DOCSLIB.ORG

Greenslade-J-2018-Phd-Pdf

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Greenslade-J-2018-Phd-Pdf The Nature and Evolution of High Redshift Dusty Star Forming Galaxies Joshua Greenslade Astrophysics Group Department of Physics Imperial College London Thesis submitted for the Degree of Doctor of Philosophy to Imperial College London - 2018 - Abstract DSFGs dominate the cosmic star formation rate (SFR) at z > 0:7, are 2 - 3 orders of magnitude −1 more populous at z = 2 than locally, and have SFRs of tens to thousands of M yr . Despite their prodigious SFR, they are heavily dust obscured, with estimates suggesting that optical/UV surveys alone miss half the star formation in the Universe. Furthermore, DSFGs are believed to be the evolutionary progenitors to the massive elliptical galaxies that today inhabit the cores of massive galaxy clusters. DSFGs however remain poorly constrained, with few constraints on their contribution to the cosmic SFR density above z > 4, disagreement over whether single- dish observations accurately reflect the underlying population, and uncertainty about DSFGs in clusters, particularly whether they trace massive overdensities at their epoch. This thesis presents a series of results that set out to address some of these questions. To begin with, and by cross-matching Planck and Herschel data, we identify 27 candidate protoclusters by searching for overdensities of DSFGs. Their colours indicate they likely lie at z = 2 − 3, their flux density is 3x brighter than predicted from models, and fitting modified blackbodies to −1 their photometry suggests they have total SFRs of several thousand M yr . We additionally present the results of an interferometric program targeting 36 single-dish DSFGs at z ∼ 4. We assess their multiplicity, finding that whilst ∼ 45% are blends of multiple sources, there are a number of highly luminous, possibly lensed, singular sources. Finally, we present the serendipitous detection of a SPIRE dropout, a source detected at 850 µm but not at any shorter wavelength, likely at z > 6, and we discuss the application of its selection to wider surveys. In closing, we discuss the future of FIR/sub-mm astronomy, new directions of the work begun here, and the challenges that remain for the field. 1 2 Acknowledgements Of all of the words in this thesis, these are the hardest to write. To adequately credit all those who have borne me through to this point is simply an impossible task. Nevertheless, several of those countless individuals deserve space within these few lines. First and foremost, I would like to thank my supervisor, Dave Clements, whose infinite patience, guidance, and care have not only supported me through this journey, but whose raw passion and clear enjoyment of his subject are constantly uplifting. Quite simply, without Dave, none of this would have been possible. I also wish to pay thanks to my academic brother Tai-An, whose insight and determination serve as an inspiration every day, and whose comments and questions have helped me to refine and polish every aspect of this thesis. I cannot pass by without mentioning my other academic siblings, in particular those who shared so much of this journey with me. Ciar^an,Charlotte, Claude, Rhys, Hik and Nat, with whom I have all shared so my laughs, jokes, pints, puzzles and emergency tea, thank you for everything and for making this journey endurable. Special mention should also go out to everyone involved in the planetarium shows (thanks Cat for dumping that on my desk at the end of first year!), in particular to Tom, Dan, Charlotte, Hik, George, Wahid, Emily, and everyone who've I've inevitably forgotten to mention and who've been involved. Without you all, it would never had gotten to the point it is now, so thank you. It goes too, without saying, my thanks to those involved and who enjoy the cryptic puzzle group that has been springing up in the interaction area over the last few years. It is my great hope that someone else takes over the posting of new puzzles and clues, and my thanks to all who indulged in these interesting titbits. To my friends, too numerous to mention but too extraordinary not to, yours has been the guiding light; each and every one of you a shimmering, blazing star in your own right, against the backdrop of what has been a long, dark nights sky for me. Yours, all of yours, are the lights which have guided me, comforted me, and given me hope. Special mention to those that have suffered me most: Henry Wearing, whose honesty and kinship gave me joy at the lowest of points, James Hickson, who together in mutual suffering we shared laughter and drunken despondence at our lot, Heather Thomas, whose shining love, altruistic care, and unwavering patience with my ups and downs have carried me more than any other through the last few years, and finally Chris Love, for whom no earthen language, script or motion possess the requisite intricacy to describe my unceasing gratitude for your friendship. 3 Finally, I would like to thank my brother Chris, my sister Faye, my mother Debra, my father Ian, my aunt NJ, my cousin Kai, my grandma Joan (Guv), and my grandma Valerie. They have all shown an inhuman level of patience with me as I've been writing this, picking up the slack whilst I effectively dropped off the radar for six months. Their continued words and actions of kindness and compassion serve as a constant reminder that whilst the Universe may hold infinite possibility, there is no place I would rather be than within their familial embrace. 4 Dedication For Ian Stuart Greenslade. A teacher of unparalleled passion, A inquirer of unequalled eagerness, And a father of indisputable devotion, Whose hope, curiosity, and love, Thunder into the cosmos. 5 The copyright of this thesis rests with the author. Unless otherwise indicated, its contents are licensed under a Creative Commons Attribution-Non Commercial 4.0 International Licence (CC BY-NC)1. Under this licence, you may copy and redistribute the material in any medium or format. You may also create and distribute modified versions of the work. This is on the condition that: you credit the author and do not use it, or any derivative works, for a commercial purpose. 1https://creativecommons.org/licenses/by/4.0/ 6 The work contained herein is the result of the authors own work. Any work that is not the authors own is correctly referenced and attributed to its original source. 7 8 Contents Abstract 1 Acknowledgements 2 Copyright Declaration 6 Declaration of Originality 7 1 Introduction 22 1.1 The Infrared Sky . 22 1.1.1 Cosmology . 22 1.1.2 The Cosmic Infrared Background . 24 1.1.3 Local Infrared Bright Galaxies . 27 1.2 Infrared Astronomy . 32 1.2.1 Atmospheric Opacity . 32 1.2.2 Single Dish Observations . 33 1.2.3 An Extremely Negative K-correction . 36 1.2.4 Instrumentation . 38 9 10 CONTENTS 1.3 Dusty Star Forming Galaxies . 40 1.3.1 Redshift Distributions . 41 1.3.2 The Luminosity Evolution of Dusty Star Forming Galaxies . 44 1.3.3 Scaled up Local (U)LIRGs . 47 1.3.4 Multiplicity and Mergers . 48 1.3.5 Environment . 50 1.3.6 Models of DSFGs . 51 1.3.7 Our Current Understanding of High-z DSFGs . 53 1.4 This Thesis . 54 2 Protoclusters of DSFGs at z > 1 57 2.1 Introduction and Motivation . 57 2.2 The Data . 64 2.2.1 The Planck Catalogues of Compact Sources . 65 2.2.2 The Herschel Extragalactic Legacy Surveys . 69 2.3 Selection and Identification of Sources . 73 2.3.1 Source Selection . 74 2.3.2 Source Identification . 76 2.3.3 Diffuse and Dominated Sources . 80 2.3.4 Variations between the ERCSC, PCCS1 and PCCS2 . 83 2.4 Photometry . 84 2.4.1 Are the Planck and Herschel Photometry Consistent? . 85 CONTENTS 11 2.4.2 Are the Detected Herschel Sources Enough to Match the Planck Flux Density? . 87 2.5 Colours . 90 2.5.1 Planck Colours . 90 2.5.2 Herschel Colours . 95 2.6 The Candidate Protoclusters . 98 2.6.1 Line of Sight Effects . 98 2.6.2 Properties of the Protocluster Candidates . 100 2.6.3 Simulations of DSFGs in Clusters . 113 2.7 Discussion . 115 2.7.1 The HeLMS Field . 116 2.7.2 The Nature of the Planck Sources . 116 2.7.3 The Nature of the Candidate Protoclusters . 121 2.7.4 Future Work . 122 2.8 Conclusions . 123 3 Multiplicities of 500 Micron Risers 126 3.1 Introduction and Motivation . 126 3.2 Target Selection . 129 3.3 Methods . 132 3.3.1 Interferometry . 132 3.3.2 Data Reduction . 134 12 CONTENTS 3.3.3 Source Extraction . 135 3.3.4 The Detected Sources . 148 3.4 Extraction of Physical Properties . 153 3.5 Discussion . 158 3.5.1 Number Counts . 158 3.5.2 Lensing . 159 3.5.3 Blended Sources . 160 3.5.4 Extreme Luminosities . 161 3.5.5 Multi-Wavelength Counterparts . 162 3.6 Conclusions . 163 4 SPIRE dropouts 166 4.1 Introduction and Motivation . 166 4.2 Serendipitous Discovery of NGP6 D1........................ 170 4.3 Photometric Observations . 173 4.3.1 SMA . 173 4.3.2 NIKA . 177 4.3.3 VLA . 177 4.3.4 SDSS, UKIDSS and WISE . 178 4.4 Spectroscopic Observations . 180 4.4.1 RSR . 180 4.4.2 EMIR . 183 CONTENTS 13 4.4.3 NOEMA . 183 4.5 Photometric Analysis . 184 4.5.1 Template Fitting . 185 4.5.2 Fitting Modified Blackbodies . 188 4.5.3 The NIKA Observations . 196 4.5.4 The Statistics of Tdust=(1 + z).......................
Load more

Recommended publications
  • The HERACLES View of the H -To-HI Ratio in Galaxies
    The HERACLES View of the H2-to-HI Ratio in Galaxies Adam Leroy (NRAO, Hubble Fellow) Fabian Walter, Frank Bigiel, the HERACLES and THINGS teams The Saturday Morning Summary • Star formation rate vs. gas relation on ~kpc scales breaks apart into: A relatively universal CO-SFR relation in nearby disks Systematic environmental scalings in the CO-to-HI ratio • The CO-to-HI ratio is a strong function of radius, total gas, and stellar surface density correlated with ISM properties: dust-to-gas ratio, pressure harder to link to dynamics: gravitational instability, arms • Interpretation: the CO-to-HI ratio traces the efficiency of GMC formation Density and dust can explain much of the observed behavior heracles Fabian Walter Erik Rosolowsky MPIA UBC Frank Bigiel Eva Schinnerer UC Berkeley THINGS plus… MPIA Elias Brinks Antonio Usero Gaelle Dumas U Hertfordshire OAN, Madrid MPIA Erwin de Blok Andreas Schruba Helmut Wiesemeyer U Cape Town IRAM … MPIA Rob Kennicutt Axel Weiss Karl Schuster Cambridge MPIfR IRAM Barry Madore Carsten Kramer Karin Sandstrom Carnegie IRAM MPIA Michele Thornley Daniela Calzetti Kelly Foyle Bucknell UMass MPIA Collaborators The HERA CO-Line Extragalactic Survey First maps Leroy et al. (2009) • IRAM 30m Large Program to map CO J = 2→1 line • Instrument: HERA receiver array operating at 230 GHz • 47 galaxies: dwarfs to starbursts and massive spirals -2 • Very wide-field (~ r25) and sensitive (σ ~ 1-2 Msun pc ) NGS The HI Nearby Galaxy Survey HI Walter et al. (2008), AJ Special Issue (2008) • VLA HI maps of 34 galaxies:
    [Show full text]
  • Ubiquitous Ram Pressure Stripping in the Coma Cluster of Galaxies
    Astronomy & Astrophysics manuscript no. 33427˙corr c ESO 2018 August 17, 2018 Ubiquitous ram pressure stripping in the Coma cluster of galaxies⋆ G. Gavazzi1, G. Consolandi1, M. L. Gutierrez2, A. Boselli3, and M. Yoshida4 1 Universit`adegli Studi di Milano-Bicocca, Piazza della Scienza 3, 20126 Milano, Italy e-mail: [email protected] 2 nstituto de Astronomia, UNAM, Km 107 Carretera Tijuana-Ensenada, Ensenada, B.C., Mexico 22860 3 Aix Marseille Univ, CNRS, CNES LAM, Laboratoire d’Astrophysique de Marseille, Marseille, France 4 Subaru Telescope, National Astronomical Observatory of Japan, National Institutes of Natural Sciences, 650 A’ohoku Place, Hilo, Hawaii 96720, USA Received; accepted ABSTRACT We report the detection of Hα trails behind three new intermediate-mass irregular galaxies in the NW outskirts of the nearby cluster of galaxies Abell 1656 (Coma). Hints that these galaxies possess an extended component were found in earlier, deeper Hα observations carried out with the Subaru telescope. However the lack of a simultaneous r-band exposure, together with the presence of strong stellar ghosts in the Subaru images, prevented us from quantifying the detections. We therefore devoted one full night of Hα observation to each of the three galaxies using the San Pedro Martir 2.1m telescope. One-sided tails of Hα emission of 10-20 kpc projected size were detected, suggesting an ongoing ram pressure stripping event. We added these 3 new sources of extended ionized gas (EIG) added to the 12 found by Yagi et al. (2010), NGC 4848 (Fossati et al. 2012), and NGC 4921 whose ram pressure stripping is certified by HI asymmetry.
    [Show full text]
  • Constructing a Galactic Coordinate System Based on Near-Infrared and Radio Catalogs
    A&A 536, A102 (2011) Astronomy DOI: 10.1051/0004-6361/201116947 & c ESO 2011 Astrophysics Constructing a Galactic coordinate system based on near-infrared and radio catalogs J.-C. Liu1,2,Z.Zhu1,2, and B. Hu3,4 1 Department of astronomy, Nanjing University, Nanjing 210093, PR China e-mail: [jcliu;zhuzi]@nju.edu.cn 2 key Laboratory of Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education, Nanjing 210093, PR China 3 Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008, PR China 4 Graduate School of Chinese Academy of Sciences, Beijing 100049, PR China e-mail: [email protected] Received 24 March 2011 / Accepted 13 October 2011 ABSTRACT Context. The definition of the Galactic coordinate system was announced by the IAU Sub-Commission 33b on behalf of the IAU in 1958. An unrigorous transformation was adopted by the Hipparcos group to transform the Galactic coordinate system from the FK4-based B1950.0 system to the FK5-based J2000.0 system or to the International Celestial Reference System (ICRS). For more than 50 years, the definition of the Galactic coordinate system has remained unchanged from this IAU1958 version. On the basis of deep and all-sky catalogs, the position of the Galactic plane can be revised and updated definitions of the Galactic coordinate systems can be proposed. Aims. We re-determine the position of the Galactic plane based on modern large catalogs, such as the Two-Micron All-Sky Survey (2MASS) and the SPECFIND v2.0. This paper also aims to propose a possible definition of the optimal Galactic coordinate system by adopting the ICRS position of the Sgr A* at the Galactic center.
    [Show full text]
  • Stellar Tidal Streams As Cosmological Diagnostics: Comparing Data and Simulations at Low Galactic Scales
    RUPRECHT-KARLS-UNIVERSITÄT HEIDELBERG DOCTORAL THESIS Stellar Tidal Streams as Cosmological Diagnostics: Comparing data and simulations at low galactic scales Author: Referees: Gustavo MORALES Prof. Dr. Eva K. GREBEL Prof. Dr. Volker SPRINGEL Astronomisches Rechen-Institut Heidelberg Graduate School of Fundamental Physics Department of Physics and Astronomy 14th May, 2018 ii DISSERTATION submitted to the Combined Faculties of the Natural Sciences and Mathematics of the Ruperto-Carola-University of Heidelberg, Germany for the degree of DOCTOR OF NATURAL SCIENCES Put forward by GUSTAVO MORALES born in Copiapo ORAL EXAMINATION ON JULY 26, 2018 iii Stellar Tidal Streams as Cosmological Diagnostics: Comparing data and simulations at low galactic scales Referees: Prof. Dr. Eva K. GREBEL Prof. Dr. Volker SPRINGEL iv NOTE: Some parts of the written contents of this thesis have been adapted from a paper submitted as a co-authored scientific publication to the Astronomy & Astrophysics Journal: Morales et al. (2018). v NOTE: Some parts of this thesis have been adapted from a paper accepted for publi- cation in the Astronomy & Astrophysics Journal: Morales, G. et al. (2018). “Systematic search for tidal features around nearby galaxies: I. Enhanced SDSS imaging of the Local Volume". arXiv:1804.03330. DOI: 10.1051/0004-6361/201732271 vii Abstract In hierarchical models of galaxy formation, stellar tidal streams are expected around most galaxies. Although these features may provide useful diagnostics of the LCDM model, their observational properties remain poorly constrained. Statistical analysis of the counts and properties of such features is of interest for a direct comparison against results from numeri- cal simulations. In this work, we aim to study systematically the frequency of occurrence and other observational properties of tidal features around nearby galaxies.
    [Show full text]
  • Studying the ISM at ∼ 10 Pc Scale in NGC 7793 with MUSE - I
    Astronomy & Astrophysics manuscript no. dellabruna_2020 c ESO 2020 February 24, 2020 Studying the ISM at ∼ 10 pc scale in NGC 7793 with MUSE - I. Data description and properties of the ionised gas Lorenza Della Bruna1, Angela Adamo1, Arjan Bik1, Michele Fumagalli2; 3; 4, Rene Walterbos5, Göran Östlin1, Gustavo Bruzual6, Daniela Calzetti7, Stephane Charlot8, Kathryn Grasha9, Linda J. Smith10, David Thilker11, and Aida Wofford12 1 Department of Astronomy, Oskar Klein Centre, Stockholm University, AlbaNova University Centre, SE-106 91 Stockholm, Swe- den 2 Institute for Computational Cosmology, Durham University, South Road, Durham, DH1 3LE, UK 3 Centre for Extragalactic Astronomy, Durham University, South Road, Durham, DH1 3LE, UK 4 Dipartimento di Fisica G. Occhialini, Università degli Studi di Milano Bicocca, Piazza della Scienza 3, 20126 Milano, Italy 5 Department of Astronomy, New Mexico State University, Las Cruces, NM, 88001, USA 6 Instituto de Radioastronomía y Astrofísica, UNAM, Campus Morelia, Michoacan, C.P. 58089, México 7 Department of Astronomy, University of Massachusetts, Amherst, MA 01003, USA 8 Sorbonne Université, CNRS, UMR7095, Institut d’Astrophysique de Paris, F-75014, Paris, France 9 Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611, Australia 10 Space Telescope Science Institute and European Space Agency, 3700 San Martin Drive, Baltimore, MD 2121, USA 11 Department of Physics and Astronomy, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA 12 Instituto de Astronomía, Universidad Nacional Autónoma de México, Unidad Académica en Ensenada, Km 103 Carr. Tijuana−Ensenada, Ensenada 22860, México Received XXX / Accepted YYY ABSTRACT Context. Studies of nearby galaxies reveal that around 50% of the total Hα luminosity in late-type spirals originates from diffuse ionised gas (DIG), which is a warm, diffuse component of the interstellar medium that can be associated with various mechanisms, the most important ones being ’leaking’ HII regions, evolved field stars, and shocks.
    [Show full text]
  • 1. Introduction
    THE ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES, 122:109È150, 1999 May ( 1999. The American Astronomical Society. All rights reserved. Printed in U.S.A. GALAXY STRUCTURAL PARAMETERS: STAR FORMATION RATE AND EVOLUTION WITH REDSHIFT M. TAKAMIYA1,2 Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL 60637; and Gemini 8 m Telescopes Project, 670 North Aohoku Place, Hilo, HI 96720 Received 1998 August 4; accepted 1998 December 21 ABSTRACT The evolution of the structure of galaxies as a function of redshift is investigated using two param- eters: the metric radius of the galaxy(Rg) and the power at high spatial frequencies in the disk of the galaxy (s). A direct comparison is made between nearby (z D 0) and distant(0.2 [ z [ 1) galaxies by following a Ðxed range in rest frame wavelengths. The data of the nearby galaxies comprise 136 broad- band images at D4500A observed with the 0.9 m telescope at Kitt Peak National Observatory (23 galaxies) and selected from the catalog of digital images of Frei et al. (113 galaxies). The high-redshift sample comprises 94 galaxies selected from the Hubble Deep Field (HDF) observations with the Hubble Space Telescope using the Wide Field Planetary Camera 2 in four broad bands that range between D3000 and D9000A (Williams et al.). The radius is measured from the intensity proÐle of the galaxy using the formulation of Petrosian, and it is argued to be a metric radius that should not depend very strongly on the angular resolution and limiting surface brightness level of the imaging data. It is found that the metric radii of nearby and distant galaxies are comparable to each other.
    [Show full text]
  • Spatial Distribution of Galactic Globular Clusters: Distance Uncertainties and Dynamical Effects
    Juliana Crestani Ribeiro de Souza Spatial Distribution of Galactic Globular Clusters: Distance Uncertainties and Dynamical Effects Porto Alegre 2017 Juliana Crestani Ribeiro de Souza Spatial Distribution of Galactic Globular Clusters: Distance Uncertainties and Dynamical Effects Dissertação elaborada sob orientação do Prof. Dr. Eduardo Luis Damiani Bica, co- orientação do Prof. Dr. Charles José Bon- ato e apresentada ao Instituto de Física da Universidade Federal do Rio Grande do Sul em preenchimento do requisito par- cial para obtenção do título de Mestre em Física. Porto Alegre 2017 Acknowledgements To my parents, who supported me and made this possible, in a time and place where being in a university was just a distant dream. To my dearest friends Elisabeth, Robert, Augusto, and Natália - who so many times helped me go from "I give up" to "I’ll try once more". To my cats Kira, Fen, and Demi - who lazily join me in bed at the end of the day, and make everything worthwhile. "But, first of all, it will be necessary to explain what is our idea of a cluster of stars, and by what means we have obtained it. For an instance, I shall take the phenomenon which presents itself in many clusters: It is that of a number of lucid spots, of equal lustre, scattered over a circular space, in such a manner as to appear gradually more compressed towards the middle; and which compression, in the clusters to which I allude, is generally carried so far, as, by imperceptible degrees, to end in a luminous center, of a resolvable blaze of light." William Herschel, 1789 Abstract We provide a sample of 170 Galactic Globular Clusters (GCs) and analyse its spatial distribution properties.
    [Show full text]
  • Modeling and Interpretation of the Ultraviolet Spectral Energy Distributions of Primeval Galaxies
    Ecole´ Doctorale d'Astronomie et Astrophysique d'^Ile-de-France UNIVERSITE´ PARIS VI - PIERRE & MARIE CURIE DOCTORATE THESIS to obtain the title of Doctor of the University of Pierre & Marie Curie in Astrophysics Presented by Alba Vidal Garc´ıa Modeling and interpretation of the ultraviolet spectral energy distributions of primeval galaxies Thesis Advisor: St´ephane Charlot prepared at Institut d'Astrophysique de Paris, CNRS (UMR 7095), Universit´ePierre & Marie Curie (Paris VI) with financial support from the European Research Council grant `ERC NEOGAL' Composition of the jury Reviewers: Alessandro Bressan - SISSA, Trieste, Italy Rosa Gonzalez´ Delgado - IAA (CSIC), Granada, Spain Advisor: St´ephane Charlot - IAP, Paris, France President: Patrick Boisse´ - IAP, Paris, France Examinators: Jeremy Blaizot - CRAL, Observatoire de Lyon, France Vianney Lebouteiller - CEA, Saclay, France Dedicatoria v Contents Abstract vii R´esum´e ix 1 Introduction 3 1.1 Historical context . .4 1.2 Early epochs of the Universe . .5 1.3 Galaxytypes ......................................6 1.4 Components of a Galaxy . .8 1.4.1 Classification of stars . .9 1.4.2 The ISM: components and phases . .9 1.4.3 Physical processes in the ISM . 12 1.5 Chemical content of a galaxy . 17 1.6 Galaxy spectral energy distributions . 17 1.7 Future observing facilities . 19 1.8 Outline ......................................... 20 2 Modeling spectral energy distributions of galaxies 23 2.1 Stellar emission . 24 2.1.1 Stellar population synthesis codes . 24 2.1.2 Evolutionary tracks . 25 2.1.3 IMF . 29 2.1.4 Stellar spectral libraries . 30 2.2 Absorption and emission in the ISM . 31 2.2.1 Photoionization code: CLOUDY .......................
    [Show full text]
  • The Dynamical State of the Coma Cluster with XMM-Newton?
    A&A 400, 811–821 (2003) Astronomy DOI: 10.1051/0004-6361:20021911 & c ESO 2003 Astrophysics The dynamical state of the Coma cluster with XMM-Newton? D. M. Neumann1,D.H.Lumb2,G.W.Pratt1, and U. G. Briel3 1 CEA/DSM/DAPNIA Saclay, Service d’Astrophysique, L’Orme des Merisiers, Bˆat. 709, 91191 Gif-sur-Yvette, France 2 Science Payloads Technology Division, Research and Science Support Dept., ESTEC, Postbus 299 Keplerlaan 1, 2200AG Noordwijk, The Netherlands 3 Max-Planck Institut f¨ur extraterrestrische Physik, Giessenbachstr., 85740 Garching, Germany Received 19 June 2002 / Accepted 13 December 2002 Abstract. We present in this paper a substructure and spectroimaging study of the Coma cluster of galaxies based on XMM- Newton data. XMM-Newton performed a mosaic of observations of Coma to ensure a large coverage of the cluster. We add the different pointings together and fit elliptical beta-models to the data. We subtract the cluster models from the data and look for residuals, which can be interpreted as substructure. We find several significant structures: the well-known subgroup connected to NGC 4839 in the South-West of the cluster, and another substructure located between NGC 4839 and the centre of the Coma cluster. Constructing a hardness ratio image, which can be used as a temperature map, we see that in front of this new structure the temperature is significantly increased (higher or equal 10 keV). We interpret this temperature enhancement as the result of heating as this structure falls onto the Coma cluster. We furthermore reconfirm the filament-like structure South-East of the cluster centre.
    [Show full text]
  • Gas and Star Formation Laws in Galaxies
    Gas and Star Formation laws in galaxies Jonathan Braine Laboratoire d'Astrophysique de Bordeaux University of Bordeaux, France Why link gas and star formation ? Stars form directly from the molecular gas. --- understand the physical conditions in molecular gas --- devise methods to estimate gas mass --- devise methods to measure the star formation rate In most galaxies, the majority of the gas is in the form of atomic Hydrogen, "HI", from which the H2 forms. So an important part of the star formation cycle is also the HI --> H2 transformation. --- Phases of gas in galaxies --- Link between SF and molecular gas and its consequences --- How do we trace star formation ? --- How can we measure the molecular gas mass ? --- HI --> H2 transformation --- Variations in Star Formation Efficiency Gas in Galaxies 3 phases: ionized (H+, HII), atomic (HI), molecular (H2) Ionized gas mass is much smaller that the atomic or molecular gas mass in spirals and star-forming Irregular galaxies. Not necessarily in Elliptical galaxies, particularly large ones. The HI is usually the dominantWhy mass care component of the gas. Not the case for galaxies with very high Star Formation Rates (SFR). Large spirals often have similar HI and H2 masses. As the metallicity (size, generally) decreases, HI becomes more and more dominant, at least in the local universe. The HI is very extended in isolated galaxies but often deficient in cluster galaxies. HI emission has not been detected at high redshift (z > 0.3) Molecular gas is organized in clouds which follow scaling laws, which will be discussed further on. Mol clouds are cool (10-30K).
    [Show full text]
  • Classification of Galaxies Using Fractal Dimensions
    UNLV Retrospective Theses & Dissertations 1-1-1999 Classification of galaxies using fractal dimensions Sandip G Thanki University of Nevada, Las Vegas Follow this and additional works at: https://digitalscholarship.unlv.edu/rtds Repository Citation Thanki, Sandip G, "Classification of galaxies using fractal dimensions" (1999). UNLV Retrospective Theses & Dissertations. 1050. http://dx.doi.org/10.25669/8msa-x9b8 This Thesis is protected by copyright and/or related rights. It has been brought to you by Digital Scholarship@UNLV with permission from the rights-holder(s). You are free to use this Thesis in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s) directly, unless additional rights are indicated by a Creative Commons license in the record and/ or on the work itself. This Thesis has been accepted for inclusion in UNLV Retrospective Theses & Dissertations by an authorized administrator of Digital Scholarship@UNLV. For more information, please contact [email protected]. INFORMATION TO USERS This manuscript has been reproduced from the microfilm master. UMI films the text directly from the original or copy submitted. Thus, some thesis and dissertation copies are in typewriter face, while others may be from any type of computer printer. The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleedthrough, substandard margins, and improper alignment can adversely affect reproduction. In the unlikely event that the author did not send UMI a complete manuscript and there are missing pages, these will be noted.
    [Show full text]
  • The Herschel Sprint PHOTO ILLUSTRATION: PATRICIA GILLIS-COPPOLA, HERSCHEL IMAGE: WIKIMEDIA S&T
    The Herschel Sprint PHOTO ILLUSTRATION: PATRICIA GILLIS-COPPOLA, HERSCHEL IMAGE: WIKIMEDIA S&T 34 April 2015 sky & telescope William Herschel’s Extraordinary Night of DiscoveryMark Bratton Recreating the legendary sweep of April 11, 1785 There’s little doubt that William Herschel was the most clearly with his instruments. As we will see, he did make signifi cant astronomer of the 18th century. His accom- occasional errors in interpretation, despite the superior plishments included the discovery of Uranus, infrared optics; for instance, he thought that the planetary nebula radiation, and four planetary satellites, as well as the M57 was a ring of stars. compilation of two extensive catalogues of double and The other factor contributing to Herschel’s interest multiple stars. His most lasting achievement, however, was the success of his sister, Caroline, in her study of the was his exhaustive search for undiscovered star clusters sky. He had built her a small telescope, encouraging her and nebulae, a key component in his quest to understand to search for double stars and comets. She located Messier what he called “the construction of the heavens.” In Her- objects and more, occasionally fi nding star clusters and schel’s time, astronomers were concerned principally with nebulae that had escaped the French astronomer’s eye. the study of solar system objects. The search for clusters Over the course of a year of observing, she discovered and nebulae was, up to that point, a haphazard aff air, with about a dozen star clusters and galaxies, occasionally not- a total of only 138 recorded by all the observers in history.
    [Show full text]