/10150/627161.
Full textAbstract:
We perform magnetohydrodynamic simulations in full general relativity of disk accretion onto nonspinning black hole binaries with mass ratio q = 29/36. We survey different disk models which differ in their scale height, total size and magnetic field to quantify the robustness of previous simulations on the initial disk model. Scaling our simulations to LIGO GW150914 we find that such systems could explain possible gravitational wave and electromagnetic counterparts such as the Fermi GBM hard x-ray signal reported 0.4 s after GW150915 ended. Scaling our simulations to supermassive binary black holes, we find that observable flow properties such as accretion rate periodicities, the emergence of jets throughout inspiral, merger and postmerger, disk temperatures, thermal frequencies, and the time delay between merger and the boost in jet outflows that we reported in earlier studies display only modest dependence on the initial disk model we consider here.
38
Rebusco, Paola. "Impact of supermassive black holes on galaxy clusters." Diss., [S.l.] : [s.n.], 2007. http://edoc.ub.uni-muenchen.de/archive/00006900.
Full text
39
Collinson, James Stuart. "Spectral and temporal studies of supermassive black holes." Thesis, Durham University, 2016. http://etheses.dur.ac.uk/11814/.
Full textAbstract:
In this thesis, I present analysis and interpretation of the multiwavelength spectra and variability of Active Galactic Nuclei (AGN). The most luminous sustained sources in the Universe, these powerful objects are consistent with being the result of gas accretion on to central galactic supermassive black holes. Due to their compact sizes, the inner regions of AGN cannot be spatially resolved by conventional means, so we must instead use spectroscopy and temporal monitoring to determine their composition and structure. I undertake a number of studies of the spectral energy distributions (SEDs) of AGN, using data from infrared-X-ray bands and employing a range of numerical models. Results from SED modelling of 11 moderate redshift (1.5 < z < 2.2) AGN are presented, in which there is a selection bias towards nuclei with cooler accretion discs. I find that the peak of the SED is sampled by our data for 5/11 objects, thereby breaking several of the model degeneracies that affected previous studies. This results in stronger constraints on the physical processes at work in these AGN, and provides a powerful tool with which I examine and discuss the relationships between the various radiating components, including those of the emission line regions, dusty torus and host galaxy. I then explore the nature of four 'hypervariable' AGN, for which the origin of their extreme variability is currently unknown. Through an investigation of their SEDs, I find that either an accretion rate change, or gravitational microlensing by a star in a foreground galaxy, are energetically consistent with the data. The new insights provided by this work lead me to suggest several worthwhile routes for the future development of research in these areas. With the next generation of telescopes, satellites and surveys on the horizon, it will be possible to build on my results, to further our understanding of AGN.
40
Zubovas, Kastytis. "Accretion and feedback processes in supermassive black holes." Thesis, University of Leicester, 2012. http://hdl.handle.net/2381/27634.
Full textAbstract:
Supermassive black holes (SMBHs) have been gradually recognised as important elements of galaxy and cosmic structure evolution. Their connection with the large-scale environment is maintained via feedback processes – communication of a fraction of the accretion luminosity to the host galaxy. Feedback is conjectured to expel gas from galaxies, quench star formation and establish the observed correlations between SMBH mass and host galaxy properties. Efficient feedback requires rapid gas accretion and is therefore usually investigated within the context of quasar activity phases in SMBH evolution. In this Thesis, I investigate several implications of an SMBH wind feedback model, advancing our understanding of feedback processes and the immediate environment of SMBHs. I consider analytically the large-scale outflows and their observable properties. I find that rapidly accreting SMBHs may sweep galaxies clear of gas, turning them into red-and-dead spheroids. I apply the same feedback model to our Galaxy. Its SMBH, Sgr A∗, is currently exceptionally quiescent, although it must have been more active in the past in order to have grown to its present size. I investigate, both analytically and numerically, a short burst of activity which may have occurred ∼ 6 million years ago, producing an outflow which formed two large γ-ray emitting bubbles perpendicular to the Galactic plane. The results show that dynamical footprints of outflows may persist for a long time and provide evidence of past AGN activity in quiescent galaxies. I also present a model for the short-timescale flares observed daily in Sgr A∗, based on tidal disruption and evaporation of asteroids in the vicinity of the SMBH. The model explains some observed flare properties, and thus improves our understanding of the processes occurring close to the SMBH. It also provides predictions for observable effects as the quiescent luminosity of Sgr A∗ varies on long timescales.
41
Stone, Nicholas Chamberlain. "Tidal Disruption of Stars by Supermassive Black Holes." Thesis, Harvard University, 2013. http://dissertations.umi.com/gsas.harvard:10998.
Full textAbstract:
This thesis presents theoretical results on the tidal disruption of stars by supermassive black holes (SMBHs). The multiwavelength ares produced by tidal disruption events (TDEs) have supernova-like luminosities, and associated relativistic jets can be visible to cosmological distances. TDEs probe the demography of quiescent SMBHs, and are natural laboratories for jet launching mechanisms and super-Eddington accretion. The first chapter broadly surveys TDE physics. The second and third chapters estimate the TDE rate following gravitational wave (GW) recoil of a SMBH (after a SMBH binary merger). Immediately after GW recoil, the TDE rate increases, sometimes to \(~10^{-1}\) TDEs per year. This "burst" of TDE flares can provide an electromagnetic counterpart to low frequency GW signals, localizing sources and measuring cosmological parameters. Millions of years later, recoiled SMBHs wandering through their host galaxies will produce spatially offset TDEs at a rate which is likely detectable with the LSST. In the fourth chapter, we show that standard estimates for \(\Delta\epsilon\), the energy spread of TDE debris, are wrong, sometimes by orders of magnitude. Correcting this error reduces the observability of many TDEs. We introduce a new analytic model for tidal disruption, calculate \(\Delta\epsilon\)'s dependence on stellar spin, estimate general relativistic corrections to \(\Delta\epsilon\), and quantify the GW signal generated from tidal compression. The fifth chapter presents hydrodynamical simulations of TDE debris circularization, focusing on eccentric, rather than parabolic, orbits. General relativistic precession drives debris circularization, in contrast to past simulations using smaller black holes. In the sixth chapter, we show that TDE light curves can constrain or measure SMBH spins, as Lense-Thirring torques produce quasiperiodic variability in disk emission. Precession of a relativistic jet could also measure SMBH spin, and we apply our model to the relativistic Swift 1644+57 TDE. The seventh chapter considers the disruption of neutron stars (NSs) by stellar mass black holes (BHs) or other NSs. Jet precession in associated short-hard gamma ray bursts is uniquely possible for NS-BH (not NS-NS) mergers. We quantify typical precession amplitudes and periods, and calculate their time evolution. If disk viscosities are relatively low, electromagnetic observations alone could distinguish NS-BH from NS-NS mergers.Astronomy
42
Ghosh, Himel. "A Search for the Smallest Supermassive Black Holes." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1253492291.
Full text
43
Ichikawa, Kohei. "Study of Dust-Torus Properties around Supermassive Black Holes." 京都大学 (Kyoto University), 2015. http://hdl.handle.net/2433/199105.
Full text
44
Hartwig, Tilman. "Formation and growth of the first supermassive black holes." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066386/document.
Full textAbstract:
Les trous noirs supermassifs résident dans les centres de la plupart des galaxies massives et on observe des corrélations entre leurs masses et les propriétés de leurs galaxies hôtes. De plus, on observe des trous noirs de plus d’un milliard de masses solaires quelques centaines de millions d’années seulement après le Big Bang. Ces trous noirs supermassifs présents dans l’univers jeune ne sont que le sommet de l’iceberg de l’ensemble de la population de trous noirs, mais ils mettent en question notre compréhension de la formation et de la croissance des premiers trous noirs. Notre nouvelle méthode améliorant le calcul de la densité de colonne de H2 donne des probabilités pour former des graines massives de trous noirs qui sont plus d’un ordre de grandeur plus élevées que prédit précédemment. Nous trouvons que CR7 pourrait être le premier candidat à héberger un tel trou noir formé par effondrement direct et nous démentons l’existence initialement revendiquée d’une population stellaire massive primordial dans CR7. Nous calculons la densité des taux de fusion des trous noirs binaires des premières étoiles et leurs taux de détection avec aLIGO. Notre modèle démontre que les détections des ondes gravitationnelles à venir au cours des prochaines décennies permettront d’imposer des contraintes plus strictes sur les propriétés des premières étoiles et donc sur les scénarios de formation des premiers trous noirs. Nous développons un modèle analytique en 2D de la rétroaction des noyaux actifs de galaxie pour démontrer qu’un profil de disque plus réaliste réduit la quantité de gaz qui est éjectée du halo par rapport aux modèles 1D existants. La rétroaction empêche l’accretion de gaz sur le trou noir central pendant seulement ∼1 million d’année environ, ce qui permet une accretion de gaz presque continue dans le plan du disque. Avec cette thèse, je contribue à une meilleure compréhension de la formation et la croissance des premiers trous noirs supermassifsSupermassive black holes reside in the centres of most massive galaxies and we observe correlations between their mass and properties of the host galaxies. Besides this correlation between a galaxy and its central black hole (BH), we see BHs more massive than one billion solar masses already a few hundred million years after the Big Bang. These supermassive BHs at high redshift are just the tip of the iceberg of the entire BH population, but they challenge our understanding of the formation and growth of the first BHs. Our improved method to calculate H2 self-shielding yields probabilities to form massive seed BHs that are more than one order of magnitude higher, than previously expected. We find that CR7 might be the first candidate to host such a direct collapse BH and we disprove the initially claimed existence of a massive metal-free stellar population in CR7. We calculate the merger rate density of binary BHs from the first stars and their detection rates with aLIGO. Our model demonstrates that upcoming detections of gravitational waves in the next decades will allow to put tighter constraints on the properties of the first stars and therefore on formation scenarios of the first BHs. We develop a 2D analytical model of active galactic nuclei-driven outflows to demonstrate that a more realistic disc profile reduces the amount of gas that is ejected out of the halo, compared to existing 1D models. The outflow prevents gas accretion on to the central BH for only about ∼1Myr, which permits almost continuous gas inflow in the disc plane. With this thesis, I contribute to a better understanding of the formation and growth of the first supermassive BHs
45
Schulze, Andreas [Verfasser], and Lutz [Akademischer Betreuer] Wisotzki. "Demographics of supermassive black holes / Andreas Schulze. Betreuer: Lutz Wisotzki." Potsdam : Universitätsbibliothek der Universität Potsdam, 2011. http://d-nb.info/1016576269/34.
Full text
46
Bradshaw, Emma J. "Supermassive black holes and feedback in the high redshift universe." Thesis, University of Nottingham, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.604307.
Full textAbstract:
In this thesis I use the UKIDSS Ultra-Deep Survey and complementary spectroscopic survey (the UDSz) to investigate AGN and galaxy evolution across a wide redshift range 1.0 < z < 2.5. The work presented here is divided broadly into two themes: a study of AGN and how they are affected by their environment, and a study of galactic winds and feedback processes. To explore how AGN are affected by their environment, I use angular crosscorrelation techniques to study X-ray and radio-loud AGN as a function of galaxy density in the red shift range 1.0 < z < 1.5. I find that AGN preferentially reside in over dense environments at these epochs, typically residing in dark matter halos of mass M2: 5x 1013 M0 . This is in contrast to what I find in the local Universe, where typical X-ray AGN reside in a range of environments, including small groups of galaxies and the outskirts of moderately dense clusters. To study galactic winds and feedback processes, I use spectra from the UDSz spectroscopic survey. This survey is a recent enhancement of the UDS, in which rv3500 high redshift galaxy spectra were obtained using the VIMOS and FORS2 spectrographs on the VLT. I discuss the data reduction and the process of redshift determination of the VIMOS data. rv1600 galaxy spectra are used in the work on feedback and galactic winds as a direct consequence of the reduction. Using the UDSz spectra, I then present a study of galactic-scale outflows at redshift 0.71 < z < 1.63. For this work, I use a large sample of galaxies with an average stellar mass of rv 109.5 M0 and spanning a wide range of rest-frame colours, which represent typical star-forming galaxies at this epoch. By stacking the data by galaxy property, I find that outflows are present in virtually all spectral stacks, with velocities ranging from 100-1000 km S-1. The highest velocity outflows (2:500 km S-1) are found in galaxies with the highest stellar masses and the youngest stellar populations. Our findings suggest that high velocity outflows are mostly driven by star-forming processes rather than AGN, with implied mass outflow rates COlTlparable to the rates of star formation. Such behaviour is consistent with models required to reproduce the high redshift mass-metallicity relation. To investigate the mass-metallicity relation further, I use the UV region of the electromagnetic spectrum to investigate metallicities of galaxies at redshifts 1.0 < z < 2.5. I confirm that, at this epoch, the most massive galaxies tend to be the most metal rich. I also find that these galaxies have a lower metallicity than analogous galaxies in the local Universe. From our investigation into galactic winds and feedback processes, I conclude that these mechanisms have an extremely important role to play in galaxy evolution. Consequently. disentangling the precise balance of star formation, galactic winds and AGN-driven winds in galaxies will remain a significant topic of research in astronomy in years to come. ix \.
47
Inayoshi, Kohei. "Formation of supermassive black holes in the high-redshift universe." 京都大学 (Kyoto University), 2014. http://hdl.handle.net/2433/188476.
Full text
48
Bhayani, Shyam. "X-ray diagnostics of relativistic reflection around supermassive black holes." Thesis, Imperial College London, 2011. http://hdl.handle.net/10044/1/8957.
Full textAbstract:
This thesis presents an investigation into the X-ray energy and variability spectra of Seyfert galaxies. Reflection of the X-ray continuum by the accretion disc in these Active Galactic Nuclei (AGN) is expected to produce an iron line and an associated reflection continuum. The iron line should be relativistically broadened as it is subject to the strong gravitational field of the central black hole. Often, such a line is never found either because it appears not to be present or if it is, the magnitude of the broadening is less than expected. These cases pose a problem for the current understanding of accretion onto the black hole in AGN. We analyse the XMM-Newton observations of such objects to determine if the relativistically broadened iron line only appears to be “missing” because the accretion disc is ionised and/or there is a strong concentration of the line emission in the central disc regions. In the latter scenario, it is possible for the iron line to be smeared to such an extent that it blends into the continuum and is therefore difficult to disentangle. A combination of both effects leads to the identification of a relativistically broadened iron line in the majority of the observations where it could not be detected previously. In some of these objects, blurred disc reflection can also be detected if there is an additional source of iron line emission that arises further from the black hole such as in the Broad Line Region. We find that the strength of the blurred iron line and associated reflection continuum in these objects is consistent with the sources that exhibit a “classical” relativistically broadened iron line. Following this, we investigate the variability of the iron line in our sample of Seyferts. In models of accretion disc reflection, a simple prediction is that variations in the reflection component should follow variations in the X-ray continuum that illuminates the disc. Using unnormalised rms variance-spectra, we investigate if this scenario is typical in our sample of observations and find that it is not generally confirmed. Instead, there is a large amount of diversity in the behaviour of the iron line variability. For example, some observations possess an iron line that is more variable than the continuum, while other iron lines exhibit variability only bluewards of the line core. Most interestingly, a large group of observations possess a broad iron line that is invariant to the continuum and there are changes in the variability of the iron line between multiple observations of the same object. In some cases, the rms spectra can distinguish between models that explain the broad red wing of the iron line. Finally, we expand the variability analysis to between 0.3 – 10 keV and focus on the broadband X-ray variability on short time-scales (~ 40 ks). After normalising the variance spectra by the X-ray flux, a diverse range of amplitudes and shapes are found in the variance-spectra of both different objects and the same object. Part of the scatter in the amplitudes is due to the anti-correlation between the black hole mass of an AGN and its variance, while the various classes of profile shapes suggest that there are intrinsic differences in the spectral variability throughout the sample, as found with the iron line. We model variance-spectra that are based on relativistic disc reflection and velocity-smeared models of the broadband X-ray spectra of AGN and find that a range of profile shapes are possible. The mean variance-spectrum of those that are humped in the sample can be explained solely by a small increase in the slope of the continuum as the X-ray flux increases in a reflection-based model. Interestingly, there is no requirement for either the disc reflection or absorbers local to the AGN to respond to the changing illuminating intensity.
49
Lusso, Elisabeta <1983>. "A panchromatic view of the evolution of supermassive black holes." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2011. http://amsdottorato.unibo.it/3740/1/Lusso_Elisabeta_tesi.pdf.
Full textAbstract:
This PhD Thesis is devoted to the accurate analysis of the physical properties of Active Galactic Nuclei (AGN) and the AGN/host-galaxy interplay. Due to the broad-band AGN emission (from radio to hard X-rays), a multi-wavelength approach is mandatory.
Our research is carried out over the COSMOS field, within the context of the XMM-Newton wide-field survey. To date, the COSMOS field is a unique area for comprehensive multi-wavelength studies, allowing us to define a large and homogeneous sample of QSOs with a well-sampled spectral coverage and to keep selection effects under control. Moreover, the broad-band information contained in the COSMOS database is well-suited for a detailed analysis of AGN SEDs, bolometric luminosities
and bolometric corrections.
In order to investigate the nature of both obscured (Type-2) and unobscured (Type-1) AGN, the observational approach is complemented with a theoretical modelling of the AGN/galaxy co-evolution.
The X-ray to optical properties of an X-ray selected Type-1 AGN sample are discussed in the first part. The relationship between X-ray and optical/UV luminosities, parametrized by the spectral index αox, provides a first indication about the nature of the central engine powering the AGN.
Since a Type-1 AGN outshines the surrounding environment, it is extremely difficult to constrain the properties of its host-galaxy. Conversely, in Type-2 AGN the host-galaxy light is the dominant component of the optical/near-IR SEDs, severely affecting the recovery of the intrinsic AGN emission. Hence a multi-component SED-fitting code is developed to disentangle the emission of the stellar populationof the galaxy from that associated with mass accretion.
Bolometric corrections, luminosities, stellar masses and star-formation rates, correlated with the morphology of Type-2 AGN hosts, are presented in the second part, while the final part concerns a physically-motivated model for the evolution of spheroidal galaxies with a central SMBH. The model is able to reproduce two important stages of galaxy evolution, namely the obscured cold-phase and the subsequent quiescent hot-phase.
50
Lusso, Elisabeta <1983>. "A panchromatic view of the evolution of supermassive black holes." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2011. http://amsdottorato.unibo.it/3740/.
Full textAbstract:
This PhD Thesis is devoted to the accurate analysis of the physical properties of Active Galactic Nuclei (AGN) and the AGN/host-galaxy interplay. Due to the broad-band AGN emission (from radio to hard X-rays), a multi-wavelength approach is mandatory.
Our research is carried out over the COSMOS field, within the context of the XMM-Newton wide-field survey. To date, the COSMOS field is a unique area for comprehensive multi-wavelength studies, allowing us to define a large and homogeneous sample of QSOs with a well-sampled spectral coverage and to keep selection effects under control. Moreover, the broad-band information contained in the COSMOS database is well-suited for a detailed analysis of AGN SEDs, bolometric luminosities
and bolometric corrections.
In order to investigate the nature of both obscured (Type-2) and unobscured (Type-1) AGN, the observational approach is complemented with a theoretical modelling of the AGN/galaxy co-evolution.
The X-ray to optical properties of an X-ray selected Type-1 AGN sample are discussed in the first part. The relationship between X-ray and optical/UV luminosities, parametrized by the spectral index αox, provides a first indication about the nature of the central engine powering the AGN.
Since a Type-1 AGN outshines the surrounding environment, it is extremely difficult to constrain the properties of its host-galaxy. Conversely, in Type-2 AGN the host-galaxy light is the dominant component of the optical/near-IR SEDs, severely affecting the recovery of the intrinsic AGN emission. Hence a multi-component SED-fitting code is developed to disentangle the emission of the stellar populationof the galaxy from that associated with mass accretion.
Bolometric corrections, luminosities, stellar masses and star-formation rates, correlated with the morphology of Type-2 AGN hosts, are presented in the second part, while the final part concerns a physically-motivated model for the evolution of spheroidal galaxies with a central SMBH. The model is able to reproduce two important stages of galaxy evolution, namely the obscured cold-phase and the subsequent quiescent hot-phase.