Doctoral thesis (Dissertations and theses)
The ARGOS Wavefront Sensor Detector and Computer and The Black Hole Growth of Narrow-Line Seyfert 1 Galaxies
Orban De Xivry, Gilles
2014
 

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Abstract :
[en] This 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.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Orban De Xivry, Gilles  ;  Ludwig-Maximilians-Universität München - LMU
Language :
English
Title :
The ARGOS Wavefront Sensor Detector and Computer and The Black Hole Growth of Narrow-Line Seyfert 1 Galaxies
Defense date :
February 2014
Institution :
Ludwig-Maximilians-Universität, Munich, Germany
Degree :
doctor rerum naturalium
Promotor :
Genzel, Reinhard
President :
Kiesling, Christian
Jury member :
Bender, Ralf
Schaile, Dorothee
Available on ORBi :
since 12 September 2017

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