DOCSLIB.ORG

Dark Matter Observation Nearby and in Galaxies

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Dark Matter Observation Nearby and in Galaxies ! Dark Matter and the Universe Topic 2 Dark Matter Observation Nearby and in Galaxies Why don’t Galaxies fly apart and how does this tell us that Dark Matter exists?! Contents of Topic 2 Following our introduction to the composition of the Universe and with some basic tools of cosmology in hand from Topic 1, we begin a survey of the observational evidence for Dark Matter, starting with the local neighbourhood and in galaxies. " Dark Matter observation on different scales " Quantifying dark matter using the Mass to Light ratio " Dark Matter near the Solar System and the Oort technique " Measuring Rotation Curves of Galaxies " The observation of flat rotation curves and implications " Derivation of the mass distribution in galaxies " The isothermal sphere model of galaxies halos " Modified Newtonian Dynamics (MOND) and dark matter " Galaxy structures, N-body simulations and the Milky Way Dark Matter Scale and Observation " We have seen from Topic 1 that our current view of the Universe is that it mostly contains Dark Matter and Dark Energy but what is the real observational evidence for the Dark Matter part and how widely is it spread? " It turns out that Dark Matter is found on a vast range of scales in the Universe - from the Solar System, Milky Way and Galaxies (covered here in Topic 2) to Galaxy Clusters, Super Clusters and beyond (covered in Topic 3). " By definition Dark Matter is dark, so studying its presence usually comes from observing its gravitational effects. " There are basically four techniques that can be used: (1) The Oort Technique (2) From Galaxy Rotation Curves (3) Use of the Virial Theorem (4) Gravitational Lensing " This Topic focusses on techniques (1) & (2). Dark Matter & the Mass to Light Ratio " In general we look to measure the mass around using one or other of these techniques, then compare the value with the mass inferred from the observed luminous material. " A good way to quantify this, as used by astronomers, is simply to determine the Mass to Light (luminosity) ratio: M M⊙ = " L L⊙ " Here M⊙ and L⊙ refer to the mass and luminosity of the Sun. Thus the Mass to Light ratio M/L for any system being studied (e.g. galaxy, cluster etc) is simply a number " in units of M⊙/L⊙. By definition " = 1.0 for the Sun. " The actual value of M⊙/L⊙ (for the Sun) is 5133 kg/W. Dark Matter & the Mass to Light Ratio " Measurement of the Mass to Light ratio M/L can tell is if there might be hidden dark matter around, for instance: (1) M/L < 1 likely implies we might have a system of luminous main sequence stars only. (2) M/L > 1 likely implies a system with hidden matter. " How you measure M/L depends where you are measuring. " e.g. near our Solar System you might count up the luminosity of nearby stars and objects and compare with the mass inferred from their motions (the Oort technique). " e.g. in a Galaxy Cluster you might measure the total luminosity of the galaxies and use the Virial Theorem to estimate the total mass of the cluster (covered in Topic 3). Dark Matter & the Mass to Light Ratio " It is important to distinguish stars or objects which are intrinsically so dim that we can not see them from those which we can not see just because they are far away. " i.e. there will always be stars that are intrinsically faint and so “hidden” just because of the luminosity rule: observed intensity of object distance to object 2 ls = Ls/4#d intrinsic luminosity of object " Examples of faint astronomical objects are: Brown Dwarfs, White Dwarfs, Black Holes and Neutron Stars. Dark Matter Nearby " As we found in Topic 1 with the mass of the Earth problem, the idea of “hidden” matter revealed by its gravitational effect is not new. Examples in and around the Solar System are: (1) Observation of the anomalous orbit of Uranus due to “hidden” matter led to discovery of Neptune by Galle (1846). (2) Observation of the anomalous motion of the star Sirius (a near neighbour of the Sun at 8.6 ly away) led to discovery of a companion star Sirius B by Clark (1862). The Oort Technique " One of the first techniques used to examine hidden mass in the Galaxy close to us was by Jan Oort (1932). The idea is to use the motion of nearby stars at right angles to the plane of the Galaxy to derive the total mass near the Sun. z direction motion of stars caused by the gravitational potential of the galactic disk is an up and down motion " This “vertical” motion of stars (let’s say in the z-direction) is expected to be like that of a Harmonic Oscillator with form F (= ma) = -kz where k is the restoring force constant due here to the gravitational potential of the galactic disk. Thus: d2z 2 = -4#$0Gz dt density of acceleration material in disk The Oort Technique " Integration gives the velocity and the Vertical Frequency %: dz = vz = vz,0 cos %t dt 1/2 % = (4#$0G) " So by measuring the Vertical Velocity of stars it is possible to determine #0. However, this is very hard in practice and you have to assume that vz depends only on #0. " Better is to assume that the number of oscillations made is much greater than the age of the galaxy. Then examine the distribution of stars away from the galactic plane. " Oort did such measurements of observed vertical distances of stars and derived #0 ~ 0.2 M⊙/pc-3. " This is about twice the visible matter near the Sun, hence the Mass to Light Ratio is "(near the Sun) = ~2. Mass to Light Ratio on Bigger Scales " The Oort measurement is hard and controversial and specific to our neighbourhood, near the Sun. The technique is also only really looking at mass in the disc of our galaxy. " However, it was a first hint from near the Galactic Centre that there is more matter than can be accounted for by the stars alone. Obviously this still could be gas and dust (at the time cold hydrogen could not be seen). " But we now know things get far more obvious as we move to larger scales and use new techniques, in summary: η(near Sun) = ~2 η(our Galaxy, inner part) = ~6 η(our Galaxy, outer part) = ~40 η(galaxy pairs) = ~80 η(galaxy local group) = ~160 η(galaxy clusters) = ~500 η(Abell clusters) = ~500 Mass to Light Ratio on Bigger Scales " Here is some data showing the Mass to Light Ratio for various objects going to greater and greater scale, out to galaxy clusters. " Note the lines marking the equivalent value of & and how at the largest scale the value appears to saturate at ~ & = 0.3. " This is suggestive that there is not enough matter in the Universe to give us a flat geometry with & = 1.0. The missing factor will eventually turn out to be Dark Energy. Dark Matter in Whole Galaxies " A big advance came in the 1970’s with the advent of Radio Astronomy. In particular, observations of the velocity of HI Hydrogen Clouds orbiting galaxies, started by Vera Rubin. " This is her paper and an early result. " This allowed production of Galaxy Rotation Curves - plots of circular radial velocities vc in the plane of the disc of a galaxy vs. distance r from the centre at distances beyond the visible. Basics of Rotation Curves " The concept and importance of Galaxy Rotation Curve measurements is illustrated below. Here we see a satellite HI cloud of mass m orbiting a galaxy of mass M at velocity vc with distance r from the centre. vc M m r mass m in orbit with circular velocity vc " Newton’s laws of gravity should tell us the relationship between the masses and the velocity. But first let’s consider how the measurement itself is possible. Rotation Curve Measurements " The measurement is possible because HI (atomic hydrogen) emits 21cm Wavelength Radio radiation (or 1.42 GHz). " This radiation arrises because the hydrogen 1s ground energy state is slightly split by the interaction between the electron spin and nuclear spin. " A 21cm photon is emitted when there is a transition from the state with nuclear and electron spin aligned parallel (the so- called F = 1 Hyperfine State) to the state where the nuclear and electron spins are antiparallel (F = 0 Hyperfine State). " This transition is sometimes called the Spin-flip Transition. Rotation Curve Measurements The 21cm Radio Line from HI is " Messier 83: 21-cm and Optical very useful because there is lots of HI rotating it at the edges of galaxies. towards us " The 21cm Radio Line also penetrates well through dust. " The figure here shows an example measurement from M83. Note how HI rotating away the radio emission extends to greater radius than the optical (lower image on the same scale). " Use of the Doppler Shift allows the velocities of the HI to be measured. (the blue in the top image signifies gas moving towards us, the red is moving away). Rotation Curve Measurements " The cartoon here illustrates how the Doppler Shift works to allow rotation of a Galaxy to be observed. 21cm Radio from the Milky Way " Below shows an image of 21cm Radio Line emission from our own Galaxy. Here we are looking through the disc. Caution Measuring Rotation Curves " Although the 21cm Line can be used in principle to measure the circular velocity of orbiting clouds via the Doppler Effect in practice caution is needed for several reasons: (1) There can be random Peculiar Motions of the clouds and the galaxy observed could also be moving away/towards us as a whole.
Load more

Recommended publications
  • (Dark) Matter! Luminous Matter Is Concentrated at the Center
    Cosmology Two Mysteries and then How we got here Dark Matter Orbital velocity law Derivable from Kepler's 3rd law and Newton's Law of gravity r v2 M = r G M : mass lying within stellar orbit r r: radius from the Galactic center v: orbital velocity From Sun's r and v: there are about 100 billion solar masses inside the Sun's orbit! 4 Rotation curve of the Milky Way: Speed of stars and clouds of gas (from Doppler shift) vs distance from center Galaxy: rotation curve flattens out with distance Indicates much more mass in the Galaxy than observed as stars and gas! Mass not concentrated at center5 From the rotation curve, inferred distribution of dark matter: The Milky Way is surrounded by an enormous halo of non-luminous (dark) matter! Luminous matter is concentrated at the center 6 We can make measurements for other galaxies Weighing spiral galaxies C Compare shifts of spectral lines (in atomic H gas clouds) as a function of distance from the center 7 Rotation curves for various spiral galaxies First measured in 1960's by Vera Rubin They all flatten out with increasing radius, implying that all spiral galaxies have vast haloes of dark matter – luminous matter 1/6th of mass 8 This mass is the DARK MATTER: It's some substance that interacts gravitationally (equivalent to saying that it has mass)... It neither emits nor absorbs light in any form (equivalent to saying that it does not interact electromagnetically) Dark matter might conceivably have 'weak' (radioactive force) interactions 9 Gaggles of Galaxies • Galaxy groups > The Local group
    [Show full text]
  • A Case for Alternate Theories of Gravity C Sivaram Indian Institute Of
    Preprints (www.preprints.org) | NOT PEER-REVIEWED | Posted: 19 June 2020 doi:10.20944/preprints202006.0239.v1 Non-detection of Dark Matter particles: A case for alternate theories of gravity C Sivaram Indian Institute of Astrophysics, Bangalore, 560 034, India e-mail: [email protected] Kenath Arun Christ Junior College, Bangalore, 560 029, India e-mail: [email protected] A Prasad Center for Space Plasma & Aeronomic Research, The University of Alabama in Huntsville, Huntsville, Alabama 35899 email: [email protected] Louise Rebecca Christ Junior College, Bangalore - 560 029, India e-mail: [email protected] Abstract: While there is overwhelming evidence for dark matter (DM) in galaxies and galaxy clusters, all searches for DM particles have so far proved negative. It is not even clear whether only one particle is involved or a combination or particles, their masses not precisely predicted. This non-detectability raises the possible relevance of modified gravity theories – MOND, MONG, etc. Here we consider a specific modification of Newtonian gravity (MONG) which involves gravitational self-energy, leading to modified equations whose solutions imply flat rotation curves and limitations of sizes of clusters. The results are consistent with current observations including that involving large spirals. This modification could also explain the current Hubble tension. We also consider effects of dark energy (DE) in terms of a cosmological constant. 1 © 2020 by the author(s). Distributed under a Creative Commons CC BY license. Preprints (www.preprints.org) | NOT PEER-REVIEWED | Posted: 19 June 2020 doi:10.20944/preprints202006.0239.v1 Over the past few decades there have been a plethora of sophisticated experiments involving massive sensitive detectors trying to catch faint traces of the elusive Dark Matter (DM) particles.
    [Show full text]
  • Modified Newtonian Dynamics, an Introductory Review
    Modified Newtonian Dynamics, an Introductory Review Riccardo Scarpa European Southern Observatory, Chile E-mail [email protected] Abstract. By the time, in 1937, the Swiss astronomer Zwicky measured the velocity dispersion of the Coma cluster of galaxies, astronomers somehow got acquainted with the idea that the universe is filled by some kind of dark matter. After almost a century of investigations, we have learned two things about dark matter, (i) it has to be non-baryonic -- that is, made of something new that interact with normal matter only by gravitation-- and, (ii) that its effects are observed in -8 -2 stellar systems when and only when their internal acceleration of gravity falls below a fix value a0=1.2×10 cm s . Being completely decoupled dark and normal matter can mix in any ratio to form the objects we see in the universe, and indeed observations show the relative content of dark matter to vary dramatically from object to object. This is in open contrast with point (ii). In fact, there is no reason why normal and dark matter should conspire to mix in just the right way for the mass discrepancy to appear always below a fixed acceleration. This systematic, more than anything else, tells us we might be facing a failure of the law of gravity in the weak field limit rather then the effects of dark matter. Thus, in an attempt to avoid the need for dark matter many modifications of the law of gravity have been proposed in the past decades. The most successful – and the only one that survived observational tests -- is the Modified Newtonian Dynamics.
    [Show full text]
  • Disk Galaxy Rotation Curves and Dark Matter Distribution
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by CERN Document Server Disk galaxy rotation curves and dark matter distribution by Dilip G. Banhatti School of Physics, Madurai-Kamaraj University, Madurai 625021, India [Based on a pedagogic / didactic seminar given by DGB at the Graduate College “High Energy & Particle Astrophysics” at Karlsruhe in Germany on Friday the 20 th January 2006] Abstract . After explaining the motivation for this article, we briefly recapitulate the methods used to determine the rotation curves of our Galaxy and other spiral galaxies in their outer parts, and the results of applying these methods. We then present the essential Newtonian theory of (disk) galaxy rotation curves. The next two sections present two numerical simulation schemes and brief results. Finally, attempts to apply Einsteinian general relativity to the dynamics are described. The article ends with a summary and prospects for further work in this area. Recent observations and models of the very inner central parts of galaxian rotation curves are omitted, as also attempts to apply modified Newtonian dynamics to the outer parts. Motivation . Extensive radio observations determined the detailed rotation curve of our Milky Way Galaxy as well as other (spiral) disk galaxies to be flat much beyond their extent as seen in the optical band. Assuming a balance between the gravitational and centrifugal forces within Newtonian mechanics, the orbital speed V is expected to fall with the galactocentric distance r as V 2 = GM/r beyond the physical extent of the galaxy of mass M, G being the gravitational constant.
    [Show full text]
  • Chapter 5 Rotation Curves
    Chapter 5 Rotation Curves 5.1 Circular Velocities and Rotation Curves The circular velocity vcirc is the velocity that a star in a galaxy must have to maintain a circular orbit at a specified distance from the centre, on the assumption that the gravitational potential is symmetric about the centre of the orbit. In the case of the disc of a spiral galaxy (which has an axisymmetric potential), the circular velocity is the orbital velocity of a star moving in a circular path in the plane of the disc. If 2 the absolute value of the acceleration is g, for circular velocity we have g = vcirc=R where R is the radius of the orbit (with R a constant for the circular orbit). Therefore, 2 @Φ=@R = vcirc=R, assuming symmetry. The rotation curve is the function vcirc(R) for a galaxy. If vcirc(R) can be measured over a range of R, it will provide very important information about the gravitational potential. This in turn gives fundamental information about the mass distribution in the galaxy, including dark matter. We can go further in cases of spherical symmetry. Spherical symmetry means that the gravitational acceleration at a distance R from the centre of the galaxy is simply GM(R)=R2, where M(R) is the mass interior to the radius R. In this case, 2 vcirc GM(R) GM(R) = 2 and therefore, vcirc = : (5.1) R R r R If we can assume spherical symmetry, we can estimate the mass inside a radial distance R by inverting Equation 5.1 to give v2 R M(R) = circ ; (5.2) G and can do so as a function of radius.
    [Show full text]
  • A Comparison of the DC14 and Corenfw Dark Matter Halo Models on Galaxy Rotation Curves F
    A&A 605, A55 (2017) Astronomy DOI: 10.1051/0004-6361/201730402 & c ESO 2017 Astrophysics Testing baryon-induced core formation in ΛCDM: A comparison of the DC14 and coreNFW dark matter halo models on galaxy rotation curves F. Allaert1, G. Gentile2, and M. Baes1 1 Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281, 9000 Gent, Belgium e-mail: [email protected] 2 Department of Physics and Astrophysics, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium Received 6 January 2017 / Accepted 15 June 2017 ABSTRACT Recent cosmological hydrodynamical simulations suggest that baryonic processes, and in particular supernova feedback following bursts of star formation, can alter the structure of dark matter haloes and transform primordial cusps into shallower cores. To assess whether this mechanism offers a solution to the long-standing cusp-core controversy, simulated haloes must be compared to real dark matter haloes inferred from galaxy rotation curves. For this purpose, two new dark matter density profiles were recently derived 10 11 from simulations of galaxies in complementary mass ranges: the DC14 halo (10 < Mhalo=M < 8 × 10 ) and the coreNFW halo 7 9 (10 < Mhalo=M < 10 ). Both models have individually been found to give good fits to observed rotation curves. For the DC14 model, however, the agreement of the predicted halo properties with cosmological scaling relations was confirmed by one study, but strongly refuted by another. A next important question is whether, despite their different approaches, the two models converge to the same solution in the mass range where both should be appropriate. To investigate this, we tested the DC14 and coreNFW halo 9 10 models on the rotation curves of a selection of galaxies with halo masses in the range 4 × 10 M – 7 × 10 M and compared their 11 predictions.
    [Show full text]
  • Possible Evidence for the Ejection of a Supermassive Black Hole from An
    Mon. Not. R. Astron. Soc. 000, 000–000 (0000) Printed 4 June 2021 (MN LATEX style file v2.2) Possible evidence for the ejection of a supermassive black hole from an ongoing merger of galaxies Martin G. Haehnelt1⋆, Melvyn B. Davies2 and Martin J. Rees1 1Institute of Astronomy, Madingley Road, Cambridge, CB3 OHA 2Lund Observatory, Box 43, SE–221 00, Lund, Sweden 4 June 2021 ABSTRACT Attempts of Magain et al (2005) to detect the host galaxy of the bright QSO HE0450– 2958 have not been successful. We suggest that the supermassive black hole powering the QSO was ejected from the observed ULIRG at the same redshift and at 1.5 arcsec distance. Ejection could have either be caused by recoil due to gravitational wave emission from a coalescing binary of supermassive black holes or the gravitational slingshot of three or more supermassive black holes in the ongoing merger of galaxies which triggered the starburst activity in the ULIRG. We discuss implications for the possible hierarchical build-up of supermassive black holes from intermediate and/or stellar mass black holes, and for the detection of coalescing supermassive binary black holes by LISA. Key words: Black hole physics; Celestial mechanics, stellar dynamics; Binaries: general; Galaxies:nuclei 1 INTRODUCTION jevic & Merritt 2001). The further evolution is somewhat uncertain. Hardening by gravitational interaction with stars In their recent paper, Magain et al (2005) describe observa- passing close to the binary will be much slower than the typ- tions of the bright quasar HE0450–2958 which suggest that ical duration of the star formation bursts in ULIRGs.
    [Show full text]
  • Physics Beyond the Standard Model and Dark Matter.Pdf
    Physics Beyond the Standard Model and Dark Matter Elise Wursten CERN, RIKEN AVA School on Precision Physics 25th of March 2020 1 Contents • Standard Model • Introduction • Open issues & Beyond • Dark Matter • Why do we think it exists? • Dark Matter Candidates • Searches for Dark Matter 2 Standard Model 3 Standard Model Fundamental constants have to be determined by experiment 4 Standard Model – Open Issues & Beyond Fundamental constants have to be determined by experiment • The strong CP problem: CP violating θ- term in Lagrangian is suppressed by 9 orders of magnitude. Why? • Possible solution: There is a particle called the axion, which makes this parameter small because of a spontaneously broken symmetry (Peccei-Quinn) • Candidate for dark matter 5 Standard Model – Open Issues & Beyond Fundamental constants have to be determined by experiment • Hierarchy problem: why is the Higgs mass so low? • Quantum corrections would make the mass huge! • Proposed solution is supersymmetry: fermionic and bosonic loop corrections cancel each other out • Lightest SUSY particle is candidate for dark matter 6 Standard Model – Open Issues & Beyond Fundamental constants have to be determined by experiment • What about the neutrino masses? • Are these fundamental constants really constant? (see next talk) 7 Standard Model – Open Issues & Beyond • Why is there so much more matter than antimatter in the universe? Baryon asymmetry parameter: Observed: Standard Model prediction: 5 Standard Model – Open Issues & Beyond • Why is there so much more matter than antimatter in the universe? Baryon asymmetry parameter: Observed: Standard Model prediction: • Conditions for baryon asymmetry by Sakharov: • Baryon number violation • C and CP violation • Departure from local equilibrium (or CPT violation) [1] JETP Lett 5, 24-27 (1967).
    [Show full text]
  • Turbulent Formation of Protogalaxies at the End of the Plasma Epoch: Theory and Observations
    Turbulent formation of protogalaxies …, Nova Book, Galaxies: Dynamics, Formation and Evolution 1 Turbulent formation of protogalaxies at the end of the plasma epoch: theory and observations Rudolph E. Schild1,2 1 Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA 2 [email protected] and Carl H. Gibson 3,4 3 University of California San Diego, La Jolla, CA 92093-0411, USA [email protected], http://sdcc3.ucsd.edu/~ir118 ABSTRACT The standard model of gravitational structure formation is based on the Jeans 1902 acoustic theory, neglecting nonlinear instabilities controlled by viscosity, turbulence and diffusion. A linear insta- bility length scale equal to the sound speed times the gravitational freefall time emerges. Because the Jeans scale LJ for the hot primordial plasma is always slightly larger than the scale of causal connection ct, where c is the speed of light and t is the time after the big bang, it has been assumed that no plasma structures could form without guidance from a cold (so LJ CDM is small) collisionless cold-dark-matter CDM fluid to give condensations that gravitationally collect the plasma. Galaxies by this CDM model are therefore produced by gradual hierarchical-clustering of CDM halos to gal- axy mass over billions of years, contrary to observations showing that well formed galaxies existed much earlier. No observations exist of CDM halos. However, Gravitational instability is non- linear and absolute, controlled by viscous and turbulent forces or by diffusivity at Schwarz length scales smaller than ct. Because the universe during the plasma epoch is rapidly expanding, the first structures formed were at density minima by fragmentation when the viscous-gravitional scale LSV first matched ct at 30,000 years to produce protosupercluster voids and protosuperclusters.
    [Show full text]
  • Explosion of the Science Modification of Newtonian Dynamics Via Mach's
    Physics International Original Research Paper Explosion of the Science Modification of Newtonian Dynamics Via Mach’s Inertia Principle and Generalization in Gravitational Quantum Bound Systems and Finite Range of the Gravity-Carriers, Consistent Merely On the Bosons and the Fermions Mohsen Lutephy Faculty of Science, Azad Islamic University (IAU), South Tehran branch, Iran Article history Abstract: Newtonian gravity is modified here via Mach's inertia principle Received: 29-04-2020 (inertia fully governed by universe) and it is generalized to gravitationally Revised: 11-05-2020 quantum bound systems, resulting scale invariant fully relational dynamics Accepted: 24-06-2020 (mere ordering upon actual objects), answering to rotation curves and velocity dispersions of the galaxies and clusters (large scale quantum bound Email: [email protected] systems), successful in all dimensions and scales from particle to the universe. Against the Milgrom’s theory, no fundamental acceleration to separate the physical systems to the low and large accelerations, on the contrary the Newtonian regime of HSB galaxies sourced by natural inertia constancy there. All phenomenological paradigms are argued here via Machian modified gravity generalized to quantum gravity, especially Milgrom empirical paradigms and even we have resolved the mystery of missing dark matter in newly discovered Ultra Diffuse Galaxies (UDGs) for potential hollow in host galaxy generated by sub quantum bound system of the globular clusters. Also we see that the strong nuclear force (Yukawa force) is in reality, the enhanced gravity for limitation of the gravitational potential because finite-range of the Compton wavelength of hadronic gravity-carriers in the nucleuses, reasoning to resolve ultimately, one of the biggest questions in the physics, that is, so called the fine structure constant and answering to mysterious saturation features of the nuclear forces and we have resolved also the mystery of the proton stability, reasonable as a quantum micro black hole and the exact calculation of the universe matter.
    [Show full text]
  • Cycle 15 Approved Programs
    Cycle 15 Approved Programs As of 4/19/06 First Name Last Name Type Phase II ID Institution Country Science Category Title Alessandra Aloisi GO 10885 Space Telescope USA Unresolved Stellar Deep Photometry of NGC 1569: Science Institute - Populations Understanding the Closest and Strongest ESA Starburst of the Nearby Universe Scott Anderson GO 10907 University of USA Quasar Absorption Lines New Sightlines for the Study of Intergalactic Washington and IGM Helium: A Dozen High-Confidence, UV-Bright Quasars from SDSS/GALEX Jack Baldwin AR 10932 Michigan State USA AGN/Quasars Hard Ionizing Photons at High Redshift --- A University New Method for Measuring the QSO Continuum Shape Bruce Balick AR 10933 University of USA ISM and Circumstellar Planetary Nebula Image Catalogue: HST Washington Matter data Dinshaw Balsara AR 10934 University of Notre USA ISM and Circumstellar The Interaction of Supernova Remnant Dame Matter Shocks with Interstellar Clouds Nate Bastian GO 10785 University College UK Unresolved Stellar Luminosity Profiles of Extremely Massive London (UCL) Populations Clusters in NGC 7252 Dan Batcheldor GO 10839 Rochester Institute of USA AGN/Quasars The NICMOS Polarimetric Calibration Technology Dan Batcheldor AR 10935 Rochester Institute of USA AGN/Quasars Resolving the Critical Ambiguities of the M- Technology Sigma Relation Edo Berger GO 10908 Carnegie Institution USA Cosmology Gotcha! Using Swift GRBs to Pinpoint the of Washington Highest Redshift Galaxies Edwin Bergin GO 10810 University of USA Star Formation The Gas Dissipation
    [Show full text]
  • Rotation and Mass in the Milky Way and Spiral Galaxies
    Publ. Astron. Soc. Japan (2014) 00(0), 1–34 1 doi: 10.1093/pasj/xxx000 Rotation and Mass in the Milky Way and Spiral Galaxies Yoshiaki SOFUE1 1Institute of Astronomy, The University of Tokyo, Mitaka, 181-0015 Tokyo ∗E-mail: [email protected] Received ; Accepted Abstract Rotation curves are the basic tool for deriving the distribution of mass in spiral galaxies. In this review, we describe various methods to measure rotation curves in the Milky Way and spiral galaxies. We then describe two major methods to calculate the mass distribution using the rotation curve. By the direct method, the mass is calculated from rotation velocities without employing mass models. By the decomposition method, the rotation curve is deconvolved into multiple mass components by model fitting assuming a black hole, bulge, exponential disk and dark halo. The decomposition is useful for statistical correlation analyses among the dynamical parameters of the mass components. We also review recent observations and derived results. Full resolution copy is available at URL: http://www.ioa.s.u-tokyo.ac.jp/∼sofue/htdocs/PASJreview2016/ Key words: Galaxy: fundamental parameters – Galaxy: kinematics and dynamics – Galaxy: structure – galaxies: fundamental parameters – galaxies: kinematics and dynamics – galaxies: structure – dark matter 1 INTRODUCTION rotation curves of the Milky Way and spiral galaxies, respec- tively, and describe the general characteristics of observed rota- tion curves. The progress in the rotation curve studies will be Rotation of spiral galaxies is measured by spectroscopic ob- also reviewed briefly. In section 4 we review the methods to de- arXiv:1608.08350v1 [astro-ph.GA] 30 Aug 2016 servations of emission lines such as Hα, HI and CO lines from termine the mass distributions in disk galaxies using the rotation disk objects, namely population I objects and interstellar gases.
    [Show full text]