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Spectroscopic Studies on Agns and High Angular Resolution in the NIR: the Construction of an Imaging Beam Combiner for the LBT

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Spectroscopic Studies on Agns and High Angular Resolution in the NIR: the Construction of an Imaging Beam Combiner for the LBT Spectroscopic studies on AGNs and High angular resolution in the NIR: The construction of an imaging beam combiner for the LBT INAUGURAL-DISSERTATION zur Erlangung des Doktorgrades der Mathematisch-Naturwissenschaftlichen Fakult¨at der Universit¨at zu K¨oln vorgelegt von Evangelia Tremou aus Trikala, Griechenland K¨oln 2011 Berichterstatter: Prof. Dr. J. Anton Zensus Prof. Dr. Andreas Eckart Tag der letzten m¨undlichen Pr¨ufung: 04. April 2011 To my soul mate N.P. Abstract The current thesis is divided into two projects. The first part deals with studies on active galaxies hosting an Active Galactic Nucleus (AGN). Specifically, an optical spectroscopic study of a nearby (z < 0.06) volume - limited sample of Low - Luminosity Quasi - Stellar Objects (LLQSOs) has been carried out. The sample has been drawn from the Ham- burg/ESO QSO survey (HES), which has a well-defined flux limit of Bj < 17.3. The aim of the present project is to characterize the excitation degree of the sample, distin- guish between possible star forming and Seyfert activity and to investigate the spectral characteristics of the sample. The spectroscopic data were analyzed and emission lines were fitted using a routine, which employs Levenberg - Marquardt least square minimization. The same analysis was also applied for some additional archival data from the 6 Degree Field Galaxy Survey (6dFGS). The objects of the LLQSOs sample are classified according to the classical optical diagnostic diagrams, based on optical emission lines close in wavelength, avoiding almost any impact of reddening. The diagrams provide a diagnosis of the ionizing source within a galaxy, hence activity between H ii, LINERs (Low Ionization Nuclear Emission- line Region), and Seyfert galaxies can be clearly distinguished. The classification of all members of the LLQSOs sample is shown in chapter 3. The broadness of the emission lines, cases with double components and the electron density are also analyzed. The comparison of the diagnostic diagrams between the two data sets (HES and 6DFGS) results in different classifications of most of the sources. This is due to the different spectroscopic techniques applied in the two data sets during the observations, and is sketched in chapter 4. Several galaxies at a variety of cosmological distances, with elliptical and circular morphologies, were simulated. In these simulations, different in- struments (different spectroscopic techniques, i.e. slit, fiber) were applied to the galaxies, in order to study the instrumental effect (aperture effect). The impact of the aperture effect in local and high redshift universe is discussed in detail. The second project of the thesis focuses on the construction of an image beam com- biner for the Large Binocular Telescope (LBT). The LINC - NIRVANA instrument will be operating in the near - infrared (1 - 2.4 µm) and will provide a high angular resolution (∼9 mas at 1.25 µm) over a wide field of view (∼ 100 arcsec at 1.25 µm). A fundamental com- ponent of the instrument, the Fringe and Flexure Tracking System (FFTS) is responsible to ensure a complete and time-stable wavefront correction at the position of the science detector. This will allow for long integration times at interferometric angular resolutions. A historical overview and our current achievements are also discussed in chapter 5. Laboratory tests of specific parts of the FFTS are presented in chapter 6. Especially, the subparts of the Detector Positioning Unit (DPU), which has to be moved with respect to an altitude - azimuth mounting under vacuum conditions, are characterized. The tilting ii of the instrument as a function of elevation results in a flexure of the system that has to be corrected by an algorithm. Zusammenfassung Die vorliegende Arbeit unterteilt sich in zwei Bereiche. Der erste Teil besch¨aftigt sich mit Galaxien, die einen Aktiven Galaktischen Nukleus (AGN) besitzen. Hierzu wird eine volumenlimitierte Stichprobe von optische selektierten Low-Luminosity Quasi-Stellar Ob- jects (LLQSOs) benutzt. Diese basiert auf dem Hamburg/ESO QSO Survey (HES) und besitzt eine wohldefinierte Flussbegrenzung von Bj < 17.3. Ziel ist es, die Anregungs- bedingungen der Linienstrahlung und die relative Bedeutung von Sternentstehungs- und Seyfert-Aktivit¨at f¨ur diese Stichprobe zu untersuchen. Die Analyse der spektroskopischen Daten fokussiert sich dabei auf die Anpassung von Emissionslinien mittels Levenberg - Marquardt Minimierung der kleinsten Quadrate. Zus¨atzlich wurden Archivdaten des 6 Degree Field Galaxy Survey (6dFGS) f¨ur einen Teil der Quellen der Stichprobe untersucht. Die LLQSOs werden entsprechend der klas- sischen optischen Diagnostik klassifiziert, die auf Flussverh¨altnissen von benachbarten Emissionlinien beruht. Dies minimiert den Einfluss von R¨otung auf die Bestimmung der Linienfl¨usse. Diese Diagnostik erlaubt eine Unterscheidung von H ii, LINERs (Low Ionization Nuclear Emission-line Region), and Seyfert Galaxien, d.h. der dominieren- den Quellen der ionisierenden Strahlung. Die Ergebnisse f¨ur die vorliegende Stichprobe werden in Kap. 3 pr¨asentiert. F¨ur den Großteil der Stichprobe, f¨ur den sowohl HES als auch 6DFGS Daten vorliegen, ergibt die Analyse eine unterschiedlich Klassifikation. Dies liegt in den unterschiedlichen Beobachtungstechniken begr¨undet und wird im Kap. 4 untersucht. Hierzu wurden Galax- ien unterschiedlicher (elliptischer und zirkulrer) Morphologie und bei verschiedenen kos- moligischen Abst¨anden als Funktion der instrumentellen Apertur, d.h. Schlitz- vs. Fiber- spektrograph, simuliert. Der Einfluss der Apertur auf die Beobachtung im nahen und hochrotverschobenen Universum wird im Detail diskutiert. Der zweite Teil der Arbeit handelt von der Konstruktion von LINC-NIRVANA, der abbildenden Strahlvereiniger Kamera f¨ur das Large Binocular Telescope (LBT). Das In- strument arbeitet im Nahinfraroten (von 1.0-2.4µm) und liefert hohe r¨aumliche Aufl¨osung (∼9 mas at 1.25 µm) ¨uber ein großes Gesichtsfeld (∼ 100 arcsec at 1.25 µm). Eine wichtige Komponente des Instruments ist das Fringe and Flexure Tracking System (FFTS), das eine phasenkoh¨arente Strahlvereinigung (d.h. bei interferometrischer Winkelaufl¨osung) ¨uber lange Integrationszeiten an der Position des wissenschaftlichen Detektors erm¨oglicht. In Kap. 6 werden Labortests von spezifischen Komponenten des FFTS pr¨asentiert. Im Speziellen wird die Detektorpositionierungseinheit (Detector Positioning Unit kurz DPU) charakterisiert. Diese bewegt sich unter Vakuumbedingungen in der Fokalebene des Instruments entsprechend der Alt-Azimuth Aufh¨angung des Teleskops. Das Kippen des Instruments als Funktion der Elevation bedingt Verspannungen innerhalb des Systems, die bei der Bewegung des FFTS Detektors in der Fokalebene ber¨ucksichtigt werden m¨ussen. iv Contents 1 Motivation and Thesis Outline 1 1.1 Galaxy evolution and interaction . 1 1.2 Quest for High Angular Resolution . 4 1.3 OutlineofthecurrentThesis. 6 2 AGN properties and Optical Spectroscopy 9 2.1 Host galaxies and their Active Galactic Nuclei . 9 2.1.1 The Unification model . 11 2.2 Opticalspectroscopy .............................. 13 2.2.1 Techniques................................ 14 2.2.2 Emission Lines of extragalactic objects . 17 2.3 Sorting out Active Galactic Nuclei . 20 3 Optical spectroscopic studies on the Low Luminosity Quasi Stellar Ob- jects sample 25 3.1 The nearby low luminosity QSO sample . 25 3.2 ObservationsandDataReduction . 28 3.2.1 Hamburg/ESOSurveyObservations. 28 3.2.2 6 Degree Field Galaxy Survey . 30 3.3 DataAnalysis.................................. 34 3.4 ResultsandDiscussion ............................. 36 3.4.1 Classification using the BPT diagrams . 37 3.4.2 Analysisofthebroadcomponent . 40 3.4.3 Electron density analysis . 46 3.5 ConcludingRemarks .............................. 46 4 Simulating the Aperture Effect 49 4.1 Motivation.................................... 49 4.1.1 Previous Investigations . 50 4.2 StudiesontheApertureEffect. 52 4.2.1 Nearby galaxies at high redshifts . 53 4.2.2 Software algorithm for the simulations . 57 4.2.3 The aperture effect in the local universe . 59 4.2.4 Aperture effect at high redshift: Cosmological implications . 63 4.3 ConcludingRemarks .............................. 66 vi CONTENTS 5 Optical/Infrared Interferometry - LINC NIRVANA 69 5.1 Interferometryretrospection . ... 69 5.1.1 Adaptive Optics . 71 5.1.2 Multi-Conjugate Adaptive Optics . 73 5.2 TheLargeBinocularTelescope . 74 5.2.1 TheLBTInstruments ......................... 74 5.3 The LINC-NIRVANA Instrument . 76 5.3.1 Principle of operation . 78 5.4 TheFringeandFlexureTrackingSystem . 78 6 Laboratory Tests of FFTS-DPU 81 6.1 The Detector Positioning Unit . 81 6.2 LaboratoryTestsofFFTS .. .. .. 84 6.2.1 Temperature and heat transfer tests of the linear stages . ..... 84 6.2.2 Tip-Tilt test . 86 6.2.3 Software................................. 89 6.2.4 DPU Repeatability and Flexure . 90 6.3 ConcludingRemarks .............................. 94 6.3.1 Outlook through High Angular Resolution Interferometry . .. 94 A Appendix 97 A.1 Theopticalspectraof6dFGS . 97 Bibliography 145 List of Acronyms 153 Acknowledgements 155 Erkl¨arung 157 Lebenslauf 161 List of Figures 1.1 ArtisticrepresentationofthecenterofanAGN . ... 2 1.2 Projected gas density of the merger of two galaxies. .... 3 1.3 The transparency of the atmosphere at different wavelengths......... 5 2.1 Microphotometer tracings in the nebula NGC 1068. .. 10 2.2 Schematic View of the Unification model of AGNs . 12 2.3 Instrumental profiles for a perfect spectroscope
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