DOCSLIB.ORG

Brian Mcnamara Intro to Clusters of Galaxies

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Brian Mcnamara Intro to Clusters of Galaxies General Introduction to Galaxy Clusters: Scaling Relations Brian McNamara University of Waterloo With thanks to Helen Russell Astronomical Units & Terminology 1 " T % 2 r2500 = 500kpc$ ' # 5keV & 1 2 14 # T & M2500 = 2x10 M"% ( 5keV scaled to critical density of Universe ! $ ' 21 Kiloparsec! Distance 1000 parsecs = 3x10 cm Light year Distance 3.26 parsecs Milky Way Diameter = 100,000 ly = 30 kpc 1053 erg Energy supernova explosion/GRB keV Temperature 1 keV = 1.16 x 107 K dynes/cm2 Pressure cluster center P=10-10 dyne/cm2 10-16 Atm Why Study Galaxy Clusters? • Cosmology - evolve by gravity: largest structures evolve slowly--dominated by dark maer, sensiWve to maer and energy density of the Universe - fair sample hypothesis: baryons, dark maer, baryon fracWon - observaonal goal: measuring masses; observaonal proxies for mass (Lx, T, etc.) • Galaxy formaon & Evoluon - closed boxes: retain byproducts of stellar evoluWon; history of star formaon - galaxies at same redshi^: uniform sampling in space & Wme - merging & perturbaon: dynamical evoluWon of galaxies • Cosmic cooling problem - only few percent of baryons have condensed in clusters - cooling flows/feedback Gaussian density perturbaons 10 Mpc "# /# a ! Ncl " a Hierarchical clustering ! Number density of clusters: amplitude of perturbaons, a Degree of clustering: "m ! Galaxy Cluster Virgo Consorum, Springel et al. 05 Galaxy Cluster at X-ray & Visual wavelengths X-ray visual 100 kpc 43 45 -1 2 7 8 Lx = 10 - 10 erg s kTgas " µmp# Tgas = 10 - 10 K $1 $4 $3 $h% / kT "gas #10 $10 cm Bremsstrahlung emissivity: " # neni Te 2 X-ray emission ~ne! unambiguous tracer of deep potenWal well ie., clusters ! ! What is a galaxy Cluster? Abell 1689 RC =4 Richness Classes Sizes 1-3 Mpc M3 + 2 " # 300 $1000km s$1 0 30-49 13 15 1 50-79 Mcl "10 #10 M$ 2 80-129 3 130-199! 4 200-299 5 300> ! 2 15 $1 Mvir " 3# r /G "10 h M% for " #1000km s$1 ! ! Gravitaonally bound systems Crossing time for the galaxies: R t cr , gal= 1/2 〈v2〉 t ≈ 2× 109 yr cr , gal → clusters are gravitationally bound Galaxy cluster mass parWWoning ICM 13% Stars 3% Credit: Abell 1689, X-ray: NASA/CXC/MIT/ E.-H Peng et al.; Optical: NASA/STScl Dark matter 84% ? Virial Theorem For gravitationally bound systems: 2EK +EP = 0 〈v2 〉 R M = tot tot G Assuming random uncorrelated velocity vectors: 3! 2 R M = r tot tot G 15 For velocities 1000km/s and R = 1Mpc => Mtot = 10 Msun Sound crossing me Sound crossing time for X-ray gas: D t cr , gas= cs For an ideal gas the adiabatic sound speed is: 2 dP P kBT cs = =" =" d! ! µmH For a monatomic gas the adiabatic index is 5/3. 8 t cr , gas≈ few× 10 yr 10 Much shorter than age of cluster ~10 yrs Hydrostac Equilibrium Hydrostac equilibrium: compression due to gravity is balanced by a pressure gradient force. AssumpWons: Sound crossing Wme much less than the age of the cluster Timescale for elasWc collisions much shorter than Wmescale for heang or cooling Kinec Equilibrium Timescales for electrons and ions to form a Maxwellian distribuWon electrons via Coulomb collisions: 1/2 teq (p, p) ! (mp / me ) teq (e,e) ~ 43teq (e,e) teq (p,e) ! (mp / me ) teq (e,e) ~ 1870teq (e,e) for typical condiWons Electrons & ions in equiparWWon, such that T = Te= Tp DetecWng Clusters with X-rays Chandra XMM-Newton Suzaku E = 0.5-10 keV E = 0.1-15 keV E = 0.4-600 keV EA = 600 cm2 @1.5 keV EA = 922 cm2 @ 1 keV EA = 900 cm2 @ 1.5 keV FOV = 16.9x16.9 arcmin FOV = 33 x 33 arcmin FOV = 20 arcmin @1keV PSF = 0.5 arcsec FWHM PSF ~ 4 arcsec FWHM PSF ~ 2 arcmin (HPD) Chandra’s mirrors Grazing incidence optics critical angle few degrees Wolter Type 1 Hundreds of Clusters Detected with ROSAT NRAO-VLA Sky Survey (NVSS) ROSAT X-ray Imaging J1221+4918 z = 0.7 Lx = 1.2x1045 erg s-1 19 kT = 6.5 keV 18 Declination (2000) Ma + 11 49! 17v 35s 30s 25s 20s 12h 21m 15s Right Ascension (2000) “red sequence” Gladders & Yee 05 Optical: good for finding distant clusters poor measure of cluster properties X-ray: good measure of cluster properties poor tracer beyond z ~ 1 Borgani & Guzzo 01 Thermal Bremsstrahlung Primary source of X-ray emission from clusters due to diffuse intracluster plasma at 108K Power radiated by accelerang charge: Larmor's equation 2e2a2 P = 3c3 a = acceleraon Thermal Bremsstrahlung Power per unit frequency and per unit volume: See Rybicki + Lightman or Longair Thermal Bremsstrahlung Total Power Radiated power per unit volume: L∝ n n T 1/2 e H Two body collision → power strongly dependent on density2 emitted spectrum observed spectrum Fe L Fe K s "#(E,T,Z) $ R(E,%) " # g(E,T,Z)T$1/ 2 exp($E /kT) • ionization equilibrium ! Normalization: EM " n p nedV • temperature sensitivity # ! • metallicity sensitivity • Z ~ 1/3 solar Arnaud 05 ! Thermal Bremsstrahlung Spectrum Model cluster spectrum, 1/3 solar abundance 8 keV cluster 1 keV group Line Emission Emissivity from collisionally excited line (electrons) dE- excitaon energy of line above ground state B – branching rao (probability that excited state decays to given state) Omega – Collision strength omega_gs- stasWcal weight of ground state Luminosity per frequency Emissivity: !" = !" (z,T)nenp (erg/cm3) Significant So^ X-ray Lines Peterson + 01 X-ray cooling funcWon Solar abundance !(T, Z) 1/3 solar abundance Pure hydrogen, Helium !" = !" (z,T)nenp Peterson & fabian 06 X-ray cooling fluncon !(T, Z) !" = !" (z,T)nenp Abundances from X-ray emission 2 • Line emissivity proporWonal ne and elemental abundance 2 • Thermal bremsstrahlung proporWonal to ne • rao of line emission to brems connuum indep of density • Temperature sensiWve to brems shape and line raos (low T) • Hence, line equivalent width gives elemental abundance M87 Observed with the ReflecWon Grang Spectrometer Early metal enrichment by core collapse SN, ongoing Sn Ia 60% core collapse Werner .. Kaastra, De Plaa…06 40% Sn Ia Metallicity Distribution SN Ia SN II De Grandi & Molendi 01 " element enhanced (Si, S, Ne, Mg) early enrichment z >> 0.5 top-heavy IMF? ! Wise et al. 04 X-ray surface brighness profile #3 Ix " r ! Isothermal Beta Model: Cavaliere & Fusco-Femiano (76) 1 ratio of energy #3$ + 2 per unit mass in surface brightness: Ix "[1+ (r /rc )] " # 2/3 galaxies to that in 2 "3# / 2 electron density: ne (r) = n0[1+ (r /rc ) ] gas I =0.35 I n = 0.5 n ! ! c 0 c 0 See Vikhlinin! + 06 for more sophisWcated models Cluster Density Profiles - Vikhlinin 06 NFW profile Mass Profiles dlnT = 0 dlnr ! " model Gitti et al. 07 ! kTr # dln" dlnT & Mtot (< r) = % + ( Gµmp $ dlnr dlnr ' ) 2,/ 30 / 2 # r & Assume "(r) = "0+1 + % ( . ! *+ $ rc ' -. - hydrostac equil. - spherical symmetry kr2 $ 3"rT dT ' - only gas pressure Mtot (< r) = & 2 2 # ) Gµmp % r + rc dr ( ! Vikhlinin + 05 ! Typcal Gas Profiles H Clusters & Cosmology mass & luminosity function sensitivity to "m,# ! 1015 N(L) N(M) Eke et al. 92 Mullis et al. 04 M Lx 44 -1 Evolution: Lx > 5x10 erg s z > 0.5 "m =1 "m = 0.3,"# = 0.7 Problem: Lx to M ? Need L-T, M-T, relaons L-T – baryon physics ! ! Cluster Cosmology requires: Simulations + Observations Is cluster maer distribuWon only a funcWon of Mass and Redshi^? Compare observations to scaling relations Deviations: models deal primarily with DM mass observations deal with luminous baryons simulated & observed parameters (eg. L,T) do not always probe same quantity mean matter density Mass Function constrains in units of critial density, "m,# 8 amplitude of primordial density fluctuations strategy: find observational proxies for mass ! Lx - easy to measure, sensitive to non-gravitational processes Tx - difficult to measure except for brightest objects M - even tougher Clusters Grow by Mergers Cold fronts – mildly transonic mergers/sloshing Contact disconity Markevich & Vikhlinin 06 Contact DisconWnuity: Abell 2142 Markevich & Vikhlinin 06 Cluster Scaling Relations Simple assumptions: gravity, adiabatic compression, shocks self similarity: scale free, cluster defined by its mass and redshift 3 / 2 #1 M "Tx (1+ z) 2 3 / 2 Lx "Tx (1+ z) 4 / 3 7 / 2 Lx " M (1+ z) Implications:! Same internal structure, but distant clusters denser, smaller, more luminous ! Observables in reverse order of difficulty: Lx, Tx, M !Departures from scaling relations: additional physics (cooling, feedback, etc.) Evolution of scaling laws: Ettori et al. 04 Are clusters self-similar ? Do they scale as expected? Do they evolve as expected? Relaonship between Mass, Temperature, Luminosity examples: 2 M "TR Lx " # V$ cooling 1/ 2 R "T M " #V " Mgas 1/ 2 (T > 2 keV) 3 / 2 " #T M "T ! ! 1/ 2 Lx " M#T ! ! M "T1.5 ! 4/3 ! L ~ M L T 2 ! x ! ! Gas Temperature is related to velocity dispersion, Mass ! !T 0.59 1/2 Mushotzky 2004 Scaling relaons ! !T Gas temperature => GM/R Cluster Mass Profiles closely follow Universal NfW Profile Good News for Cluster Cosmology M/M200 R/R200 Mass-Temperature Relation: Temperature good Mass proxy Problem: Hard to measure in abundance Scaling relation: M ~ T3/2 r500 M "T1.5 r Vikhlinin et al. 06 2500! Ettori et al. 04 Arnaud 05 Issues: • Beta model fits • inner core • small deviations from self similarity for cool clusters • reference radius • normalization varies by ~30% between studies • redshift range • least affected by non-gravitational physics • consistent with self-similar evolution -Ettori et al. 04 Mass-luminosity Relation: clusters too luminous for their masses scaling relation: L~M4/3 L " M1.59±0.05 ! Stanek et al. 06 L " M p P = 1.59 +/- 0.05 Stanek et al.
Load more

Recommended publications
  • Galaxy Clusters: Waking Perseus
    PUBLISHED: 2 JUNE 2017 | VOLUME: 1 | ARTICLE NUMBER: 164 news & views GALAXY CLUSTERS Waking Perseus The Perseus cluster contains over 1,000 a Kelvin–Helmholtz instability, which galaxies packed into a region ~3,500 kpc propagates in the wave direction and in extent. It is inevitable that such close- causes the dark area indicated in the packed galaxies will interact, and the image. This dark ‘bay-like’ feature is Chandra X-ray Observatory has observed approximately the size of the Milky Way, the beautiful result of that interaction and may be the result of a cold front in (pictured). This is no snapshot — the cluster gas: an interface where the Chandra observed the galaxy cluster temperature drops dramatically on scales for over 16 days in order to capture this much smaller than the mean free path. image. Stephen Walker and colleagues An advantage of this comparison of have retrieved the archival data and observations and simulations is that processed it to enhance the edges of (unmeasurable) physical quantities the surface brightness distribution. This can be estimated. In this case, the bay analysis, reported last year (Sanders et al., 50 kpc feature only appears in this form when Mon. Not. R. Astron. Soc. 460, 1898–1911; the ratio of the thermal pressure to the ROYAL ASTRONOMICAL SOCIETY ASTRONOMICAL ROYAL 2016), highlighted two features in the magnetic pressure is ~200, and this X-ray emission that are discussed by determination in turn allows the authors Walker et al. (Mon. Not. R. Astron. Soc. pattern seen in the image could have been to obtain an order-of-magnitude estimate 468, 2506–2516; 2017): the swirling wave generated by a passing galaxy cluster about of the magnetic field.
    [Show full text]
  • INVESTIGATING ACTIVE GALACTIC NUCLEI with LOW FREQUENCY RADIO OBSERVATIONS By
    INVESTIGATING ACTIVE GALACTIC NUCLEI WITH LOW FREQUENCY RADIO OBSERVATIONS by MATTHEW LAZELL A thesis submitted to The University of Birmingham for the degree of DOCTOR OF PHILOSOPHY School of Physics & Astronomy College of Engineering and Physical Sciences The University of Birmingham March 2015 University of Birmingham Research Archive e-theses repository This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder. Abstract Low frequency radio astronomy allows us to look at some of the fainter and older synchrotron emission from the relativistic plasma associated with active galactic nuclei in galaxies and clusters. In this thesis, we use the Giant Metrewave Radio Telescope to explore the impact that active galactic nuclei have on their surroundings. We present deep, high quality, 150–610 MHz radio observations for a sample of fifteen predominantly cool-core galaxy clusters. We in- vestigate a selection of these in detail, uncovering interesting radio features and using our multi-frequency data to derive various radio properties. For well-known clusters such as MS0735, our low noise images enable us to see in improved detail the radio lobes working against the intracluster medium, whilst deriving the energies and timescales of this event.
    [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]
  • Chapter 1 the PHYSICS of CLUSTER MERGERS
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by CERN Document Server To appear in Merging Processes in Clusters of Galaxies, edited by L. Feretti, I. M. Gioia, and G. Giovannini (Dordrecht: Kluwer), in press (2001) Chapter 1 THE PHYSICS OF CLUSTER MERGERS Craig L. Sarazin Department of Astronomy University of Virginia [email protected] Abstract Clusters of galaxies generally form by the gravitational merger of smaller clusters and groups. Major cluster mergers are the most energetic events in the Universe since the Big Bang. Some of the basic physical proper- ties of mergers will be discussed, with an emphasis on simple analytic arguments rather than numerical simulations. Semi-analytic estimates of merger rates are reviewed, and a simple treatment of the kinematics of binary mergers is given. Mergers drive shocks into the intracluster medium, and these shocks heat the gas and should also accelerate non- thermal relativistic particles. X-ray observations of shocks can be used to determine the geometry and kinematics of the merger. Many clus- ters contain cooling flow cores; the hydrodynamical interactions of these cores with the hotter, less dense gas during mergers are discussed. As a result of particle acceleration in shocks, clusters of galaxies should con- tain very large populations of relativistic electrons and ions. Electrons 2 with Lorentz factors γ 300 (energies E = γmec 150 MeV) are expected to be particularly∼ common. Observations and∼ models for the radio, extreme ultraviolet, hard X-ray, and gamma-ray emission from nonthermal particles accelerated in these mergers are described.
    [Show full text]
  • Download This Article in PDF Format
    A&A 566, A68 (2014) Astronomy DOI: 10.1051/0004-6361/201322450 & c ESO 2014 Astrophysics Mass, velocity anisotropy, and pseudo phase-space density profiles of Abell 2142 E. Munari1,A.Biviano2,3, and G. A. Mamon3 1 Astronomy Unit, Department of Physics, University of Trieste, via Tiepolo 11, 34131 Trieste, Italy e-mail: [email protected] 2 INAF/Osservatorio Astronomico di Trieste, via Tiepolo 11, 34131 Trieste, Italy e-mail: [email protected] 3 Institut d’Astrophysique de Paris (UMR 7095: CNRS & UPMC), 98 bis Bd Arago, 75014 Paris, France e-mail: [email protected] Received 6 August 2013 / Accepted 12 April 2014 ABSTRACT Aims. We aim to compute the mass and velocity anisotropy profiles of Abell 2142 and, from there, the pseudo phase–space density profile Q(r) and the density slope − velocity anisotropy β − γ relation, and then to compare them with theoretical expectations. Methods. The mass profiles were obtained by using three techniques based on member galaxy kinematics, namely the caustic method, the method of dispersion-kurtosis, and MAMPOSSt. Through the inversion of the Jeans equation, it was possible to compute the velocity anisotropy profiles. Results. The mass profiles, as well as the virial values of mass and radius, computed with the different techniques agree with one another and with the estimates coming from X-ray and weak lensing studies. A combined mass profile is obtained by averaging the lensing, X-ray, and kinematics determinations. The cluster mass profile is well fitted by an NFW profile with c = 4.0 ± 0.5. The population of red and blue galaxies appear to have a different velocity anisotropy configuration, since red galaxies are almost isotropic, while blue galaxies are radially anisotropic, with a weak dependence on radius.
    [Show full text]
  • The XMM Cluster Outskirts Project (X-COP): Physical Conditions of Abell 2142 up to the Virial Radius C
    A&A 595, A42 (2016) Astronomy DOI: 10.1051/0004-6361/201628183 & c ESO 2016 Astrophysics The XMM Cluster Outskirts Project (X-COP): Physical conditions of Abell 2142 up to the virial radius C. Tchernin1; 2, D. Eckert2; 3, S. Ettori4; 5, E. Pointecouteau6; 11, S. Paltani2, S. Molendi3, G. Hurier7; 12, F. Gastaldello3; 8, E. T. Lau9, D. Nagai9, M. Roncarelli4, and M. Rossetti10; 3 1 Center for Astronomy, Institute for Theoretical Astrophysics, Heidelberg University, Philosophenweg 12, 69120 Heidelberg, Germany e-mail: [email protected] 2 Department of Astronomy, University of Geneva, ch. d’Ecogia 16, 1290 Versoix, Switzerland 3 INAF–IASF-Milano, via E. Bassini 15, 20133 Milano, Italy 4 INAF–Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna, Italy 5 INFN, Sezione di Bologna, viale Berti Pichat 6/2, 40127 Bologna, Italy 6 CNRS, IRAP, 9 Av. colonel Roche, BP 44346, 31028 Toulouse Cedex 4, France 7 Centro de Estudios de Fisica del Cosmos de Aragon, Plaza San Juan 1, Planta-2, 44001 Teruel, Spain 8 Department of Physics and Astronomy, University of California at Irvine, 4129 Frederick Reines Hall, Irvine, CA 92697-4575, USA 9 Department of Physics, Yale University, New Haven, CT 06520, USA 10 Università degli studi di Milano, Dip. di Fisica, via Celoria 16, 20133 Milano, Italy 11 Université de Toulouse, UPS-OMP, IRAP, 38000 Toulouse, France 12 Institut d’Astrophysique Spatiale, CNRS, UMR8617, Université Paris-Sud 11, Batiment 121, Orsay, France Received 25 January 2016 / Accepted 17 June 2016 ABSTRACT Context. Galaxy clusters are continuously growing through the accretion of matter in their outskirts.
    [Show full text]
  • Size and Scale Attendance Quiz II
    Size and Scale Attendance Quiz II Are you here today? Here! (a) yes (b) no (c) are we still here? Today’s Topics • “How do we know?” exercise • Size and Scale • What is the Universe made of? • How big are these things? • How do they compare to each other? • How can we organize objects to make sense of them? What is the Universe made of? Stars • Stars make up the vast majority of the visible mass of the Universe • A star is a large, glowing ball of gas that generates heat and light through nuclear fusion • Our Sun is a star Planets • According to the IAU, a planet is an object that 1. orbits a star 2. has sufficient self-gravity to make it round 3. has a mass below the minimum mass to trigger nuclear fusion 4. has cleared the neighborhood around its orbit • A dwarf planet (such as Pluto) fulfills all these definitions except 4 • Planets shine by reflected light • Planets may be rocky, icy, or gaseous in composition. Moons, Asteroids, and Comets • Moons (or satellites) are objects that orbit a planet • An asteroid is a relatively small and rocky object that orbits a star • A comet is a relatively small and icy object that orbits a star Solar (Star) System • A solar (star) system consists of a star and all the material that orbits it, including its planets and their moons Star Clusters • Most stars are found in clusters; there are two main types • Open clusters consist of a few thousand stars and are young (1-10 million years old) • Globular clusters are denser collections of 10s-100s of thousand stars, and are older (10-14 billion years
    [Show full text]
  • A Catalogue of Zeldovich Pancakes
    A Catalogue of Zeldovich Pancakes Mikkel O. Lindholmer Supervisor: Steen H. Hansen Master’s thesis, submitted on October 18, 2015 Dark Cosmology Centre, Niels Bohr Institute, Juliane Maries Vej 30, 2100 Copenhagen, Denmark Abstract Using the standard cold dark matter model ΛCDM, it is predicted that there will be small fluctuations in the primordial energy density. These fluctuations are expected to lead to a cosmic web [1] under the influence of gravity and time. This web will consist of dense galaxy clusters interlinked by less dense two-dimensional walls, so called Zeldovich pancakes [2], and one-dimensional filaments. Galaxy clusters and filaments have been observed for a long time, but only recently have Zeldovich pancakes been observed outside of simulations [6]. The reason these have only recently been observed is because they are much less dense than filaments and clusters, to the point of being hard to differentiate from the average density of their environs [4,5]. Using the method we invented in Falco et. al [6] to find 2 pancakes as a basis, I create a fully automatic program capable of finding pancakes without human input, in galaxy cluster widely different from each other. I apply this program to the Abell galaxy clusters and using the SDSS catalogue I check for potential pancakes in the galaxy clusters. While most of the cluster are contained in the SDSS many of the clusters are only partially covered. I try to make the program compensate for this and manage to create the first catalogue of Zeldovich pancakes by finding 197 of them in 113 different clusters.
    [Show full text]
  • Constraining Cosmic Rays and Magnetic Fields in the Perseus
    A&A 541, A99 (2012) Astronomy DOI: 10.1051/0004-6361/201118502 & c ESO 2012 Astrophysics Constraining cosmic rays and magnetic fields in the Perseus galaxy cluster with TeV observations by the MAGIC telescopes J. Aleksic´1,E.A.Alvarez2, L. A. Antonelli3, P. Antoranz4, M. Asensio2, M. Backes5, U. Barres de Almeida6, J. A. Barrio2, D. Bastieri7, J. Becerra González8,9, W. Bednarek10, A. Berdyugin11,K.Berger8,9,E.Bernardini12, A. Biland13,O.Blanch1,R.K.Bock6, A. Boller13, G. Bonnoli3, D. Borla Tridon6,I.Braun13, T. Bretz14,26, A. Cañellas15,E.Carmona6,28,A.Carosi3,P.Colin6,, E. Colombo8, J. L. Contreras2, J. Cortina1, L. Cossio16, S. Covino3, F. Dazzi16,27,A.DeAngelis16,G.DeCaneva12, E. De Cea del Pozo17,B.DeLotto16, C. Delgado Mendez8,28, A. Diago Ortega8,9,M.Doert5, A. Domínguez18, D. Dominis Prester19,D.Dorner13, M. Doro20, D. Eisenacher14, D. Elsaesser14,D.Ferenc19, M. V. Fonseca2, L. Font20,C.Fruck6,R.J.GarcíaLópez8,9, M. Garczarczyk8, D. Garrido20, G. Giavitto1, N. Godinovic´19,S.R.Gozzini12, D. Hadasch17,D.Häfner6, A. Herrero8,9, D. Hildebrand13, D. Höhne-Mönch14,J.Hose6, D. Hrupec19,T.Jogler6, H. Kellermann6,S.Klepser1, T. Krähenbühl13,J.Krause6, J. Kushida6,A.LaBarbera3,D.Lelas19,E.Leonardo4, N. Lewandowska14, E. Lindfors11, S. Lombardi7,, M. López2, R. López1, A. López-Oramas1,E.Lorenz13,6, M. Makariev21,G.Maneva21, N. Mankuzhiyil16, K. Mannheim14, L. Maraschi3, M. Mariotti7, M. Martínez1,D.Mazin1,6, M. Meucci4, J. M. Miranda4,R.Mirzoyan6, J. Moldón15,A.Moralejo1,P.Munar-Adrover15,A.Niedzwiecki10, D. Nieto2, K. Nilsson11,29,N.Nowak6, R.
    [Show full text]
  • Clusters of Galaxy Hierarchical Structure the Universe Shows Range of Patterns of Structures on Decidedly Different Scales
    Astronomy 218 Clusters of Galaxy Hierarchical Structure The Universe shows range of patterns of structures on decidedly different scales. Stars (typical diameter of d ~ 106 km) are found in gravitationally bound systems called star clusters (≲ 106 stars) and galaxies (106 ‒ 1012 stars). Galaxies (d ~ 10 kpc), composed of stars, star clusters, gas, dust and dark matter, are found in gravitationally bound systems called groups (< 50 galaxies) and clusters (50 ‒ 104 galaxies). Clusters (d ~ 1 Mpc), composed of galaxies, gas, and dark matter, are found in currently collapsing systems called superclusters. Superclusters (d ≲ 100 Mpc) are the largest known structures. The Local Group Three large spirals, the Milky Way Galaxy, Andromeda Galaxy(M31), and Triangulum Galaxy (M33) and their satellites make up the Local Group of galaxies. At least 45 galaxies are members of the Local Group, all within about 1 Mpc of the Milky Way. The mass of the Local Group is dominated by 11 11 10 M31 (7 × 10 M☉), MW (6 × 10 M☉), M33 (5 × 10 M☉) Virgo Cluster The nearest large cluster to the Local Group is the Virgo Cluster at a distance of 16 Mpc, has a width of ~2 Mpc though it is far from spherical. It covers 7° of the sky in the Constellations Virgo and Coma Berenices. Even these The 4 brightest very bright galaxies are giant galaxies are elliptical galaxies invisible to (M49, M60, M86 & the unaided M87). eye, mV ~ 9. Virgo Census The Virgo Cluster is loosely concentrated and irregularly shaped, making it fairly M88 M99 representative of the most M100 common class of clusters.
    [Show full text]
  • Astronomy Magazine 2011 Index Subject Index
    Astronomy Magazine 2011 Index Subject Index A AAVSO (American Association of Variable Star Observers), 6:18, 44–47, 7:58, 10:11 Abell 35 (Sharpless 2-313) (planetary nebula), 10:70 Abell 85 (supernova remnant), 8:70 Abell 1656 (Coma galaxy cluster), 11:56 Abell 1689 (galaxy cluster), 3:23 Abell 2218 (galaxy cluster), 11:68 Abell 2744 (Pandora's Cluster) (galaxy cluster), 10:20 Abell catalog planetary nebulae, 6:50–53 Acheron Fossae (feature on Mars), 11:36 Adirondack Astronomy Retreat, 5:16 Adobe Photoshop software, 6:64 AKATSUKI orbiter, 4:19 AL (Astronomical League), 7:17, 8:50–51 albedo, 8:12 Alexhelios (moon of 216 Kleopatra), 6:18 Altair (star), 9:15 amateur astronomy change in construction of portable telescopes, 1:70–73 discovery of asteroids, 12:56–60 ten tips for, 1:68–69 American Association of Variable Star Observers (AAVSO), 6:18, 44–47, 7:58, 10:11 American Astronomical Society decadal survey recommendations, 7:16 Lancelot M. Berkeley-New York Community Trust Prize for Meritorious Work in Astronomy, 3:19 Andromeda Galaxy (M31) image of, 11:26 stellar disks, 6:19 Antarctica, astronomical research in, 10:44–48 Antennae galaxies (NGC 4038 and NGC 4039), 11:32, 56 antimatter, 8:24–29 Antu Telescope, 11:37 APM 08279+5255 (quasar), 11:18 arcminutes, 10:51 arcseconds, 10:51 Arp 147 (galaxy pair), 6:19 Arp 188 (Tadpole Galaxy), 11:30 Arp 273 (galaxy pair), 11:65 Arp 299 (NGC 3690) (galaxy pair), 10:55–57 ARTEMIS spacecraft, 11:17 asteroid belt, origin of, 8:55 asteroids See also names of specific asteroids amateur discovery of, 12:62–63
    [Show full text]
  • Coma Cluster of Galaxies
    Coma Cluster of Galaxies In 2006, Hubble Space Telescope aimed at a nearby collection of NAT I O N A L SC I E N C E ED U C AT I O N STA N D A R D S galaxies called the Coma Cluster. Using the HST images, astronomers • Content Standard in 9-12 Science as gained fascinating insights into the evolution of galaxies in dense Inquiry (Abilities necessary to do sci- galactic neighborhoods. In this activity, students will first learn the entific inquiry, Understanding about basics of galaxy classification and grouping, then use HST images to scientific inquiry) discover the “morphology-density effect” and make hypotheses about • Content Standard in 9-12 Earth and its causes. Space Science (Origin and evolution of the universe) MAT E R I A L S & PR E PA R AT I O N • Each student needs a copy of the next 7 pages (not this page). You may InvIsIble Clu s t e r copy the pages out of this guide, but it is recommended that you go to If you aim a big telescope at the Coma mcdonaldobservatory.org/teachers/classroom and download the student Cluster, you’ll see galaxies galore worksheets. The galaxy images in the online worksheets are “negatives” — thousands of galaxies of all sizes of the real images, which provides better detail when printing. Supple­ and shapes, from little puffballs to mental materials for this activity are also available on the website. big, fuzzy footballs. Even so, you won’t • Each student or student team will need a calculator and a magnifying see most of the cluster because it’s invis­ glass (a linen tester works well).
    [Show full text]