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Viktor Zacek, Université de Montréal

DARK MATTER. Part I. Lake Louise Winter Institute February 2007. Viktor Zacek, Université de Montréal. Lecture I Astronomical evidences for Dark Matter Dark Matter and the Dynamics of the Universe Present knowledge of the matter content of the Universe

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Viktor Zacek, Université de Montréal

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  1. DARK MATTER Part I Lake Louise Winter Institute February 2007 Viktor Zacek, Université de Montréal

  2. Lecture I • Astronomical evidences for Dark Matter • Dark Matter and the Dynamics of the Universe • Present knowledge of the matter content of the Universe • Dark Matter and structure formation • Lecture II • Dark Matter candidates (MOND, neutrinos, axions, …) • Neutralino interactions with Matter • Status of indirect search experiments • Status of direct search experiments • Future directions

  3. The Universe is a gigantic vortex! (Aristophanes) The Uiverse is finite, static and ever lasting. (Aristoteles) The Universe is infinite and cyclic ! (Anaximander) The Universe is a big rectangular box with Egypt at the center. (the Egyptians) The World was created on October 22, 4004BC at 6 o’clock in the evening. (Bishop Ussher 1650) If God the Almighty would only have consulted me before creation, I would have proposed something simpler. (A.de Rujula) The visible Universe is only a fraction of the total Universe, it is 13.7 billion years old, with flat geometry and most of its mass is non-baryonic (WMPA March 2006)

  4. THE DARK MATTER PROBLEM - FIRST INDICATIONS • Studies kinetic energies of 8 galaxies of the Coma Cluster • finds velocities are much larger than expected • apparently Coma cluster contains 200 x more mass than is visible in form of galaxies Fritz Zwicky, 1937 The “hidden mass” problem becomes a “key problem” of modern cosmology

  5. DARK MATTER & GALACTIC ROTATION CURVES Vera Rubin, 1974 M(r) mass within r M increses linearly for vrot = ct. for large r halos of galaxies start to overlap Doppler shift of star light and of HI distribution Mhalo > 10 x (Mlum + Mgas)

  6. DARK MATTER IN OUR MILKY WAY 1kpc = 3.259 103 Ly DM  0.3 mp/cm3 …only 5-10% of matter visible! 2MASS two Micron All Sky Survey

  7. VIRGOHI21: A GALAXY OF DARK MATTER ! (50 M Ly) Visible spectrum RF-hydrogen emission 1000 x more Dark Matter than hydrogen! M  0.1 MMW (Feb. 2005)

  8. DARK MATTER AROUND OTHER GALAXIES • Abell 2029 • a cluster of thousands of galaxies • surrounded by gigantic clouds of hot gas • T 106 K MTot> 10 Mvis

  9. DARK MATTER AT LARGER SCALES • Size of Local group 2.2 MLy • MW & M31 dominate Local Group • Enormous gravit. pull between the two galaxies • Invisible mass > 10 x MMW • Local group at fringe of Virgo cluster V= 3x105 km/h Virgo cluster v  1.6x106 km/h v  2 x 106 km/h • Size of Virgo cluster 50MLy • Local group pulled towards Virgo cluster • invisible mass > 10 x Mvis Virgo Cluster pulled towards an invisible “Great Attractor”

  10. DARK MATTER AT AT LARGE SCALES • Gravitational lensing • provides evidence of large masses between source and MW • recently 3D reconstruction of clusters of Dark Matter HST CL0024+1654 Mdark>50 Mvis

  11. THE BULLET CLUSTER IE0657-56 (3.4 109 LY) High velocity merger of clusters of galaxies 4500 km/s 108K Mdark > 49 Mvis M. Markewitch et al: HST, Magellan, Chandra (August 2006)

  12. DARK MATTER & DYNAMICS OF THE UNIVERSE m M = mass of Universe R = radius of Universe m = mass of a border galaxy R M Energy density of vacuum v = c2/8G Ekin + Epot = Etot « Friedmann equation »  adds to gravitation!

  13. THE FRIEDMANN EQUATION A. Einstein: • k: curvature of space! • k = 0: flat • k > 0: closed • k < 0 open (Robertson-Walker metric) repulsive attractive

  14. HUBBLES LAW & CRITICAL DENSITY v = H0R Hubbles law! H0= 72 km s-1Mpc-1 (today!) v = c2/8G Friedmann equation “critical density”  k = 0 (for =0)

  15. THE CRITICAL DENSITY  = 0 today: c= 1.9 10-26 kg/m3  1proton/m3 Mass parameter m = 0/ c  =v/c 0: present day value tot > 1 closed U. tot < 1 open U. tot = 1 flat, euclidean, critical U. ...but lum  0.01 ( 1!)

  16. HOW TO MEASURE  ? • Count all the components of the Universe! • Luminous matter, stars • DM from galaxies and their rotation curves • DM in clusters of galaxies • DM inferred from x-ray clouds around clusters of galaxies • DM from large scale flows of galaxies • DM by gravitationallensing + Measure the geometry of the Universe!

  17. Courtesy CERN

  18. B FROM BIG BANG NUCLEOSYNTHESIS T + p  4 He 3He + n  4He D + D  4He He + T  7Li n + p  D p + D  3He n + D  T …well understood no elements A = 5 / 8 heavy elements @ T ~ 106 y Yi = fct( b, T, n, n , …) light el. abund. consistent over O(9) b = 0.04  0.007

  19. CURRENT EVIDENCE FOR m Rotation curves Velocity flows Galaxy kinematics m ~ 0.2-0.3 Hot X-ray gas Lensing

  20. CURRENT EVIDENCE FOR  2003 SN Type Ia Redshift m = 0.3,  = 0.7

  21. …AND THERE IS A COSMIC COINCIDENCE ?!  ~ m just now??

  22. tot FROM GEOMETRY OF THE UNIVERSE INFLATION* :  tot = 1 * Phase change @T 10-35s with x 1050  flat space

  23. THE ANISOTROPY OF THE COSMIC MW BACKGROUND Image of early Universe imprinted on temp. anisotropy of CMB T/T  10-5 WMAP 2001 • 300 ky after BB photons decouple from matter T  6000 K • before decoupling: plasma oscill./ of photon-baryon “liquid”  sound waves • CMB: snap shot of sound waves when rad. decoupled • Today light red shifted by 1/1000  3K • Smallness of T/T  visible Universe once causally connected  Inflation! • Image of quantum fluctuation at 1019 GeV

  24. Angular diameter of the moon Expansion in spherical harmonics of CMB temp. field • Multipole development  angular scale • l number of cycles in the sky •  =  / l • lpeak = 200 / tot • lpeak = 197  6 (0.90) Curvature of Universe: tot “Cosmic variance” (only one Universe) Baryon density small: b

  25. WMAP RESULTS: Other :  tot = 1.02.02 Inflation :  tot = 1 b= 0.04 0.004 BBN: b= 0.039 m= 0.27 0.04 clusters of galaxies, grav. lensing hot x-ray gas : m= 0.3  = 0.73 0.04SN1a –redshift :  = 0.7 H0 = 714 km/sec/Mpc Hubble: H0 =72 4 km/sec/Mpc T0= 13.7 0.02 Gyr Hubble: 11 Gyr

  26. DM & DEVELOPMENT OF STRUCTURE • BB creates DM + ord. Matter • DM decouples early • Clumps • Ordinary matter flows in • Galaxies form • Galaxies trace DM distribution

  27. DO GALAXIES TRACE THE DM DISTRIBUTION ? COSMOS EVOLUTION SURVEY: (Jan. 2007) • First large scale 3D reconstruction of DM distribution • Hubble Space Telescope: largest picture mosaic ever 1.40 x 1.40 • Distance by red shifts: ESO VLT (Chile), Magellan (Chile), Subaru (Hawaii), CHT (Hawaii) • -X-ray mapping of gas in galaxies: XMM Newton • - 0.5 M background galaxies for DM reconstruction by gravitational lensing

  28. Near infra red HST DM > six times more abundant than ordinary matter Growing clumpiness of DM & ordinary matter flowing in

  29. 3 slices of red shift 6.5 By ago 100 M Ly 5 By ago 3.5 By ago 60 M Ly Growing clumpiness of DM & ordinary matter flowing in

  30. Next: Large Synoptic Survey Telescope (2013) 8.4 m diameter mirror 30 Tbyte/night Google participates in organizing data analysis (New Scientist Jan. 2007)

  31. WHAT IS THE STRUCTURE AT LARGE SCALE SLOAN DIGITAL SKY SURVEY • SDSS I completed Jan. 2005 • SDSS II until 2008 • maps cube of 6x109 Ly sides

  32. WHAT KIND OF MATTER CAN EXPLAIN LSS? Baryonic matter @T=225s (BBN) cannot clump to form voids (200MLy) filaments & superclusters …structures thinned out by Hubble expansion Assume DM decouples earlier @ T < TBBN and interacts weakly • longer time to develop structure • clumps earlier • baryons fall into troughs • galaxy formation • Large scale structure • Dark Matter 3 problems solved:

  33. LARGE SCALE STRUCTURE & DM SPEED COLD DM • non relativistic • extremely weak interaction w. baryonic matter • clump on small scale • bottom-up model • galax. in correct mass range (10-3 < MW < 104) HOT DM • relativistic • e.g. massive ’s • before decoupling structures washed out • superclusters form first (ruled out by WMAP) cdm-hdm1-princeton.mpeg

  34. LARGE SCALE STRUCTURE Best fit: b=5% dm=25%  =70% The larger the scale we average the more uniform becomes the Universe!

  35. THE WHOLE PICTURE! 85% of gravitationally bound matter is non-baryonic ! Density of luminous matter 1% !

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