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Galactic Winds and Structure of z~2 Star-forming Galaxies
Get PDFGalactic-scale outflows are a key driver of galaxy evolution through their feedback effect on star-formation and their ejection of metals and energy into the inter-galactic medium (IGM). While it is known that outflows likely play an important role in the quenching of star-formation - transforming actively star-forming, blue galaxies into their `red and dead' counterparts - this role is currently not well understood. In particular, at z~2, during the most active epoch of star-formation, the mass and energy in these outflows is poorly constrained, as is the mechanism for launching them. Furthermore, active-galactic nuclei (AGN) in the centers of massive star-forming galaxies (SFGs) likely play an important role in star-formation quenching, but we do not have a clear understanding of how this AGN feedback compares with that of star-formation driven feedback, and it is not known how many of these massive SFGs at z~2 even have AGN. This issue is complicated by the fact that many high-z AGN are likely highly obscured, and have strong nebular emission line contributions from both star-formation and the AGN.In this dissertation, I explore these issues using high-spatial and spectral resolution integral field unit spectroscopic data of z~2 SFGs. The observations are obtained with the instrument SINFONI on the European Southern Observatory (ESO) Very Large Telescope (VLT) at Cerro Paranal. These high-quality data allow spatially-resolved studies of the gas-phase kinematics of these galaxies, as well dynamical information on their outflows. In this work, I explore outflow properties in one galaxy with exceptionally deep data, allowing detailed examination of the outflow energetics, spatial extent and underlying ISM properties, as well those from a larger sample of galaxies. I also probe the fraction of SFGs in our sample which contain (possibly obscured) AGN, and study how this affects our determination of galaxy properties, such as gas-phase metallicity. Finally, I study a subsample of z~2 galaxies whose turbulent velocities dominate the kinematic signature, and examine the link between the overall evolution of z~2 galaxies and the systems we see today. Together this body of work explores how galactic-scale outflows in z~2 SFGs are launched, effect the IGM and eventually shape the evolution of their host galaxies
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On the Evolution of Massive Galaxies
Get PDFGalaxies, as the fundamental building blocks of the Universe, are the critical link between the overall evolution of the Universe and the assembly of small-scale structures, such as stars and planets, within it. Unfortunately, the formation and evolution of galaxies remains poorly understood, due to the incredible complexity of the physics that governs these processes. To study and constrain these processes, a particularly useful galaxy population are bulge-dominated galaxies such as elliptical and large spiral galaxies, which together are the most massive and most evolved components of the local Universe. In the present day, these galaxies are dominated by old stars; however, their histories likely include an epoch of powerful star formation and rapid growth of their supermassive black holes.Progress in understanding the evolution of massive galaxies can therefore proceed on two fronts -- 1) observations of their formation in situ in the early Universe, and 2) detailed studies of the fossil relics of this process in the local Universe -- with the ultimate goal being to link progenitors and descendants. A key epoch for such investigations is 10 billion years ago, the most active period in the Universe's history, at which time the vast majority of stellar material in galaxies was assembled. Recent comparisons of the observed properties of galaxy populations across cosmic time have shown that the dominant star-forming galaxy population at these early times were the probable ancestors of present-day massive (bulge-dominated spiral and elliptical) galaxies. The obvious direction for current and future research is therefore to probe the detailed evolution with time of the properties and sub-structures that define this local galaxy population.This goal has guided my dissertation research, as described in the following pages. Using photometric, spectroscopic, and integral-field observations at optical through mid-infrared wavelengths, I have studied both star-forming galaxies in the early Universe and their present-day descendants. Specifically, this thesis explores the dynamical, star-forming, and black hole properties of galaxies 10 billion years ago and shows that these young galaxies must be assembled via a rapid but steady influx of gas from the surrounding cosmic structure. The resulting large quantity of gas in these galaxies causes super-large star-forming gas clouds to form, and the dynamical interactions of these clouds control the evolution of the galaxies' supermassive black holes and internal sub-structures, producing the bulges and globular cluster populations observed in the present day. Studies of the resulting local massive galaxy population, also presented herein, confirm that such successive minor dynamical disturbances were important to the assembly of these bulge-dominated galaxies and their supermassive black holes. In the pages of this thesis, an exciting link is emerging in which many observed properties of local galaxies can be explained by the dramatic internal processes occurring in galaxies 10 billion years ago, during the era of the most rapid galaxy assembly
The ARGOS wavefront sensor detector and computer and the black hole growth of narrow-line Seyfert 1 galaxies
Get PDFThis thesis addresses both the development of a unique adaptive optics system and the applica-
tion of high resolution observations to astrophysics. The first part describes the development,
validation and implementation of the wavefront sensor detector and computer of the laser
guide star adaptive optics system for the Large Binocular Telescope (LBT), Argos. The
second part demonstrates the important role of secular evolution in the black hole growth of
narrow-line Seyfert Type 1 galaxies by studying their bulges and comparing it to more typical
Seyfert type 1 galaxies, and by studying the inner regions of one NLS1, NGC1365.
Argos is the laser guided ground-layer adaptive optics system for the LBT. It aims to
provide a factor 2-3 improvement in resolution over a wide field of view of 4×4 arcminutes2 ,
and is intended for Luci, the near-infrared imager, longslit, and multi-object spectrograph.
As such it will be the first wide-field Ground-Layer Adaptive Optics facility dedicated for
science operation. This instrument is a joint project of European and American institutes
lead by the Max-Planck-Institut für extraterrestrische Physik.
Part I provides a detailed analysis of the wavefront sensor detector and the wavefront
computer, the nerve center of the Argos wavefront sensing capability. In order to perform
its wide-field correction, Argos uses three laser guide stars to sample the atmospheric tur-
bulence. The residual wavefront error of these three guide stars is measured by the wavefront
sensing system that creates three Shack-Hartmann patterns on a single pnCCD camera, i.e.
a total of 525 spots each allowed to move in its 8×8 pixels region. In the framework of
this thesis, I develop in collaboration with the company pnSensor this state-of-the-art cam-
era implementing a pnCCD. My contribution covers all aspects of the system : integrating
the entire control electronics, developing the camera control software, and performing exten-
sive tests of the camera housing, the pnCCD, and the acquisition electronics at the various
stages of the project. In particular, I also carry out an extensive test campaign and support
the development of new power supplies by the MPE electronics department to tackle the
pnCCD characteristic noise. In that frame, I perform several noise analyses, from optical
setups to closed-loop adaptive optics simulations. The final excellent characteristics of the
camera are demonstrated. With its 1kHz framerate, 3.5e− readout noise, and its compact,
low-maintenance housing, the integrated system fully answers the Argos requirements. In
parallel to the detector work, I define the required architecture of the Argos wavefront com-
puter at the center of the wavefront sensing. This DSP-based computer processes the detector
images, computes the LGS local wavefront gradients, and collects the measurements of the
natural guide star tip-tilt sensor and of a possible third wavefront sensor. The latter wave-
front sensor can probe higher layer turbulence with either a natural or a future Sodium laser
guide star. I support its development by Microgate, develop the initial configuration tools,
debug its different hardware interfaces and demonstrate its real-time functionality.
As part of this thesis, I pave the way for the wavefront sensor system integration by pre-
liminarily integrating the wavefront sensor detector, the gating system, and the wavefront
computer. The units are now fully integrated into the wavefront sensor and are undergoing
system tests before being assembled at LBT.
In Part II, I study the co-evolution of central super-massive black holes and their host
galaxies. I focus on narrow-line Seyfert type 1 galaxies (NLS1), revealing the major role
played by secular evolution in driving the black hole growth in those galaxies. I extensively
review the literature for signs of present day secular processes. I then use high-resolution HST
archive images to study the bulge properties in a sample of NLS1s and compare them to more
typical Seyfert type 1 galaxies. By doing so I show the importance of secular processes in
NLS1s and discuss how this can be understood in a cosmological context of galaxy evolution.
Building on this work, I analyze the inner hundreds of parsecs region of NGC1365, a nearby
NLS1s, with data from the adaptive optics integral field spectrometer SINFONI at VLT. I
study the different phases of the interstellar medium and find that a large fraction of the
stellar population consists of young stars of less than 10Myr. This reveals, together with the
stellar and gas kinematics and the broader context found in the literature, the major role of
secular processes in this galaxy, displaying an unperturbed alignment from large scales down
to the central black hole. Those same secular processes may be responsible for the gas settling
in a nuclear ring, currently preventing more gas from being accreted while the gas reservoir
is replenished, and explain the relatively low luminosity of the AGN and the faintness of the
molecular gas
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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