Reference : The ARGOS Wavefront Sensor Detector and Computer and The Black Hole Growth of Narrow-...
Dissertations and theses : Doctoral thesis
Physical, chemical, mathematical & earth Sciences : Space science, astronomy & astrophysics
The ARGOS Wavefront Sensor Detector and Computer and The Black Hole Growth of Narrow-Line Seyfert 1 Galaxies
Orban De Xivry, Gilles mailto [Ludwig-Maximilians-Universität München - LMU > > > >]
Ludwig-Maximilians-Universität, ​Munich, ​​Germany
doctor rerum naturalium
Genzel, Reinhard
Kiesling, Christian
Bender, Ralf
Schaile, Dorothee
[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.

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