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CMB observations and results

CMB observations and results. Dmitry Pogosyan University of Alberta. Lecture 1: What can Cosmic Microwave Background tell us about the Universe ? A theoretical introduction . Lecture 2: Recent successes in the mapping of CMB anisotropy: what pre-WMAP and WMAP data reveals.

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CMB observations and results

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  1. CMB observations and results Dmitry Pogosyan University of Alberta • Lecture 1: What can Cosmic Microwave Background tell us about the Universe ? A theoretical introduction. • Lecture 2: Recent successes in the mapping of CMB anisotropy: what pre-WMAP and WMAP data reveals. Lake Louise, February, 2003

  2. ∆T/T ~ 10-5

  3. Phenomenology of the Angular Power Spectrum Curvature Acoustic Oscillations Drag Reionization Sachs-Wolfe Effect Damping Doppler Tensors large <-- scales --> small

  4. Error origins – noise and ‘cosmic variance’ Cosmic Variance ~ Cl / √fsky Noise

  5. Relikt, 1983 (USSR) • First CMB anisotropy data actively used to restrict cosmological models • Quadrupole dT/T < 4 x 10-5 • Many models where dismissed for failing this limit – hot (massive neutrino) dark matter, late decaying neutrinos ….

  6. COBE-DMR, 1992 First detection of anisotropy large angular scale l < 20 growing initial slope ns=1.20.2 Low quadrupole power

  7. Search for the first acoustic peak: • TOCO 1998 • Boomerang NAmerica, 1997

  8. Mapping acoustic oscillations: • Boomerang 2000-2002 • Maxima 2000-2001 • DASI 2001

  9. 2002 CBI – damping tail Archeops – low l link to COBE ACBAR - medium-high l DASI – detection of polarization

  10. Pre WMAP parameters (Jan 2003)

  11. Deficiencies • Covering only part of the sky leads to high cosmic variance uncertainties. (Noise is not an issue at l < 1000) • Patched coverage of the angular scales enhances role of systematics (e.g., calibration and beam uncertainties) which dominates analysis. • As the result – limited success of breaking some degeneracies • c – 8 as predictedfrom CMB • c – ns • c – gravitational waves

  12. Wilkinson Microwave Probe (WMAP) – launch June 2001, first year data release – Feb 11, 2003 • 75-85% of full sky • 5 frequency channels at 23-94 Ghz • First 1year data – sky is covered twice • Each pixel observed ~3000 times. Cosmic variance limited up to l~600 • 0.5% calibration uncertainty

  13. WMAP high S/N, high resolution CMB map of the full sky

  14. WMAPext k= -0.02  0.02 b = 0.0224 0.0009 cdm=0.135  0.009 h =0.71  0.04 ns = runs 1.2-0.93 c = 0.17  0.04 WMAP alone k= -0.03  0.05 b = 0.024 0.001 cdm=0.14  0.02 h =0.72  0.05 ns = 0.99 0.04 c= 0.15  0.07 Joint pre-WMAP k= -0.05  0.05 b = 0.022 0.002 cdm = 0.12  0.02 ns = 0.95 0.04 c<0.3-0.4

  15. WMAP new advances – TE: c, adiabaticity • Measurement of TE polarization • Prove of adiabatic perturbation origin (TE anticorrelation at ~ 100) • c determination from TE enhancement at l < 20.

  16. CMB Polarization • Full description of radiation is by polarization matrix, not just intensity – Stockes parameters, I,Q,U,V • Why would black-body radiation be polarized ? Well, it is not in equilibrium, it is frozen with Plankian spectrum, after last Thompson scattering, which is a polarizing process. • But only, because there is local quadrupole anisotropy of the photon flux scattered of electron. Thus, P and dT/T are intimately related, second sources first (there is back-reaction as well). • There is no circular polarization generated, just linear – Q,U. Level of polarization ~10% for scalar perturbations, factor of 10 less for tensors. Thus needed measurements are at dT/T~10-6 – 10-8 level. • As field on the sky – B, E modes (think vectors, but in application to second rank tensor), distinguished by parity.

  17. WMAP new advances – extending the parameter list • Do we need ever precise determination of the parameters? Yes, if we want to explore larger parameter space., • WMAP: • Running ns – positive slope at low l, negative at higher l Recall COBE-DMR, it also preferred n~1.2 ! Also, low quadrupole – hint to new physics ? • Gravitational wave (tensor) contribution to dT/T is small < 0.72 of scalar component

  18. “The Seven Pillars” of the CMB(of inflationary adiabatic fluctuations) • Large Scale Anisotropies • Acoustic Peaks/Dips • Gaussianity • Polarization, TE correlation • Damping Tail • Secondary Anisotropies • Gravity Waves, B-type polarization pattern Minimal Inflationary parameter set Quintessesnce Tensor fluc. Broken Scale Invariance

  19. Cosmic Background Imager (CBI) BOOMERANG ACBAR

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