@phdthesis{Schulze2011,
  author    = {Schulze, Andreas},
  title     = {Demographics of supermassive black holes},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-54464},
  school      = {Universit{\"a}t Potsdam},
  year      = {2011},
  abstract  = {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.},
  language  = {en}
}
@phdthesis{Renard2019,
  author    = {Renard, L{\´e}a},
  title     = {Socio-histoire de l'observation statistique de l'alt{\´e}rit{\´e}},
  school      = {Universit{\"a}t Potsdam},
  pages     = {590},
  year      = {2019},
  abstract  = {Autour de 1990 en France et de 2005 en Allemagne, deux nouvelles cat{\´e}gories sont introduites dans le champ de la statistique de la population. Toutes deux, « immigr{\´e} » et « Person mit Migrationshintergrund », font appel au registre de la migration pour qualifier un groupe de population. Notre analyse montre que ces deux {\´e}v{\´e}nements sont r{\´e}v{\´e}lateurs d'un changement de signification des cat{\´e}gorisations statistiques de la migration dans les deux pays, de la description de la mobilit{\´e} vers l'observation de l'alt{\´e}rit{\´e} de la population, changement li{\´e} au contexte de la politique publique dite d'« int{\´e}gration » qui se d{\´e}veloppe en France et en Allemagne dans les ann{\´e}es 1990-2000. La th{\`e}se interroge ainsi la mani{\`e}re dont la statistique rend la migration socialement pertinente pour construire l'alt{\´e}rit{\´e}. Pour pouvoir comprendre le virage entrepris dans les nomenclatures statistiques et le resituer dans une perspective de longue dur{\´e}e, nous avons postul{\´e} qu'il fallait aller chercher dans l'histoire de la statistique ce qui avait tenu lieu de classification principale de la population, en lieu et place des nouvelles cat{\´e}gories invent{\´e}es au tournant des XXe et XXIe si{\`e}cles. Nous nous sommes donc interrog{\´e}e sur la gen{\`e}se et l'institutionnalisation des cat{\´e}gories de l'alt{\´e}rit{\´e} et de la mobilit{\´e} dans la p{\´e}riode 1880-1914, alors que la France et l'Allemagne, {\`a} l'{\´e}poque le Deutsches Kaiserreich, se constituent en {\´E}tats-nations et en empires coloniaux. Pour observer ces processus empiriquement, nous avons choisi de comparer les pratiques de cat{\´e}gorisation de l'alt{\´e}rit{\´e} et la mobilit{\´e} (1) en France et en Allemagne, (2) {\`a} deux p{\´e}riodes diff{\´e}rentes, 1880-1914 et 1990-2010, et (3) dans le contexte m{\´e}tropolitain et colonial. L'analyse socio-historique compar{\´e}e d'apr{\`e}s la m{\´e}thodologie de la comparaison en contexte a repos{\´e} sur une asym{\´e}trie assum{\´e}e entre les deux p{\´e}riodes {\´e}tudi{\´e}es : tandis qu'il s'agissait de reconstruire la gen{\`e}se des cat{\´e}gories « immigr{\´e} » et « Person mit Migrationshintergrund » {\`a} deux moments distincts temporellement en France et en Allemagne, l'analyse de la p{\´e}riode 1880-1914 a consist{\´e} {\`a} mettre au jour ruptures et continuit{\´e}s historiques des principes de classification sur l'ensemble de la p{\´e}riode dans une perspective crois{\´e}e. La d{\´e}marche n'est ni chronologique ni r{\´e}trospective : elle contraste deux configurations historiques pour tenter d'identifier des ressemblances et des diff{\´e}rences. Nos r{\´e}sultats montrent qu'entre 1880 et 1914, la cat{\´e}gorie de migration est majoritairement associ{\´e}e {\`a} un ph{\´e}nom{\`e}ne de mobilit{\´e} dans les discours politiques et statistiques. {\`A} cette {\´e}poque, la focale se porte sur l'{\´e}migration, red{\´e}finie comme un d{\´e}placement g{\´e}ographique en dehors des fronti{\`e}res de la nation et de l'Empire. Le transport des « {\´e}migrants », cat{\´e}gorie de population qui nourrit le d{\´e}bat et les tableaux statistiques, fait l'objet des probl{\´e}matisations politiques. Les statistiques relatives {\`a} l'{\´e}migration comme mobilit{\´e} {\´e}taient alors s{\´e}par{\´e}es de l'observation de la composition de la population, {\`a} travers le crit{\`e}re de la nationalit{\´e} dans le contexte m{\´e}tropolitain et des sch{\´e}mas « raciaux » dans le contexte colonial. En 1990 en France et 2005 en Allemagne, le registre de la migration est mobilis{\´e} cette fois pour observer statistiquement la composition de la population. Nos r{\´e}sultats ont permis de mettre au jour trois principes de construction de l'alt{\´e}rit{\´e} dans les deux pays et dans les deux p{\´e}riodes {\´e}tudi{\´e}es : un principe national, un principe colonial et un principe migratoire. La th{\`e}se d{\´e}veloppe ainsi une approche renouvel{\´e}e des interactions entre observation statistique et politique publique, en testant empiriquement sur le terrain des statistiques relatives {\`a} la migration l'hypoth{\`e}se de la « circularit{\´e} du savoir et de l'action » mise au point par Alain Desrosi{\`e}res},
  language  = {fr}
}
@phdthesis{DeAndradeQueiroz2023,
  author    = {De Andrade Queiroz, Anna Barbara},
  title     = {The Milky Way disks, bulge, and bar sub-populations},
  doi       = {10.25932/publishup-59061},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-590615},
  school      = {Universit{\"a}t Potsdam},
  pages     = {xii, 187},
  year      = {2023},
  abstract  = {In recent decades, astronomy has seen a boom in large-scale stellar surveys of the Galaxy. The detailed information obtained about millions of individual stars in the Milky Way is bringing us a step closer to answering one of the most outstanding questions in astrophysics: how do galaxies form and evolve? The Milky Way is the only galaxy where we can dissect many stars into their high-dimensional chemical composition and complete phase space, which analogously as fossil records can unveil the past history of the genesis of the Galaxy. The processes that lead to large structure formation, such as the Milky Way, are critical for constraining cosmological models; we call this line of study Galactic archaeology or near-field cosmology. At the core of this work, we present a collection of efforts to chemically and dynamically characterise the disks and bulge of our Galaxy. The results we present in this thesis have only been possible thanks to the advent of the Gaia astrometric satellite, which has revolutionised the field of Galactic archaeology by precisely measuring the positions, parallax distances and motions of more than a billion stars. Another, though not less important, breakthrough is the APOGEE survey, which has observed spectra in the near-infrared peering into the dusty regions of the Galaxy, allowing us to determine detailed chemical abundance patterns in hundreds of thousands of stars. To accurately depict the Milky Way structure, we use and develop the Bayesian isochrone fitting tool/code called StarHorse; this software can predict stellar distances, extinctions and ages by combining astrometry, photometry and spectroscopy based on stellar evolutionary models. The StarHorse code is pivotal to calculating distances where Gaia parallaxes alone cannot allow accurate estimates. We show that by combining Gaia, APOGEE, photometric surveys and using StarHorse, we can produce a chemical cartography of the Milky way disks from their outermost to innermost parts. Such a map is unprecedented in the inner Galaxy. It reveals a continuity of the bimodal chemical pattern previously detected in the solar neighbourhood, indicating two populations with distinct formation histories. Furthermore, the data reveals a chemical gradient within the thin disk where the content of 𝛼-process elements and metals is higher towards the centre. Focusing on a sample in the inner MW we confirm the extension of the chemical duality to the innermost regions of the Galaxy. We find stars with bar shape orbits to show both high- and low-𝛼 abundances, suggesting the bar formed by secular evolution trapping stars that already existed. By analysing the chemical orbital space of the inner Galactic regions, we disentangle the multiple populations that inhabit this complex region. We reveal the presence of the thin disk, thick disk, bar, and a counter-rotating population, which resembles the outcome of a perturbed proto-Galactic disk. Our study also finds that the inner Galaxy holds a high quantity of super metal-rich stars up to three times solar suggesting it is a possible repository of old super-metal-rich stars found in the solar neighbourhood. We also enter into the complicated task of deriving individual stellar ages. With StarHorse, we calculate the ages of main-sequence turn-off and sub-giant stars for several public spectroscopic surveys. We validate our results by investigating linear relations between chemical abundances and time since the 𝛼 and neutron capture elements are sensitive to age as a reflection of the different enrichment timescales of these elements. For further study of the disks in the solar neighbourhood, we use an unsupervised machine learning algorithm to delineate a multidimensional separation of chrono-chemical stellar groups revealing the chemical thick disk, the thin disk, and young 𝛼-rich stars. The thick disk is shown to have a small age dispersion indicating its fast formation contrary to the thin disk that spans a wide range of ages. With groundbreaking data, this thesis encloses a detailed chemo-dynamical view of the disk and bulge of our Galaxy. Our findings on the Milky Way can be linked to the evolution of high redshift disk galaxies, helping to solve the conundrum of galaxy formation.},
  language  = {en}
}