Neutron-Capture Elements in Dwarf Galaxies III
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Tidal Disruption of Globular Clusters in Dwarf Galaxies with Triaxial Dark Matter Haloes.” by J
“Tidal disruption of globular clusters in dwarf galaxies with triaxial dark matter haloes.” by J. Peñarrubia, M.J. Walker, and G. Gilmore University of Cambridge and University of Victoria MNRAS accepted Journal Club 5/15/09 Daniel Grin 1/19 Wednesday, September 2, 2009 1 Punchline 2/19 • Globular clusters (GCs) around dwarf spheroidal (dSph) galaxies may survive tidal encounters • Stellar substructure (morphology and kinematics) in dSph galaxies may be explained by past disruptions of GCs • Simulation techniques grossly over-simplify the problem, but useful first step Wednesday, September 2, 2009 2 Outline 3/19 • Motivation: subtructure in dSphs and existence of GCs near them. • Properties of systems modeled • Simulation techniques/caveats • Results Wednesday, September 2, 2009 3 Motivation: Substructure in dSph galaxies 4/19 • Milky Way (MW) dSph galaxies are DM dominated-- : • Ideal testbed for CDM scenario • Standing dispute about presence of cores (triaxiality? projection effect? see work by J. Simon) • dSph galaxies have substructure, contrary to expectation that it should be erased in a few crossing times (~100 Myr): • Morphology: Kinematically cold core in Sextans, kinematically distinct shell in Fornax, asymmetries across major/minor axes in Fornax (claims of butterfly shapes are sketchy) • Ages: 2 Gyr-old stellar populations in Fornax shell • Can prolong life of stellar substructure with cored density profile, challenge to CDM? • Can save CDM with formation of substructure that is not in situ • Blue stragglers in Sextans are mass segregated, not enough time for this in Sextans, do it elsewhere (like a merging G.C.) and disrupt? Wednesday, September 2, 2009 4 Motivation: Globular clusters in dSph 5/19 • Fornax (5) and Sagitarrius (4) contain GCs near : Name Angular sep. -
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. -
Young Globular Clusters and Dwarf Spheroidals
View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by CERN Document Server Young Globular Clusters and Dwarf Spheroidals Sidney van den Bergh Dominion Astrophysical Observatory Herzberg Institute of Astrophysics National Research Council of Canada 5071 West Saanich Road Victoria, British Columbia, V8X 4M6 Canada ABSTRACT Most of the globular clusters in the main body of the Galactic halo were formed almost simultaneously. However, globular cluster formation in dwarf spheroidal galaxies appears to have extended over a significant fraction of a Hubble time. This suggests that the factors which suppressed late-time formation of globulars in the main body of the Galactic halo were not operative in dwarf spheroidal galaxies. Possibly the presence of significant numbers of “young” globulars at RGC > 15 kpc can be accounted for by the assumption that many of these objects were formed in Sagittarius-like (but not Fornax-like) dwarf spheroidal galaxies, that were subsequently destroyed by Galactic tidal forces. It would be of interest to search for low-luminosity remnants of parental dwarf spheroidals around the “young” globulars Eridanus, Palomar 1, 3, 14, and Terzan 7. Furthermore multi-color photometry could be used to search for the remnants of the super-associations, within which outer halo globular clusters originally formed. Such envelopes are expected to have been tidally stripped from globulars in the inner halo. Subject headings: Globular clusters - galaxies: dwarf The galaxy is, in fact, nothing but a congeries of innumerable stars grouped together in clusters. Galileo (1610) –2– 1. Introduction The vast majority of Galactic globular clusters appear to have formed at about the same time (e.g. -
Searching for Dark Matter Annihilation in Recently Discovered Milky Way Satellites with Fermi-Lat A
The Astrophysical Journal, 834:110 (15pp), 2017 January 10 doi:10.3847/1538-4357/834/2/110 © 2017. The American Astronomical Society. All rights reserved. SEARCHING FOR DARK MATTER ANNIHILATION IN RECENTLY DISCOVERED MILKY WAY SATELLITES WITH FERMI-LAT A. Albert1, B. Anderson2,3, K. Bechtol4, A. Drlica-Wagner5, M. Meyer2,3, M. Sánchez-Conde2,3, L. Strigari6, M. Wood1, T. M. C. Abbott7, F. B. Abdalla8,9, A. Benoit-Lévy10,8,11, G. M. Bernstein12, R. A. Bernstein13, E. Bertin10,11, D. Brooks8, D. L. Burke14,15, A. Carnero Rosell16,17, M. Carrasco Kind18,19, J. Carretero20,21, M. Crocce20, C. E. Cunha14,C.B.D’Andrea22,23, L. N. da Costa16,17, S. Desai24,25, H. T. Diehl5, J. P. Dietrich24,25, P. Doel8, T. F. Eifler12,26, A. E. Evrard27,28, A. Fausti Neto16, D. A. Finley5, B. Flaugher5, P. Fosalba20, J. Frieman5,29, D. W. Gerdes28, D. A. Goldstein30,31, D. Gruen14,15, R. A. Gruendl18,19, K. Honscheid32,33, D. J. James7, S. Kent5, K. Kuehn34, N. Kuropatkin5, O. Lahav8,T.S.Li6, M. A. G. Maia16,17, M. March12, J. L. Marshall6, P. Martini32,35, C. J. Miller27,28, R. Miquel21,36, E. Neilsen5, B. Nord5, R. Ogando16,17, A. A. Plazas26, K. Reil15, A. K. Romer37, E. S. Rykoff14,15, E. Sanchez38, B. Santiago16,39, M. Schubnell28, I. Sevilla-Noarbe18,38, R. C. Smith7, M. Soares-Santos5, F. Sobreira16, E. Suchyta12, M. E. C. Swanson19, G. Tarle28, V. Vikram40, A. R. Walker7, and R. H. Wechsler14,15,41 (The Fermi-LAT and DES Collaborations) 1 Los Alamos National Laboratory, Los Alamos, NM 87545, USA; [email protected], [email protected] 2 Department of Physics, Stockholm University, AlbaNova, SE-106 91 Stockholm, Sweden; [email protected] 3 The Oskar Klein Centre for Cosmoparticle Physics, AlbaNova, SE-106 91 Stockholm, Sweden 4 Dept. -
Galactic Metal-Poor Halo E NCYCLOPEDIA of a STRONOMY and a STROPHYSICS
Galactic Metal-Poor Halo E NCYCLOPEDIA OF A STRONOMY AND A STROPHYSICS Galactic Metal-Poor Halo Most of the gas, stars and clusters in our Milky Way Galaxy are distributed in its rotating, metal-rich, gas-rich and flattened disk and in the more slowly rotating, metal- rich and gas-poor bulge. The Galaxy’s halo is roughly spheroidal in shape, and extends, with decreasing density, out to distances comparable with those of the Magellanic Clouds and the dwarf spheroidal galaxies that have been collected around the Galaxy. Aside from its roughly spheroidal distribution, the most salient general properties of the halo are its low metallicity relative to the bulk of the Galaxy’s stars, its lack of a gaseous counterpart, unlike the Galactic disk, and its great age. The kinematics of the stellar halo is closely coupled to the spheroidal distribution. Solar neighborhood disk stars move at a speed of about 220 km s−1 toward a point in the plane ◦ and 90 from the Galactic center. Stars belonging to the spheroidal halo do not share such ordered motion, and thus appear to have ‘high velocities’ relative to the Sun. Their orbital energies are often comparable with those of the disk stars but they are directed differently, often on orbits that have a smaller component of rotation or angular Figure 1. The distribution of [Fe/H] values for globular clusters. momentum. Following the original description by Baade in 1944, the disk stars are often called POPULATION I while still used to measure R . The recognizability of globular the metal-poor halo stars belong to POPULATION II. -
14734 (Stsci Edit Number: 18, Created: Wednesday, August 30, 2017 2:19:23 PM EST) - Overview
Proposal 14734 (STScI Edit Number: 18, Created: Wednesday, August 30, 2017 2:19:23 PM EST) - Overview 14734 - Milky Way Cosmology: Laying the Foundation for Full 6-D Dynamical Mapping of the Nearby Universe Cycle: 24, Proposal Category: GO (Treasury, JWST Initative) (Availability Mode: SUPPORTED) INVESTIGATORS Name Institution E-Mail Dr. Nitya Kallivayalil (PI) (Contact) The University of Virginia [email protected] Prof. Andrew Wetzel (CoI) (Contact) University of California - Davis [email protected] Dr. Joshua D. Simon (CoI) Carnegie Institution of Washington [email protected] Dr. Tobias Fritz (CoI) The University of Virginia [email protected] Dr. Erik Tollerud (CoI) Space Telescope Science Institute [email protected] Dr. Alis Deason (CoI) (ESA Member) Durham Univ. [email protected] Dr. Sangmo Tony Sohn (CoI) Space Telescope Science Institute [email protected] Dr. Roeland P. van der Marel (CoI) Space Telescope Science Institute [email protected] Dr. Gurtina Besla (CoI) University of Arizona [email protected] Prof. Marla C. Geha (CoI) Yale University [email protected] Dr. Steven R. Majewski (CoI) The University of Virginia [email protected] Dr. Evan Kirby (CoI) California Institute of Technology [email protected] Prof. Puragra Guhathakurta (CoI) University of California - Santa Cruz [email protected] Dr. Thomas M. Brown (CoI) Space Telescope Science Institute [email protected] Dr. Jay Anderson (CoI) Space Telescope Science Institute [email protected] VISITS 1 Proposal 14734 (STScI Edit Number: 18, -
Gaia RR Lyrae Stars in Nearby Ultra-Faint Dwarf Satellite Galaxies
Draft version January 7, 2020 Typeset using LATEX twocolumn style in AASTeX62 Gaia RR Lyrae Stars in Nearby Ultra-Faint Dwarf Satellite Galaxies A. Katherina Vivas,1 Clara Mart´ınez-Vazquez´ ,1 and Alistair R. Walker1 1Cerro Tololo Inter-American Observatory, NSF's National Optical-Infrared Astronomy Research Laboratory, Casilla 603, La Serena, Chile Submitted to ApJSS ABSTRACT We search for RR Lyrae stars in 27 nearby (< 100 kpc) ultra-faint dwarf satellite galaxies using the Gaia DR2 catalog of RR Lyrae stars. Based on proper motions, magnitudes and location on the sky, we associate 47 Gaia RR Lyrae stars to 14 different satellites. Distances based on RR Lyrae stars are provided for those galaxies. We have identified RR Lyrae stars for the first time in the Tucana II dwarf galaxy, and find additional members in Ursa Major II, Coma Berenices, Hydrus I, Bootes I and Bootes III. In addition we have identified candidate extra-tidal RR Lyrae stars in six galaxies which suggest they may be undergoing tidal disruption. We found 10 galaxies have no RR Lyrae stars neither in Gaia nor in the literature. However, given the known completeness of Gaia DR2 we cannot conclude these galaxies indeed lack variable stars of this type. Keywords: galaxies: dwarf | galaxies: stellar content | Local Group | stars: variables: RR Lyrae stars 1. INTRODUCTION horizontal branch (HB), which makes the task of mea- Ultra-Faint dwarfs (UFDs) are the most common suring an accurate distance to the UFDs very difficult. type among the satellite galaxies of the Milky Way. The main sequence turnoff is not generally available These tiny galaxies are valuable for our understanding from the discovery (survey) photometry if the galaxy of galaxy formation since they are the smallest dark- is more than ∼ 50 kpc distant, and in addition, the con- matter dominated systems known. -
Arxiv:1508.03622V2 [Astro-Ph.GA] 6 Nov 2015 – 2 –
Eight Ultra-faint Galaxy Candidates Discovered in Year Two of the Dark Energy Survey 1; 2;3; 4;5 6;7 6;7 8;4;5 A. Drlica-Wagner ∗, K. Bechtol y, E. S. Rykoff , E. Luque , A. Queiroz , Y.-Y. Mao , R. H. Wechsler8;4;5, J. D. Simon9, B. Santiago6;7, B. Yanny1, E. Balbinot10;7, S. Dodelson1;11, A. Fausti Neto7, D. J. James12, T. S. Li13, M. A. G. Maia7;14, J. L. Marshall13, A. Pieres6;7, K. Stringer13, A. R. Walker12, T. M. C. Abbott12, F. B. Abdalla15;16, S. Allam1, A. Benoit-L´evy15, G. M. Bernstein17, E. Bertin18;19, D. Brooks15, E. Buckley-Geer1, D. L. Burke4;5, A. Carnero Rosell7;14, M. Carrasco Kind20;21, J. Carretero22;23, M. Crocce22, L. N. da Costa7;14, S. Desai24;25, H. T. Diehl1, J. P. Dietrich24;25, P. Doel15, T. F. Eifler17;26, A. E. Evrard27;28, D. A. Finley1, B. Flaugher1, P. Fosalba22, J. Frieman1;11, E. Gaztanaga22, D. W. Gerdes28, D. Gruen29;30, R. A. Gruendl20;21, G. Gutierrez1, K. Honscheid31;32, K. Kuehn33, N. Kuropatkin1, O. Lahav15, P. Martini31;34, R. Miquel35;23, B. Nord1, R. Ogando7;14, A. A. Plazas26, K. Reil5, A. Roodman4;5, M. Sako17, E. Sanchez36, V. Scarpine1, M. Schubnell28, I. Sevilla-Noarbe36;20, R. C. Smith12, M. Soares-Santos1, F. Sobreira1;7, E. Suchyta31;32, M. E. C. Swanson21, G. Tarle28, D. Tucker1, V. Vikram37, W. Wester1, Y. Zhang28, J. Zuntz38 (The DES Collaboration) arXiv:1508.03622v2 [astro-ph.GA] 6 Nov 2015 { 2 { *[email protected] [email protected] 1Fermi National Accelerator Laboratory, P. -
The Velocity Anisotropy of the Milky Way Satellite System
MNRAS 000,1–16 (2019) Preprint 6 August 2019 Compiled using MNRAS LATEX style file v3.0 The velocity anisotropy of the Milky Way satellite system Alexander H. Riley,1? Azadeh Fattahi,2 Andrew B. Pace,1y Louis E. Strigari,1 Carlos S. Frenk,2 Facundo A. Gómez,3;4 Robert J. J. Grand,5;6;7 Federico Marinacci,8 Julio F. Navarro,9 Rüdiger Pakmor,7 Christine M. Simpson,10;11 and Simon D. M. White7 1Department of Physics and Astronomy, Mitchell Institute for Fundamental Physics and Astronomy, Texas A&M University, College Station, TX 77843, USA 2Institute for Computational Cosmology, Department of Physics, Durham University, South Road, Durham DH1 3LE, UK 3Instituto de Investigación Multidisciplinar en Ciencia y Tecnología, Universidad de La Serena, Raúl Bitrán 1305, La Serena, Chile 4Departamento de Física y Astronomía, Universidad de La Serena, Av. Juan Cisternas 1200 N, La Serena, Chile 5Heidelberger Institut für Theoretische Studien, Schloß-Wolfsbrunnenweg 35, 69118 Heidelberg, Germany 6Zentrum für Astronomie der Universität Heidelberg, Astronomisches Recheninstitut, Mönchhofstr. 12-14, 69120 Heidelberg, Germany 7Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, D-85748, Garching, Germany 8Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA 9Department of Physics and Astronomy, University of Victoria, Victoria, BC, V8P 1A1, Canada 10Enrico Fermi Institute, The University of Chicago, Chicago, IL 60637, USA 11Department of Astronomy & Astrophysics, University of Chicago, Chicago, IL 60637, USA Accepted 2019 April 4. Received 2019 March 24; in original form 2018 October 24 ABSTRACT We analyse the orbital kinematics of the Milky Way (MW) satellite system utilizing the latest systemic proper motions for 38 satellites based on data from Gaia Data Release 2. -
Pos(ICRC2019)509 Factors and Incorporate the − J Factor in a Combined Analysis
Prospect for dark matter annihilation signatures from gamma-ray observation of dwarf galaxies by LHAASO PoS(ICRC2019)509 Xiao-Jun Bi∗ Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China E-mail: [email protected] Su-Jie Lin Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China E-mail: [email protected] Peng-Fei Yin Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China E-mail: [email protected] The Large High Altitude Air Shower Observatory (LHAASO) is a next generation observatory for high energy gamma-rays and cosmic rays with a wide field of view, which is sensitive to gamma-rays from 300 GeV to 1 PeV. LHAASO is an ideal experiment to explore the gamma-ray signatures induced by annihilation of heavy dark matter (DM) particles in dwarf spheroidal satel- lite galaxies (dSphs). In this study, we investigate the LHAASO sensitivity to the DM annihilation at DM masses above 1TeV. We consider nineteen dSphs with large J−factors and incorporate the statistical uncertainties of the J−factor in a combined analysis. Comparing with current limits, we find that LHAASO is sensitive to the annihilation signatures for DM masses from several TeV up to 100 TeV. 36th International Cosmic Ray Conference -ICRC2019- July 24th - August 1st, 2019 Madison, WI, U.S.A. ∗Speaker. ⃝c Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0). -
Dark Matter Gets a Little Darker
Spotlights Dark Matter Gets Such a weakly interacting massive HAWC is not a system of lenses and mirrors a Little Darker particle (WIMP) could account for the but a collection of ultrapure water tanks In the 1970s, astronomers realized that majority of dark matter (with comparatively wired up with ultrasensitive light detectors. galaxies are filled with dark matter: little dark matter in the form of chunkier Whenever a very-high-energy particle matter that doesn’t emit, absorb, or block things like black holes and very dim stars). from space collides with an air molecule light (like stars, gas, or dust) but still But if a WIMP can pass clean through overhead, a spray of subatomic particles exerts a gravitational force, as measured the earth, then it can also pass clean rains downward and generates a faint flash by the orbital speeds of stars and other through the specialized machines that of blue light in HAWC’s water tanks. It just objects circling around the centers of earthlings build to detect it. Nonetheless, so happens that—in theory, at least— galaxies. For a typical galaxy like our own a number of dark matter detectors have WIMPs that collide with one another or Milky Way, there is about ten times more been built, running for years on end and decay should produce very-high-energy dark matter than all the “regular” forms accumulating enough non-detections to gamma rays capable of triggering of matter combined. rule out various categories of WIMPs and this event. Four decades of intensive scrutiny other dark matter candidates. -
Assessing the Milky Way Satellites Associated with the Sagittarius Dwarf Spheroidal Galaxy
DRAFT: November 8, 2018 Preprint typeset using LATEX style emulateapj v. 11/10/09 ASSESSING THE MILKY WAY SATELLITES ASSOCIATED WITH THE SAGITTARIUS DWARF SPHEROIDAL GALAXY David R. Law1,2, Steven R. Majewski3 DRAFT: November 8, 2018 ABSTRACT Numerical models of the tidal disruption of the Sagittarius (Sgr) dwarf galaxy have recently been developed that for the first time simultaneously satisfy most observational constraints on the angular position, distance, and radial velocity trends of both leading and trailing tidal streams emanating from the dwarf. We use these dynamical models in combination with extant 3-D position and velocity data for Galactic globular clusters and dSph galaxies to identify those Milky Way satellites that are likely to have originally formed in the gravitational potential well of the Sgr dwarf, and have been stripped from Sgr during its extended interaction with the Milky Way. We conclude that the globular clusters Arp 2, M 54, NGC 5634, Terzan 8, and Whiting 1 are almost certainly associated with the Sgr dwarf, and that Berkeley 29, NGC 5053, Pal 12, and Terzan 7 are likely to be as well (albeit at lower confidence). The initial Sgr system therefore may have contained 5-9 globular clusters, corresponding to a specific frequency SN =5−9 for an initial Sgr luminosity MV = −15.0. Our result is consistent with the 8±2 genuine Sgr globular clusters expected on the basis of statistical modeling of the Galactic globular cluster distribution and the corresponding false-association rate due to chance alignments with the Sgr streams. The globular clusters identified as most likely to be associated with Sgr are consistent with previous reconstructions of the Sgr age-metallicity relation, and show no evidence for a second- parameter effect shaping their horizontal branch morphologies.