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The dark side of the Universe: dark energy and dark matter Harutyun Khachatryan

The dark side of the Universe: dark energy and dark matter Harutyun Khachatryan Center for Cosmology and Astrophysics. Content of the Universe after Planck. Density proportion evolution. Lambda chronology. 2013 Planck, density content revision. Cosmological models.

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The dark side of the Universe: dark energy and dark matter Harutyun Khachatryan

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  1. The dark side of the Universe: dark energy and dark matter Harutyun Khachatryan Center for Cosmology and Astrophysics

  2. Content of the Universe after Planck

  3. Density proportion evolution

  4. Lambda chronology 2013 Planck, density content revision

  5. Cosmological models Friedmann-Robertson-Walker metric Spatial curvature K=0 flat (Minkowski), K=+1 positive curvature(sphere) K=-1 negative curvature spectral redshift cosmic redshift Continuity equation Evolution equation

  6. Friedmann equations

  7. Energy-momentum tensor

  8. Omega budget

  9. Luminosity distance For concordance model for flat universe dark energy 0.69 matter density 0.31 radiation density 10^-4

  10. Cosmological constant Λ? Einstein equations 1916 Einstein 1917

  11. Dark energy 1998 Hubble diagram

  12. 2011 Nobel Prize in Physics

  13. Extragalactic Distance ladder

  14. Astrophysical parameters L luminosity, total energy emitted by an object per second. m apparent magnitude, observed brightness. M absolute magnitude, calibrated brightness. M=m-5(log10(DL)-1)

  15. Standard candles Classical Cepheids Type Ia Supernovae

  16. Cepheid light curve

  17. Type Ia Supernovae

  18. Crab nebula 1054 A.D. supernova remnant

  19. SN Ia light curve

  20. Hubble’s law Theory: from FRW metric follows V=H(r)r for small distances, z << 1. Observations: Hubble redshift-distance law of galaxies V = H r V- velocity of the galaxy, r- distance to the galaxy, Hubble’s constant H = 69.32 ± 0.80 (km/s)/Mpc (after Planck).

  21. Hubble’s or Lemaitre’s law? Hubble 1929 Lemaitre 1927

  22. Hubble diagram indicating accelerated expansion Riess et al. 1998

  23. Higher redshifts: gamma-ray bursters • z=1-10 and more (arguable) • emits in few seconds as much as the Sun during its lifetime • nature unknown, some empirical relations exit Can they be used for the Hubble diagram?

  24. Calibrating GRBs Empirical relations Amati relation lag versus luminosity relation variability versus luminosity relation H. J. M. Cuesta…..H. G. Khachatryan,.. A&A, 2008

  25. Vacuum fluctuations Zeldovich 1967

  26. Cosmic coincidence

  27. Equation of state, w

  28. Dark energy summary • Negative pressure, p=-ρ • Ω=0.69 • Equation of state, cosmological constant w=-1 • Various models: vacuum fluctuations, General Relativity extensions (scalar field coupled, Chern-Simons, f(R), etc), quintessence, holography…

  29. Slide by A.Taylor, Motivating EUCLID space mission, 2011

  30. Dark matter chronology • 1932- Jan Oort, stellar motion in the local galactic neighbourhood • 1933- Fritz Zwicky, motion in clusters of galaxies • 1970- Vera Rubin, galaxy rotation curves

  31. Virial theorem Dark matter Coma cluster 2<T>=Vtot Zwicky, F., Helvetica Physica Act 6 (1933)

  32. M31 rotation curve V.C. Rubin & W.K. Ford 1970

  33. Galaxy rotation curves

  34. Gravitational lensing Einstein 1912,1936

  35. Bullet cluster 1E 0657-558

  36. Bullet cluster X-ray image

  37. Modified Newtonian dynamics

  38. MOND theory (by Milgrom) MOND acceleration related to the Newtonian acceleration aN at weak acceleration limit of gravity interpolation function

  39. Dark matter summary • Ω=0.27 • Particle candidates: axion, WIMPs, neutrino (small part), supersymmetric particles… • Models: cold dark matter, warm dark matter, hot dark matter • MOND

  40. Challenge to homogeneity of the Universe? Greatest cosmic structure

  41. 73 quasar cluster z=1.27, longest dimension 1240 Mpc, mean length 500 Mpc R. Clowes et al. MN, 2013

  42. Conclusions • Modern cosmology passed to the precision • cosmology era. • Dark energy: favored, cosmological constant • w=-1. The nature unknown. • Dark matter: many candidates, none favored. • The nature unknown. • Challenges to the concordance model (CMB • low multipole anomaly, alignments, non- • Gaussianities…).

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