The goal of galaxy classification is to understand the physical basis for the wide range in shapes and structures exhibited by galaxies in the local and high redshift universe. We present a catalog of visually classified galaxies from the Sloan Digital Sky Survey with detailed morphological classifications including bars, rings, lenses, tails, warps, dustlanes, arm flocculence and multiplicity (so called ’fine structure’). This thesis explores the importance of galaxy morphology by probing its relationship to physical properties. Our analysis includes an investigation of correlations between fine structures and AGN activity. This sample defines a comprehensive local galaxy sample which we use to study the low redshift universe both qualitatively and quantitatively. We find the stellar mass appears to be a defining characteristic of a galaxy. The break in most correlations of physical properties with morphology is due to a lack of late type, massive disk galaxies. Our analysis of the size-mass relations of galaxies as a function of morphology (T-Type) has revealed many interesting connections. We find the size-mass relation of Sa, Sab, Sb, and Sbc galaxies bifurcates into two families of objects as one moves down the sequence such that the high concentration branch exhibits a similar slope to low concentration early type (E) galaxies suggesting a closer than expected physical (possibly evolutionary) connection between the two populations. We find bar fraction is bimodal with respect to mass (at 3 x 10^10 M) and color (at g - r ∼ 0.55). The dependence is seen to intimately depend on central concentration such that objects below the transition mass with low concentrations have a higher bar fraction than objects above the transition mass which have high bar fractions for high concentration systems. In addition we find the presence of an AGN alters the behavior and abundance of barred/ringed galaxies in the high mass peak such that the bar/ring fractions increase with mass in nonactive galaxies whereas they decrease with mass in active galaxies. AGN fractions are also decreasing in the same mass range possibly implying a positive correlation between fine structure and ring formation.

Active Galactic Nuclei (AGN) are some of the most extreme objects in the universe. They output copious amounts of energy spanning the entire electromagnetic spectrum. There are many different subclasses of AGN depending on your viewing angle. Blazars, viewing down the relativistic jet, are the most variable class of AGN known. They exhibit extreme variability in all wavelengths on timescales as short as minutes. In this thesis I will consider the extreme faintness of 3C279 with respect to the long-term light curve as well as recent observations of microvariability. I am able to confirm small amplitude events using simultaneous observations from two telescopes and cross correlation analysis. Transitory quasi-periodic oscillations are observed during two of the nights with confirmed microvariability.

Active Galactic Nuclei (AGN) are axisymmetric systems to first order; their observed properties are likely strong functions of inclination with respect to our line of sight. However, except for a few special cases, the specific inclinations of individual AGN are unknown. We have developed a promising technique for determining the inclinations of nearby AGN by mapping the kinematics of their narrow-line regions (NLRs), which are easily resolved with Hubble Space Telescope (HST) [O III] imaging and long-slit spectra from the Space Telescope Imaging Spectrograph (STIS). Our studies indicate that NLR kinematics dominated by radial outflow can be fit with simple biconical outflow models that can be used to determine the inclination of the bicone axis, and hence the obscuring torus, with respect to our line of sight. We present NLR analysis of 52 Seyfert galaxies and resultant inclinations from models of 17 individual AGN with clear signatures of biconical outflow. From these AGN, we can for the first time assess the effect of inclination on other observable properties in radio-quiet AGN, including the discovery of a distinct correlation between AGN inclination and X-ray column density.

A multiwavelength investigation is conducted for nineteen blazar-type active galactic nuclei. Studies of variability timescales and flux duty cycles are performed at x- and gamma-rays for each source, with the relationship between flux and spectral index also being probed at gamma wavelengths. The correlation between these two energy ranges is also investigated, by utilising the Discrete Correlation Function with both one and ten day binning. The sources were chosen for their availability over a range of different x- and gamma-ray data sources: observations utilised include 0.2 - 150 keV x-ray data from the Swift mission and 200 MeV- 300 GeV gamma-ray data from the Fermi mission. Daily-binned Fermi data is used to calculate the smallest rise and decay e-folding times in gamma for each source. The results range from 0.4 to 21 days, corresponding to limits on the size of the gamma emission region ranging from Rd^-1 = 4.39 x 10^12 to Rd^-1 = 5.14 x 10^14 m. Flux duty cycles for fourteen sources are created from Fermi data, with six displaying structure at high fluxes that indicate flaring states have occured. Five of these six sources also display clear flares in their light curves, confirming these results. The relationship between the flux and the spectral index shows eight of nineteen sources exhibit harder-when-brighter behaviour. Four of these eight have been previously confirmed to display such behaviour. Results from the Discrete Correlation Function show a correlation at a time lag of ~ 600 days for H 1426+428, of uncertain origin. Gaussian functions are fitted to possible near-zero peaks in 3C 66A, 3C 454.3 and Mrk 421, which could be indicative of a synchrotron self-Compton component to the emission of these objects.

Στόχος της παρούσης εργασίας είναι η διερεύνηση των μεταβολών της ροής της οπτικής ακτινοβολίας στα φίλτρα B, V, R στη διάρκεια μιας νύχτας του ενεργού γαλαξία S5 1803 + 784 με ανάλυση παρατηρήσεων που ελήφθησαν με το τηλεσκόπιο των1.3m του αστεροσκοπείου του Πανεπιστημίου Κρήτης (από τον Δρ. Παν. Μπούμη) με τη μέθοδο της συγκριτικής φωτομετρίας. Στο πρώτο κεφάλαιο περιγράφονται τα γενικά χαρακτηριστικά των κανονικών γαλαξιών και του δικού μας γαλαξία, ενώ στο δεύτερο τα γενικά χαρακτηριστικά των ενεργών γαλαξιών ή ενεργών γαλαξιακών πυρήνων (AGN) - επειδή τα έντονα ενεργητικά φαινόμενα επικεντρώνονται στην κεντρική περιοχή του πυρήνα. Αναφέρεται η διάκρισή τους σε κατηγορίες με βάση τα παρατηρησιακά χαρακτηριστικά και εξετάζονται οι βασικές ιδέες που οδηγούν στο επικρατέστερο μοντέλο ενοποίησης, σχετικά με την ενεργειακή μηχανή τους καθώς και η εξέλιξη και τροποποίηση του με βάση τα νέα πειραματικά δεδομένα. Το τρίτο κεφάλαιο επικεντρώνεται στα ιδιαίτερα χαρακτηριστικά των blazars στα οποία ανήκει ο S5 1803 + 784. Στο τέταρτο κεφάλαιο περιγράφονται συνοπτικά οι βασικές αρχές της φωτομετρίας αλλά και οι βασικές παράμετροι μιας CCD κάμερας. Στο τέταρτο κεφάλαιο γίνεται μια βιβλιογραφική παρουσίαση του S5 1803 +784 σε όλα τα μέρη του φάσματος και περιγράφονται αναλυτικά οι παρατηρήσεις, τα αρχικά στάδια επεξεργασίας των αστρονομικών εικόνων και τα αναλυτικά στάδια της φωτομετρίας του γαλαξία με τις απαραίτητες διορθώσεις. Τέλος στο έκτο κεφάλαιο κατασκευάζονται οι καμπύλες μεταβολής της ροής και σχολιάζονται τα αποτελέσματα Ακολουθεί στο παράρτημα, η περιγραφή των προγραμμάτων και των διαδικασιών που χρησιμοποιήθηκαν τόσο στην ανάλυση όσο και στην φωτομετρία μέσω των αστρονομικών πακέτων IRAF και MIDAS , ως μικρός οδηγός για τους επόμενους ενδιαφερόμενους. / The main aim of this dissertation entitled “Variabillity in the optical band of blazar S51803+784” is the investigation of flux microvariability through observations carried out with the 1.3 m , Ritchey-Chretien telescope at Skinakas Observatory in Crete, Greece (by Associate Researcher P. Boomis of the Institute of Astronomy and Astrophysics of the National Observatory in Athens) in 2001 under the supervision of Lecturer Mrs E-P. Christopoulou (Physics Dept. University of Patras, Greece). This work consists of six relatively distinct chapters. The first chapter summarizes the main characteristics of normal galaxies whereas the second one describes the various classes of Active Galactic Nuclei which emerge from multiwavelength studies and the unified model proposed to explain the energy source behind their taxonomy. The last section of this part focuses on the observational evidence of supermassive black holes. The third chapter focuses on the special characteristics of the class named Blazars, the proposed theoretical models for the formation of jets and the observed microvariability thought the EM spectrum. The fourth chapter describes the main philosophy of photometry, the comparison of differential and absolute photometry and the selection of photometric standard stars. The last part briefly presents the charge-coupled devices (CCDs) which are used to record astronomical images and their main properties. The fifth chapter deals with the current observations of the Blazar S51803+784 and the standard image processing (bias substraction and flat fielding using twilight –sky exposures) applied to all frames before the performance of aperture photometry techniques which is described analytically in the rest part. The topics covered include methods for image center determination, routines for estimating the sky background and the techniques of both aperture and point-spread function fitting photometry. Procedures for transforming instrumental magnitudes to those on a standard system are also discussed. The results based on the data reduction of the photometric observations of the object are presented in the last chapter together with the discussion and conclusions. Finally in the Appendix there is a mini-guide for the beginner in order to be familiar with the format of the astronomical files, and the various astronomical packages and procedures being used for the above reduction.

Active Galactic Nuclei (AGN) are cores of distant protogalaxies, with a supermassive blackhole at the center surrounded by an accretion disk, and bipolar jets. Blazars, a subset of AGN, have their jets aligned with our line of sight. Emission from blazars is highly variable on all timescales and frequencies. Microvariability refers to rapid continuum variations that arise within the jet. Bhatta et al. (2013) suggest a modified Kirk, Rieger, \& Mastichiadis (1998) model (KRM) to explain microvariability. The KRM model assumes that when shock waves passes though the jet, each turbulent cell encountered produces a pulse of emission characterized by cell size, local density enhancement, and magnetic field strength. NASA's \kepler\ has monitored optical emission from four AGN. We use the modified KRM model to analyze micro-variations in these \kepler\ data. The distribution of cell sizes computed from these data is consistent with the distribution expected from a turbulent plasma.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第22252号 / 理博第4566号 / 新制||理||1656(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)准教授 上田 佳宏, 准教授 岩室 史英, 教授 長田 哲也 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

Philosophiae Doctor - PhD / Observations of galaxies at di↵erent wavelengths have shaped our understanding of their formation and evolution through time. The commonly derived parameters, such as stellar mass and star formation rate (SFR), rely on the assumption that the radiation received is exclusively generated by the stars within the galaxy. This assumption is true for pure star-forming (SF) galaxies, but not in the presence of an active galactic nucleus (AGN). AGNs are structures that also radiate in the full electromagnetic spectrum, inducing additional flux to that emitted by stars. Their small sizes in comparison to the host galaxy (⌧1 %) generally make them invisible in galaxy images. AGNs come in many variations making the most powerful (e.g., quasi-stellar objects) easily identifiable, whereas others with much weaker signatures can be hidden in the total emission from the host. Therefore it is imperative to find accurate methods to separate and study the properties of AGNs versus pure SF galaxies.

Active galactic nuclei (AGN) ubiquitously show outflows. It is now widely recognized that these outflows are key components in the evolution of super-massive black holes and their host galaxies. As important as these outflows are, we still lack sufficient understanding of their structure and energetics. The majority of the work presented in this thesis involved photoionization modeling of AGN outflows along with analysis of density diagnostics in order to determine the distances and energetics of observed outflows. The main findings of these analyses are that 1) outflows are often at distances of hundreds to thousands of parsecs from the central supermassive black hole and 2) quasars outflows can be sufficiently powerful to provide feedback in galactic evolution scenarios. We also find in some cases that the recombination timescales of metal ions are long compared with the flux variability timescales. The large distances we find provide a challenge to current outflow models. For example, these outflows cannot be connected with an accretion disk surrounding the supermassive black hole as assumed in some models. Furthermore, the outflows may be out of equilibrium as we find in Mrk 509. In this case, a thorough understanding of time-dependent photoionization effects is necessary. In this thesis, I include early steps toward understanding time-dependent photoionization as well as ionization studies of accretion disk winds. The main results of these theoretical studies is that 1) the appearance of multiple ionization components in an outflow can be an artifact of the incorrect assumption that the outflow is in ionization equilibrium and 2) the shielding gas required in accretion-disk-wind models should have a clear signature in UV spectra, but none has been observed to date. / Ph. D.

OH Megamasers (OHMs) generally appear in luminous infrared regions i.e. merging galaxies. In this study we assume that OHMs may not be represented by their association with star formation solely, because of the possibility of a compact AGN source in the merging galaxies. In fact, previously classified starburst galaxies where OHMs are found are now optically observed as AGN. OHMs may also serve as a reasonable criterion for the evolutionary stage of the merger. This project focuses on observations from a multi-frequency analysis of merging regions with known OHMs. Optically, Hα and BVRI filters provided an environmental perspective of the "masing" components. In the radio, 18-cm data was used to determine the structure and position of the OHM. We studied the source IIZw096 and compared our results with two familiar OHM sources. We were able to look at each source at high radio resolutions and compare the structure and classification of each.