DOCSLIB.ORG

Is Dark Matter Fact Or Fantasy – Clues from the Data

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text

Load more

IS DARK MATTER FACT OR FANTASY { CLUES FROM THE DATA Philip D. Mannheim University of Connecticut Seminar at Miami 2018, Fort Lauderdale December 2018 1 THE HUNDRED YEAR DARK MATTER PROBLEM Almost as soon as it was realized the Milky Way was a galaxy, in the 1920s Oort found that the velocities of stars perpendicular to the plane of the galaxy had a missing mass problem. Almost as soon as it was realized that there were other galaxies, in the 1930s Zwicky and Smith found that the velocity dispersions of galaxies in a cluster of galaxies had a missing mass problem. Three possibilities: more galaxies than one could see, lack of virialization because of corre- lation energy, breakdown of Newton's Law of Gravity on large distance scales. In the 1970s HI radio studies of Freeman and of Roberts and Whitehurst and HII opti- cal studies of Rubin, Ford and Thonnard showed the measured rotational velocities in the outskirts of spiral galaxies greatly exceeded the luminous Newtonian expectations. Then the dam broke, with missing mass problems all the way up to cosmology. And a brand new problem to boot { dark energy. 2 Two possible astrophysical options for dark matter: faint (need better tele- scopes { now ruled out). Dead (black holes, white dwarfs { MACHOS) Ruled out by gravitational lensing off the Magellanic clouds. One particle physics option for dark matter: particles that are intrinsically unable to emit light (neutrinos, supersymmetric particles, axions, dark pho- tons { WIMPS). Extensive, decades long accelerator and underground searches have yet to find any Wimps. Not ruled out but far from being ruled in, though there is a tension for supersymmetry since no superparticles found at LHC that could solve the elementary Higgs boson hierarchy problem. 3 Additionally no solution to the dark energy/cosmological constant problem found either in the twenty years now since the discovery of the accelerating Universe. Though problem predates the accelerating Universe. 60 And if ΩΛ really is of order 10 then none of the CMB background or fluctuation tests would be successful. In fact they would actually be some of the worst if not the worst fits in the history of physics. And lurking behind all this is the hope that the standard Newton-Einstein classical gravity expectations are not destroyed by quantum mechanics. (That gravity knows about large scale quantum effects is evidenced by the stabilizing Pauli degeneracy of electrons in a white dwarf and the intrinsically quantum mechanical CMB black body radiation spectrum.) To see what to do look for clues from the data { focus on galactic rotation curves of spirals since no theory needed { just orbits. Start with solar system wisdom { more sources (Neptune) or new theory (Mercury). 4 Keplerian expectation for planetary orbital velocities { Mercury and Uranus problems 5 Face on view of a spiral galaxy 6 Edge on view of a spiral galaxy 7 70 60 50 40 30 20 10 DDO 154 0 0 2 4 6 8 NGC 3198 and DDO 154 rotation velocities from HI data 8 TO FIX THINGS UP ASSUME DARK MATTER Need dark matter where there is little luminous matter. Not a small effect at all. Dark to luminous mass ratio in a bright spiral (NGC 3198) is of order two to one, and thus four to one in potential. Dark to luminous mass ratio in a dwarf spiral (DDO 154) is of order three to one, and thus nine to one in potential. Dark to luminous ratio not universal. Bright spiral rotation curves are flat, dwarf spiral rotation curves are rising. Thus the case where dark matter dominates is the one where rotation curves are not flat but rising, with dark matter being needed in the inner region. Dwarfs thus show the dark matter problem in its starkest form. To make dark matter halo fits work for bright spirals need two free parameters per halo (e.g. Navarro-Frenk-White NFW dark matter theory profile). One parameter to match asymptotic value of velocity to inner region and second parameter to keep velocity constant in between. Also need two parameters per halo for dwarfs. Thus for 138 well-studied galaxies discussed below (need good HII to get luminous distribution and good HI to get velocity distribution) need 276 free dark matter halo parameters. 9 DIFFICULTIES FOR DARK MATTER THEORY For the moment dark matter halo parameters are not derived from dark matter theory, and basically parameterize the data { you show me the velocity and I will tell you the amount of dark matter. Objective: to make dark matter falsifiable require: YOU SHOW ME THE LUMINOUS DISTRIBUTION AND I WILL TELL YOU THE VELOCITY Thus dark matter theory does not know a priori how to match any given halo with any given luminous distribution. WHY { BECAUSE GALAXIES OBEY TULLY- FISHER RELATION. Find that v4=L is universal in spiral galaxies. Thus velocity (due to the full gravitational potential) is correlated with the luminous distribution. Thus to get Tully Fisher would need dark to luminous ratio to be universal, but it is not, so need to tune halo parameters galaxy by galaxy. So let us look for other regularities, to see what we can pull out of the 138 galaxy sample. Find that v2=c2R at last data point is universal, and not only that, it is of cosmological magnitude. 10 100 140 150 120 80 100 100 60 80 60 40 50 40 20 20 IC 2574 NGC 925 NGC 2403 0 0 0 0 2 4 6 8 10 12 0 2 4 6 8 10 12 0 5 10 15 20 100 300 250 200 250 80 200 150 200 60 150 150 100 40 100 100 50 20 50 50 NGC 2841 NGC 2903 NGC 2976 NGC 3031 0 0 0 0 0 10 20 30 40 50 0 5 10 15 20 25 30 0.0 0.5 1.0 1.5 2.0 2.5 0 2 4 6 8 10 12 14 250 200 150 150 200 150 150 100 100 100 100 50 50 50 50 NGC 3198 NGC 3521 NGC 3621 NGC 3627 0 0 0 0 0 10 20 30 0 5 10 15 20 25 30 35 0 5 10 15 20 25 0 2 4 6 8 200 250 200 200 150 200 150 150 150 100 100 100 100 50 50 50 50 NGC 4736 NGC 4826 NGC 5055 NGC 6946 0 0 0 0 0 2 4 6 8 10 0 5 10 15 0 10 20 30 40 0 5 10 15 20 140 250 120 200 100 80 150 60 100 40 70 50 20 NGC 7331 60NGC 7793 0 0 0 5 10 15 20 0 2 4 6 8 10 50 −1 FIG. 1: Fitting to40 the rotational velocities (in km sec ) of the THINGS 18 galaxy sample 30 20 10 DDO 154 0 0 2 4 6 8 11 140 200 120 150 150 100 80 100 100 60 40 50 50 20 NGC 3726 NGC 3769 NGC 3877 0 0 0 0 5 10 15 20 25 30 0 5 10 15 20 25 30 0 2 4 6 8 10 200 150 150 150 100 100 100 50 50 50 NGC 3893 NGC 3917 NGC 3949 0 0 0 0 5 10 15 20 0 2 4 6 8 10 12 14 0 1 2 3 4 5 6 7 250 140 250 200 120 200 100 150 80 150 100 60 100 40 50 50 20 NGC 3953 NGC 3972 NGC 3992 0 0 0 0 5 10 15 0 2 4 6 8 0 10 20 30 40 50 140 200 120 150 100 150 80 100 60 100 40 50 50 20 NGC 4010 NGC 4013 NGC 4051 0 0 0 0 2 4 6 8 10 0 5 10 15 20 25 30 0 2 4 6 8 10 200 150 200 150 150 100 100 100 50 50 50 NGC 4085 NGC 4088 NGC 4100 0 0 0 0 1 2 3 4 5 6 0 5 10 15 0 5 10 15 20 25 FIG. 2: Fitting to the rotational velocities of the Ursa Major 30 galaxy sample { Part 1 12 140 200 200 120 150 150 100 80 100 100 60 40 50 50 20 NGC 4138 NGC 4157 NGC 4183 0 0 0 0 5 10 15 0 5 10 15 20 25 30 0 5 10 15 200 120 100 100 150 80 80 60 100 60 40 40 50 20 20 NGC 4217 NGC 4389 UGC 6399 0 0 0 0 5 10 15 0 1 2 3 4 0 2 4 6 8 100 100 80 80 80 60 60 60 40 40 40 20 20 20 UGC 6446 UGC 6667 UGC 6818 0 0 0 0 2 4 6 8 10 12 0 2 4 6 8 0 2 4 6 8 100 120 120 100 80 100 80 80 60 60 60 40 40 40 20 20 20 UGC 6917 UGC 6923 UGC 6930 0 0 0 0 2 4 6 8 10 0 1 2 3 4 5 0 5 10 15 100 120 200 100 80 150 80 60 60 100 40 40 50 20 20 UGC 6973 UGC 6983 UGC 7089 0 0 0 0 2 4 6 8 10 0 5 10 15 0 1 2 3 4 5 6 7 FIG. 3: Fitting to the rotational velocities of the Ursa Major 30 galaxy sample { Part 2 13 120 80 120 120 100 100 100 60 80 80 80 60 60 40 60 40 40 40 20 20 20 20 DDO 64 F 563-1 F 563-V2 F 568-3 0 0 0 0 0.0 0.5 1.0 1.5 2.0 0 5 10 15 0 1 2 3 4 5 6 0 2 4 6 8 10 50 100 100 80 40 80 80 60 60 30 60 40 40 20 40 20 20 20 10 F 583-1 F 583-4 NGC 959 NGC 4395 0 0 0 0 0 2 4 6 8 10 12 14 0 1 2 3 4 5 6 7 0.0 0.5 1.0 1.5 2.0 2.5 0.0 0.2 0.4 0.6 0.8 120 140 120 80 120 100 100 60 100 80 80 80 60 40 60 60 40 40 40 20 20 20 20 NGC 7137 UGC 128 UGC 191 UGC 477 0 0 0 0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 0 10 20 30 40 50 0.0 0.5 1.0 1.5 2.0 0 2 4 6 8 10 120 50 100 120 100 40 80 100 80 30 60 80 60 60 20 40 40 40 10 20 20 20 UGC 1230 UGC 1281 UGC 1551 UGC 4325 0 0 0 0 0 5 10 15 20 25 30 35 0.0 0.5 1.0 1.5 0 1 2 3 4 5 6 0.0 0.5 1.0 1.5 2.0 2.5 3.0 120 120 80 100 150 100 80 60 80 100 60 60 40 40 40 50 20 20 20 UGC 5005 UGC 5750 UGC 5999 UGC 11820 0 0 0 0 0 5 10 15 20 25 0 2 4 6 8 0 2 4 6 8 10 12 14 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 FIG.
Recommended publications
  • Observing Galaxies in Lynx 01 October 2015 22:25

    Observing Galaxies in Lynx 01 October 2015 22:25

    Observing galaxies in Lynx 01 October 2015 22:25 Context As you look towards Lynx you are looking above the galactic plane above the Perseus spiral arm of our galaxy which itself is about 7,000 light years away. The constellation contains a number of brighter galaxies 30 - 50 million light years away and is also relatively rich in galaxies which spread out in to the distance out to over 300 million light years away. The constellation is well placed from early winter to early summer. Relatively bright galaxies This section covers the galaxies that were visible with direct vision in my 16 inch or smaller scopes. This list will therefore grow over time as I have not yet viewed all the galaxies in good conditions at maximum altitude in my 16 inch scope! NGC 2683 This is a very edge on bright galaxy which I can see in my 100mm binoculars. It is a galaxy which does not seem to be part of a group. NGC 2549 By constellation Page 1 A smaller fainter version of NGC 2683. It was still easy to see with direct vision in my 10 inch reflector. NGC 2537 Near a group of three stars in a row. Quite large looking but with a low surface brightness in my 10 inch scope. NGC 2273 By constellation Page 2 Nice circular galaxy in my 14 inch scope. I could only see the bright core in the above image. NGC 2832 This was a lovely looking galaxy in my 14 inch Dark star scope. As you can see this galaxy is the central galaxy of a group.
  • 1 Introduction

    1 Introduction

    Iranian Journal of Astronomy and Astrophysics Iranian Journal of Vol. 1, No. 1, 2013 Astronomy and © Available online at http://journals.du.ac.ir Astrophysics Evaluation of New MOND Interpolating Function with Rotation Curves of Galaxies Hosein Haghi1 ·Hamed Ghasemi2 ·HongSheng Zhao3 1 Department of Physics, Institute for Advanced Studies in Basic Sciences (IASBS), P.O. Box 11365-9161, Zanjan, Iran; email: [email protected] 2 Department of Physics, Zanjan University, Zanjan, Iran 3 SUPA, School of Physics and Astronomy, University of St. Andrews, KY16 9SS, UK Abstract. The rotation curves of a sample of 46 low- and high-surface brightness galaxies are considered in the context of Milgrom's modified dynamics (MOND) to test a new interpolating function proposed by Zhao et al. (2010) [1] and compare with the results of simple interpolating function. The predicted rotation curves are calculated from the total baryonic matter based on the B-band surface photometry, and the observed distribution of neutral hydrogen, in which the one adjustable parameter is the stellar mass-to-light ratio. The predicted rotation curves generally agree with the observed curves for both interpolating functions. We show that the fitted M=L in the B-band correlates with B-V color in the sense expected from what we know about stellar population synthesis models. Moreover, the mass-to-light ratios of MOND with new interpolating function is in consistent with scaled Salpeter's initial mass function of the SPS scheme, while those of MOND with simple interpolating function favor Kroupa IMF. Keywords: ISM: molecules, ISM: structure, instabilities 1 Introduction The rotation curves of spiral galaxies provide an accurate determination of the radial force distribution in spiral galaxies.
  • Big Halpha Kinematical Sample of Barred Spiral Galaxies - I

    Big Halpha Kinematical Sample of Barred Spiral Galaxies - I

    BhaBAR: Big Halpha kinematical sample of BARred spiral galaxies - I. Fabry-Perot Observations of 21 galaxies O. Hernandez, C. Carignan, P. Amram, L. Chemin, O. Daigle To cite this version: O. Hernandez, C. Carignan, P. Amram, L. Chemin, O. Daigle. BhaBAR: Big Halpha kinematical sample of BARred spiral galaxies - I. Fabry-Perot Observations of 21 galaxies. Monthly Notices of the Royal Astronomical Society, Oxford University Press (OUP): Policy P - Oxford Open Option A, 2005, 360 Issue 4, pp.1201. 10.1111/j.1365-2966.2005.09125.x. hal-00014446 HAL Id: hal-00014446 https://hal.archives-ouvertes.fr/hal-00014446 Submitted on 26 Jan 2021 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Mon. Not. R. Astron. Soc. 360, 1201–1230 (2005) doi:10.1111/j.1365-2966.2005.09125.x BHαBAR: big Hα kinematical sample of barred spiral galaxies – I. Fabry–Perot observations of 21 galaxies O. Hernandez,1,2 † C. Carignan,1 P. Amram,2 L. Chemin1 and O. Daigle1 1Observatoire du mont Megantic,´ LAE, Universitede´ Montreal,´ CP 6128 succ. centre ville, Montreal,´ Quebec,´ Canada H3C 3J7 2Observatoire Astronomique de Marseille Provence et LAM, 2 pl.
  • NGC-2683 (The UFO Galaxy) Edge-On Galaxy in Lynx Introduction the Purpose of the Observer’S Challenge Is to Encourage the Pursuit of Visual Observing

    NGC-2683 (The UFO Galaxy) Edge-On Galaxy in Lynx Introduction the Purpose of the Observer’S Challenge Is to Encourage the Pursuit of Visual Observing

    MONTHLY OBSERVER’S CHALLENGE Las Vegas Astronomical Society Compiled by: Roger Ivester, Boiling Springs, North Carolina & Fred Rayworth, Las Vegas, Nevada With special assistance from: Rob Lambert, Las Vegas, Nevada MARCH 2015 NGC-2683 (The UFO Galaxy) Edge-On Galaxy In Lynx Introduction The purpose of the Observer’s Challenge is to encourage the pursuit of visual observing. It’s open to everyone that’s interested, and if you’re able to contribute notes, and/or drawings, we’ll be happy to include them in our monthly summary. We also accept digital imaging. Visual astronomy depends on what’s seen through the eyepiece. Not only does it satisfy an innate curiosity, but it allows the visual observer to discover the beauty and the wonderment of the night sky. Before photography, all observations depended on what the astronomer saw in the eyepiece, and how they recorded their observations. This was done through notes and drawings, and that’s the tradition we’re stressing in the Observers Challenge. We’re not excluding those with an interest in astrophotography, either. Your images and notes are just as welcome. The hope is that you’ll read through these reports and become inspired to take more time at the eyepiece, study each object, and look for those subtle details that you might never have noticed before. NGC-2683 Almost Edge-On Galaxy In Lynx NGC-2683 is also called “The UFO Galaxy.” It was discovered by William Herschel on February 5, 1788. He gave it the designation H-200-1. It lies about 16 to 25 million light-years away and is almost edge-on from our point of view, giving it that narrow, but fat almost streak- like appearance.
  • 1. Introduction

    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.
  • Spiral Galaxy HI Models, Rotation Curves and Kinematic Classifications

    Spiral Galaxy HI Models, Rotation Curves and Kinematic Classifications

    Spiral galaxy HI models, rotation curves and kinematic classifications Theresa B. V. Wiegert A thesis submitted to the Faculty of Graduate Studies of The University of Manitoba in partial fulfillment of the requirements of the degree of Doctor of Philosophy Department of Physics & Astronomy University of Manitoba Winnipeg, Canada 2010 Copyright (c) 2010 by Theresa B. V. Wiegert Abstract Although galaxy interactions cause dramatic changes, galaxies also continue to form stars and evolve when they are isolated. The dark matter (DM) halo may influence this evolu- tion since it generates the rotational behaviour of galactic disks which could affect local conditions in the gas. Therefore we study neutral hydrogen kinematics of non-interacting, nearby spiral galaxies, characterising their rotation curves (RC) which probe the DM halo; delineating kinematic classes of galaxies; and investigating relations between these classes and galaxy properties such as disk size and star formation rate (SFR). To generate the RCs, we use GalAPAGOS (by J. Fiege). My role was to test and help drive the development of this software, which employs a powerful genetic algorithm, con- straining 23 parameters while using the full 3D data cube as input. The RC is here simply described by a tanh-based function which adequately traces the global RC behaviour. Ex- tensive testing on artificial galaxies show that the kinematic properties of galaxies with inclination > 40 ◦, including edge-on galaxies, are found reliably. Using a hierarchical clustering algorithm on parametrised RCs from 79 galaxies culled from literature generates a preliminary scheme consisting of five classes. These are based on three parameters: maximum rotational velocity, turnover radius and outer slope of the RC.
  • April Constellations of the Month

    April Constellations of the Month

    April Constellations of the Month Leo Small Scope Objects: Name R.A. Decl. Details M65! A large, bright Sa/Sb spiral galaxy. 7.8 x 1.6 arc minutes, magnitude 10.2. Very 11hr 18.9m +13° 05’ (NGC 3623) high surface brighness showing good detail in medium sized ‘scopes. M66! Another bright Sb galaxy, only 21 arc minutes from M65. Slightly brighter at mag. 11hr 20.2m +12° 59’ (NGC 3627) 9.7, measuring 8.0 x 2.5 arc minutes. M95 An easy SBb barred spiral, 4 x 3 arc minutes in size. Magnitude 10.5, with 10hr 44.0m +11° 42’ a bright central core. The bar and outer ring of material will require larger (NGC 3351) aperature and dark skies. M96 Another bright Sb spiral, about 42 arc minutes east of M95, but larger and 10hr 46.8m +11° 49’ (NGC 3368) brighter. 6 x 4 arc minutes, magnitude 10.1. Located about 48 arc minutes NNE of M96. This small elliptical galaxy measures M105 only 2 x 2.1 arc minutes, but at mag. 10.3 has very high surface brightness. 10hr 47.8m +12° 35’ (NGC 3379) Look for NGC 3384! (110NGC) and NGC 3389 (mag 11.0 and 12.2) which form a small triangle with M105. NGC 3384! 10hr 48.3m +12° 38’ See comment for M105. The brightest galaxy in Leo, this Sb/Sc spiral galaxy shines at mag. 9.5. Look for NGC 2903!! 09hr 32.2m +21° 30’ a hazy patch 11 x 4.7 arc minutes in size 1.5° south of l Leonis.
  • The Newsletter of the Barnard-Seyfert Astronomical Society

    The Newsletter of the Barnard-Seyfert Astronomical Society

    March The ECLIPSE 2018 The Newsletter of the Barnard-Seyfert Astronomical Society From the President Next Membership Meeting: Greetings, March 21, 2018, 7:30 pm February 2018 was no friend of BSAS weather wise. Te short Cumberland Valley month of February was not short on rain. We saw 18 or 19 Girl Scout Council Building days with measurable participation. Average monthly rainfall 4522 Granny White Pike in February for Nashville is 3.7 inches. We had just under 11 inches. When it wasn’t raining it was cloudy and windy. Topic: Equipment Tune-up Details on page 6. We had enough bad weather to frustrate almost all attempts to view the winter stars and deep sky objects we believe are still up there. Our public star party at Edwin Warner Park was washed out, as was the private star party on the Natchez In this Issue: Trace at Water Valley Overlook. May we turn the page on that trend? Observing Highlights 2 Tanks to Terry Reeves for his informative and helpful From A Certain Point of View presentation, All About A Messier Marathon, which he gave reviewed by Robin Byrne 3 at this month’s member meeting. We will have a chance to put that information into practice on Saturday, March 17th Deep Sky Daze when BSAS holds a Messier Marathon at Mark Manner’s by Mike Benson 4 Spot Observatory. Just in case, we are planning April 14th as Board Meeting Minutes 8 a backup date. We have that date reserved for a private star February 7, 2018 party at Water Valley Overlook.
  • Galaxy Disks Annual Reviews Content Online, Including: 1 2 • Other Articles in This Volume P.C

    Galaxy Disks Annual Reviews Content Online, Including: 1 2 • Other Articles in This Volume P.C

    AA49CH09-vanderKruit ARI 5 August 2011 9:18 ANNUAL REVIEWS Further Click here for quick links to Galaxy Disks Annual Reviews content online, including: 1 2 • Other articles in this volume P.C. van der Kruit and K.C. Freeman • Top cited articles 1 • Top downloaded articles Kapteyn Astronomical Institute, University of Groningen, 9700 AV Groningen, • Our comprehensive search The Netherlands; email: [email protected] 2Research School of Astronomy and Astrophysics, Australian National University, Mount Stromlo Observatory, ACT 2611, Australia; email: [email protected] Annu. Rev. Astron. Astrophys. 2011. 49:301–71 Keywords The Annual Review of Astronomy and Astrophysics is disks in galaxies: abundance gradients, chemical evolution, disk stability, online at astro.annualreviews.org formation, luminosity distributions, mass distributions, S0 galaxies, scaling This article’s doi: laws, thick disks, surveys, warps and truncations 10.1146/annurev-astro-083109-153241 Copyright c 2011 by Annual Reviews. Abstract ! All rights reserved The disks of disk galaxies contain a substantial fraction of their baryonic mat- 0066-4146/11/0922-0301$20.00 ter and angular momentum, and much of the evolutionary activity in these galaxies, such as the formation of stars, spiral arms, bars and rings, and the various forms of secular evolution, takes place in their disks. The formation and evolution of galactic disks are therefore particularly important for under- standing how galaxies form and evolve and the cause of the variety in which they appear to us. Ongoing large surveys, made possible by new instrumen- tation at wavelengths from the UV (Galaxy Evolution Explorer), via optical (Hubble Space Telescope and large groundbased telescopes) and IR (Spitzer Space Telescope), to the radio are providing much new information about disk galaxies over a wide range of redshift.
  • Flat Galaxy - Above 30 Deg

    Flat Galaxy - Above 30 Deg

    Flat Galaxy - Above 30 Deg. DEC A B C D E F G H I J K L 1 Const. Object ID Other ID RA Dec Size (arcmin) Mag Urano. Urano. Millennium Notes 2 RFGC NGC hh mm ss dd mm ss.s Major Minor 1st Ed. 2nd Ed. 3 CVn 2245 NGC 4244 12 17 30 +37 48 31 19.4 2.1 10.2 107 54 633 Vol II Note: 4 Com 2335 NGC 4565 12 36 21 +25 59 06 15.9 1.9 10.6 149 71 677 Vol II Note: Slightly asymmetric dust lane 5 Dra 2946 NGC 5907 15 15 52 +56 19 46 12.8 1.4 11.3 50 22 568 Vol II Note: 6 Vir 2315 NGC 4517 12 32 46 +00 06 53 11.5 1.5 11.3 238 110 773 Vol II Note: Dust spots 7 Vir 2579 NGC 5170 13 29 49 -17 57 57 9.9 1.2 11.8 285 130 842 Vol II Note: Eccentric dust lane 8 UMa 2212 NGC 4157 12 11 05 +50 29 07 7.9 1.1 12.2 47 37 592 Vol II Note: 9 Vir 2449 MCG-3-33-30 13 03 17 -17 25 23 8.0 1.1 12.5 284 130 843 Vol II Note: Four knots in the centre 10 CVn 2495 NGC 5023 13 12 12 +44 02 17 7.3 0.8 12.7 75 37 609 Vol II Note: 11 Hya 2682 IC 4351 13 57 54 -29 18 57 6.1 0.8 12.9 371 148 888 Vol II Note: Dust lane.
  • Pt Symmetry, Quantum Gravity, and the Metrication of the Fundamental Forces Philip D. Mannheim Department of Physics University

    Pt Symmetry, Quantum Gravity, and the Metrication of the Fundamental Forces Philip D. Mannheim Department of Physics University

    PT SYMMETRY, QUANTUM GRAVITY, AND THE METRICATION OF THE FUNDAMENTAL FORCES PHILIP D. MANNHEIM DEPARTMENT OF PHYSICS UNIVERSITY OF CONNECTICUT PRESENTATION AT DISCRETE 2014 KING'S COLLEGE LONDON, DECEMBER 2014 1 TOPICS TO BE DISCUSSED 1. PT SYMMETRY AS A DYNAMICS 2. HIDDEN SECRET OF PT SYMMETRY{UNITARITY/NO GHOSTS 3. PT SYMMETRY AND THE LORENTZ GROUP 4. PT SYMMETRY AND THE CONFORMAL GROUP 5. PT SYMMETRY AND GRAVITY 6. PT SYMMETRY AND GEOMETRY 7. PT SYMMETRY AND THE DIRAC ACTION i 8. PT SYMMETRY AND THE METRICATION OF Aµ AND Aµ 9. THE UNEXPECTED PT SURPRISE 10. ASTROPHYSICAL EVIDENCE FOR THE PT REALIZATION OF CONFORMAL GRAVITY 2 GHOST PROBLEMS, UNITARITY OF FOURTH-ORDER THEORIES AND PT QUANTUM MECHANICS 1. P. D. Mannheim and A. Davidson, Fourth order theories without ghosts, January 2000 (arXiv:0001115 [hep-th]). 2. P. D. Mannheim and A. Davidson, Dirac quantization of the Pais-Uhlenbeck fourth order oscillator, Phys. Rev. A 71, 042110 (2005). (0408104 [hep-th]). 3. P. D. Mannheim, Solution to the ghost problem in fourth order derivative theories, Found. Phys. 37, 532 (2007). (arXiv:0608154 [hep-th]). 4. C. M. Bender and P. D. Mannheim, No-ghost theorem for the fourth-order derivative Pais-Uhlenbeck oscillator model, Phys. Rev. Lett. 100, 110402 (2008). (arXiv:0706.0207 [hep-th]). 5. C. M. Bender and P. D. Mannheim, Giving up the ghost, Jour. Phys. A 41, 304018 (2008). (arXiv:0807.2607 [hep-th]) 6. C. M. Bender and P. D. Mannheim, Exactly solvable PT-symmetric Hamiltonian having no Hermitian counterpart, Phys. Rev. D 78, 025022 (2008).
  • The Suzaku Broadband X-Ray Spectrum of the Dwarf Seyfert Galaxy NGC 4395 K

    The Suzaku Broadband X-Ray Spectrum of the Dwarf Seyfert Galaxy NGC 4395 K

    A&A 514, A58 (2010) Astronomy DOI: 10.1051/0004-6361/200912431 & c ESO 2010 Astrophysics The Suzaku broadband X-ray spectrum of the dwarf Seyfert galaxy NGC 4395 K. Iwasawa1,, Y. Tanaka2, and L. C. Gallo3 1 INAF-Ossservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna, Italy e-mail: [email protected] 2 Max-Planck-Institut für extraterrestrische Physik, Giessenbachstraße 1, 85748 Garching, Germany e-mail: [email protected] 3 Department of Astronomy and Physics, Saint Mary’s University, Halifax, NS B3H 3C3, Canada e-mail: [email protected] Received 6 May 2009 / Accepted 21 December 2009 ABSTRACT 5 We present a Suzaku observation of the dwarf Seyfert galaxy NGC 4395 with an estimated black hole mass of ∼10 M. Rapid and strong X-ray variability with an rms amplitude of ∼60 per cent is observed in the 0.4–10 keV band with the XIS cameras. The shape of the light curve appears to depend on energies. The hard X-ray emission is detected up to 35 keV with the HXD-PIN detector at a similar flux level as observed with the INTEGRAL IBIS. The X-ray spectrum below 10 keV is strongly absorbed by partially ionized (ξ ∼ 35 erg s cm−1) gas with a mean equivalent hydrogen column density of ∼2 × 1022 cm−2, when a simple absorption model is applied. The spectral shape is also strongly variable but not a simple function of the source brightness. The spectral variability appears to be accounted for mainly by continuum slope changes, but variability in the ionized absorber may also play some part.