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CMB as a physics laboratory

CMB as a physics laboratory. Recombination. T = 0.3 eV << m e c 2. Hydrogen is ionized Thomson Scattering. Hydrogen is neutral. Cosmic. Dust. Point sources. Free free. Synchrot. Tegmark, 2000. Microwave. Decoupling: photon mean free path, l=1/ n e s T > H -1 .

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CMB as a physics laboratory

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  1. CMB as a physics laboratory

  2. Recombination T = 0.3 eV << me c2 Hydrogen is ionized Thomson Scattering Hydrogen is neutral

  3. Cosmic Dust Point sources Free free Synchrot. Tegmark, 2000

  4. Microwave Decoupling: photon mean free path, l=1/nesT > H-1. Tdec=3000K depends essentially only on the baryon density (ne) and on the total matter density (H-1 ). After 10Gyr, this has to cool by a factor of roughly 1000: the present black body spectrum at Tcmb=2.726K is then an immediate indication that the values of Wtot ,Wb H0 we currently use are in the right ballpark.

  5. Background CMB z = 1100

  6. History

  7. Is the Universe…. Open, closed, flat, compact, accelerated, decelerated, initially gaussian, scale invariant, adiabatic, isocurvature, einsteinian…? • Geometry • Dynamics • Initial conditions • Growth of fluctuations Ask the CMB….

  8. What do we expect to find on the CMB? • Wo ,WL,W b ,n R,NR ,H0 • ns, nt , s8 • inflation pot. V (f) the standard universe XXXXX boring • W f,wf,b • VEP the unexpected universe XXXXXXX exciting • topological defects • bouncing universe • Compact topology • Extra dimensions very exciting XXXX the weird universe

  9. Perturbing the CMB • Observable: radiation intensity per unit frequency per polarization state at each point in sky: DT, D P, D E(n) • In a homogeneous universe, the CMB is the same perfect black-body in every direction • In a inhomogenous universe, the CMB can vary in:

  10. Predicting the CMB • General relativistic equations for baryons, dark matter, radiation, neutrinos,... • Solve the perturbed, relativistic, coupled, Boltzmann equation • Obtain the DT/T for all Fourier modes and at all times • Convert to the DT/T on a sphere at z=1100 around the observer Complicate but linear !

  11. Fluctuation spectrum From DT/T To Cl Large scales Small scales

  12. Temperature fluctuations

  13. Archaic CMB • Sachs-Wolfe effect of superhorizon inflationary perturbations • Integrated Sachs-Wolfe effect of subhorizon fluctuations: when the gravitational potential is not constant (eg, nonflat metric, other components, non-linearity, etc)

  14. Sachs-Wolfe effect Last Scatt. Surface F z = 0 SW ISW z = 1100 . F

  15. Fluctuation spectrum

  16. Sachs-Wolfe effect Data: Cobe +Boomerang P(k)=Akn

  17. Integrated Sachs-Wolfe effect

  18. Middle age CMB • Acoustic perturbations: • perturbations oscillate acoustically when their size is smaller than the soundhorizon (the pressure wave has the time to cross the structure) • The oscillations are coherent !

  19. The sound horizon at decoupling • The decoupling occurred300,000 yrsafter the big bang • Acoustic perturbations in the photon-baryon plasma travelled at the sound speed • Therefore they propagated for • (almost) independently of cosmology.

  20. Acoustic oscillations LSS z = 0 z = 1100

  21. Coupled fluctuations D. Eisenstein

  22. Acoustic oscillations

  23. First peak: Sound horizon • angular size : sensitive to the dominant components • amplitude : sensitive to the baryoncomponent

  24. Sound horizon

  25. Acoustic peaks Data: Boomerang 1999

  26. Contemporary CMB • Processes along the line-of-sight: • SZ effect: inverse Compton scattering (cluster masses) • stochastic lensing (mass fluctuation power) • reionization (epoch of first light)

  27. Weak Lensing in CMB Lensed temperature field Temperature field Hu 2002

  28. How is polarization generated? Thomson Scattering

  29. Density pert. & Gravity Waves Gravity Waves

  30. CMBin 1999… …2001 …2003

  31. Sensitivity Hu, 2002 Now Map, 2003 Planck, 2007

  32. The geometric effect

  33. The kinematic effect

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