Download or read book Morphological and Kinematic Indicators of Structural Transformation in Galaxies written by Connor Bottrell and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The observed properties of galaxies are intricately connected to their respective evolutionary histories. Establishing these connections - tying the morphologies, dynamics, and other properties of galaxies to the dominant events and processes from which they originate - is the central challenge in creating a self-consistent framework for how galaxies form and evolve. Overcoming this challenge requires that two criteria be satisfied: (1) accurate characterization of the physical states of galaxies; and (2) creation of models that connect the observed features of galaxies to their evolutionary histories. This thesis chiefly concerns the identification and characterization of morphological and kinematic indicators for structural transformation in galaxies and their connections to galaxy mergers - including merger status (merger or non-merger) and merger stage. Accurate measurement of the morphological structures of galaxies is a cornerstone for making connections to their evolutionary pathways. However, without significant overlap between the observational footprints of deep and shallow galaxy imaging surveys, the extent to which structural measurements for large galaxy samples are robust to image quality (e.g. depth, spatial resolution) cannot be established. Deep images from the Sloan Digital Sky Survey (SDSS) Stripe 82 co-adds provide a unique solution to this problem - offering 1.6 − 1.8 magnitudes improvement in depth with respect to SDSS Legacy images. Having similar spatial resolution to Legacy, the co-adds make it possible to examine the sensitivity of parametric morphologies to depth alone. Using the GIM2D surface-brightness decomposition software, I provide public morphology catalogs for 16,908 galaxies in the Stripe 82 ugriz co-adds. The methods and selection are completely consistent with those of previous analyses in the shallow images. Measurements in the deep and shallow images are rigorously compared. No systematics in total magnitudes and sizes are found except for faint galaxies in the u-band and the brightest galaxies in each band. However, characterization of bulge-to-total fractions is significantly improved in the deep images. Furthermore, statistics used to determine whether single-Sérsic or two-component (e.g. bulge+disc) models are required become more bimodal in the deep images. Lastly, I show that morphological asymmetries (commonly linked to mergers) are enhanced in the deep images and that the enhancement is positively correlated with the asymmetries measured in Legacy images. Recently, machine learning has become a popular tool to quantify galaxy morphologies and identify mergers - exploiting the often disturbed and asymmetric morphological features present in merging galaxies. However, this technique relies on using an appropriate set of training data to be successful. By combining hydrodynamical simulations, synthetic observations and convolutional neural networks (CNNs), I quantitatively assess how realistic simulated galaxy images must be in order to reliably classify real mergers. Specifically, I compare the performance of CNNs trained with two types of galaxy images, stellar maps and images with full radiative transfer through internal dust, each with three levels of observational realism: (1) no observational effects (idealized images), (2) realistic sky and point spread function (semi-realistic images), (3) insertion into a real sky image (fully realistic images). I show that networks trained on either idealized or semi-real images have poor performance when applied to survey-realistic images. In contrast, networks trained on fully realistic images achieve 87.1% classification performance. Importantly, the level of realism in the training images is much more important than whether the images included radiative transfer, or simply used the stellar maps (87.1% compared to 79.6% accuracy, respectively). Therefore, one can avoid the large computational and storage cost of running radiative transfer with a relatively modest compromise in classification performance. Making photometry-based networks insensitive to colour incurs a very mild penalty to performance with survey-realistic data (86.0% with r-only compared to 87.1% with gri). This result demonstrates that while colour can be exploited by colour-sensitive networks, it is not necessary to achieve high accuracy and so can be avoided if desired. I provide the public release of the statistical observational realism suite, RealSim, as a companion to this work. Galaxy kinematics derived from observational integral field spectroscopy (IFS) may offer an orthogonal and highly-complimentary basis to photometry for accurately identifying and characterizing observed galaxy mergers. As with morphology, mergers can trigger kinematic disturbances in galaxies resulting in irregular and asymmetric kinematic structure. However, these kinematic disturbances are not always reflected in the morphologies. The current and future state-of-the-art IFS instruments which provide spatially-resolved kinematics for many thousands of galaxies make kinematic merger studies statistically viable. Anticipating the demand for realistic synthetic IFS and kinematic data for calibrating merger classification models with simulations, I present RealSim-IFS: a novel tool that emulates the instrumental response of current and future fibre-based IFS instruments. Components of RealSim-IFS are tested on real IFS data from the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey to demonstrate the high precision that is achieved by RealSim-IFS. In a further demonstration with RealSim-IFS, I generate realistic synthetic MaNGA kinematic observations for a sample of galaxies from the IllustrisTNG cosmological hydrodynamical simulations. The survey-realistic kinematic maps for post-merger galaxies are compared with non-merging galaxies to illustrate the potential role of kinematics in enabling more accurate identification and characterization of galaxy mergers - either independently or in tandem with photometry.

Download or read book Morphology Kinematics and Star Formation Across the Hubble Sequence of Galaxies written by Santiago Erroz-Ferrer and published by Springer. This book was released on 2015-11-21 with total page 207 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis discusses the evolution of galaxies through the study of the morphology, kinematics, and star formation properties of a sample of nearby galaxies. The main body of the thesis describes the kinematic observations with the GHaFAS Fabry-Perot instrument on the William Herschel Telescope of a sample of 29 spiral galaxies. The work is closely related to the Spitzer Survey of Stellar Structure in Galaxies, and uses the mid-infrared data of that survey to determine key parameters of the galaxies studied. From these data, important results are obtained on streaming and other non-circular motions in galaxies, on the distribution and rates of star formation, and on how correlations of these parameters and of the rotation curve shape with basic galaxy parameters yield clues on the evolutionary processes taking place in disk galaxies.

Download or read book The Kiloparsec Scale Structure and Kinematics of High Redshift Star Forming Galaxies written by David R. Law and published by Universal-Publishers. This book was released on 2008-09 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt: We study the spatially resolved properties of star-forming galaxies at redshift z 2 - 3 on scales 1 kpc using a combination of morphological and kinematic analyses in an effort to characterize the major mechanisms of galaxy formation in the young universe. Using a sample of 216 galaxies which have been spectroscopically confirmed to lie between redshifts z = 1.8 - 3.4 in the GOODS-N field we demonstrate that rest-UV morphology (as seen by the Hubble Space Telescope) is statistically uncorrelated with physical properties such as star formation rate and is therefore unable to support the hypothesis that the prevalence of irregular morphologies indicates a high major merger fraction. Further, we present a sample of 13 galaxies observed with the OSIRIS integral field spectrograph and the Keck laser-guide star adaptive optics system which demonstrate the prevalence of high velocity dispersions 80 km/s and generally little in the way of spatially resolved velocity gradients, inconsistent with favored rotating disk models. We discuss the implications of these results for galaxy formation models, including gas accretion via cold flows and gravitational instability of early gas-rich galactic disks. There is some evidence for a trend towards stronger rotational signatures in galaxies with more massive stellar populations.

Download or read book Galaxy Morphology and Classification written by Sidney Van den Bergh and published by Cambridge University Press. This book was released on 1998-04-16 with total page 125 pages. Available in PDF, EPUB and Kindle. Book excerpt: A concise and up-to-date guide to the shape of galaxies and how they can be classified, by one of the pioneers of the field.

Download or read book Dynamical Evolution of Galaxies written by Xiaolei Zhang and published by Walter de Gruyter GmbH & Co KG. This book was released on 2017-12-04 with total page 421 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research monograph presents a new dynamical framework for the study of secular morphological evolution of galaxies along the Hubble sequence. Classical approaches based on Boltzmann’s kinetic equation, as well as on its moment-equation descendants the Euler and Navier-Stokes fluid equations, are inadequate for treating the maintenance and long-term evolution of systems containing self-organized structures such as galactic density-wave modes. A global and synthetic approach, incorporating correlated fluctuations of the constituent particles during a nonequilibrium phase transition, is adopted to supplement the continuum treatment. The cutting-edge research combining analytical, N-body simulational, and observational aspects, as well as the fundamental-physics connections it provides, make this work a valuable reference for researchers and graduate students in astronomy, astrophysics, cosmology, many-body physics, complexity theory, and other related fields. Contents Dynamical Drivers of Galaxy Evolution N-Body Simulations of Galaxy Evolution Astrophysical Implications of the Dynamical Theory Putting It All Together Concluding Remarks Appendix: Relation to Kinetics and Fluid Mechanics

Download or read book Morphology and Kinematics of Interacting Galaxies written by Claudia Faye McCain and published by . This book was released on 1997 with total page 150 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Relationship Between the Morphology and Kinematics of Galaxies and Its Dependence on Dark Matter Halo Structure in Simulated Galaxies written by A. Thob and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Evolution of the Hubble Sequence written by Rodney Delgado Serrano and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The main objective of my thesis was to provide us, for the first time, with a reliable wiev of the distant Hubble sequence, and its evolution over the past 6 Gyr. To achieve this goal, we have created a new morphological classification method which (1) includes all the available observational data, (2) can be easily reproduced, and (3) presents a negligible subjectivity. This method allows us to study homogeneously the morphology of local and distant galaxies, and has the main advantage of presenting a good correlation between the morphological type and dynamical state of each galaxy. The first step has been to study the evolution of galaxies using the IMAGES survey. This survey allowed us to establish the kinematic state of distant galaxies, to study the chemical evolution of galaxies over the past 8 Gyr, and to test important dynamical relations such as the Tully-Fisher relation. The information gained from kinematics is, indeed, crucial to guarantee a robust understanding of the different physical processes leading to the present day Hubble sequence. Using Integral Field Spectroscopy, which provides a complete kinematic diagnosis, we have been able to test our new morphological classification against the kinematic state of each galaxy. We found that the morpho-kinematic correlation is much better using our classification than other morphological classifications. Applying our classification to a representative sample of galaxies at z ∼ 0.6, we found that 4/5 of spiral galaxies are rotating disks, while more than 4/5 peculiar galaxies are not in a dynamical equilibrium. Appliyng our morphological classifications to a repesentative sample of both local and distant galaxies, having equivalent observational data, we obtained a Hubble sequence both in the local and distant Universe. We found that spiral galaxies were 5/2 times less adundant in the past, which is compensated exactly by the strong decrease by a factor 5 of peculiar galaxies, while the fractional number of elliptical and lenticular galaxies remains constant. It strongly suggests that more than half of the present-day spirals had peliculiar morphologies, 6 Gyr ago. Finally, I present further studies concerning the history of individual galaxies at z

Download or read book The Structure of Galaxies written by Lee Steven Kelvin and published by . This book was released on 2013 with total page 217 pages. Available in PDF, EPUB and Kindle. Book excerpt: The mechanisms which cause galaxies to form and evolve each leave behind distinct structural markers in their wake. Dynamically hot processes (e.g., monolithic collapse, hierarchical merging) give rise to pressure-supported spheroidal structures, including elliptical galaxies and classical bulges. By contrast, dynamically cold processes (e.g., gas accretion, AGN splashback) lead to flattened rotationally-supported disk-like structures, often found on their own or as part of a spiral galaxy. If left in isolation for a sufficient length of time, secular evolutionary processes cause the formation of a bar-like structure within the disk, precipitating the genesis of a rotationally-supported pseudo-bulge. Robustly measuring galaxy structure enables us to ascertain the relative importance of these competing evolutionary mechanisms and; in so doing, help broaden our understanding of how the Universe around us came to be. This thesis explores the relation between galaxy structure, morphology and stellar mass. In the first part I present single-Sérsic two-dimensional model fits to 167,600 galaxies modelled independently in the ugrizYJHK bandpasses using reprocessed Sloan Digital Sky Survey Data Release Seven (SDSS DR7) and UKIRT Infrared Deep Sky Survey Large Area Survey (UKIDSS LAS) imaging data available via the Galaxy and Mass Assembly (GAMA) data base. In order to facilitate this study, we developed Structural Investigation of Galaxies via Model Analysis (SIGMA): an automated wrapper around several contemporary astronomy software packages. We confirm that variations in global structural measurements with wavelength arise due to the effects of dust attenuation and stellar population/metallicity gradients within galaxies. In the second part of this thesis we establish a volume-limited sample of 3,845 galaxies in the local Universe and visually classify these galaxies according to their morphological Hubble type. We find that single-Sérsic photometry accurately reproduces the morphology luminosity functions predicted in the literature. We employ multi-component Sérsic profiling to provide bulge-disk decompositions for this sample, allowing for the luminosity and stellar mass to be divided between the key structural components: spheroids and disks. Grouping the stellar mass in these structures by the evolutionary mechanisms that formed them, we find that hot-mode collapse, merger or otherwise turbulent mechanisms account for ~46% of the total stellar mass budget, cold-mode gas accretion and splashback mechanisms account for ~48% of the total stellar mass budget and secular evolutionary processes for ~6.5% of the total stellar mass budget in the local (z

Download or read book Unveiling Galaxies written by Jean-René Roy and published by Cambridge University Press. This book was released on 2018 with total page 311 pages. Available in PDF, EPUB and Kindle. Book excerpt: A thought provoking study of the powerful impact of images in guiding astronomers' understanding of galaxies through time.

Download or read book Fundamentals of Galaxy Dynamics Formation and Evolution written by Ignacio Ferreras and published by UCL Press. This book was released on 2019-04-02 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt: Galaxies, along with their underlying dark matter halos, constitute the building blocks of structure in the Universe. Of all fundamental forces, gravity is the dominant one that drives the evolution of structures from small density seeds at early times to the galaxies we see today. The interactions among myriads of stars, or dark matter particles, in a gravitating structure produce a system with fascinating connotations to thermodynamics, with some analogies and some fundamental differences. Ignacio Ferreras presents a concise introduction to extragalactic astrophysics, with emphasis on stellar dynamics, and the growth of density fluctuations in an expanding Universe. Additional chapters are devoted to smaller systems (stellar clusters) and larger ones (galaxy clusters). Fundamentals of Galaxy Dynamics, Formation and Evolution is written for advanced undergraduates and beginning postgraduate students, providing a useful tool to get up to speed in a starting research career. Some of the derivations for the most important results are presented in detail to enable students appreciate the beauty of maths as a tool to understand the workings of galaxies. Each chapter includes a set of problems to help the student advance with the material.

Download or read book Galaxy Evolution Across the Hubble Time IAU S235 written by International Astronomical Union. Symposium and published by Cambridge University Press. This book was released on 2007-05-17 with total page 480 pages. Available in PDF, EPUB and Kindle. Book excerpt: This last decade has witnessed a revolution in our observations of galaxies; in particular deep imaging with HST and spectroscopy with 10m-class ground-based telescopes have uncovered many objects that are difficult to place along the Hubble sequence. High resolution spectroscopy of extremely faint objects has enabled the study of the kinematic evolution and, hence, the mass assembly of galaxies to unprecedented look-back times for direct comparison with cosmological structure formation scenarios. Thus, it is now possible to study all three aspects of galaxy evolution - their morphological-dynamical, chemical and spectral evolution out to redshift larger than six, exploring more than 95% of the age of the universe. These Proceedings of the IAU Symposium 235 report the considerable progress made in recent years on galaxy formation and evolution, and look forward to the expected breakthroughs in the domain of remote galaxies, with ALMA, the ELT and the next generation space telescopes.

Download or read book Astrophotonics written by Stefano Minardi and published by VCH. This book was released on 2012-04-04 with total page 350 pages. Available in PDF, EPUB and Kindle. Book excerpt: Written by well-known scientists in the field with vast experience in teaching astrophotonics, this is the first book to bridge astronomy and photonics for the benefit of developing new astronomical instrumentation. The textbook is clearly structured and covers four main methods relevant to observational astronomy: adaptive optics, photometry, interferometry and spectroscopy. It follows a progressive didactical path in photonics, starting from fundamentals of wave- and micro-optics and developing step-by-step the formalisms required for the treatment of optical multilayers, fiber optics and diffraction/holographic gratings. This approach allows students with a physics/engineering background to learn about the problematic of observational astronomy, while, conversely, students of astronomy are exposed to topics in modern photonics. Each chapter is divided into three main sections devoted to the discussion of astronomical concepts required to size an instrument designed for the particular method, the photonic concepts that most suit that instrument, and an analysis of existing, related photonic instruments. A set of exercises and a bibliography complete each chapter. Appendices include a short review of fundamentals of wave optics and photon detectors, plus an overview of project design and management using a real-life example of an astronomical instrumentation project. With its review of the latest instrumentation and techniques, this is invaluable for graduate and post-graduate students in astronomy, physics and optical engineering.

Download or read book Back to the Galaxy written by Stephen S. Holt and published by A I P Press. This book was released on 1993 with total page 720 pages. Available in PDF, EPUB and Kindle. Book excerpt: The proceedings of the third October Astrophysics Conference represent a summary of the current state of knowledge of the large-scale properties of the Milky Way. Virtually all the new relevant data are presented, including those from the current space-borne observatories like the Cosmic Background

Download or read book Formation and Evolution of Galaxy Disks written by José G. Funes and published by . This book was released on 2008 with total page 548 pages. Available in PDF, EPUB and Kindle. Book excerpt: "These are the proceedings of the international conference "Formation and Evolution of Galaxy Disks" organized by the Specola Vaticana (the Vatican Observatory). The meeting hosted 198 participants from 26 countries. The program consisted of 61 talks and about 130 poster papers. In 2000 the Vatican Observatory organized a conference on Galaxy Disks and Disk Galaxies, the proceedings of which were published in ASP Conference Series Vol. 230. Since that time, a great amount of work has been done in this very active field. October 2007 was deemed an appropriate time to hold another similar conference where outstanding senior and junior astronomers in this field could air new results. The conference was focused on the formation and evolution of galaxy disks and covered the following topics: (1) properties of nearby galaxy disks; (2) interstellar medium, star formation, and chemical evolution; (3) disk edges, outskirts, and environment; (4) accretion onto disks, interactions, and mergers; (5) secular evolution of disks and bar/spiral driven evolution of galaxies; (6) evolution of disk structural properties; and (7) disk formation in a hierarchical universe. This books is of interest for researchers in extragalactic astronomy. It presents an overview of the relevant results and the progress made in the field in the last seven years."--Publisher's website

Download or read book Morphological Astronomy written by Fritz Zwicky and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt: Man has a great tendency to get lost or to hide, as the case may be, in a jungle of details and in unnecessary complications. Why do anything simply if you can do it complicated? And still, life itself presents a sufficient number of problems to keep us busy. There would seem to be no need to create additional difficulties, just for the fun of it, especially if these self-made difficulties become practically insuperable and if in the end they cause much unhappiness. The morphological mode of thought and of action was conceived to break the vicious hold which the parasitic wild growth of complications exerts on life in all of its phases. Morphological thought and action are likely to be of value in all human activities, once such thought and action have been clearly delineated and fully developed, and once they have been practised by a sufficiently large number of people. Since the morphological method is of the greatest universality, the choice of the field to which one applies it first is not particulary critical. The author intends to write two or three books on the morphology of several large scale problems, which are both of a technical and of a general social nature. The present book is concerned in particular with some implications of morphological thinking in astronomy. We shall above all emphasize the basic character of the morphological approach, and we shall demonstrate its constructive power in a number of specific cases.

Download or read book Dynamics of Galaxies written by Giuseppe Bertin and published by Cambridge University Press. This book was released on 2014-04-21 with total page 487 pages. Available in PDF, EPUB and Kindle. Book excerpt: Provides advanced students with an introduction to modern galactic dynamics, and equips them with useful observational and theoretical tools.