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The Universe according to WMAP III

The Universe according to WMAP III. Jan Pieter van der Schaar University of Amsterdam. Outline. Introduction CMB basics WMAP mission First year data release The WMAP III data release Main new features and results Third year spectra Implications for Cosmology Cosmological parameters

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The Universe according to WMAP III

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  1. The Universe according to WMAP III Jan Pieter van der Schaar University of Amsterdam ITF Colloquium

  2. Outline • Introduction • CMB basics • WMAP mission • First year data release • The WMAP III data release • Main new features and results • Third year spectra • Implications for Cosmology • Cosmological parameters • Consistency with other data • Conclusions ITF Colloquium

  3. Too much anticipation…? • December 2004 email exchange: …There are rumours that the wiggles in the spectrum are confirmed in the new Wmap release so it may really be interesting… "...wiggles in the spectrum have been confirmed..." ??? I have not heard these rumors. Have any of you? Is it true? …there are several rumours about the new WMAP data (you know, they are delaying so much the release that everybody thinks there must be unexpected things); …but I also heard independently from two persons, who heard it from people involved in Wmap, that the wiggles in the spectrum are confirmed, within the errors (which are anyway very small already)… • Final release date: March 16 2006! ITF Colloquium

  4. 1 ¡ ( ) k k P n 1 6 2 ¡ + s n / ² ´ = s s CMB basics • Photon afterglow after decoupling • Last scattering surface z ~ 1100 • Perfect black body: T=2.725 K • Homogeneous and isotropic universe • Structure formation `predicts’ small CMB temperature anisotropies • First detected by COBE at 10-5 level (1992) • Precision probe of many, almost all, cosmological parameters • Subsequently: ACBAR, BOOMERanG, MAXIMA, CBI, …, WMAP Inflation: solves horizon, flatness, defect problem Beautiful mechanism for the generation of a scale invariant, adiabatic, Gaussian spectrum of super-horizon scalar + tensor perturbations ITF Colloquium

  5. ³ ´ q ¢ T P ¢ C ± ± Y C 2 0 < > < > l a a ; a a = = = l l l l l l l l 0 0 0 0 l = m m m m m m m T m l C 2 1 + ; l i i c o s m c v a r a n c e CMB anisotropies • Tightly coupled baryon-photon fluid • Pressure vs gravity (within sound horizon) • Forced damped oscillator equation • Produces acoustic peaks • After decoupling: free streaming from last scattering surface • Large scale primordial modes (low l) hardly affected (Sachs-Wolfe plateau) • Gaussian distribution for every l • Cosmic variance: 2l+1 samples ITF Colloquium

  6. P k P n 1 6 t t ´ r / ² = t P s Polarization • Quadrupole anisotropy : E-mode • Cross-correlated spectrum <TE> • Super-horizon adiabatic perturbations • Probe of optical depth (reionization) • Removes certain degeneracies • Tensor perturbations : E+B-mode • E-mode: gradient of potential • B-mode: curl of potential ITF Colloquium

  7. WMAP mission • Launched in 2001 • L2 orbit • Full sky observations in 6 month period • In operation until 2008 WMAP team, C.L. Bennett (PI) : NASA and Princeton University. Around 27 people, including UCLA, U. Chicago, UBC, Toronto and Brown. ITF Colloquium

  8. 2 H 3 = = h k H M 1 0 0 ½ ­ 0 m s p c = ´ ´ 0 ½ i t c r G , 8 ½ ¼ i t c r First year data release • Februari 2003: very impressive results! • Consistent with other data • Small scale CMB measurements • Large scale structure (SDDS,2dFGRS) • Supernovae type IA measurements • Room for improvement • Foregrounds (particularly for polarization) • Data analysis, integration • #1 breakthrough of the year 2003 [SCIENCE] ITF Colloquium

  9. Some surprises • Large optical depth • Early reionization (stars) • Low l anomalies • Running spectral index? • Position and height of peaks • Curvature (flat!) • Baryon density • Matter density • Important degeneracy • Optical depth and spectral index ITF Colloquium

  10. WMAP 3rd year release • More integration time, better (foreground) analysis • Smaller errors at high multipoles • Better determination of 3rd peak • Now includes E-E polarization spectrum • Better determination of optical depth • Breaking optical depth/spectral index degeneracy • Important results • Optical depth decreased, later reionization • Spectral index < 1 ! • Dark Energy equation of state w ~ -1 • Octupole (l=3) anomaly gone • More accurate and shift in matter density • Running spectral index no longer significant • Still in excellent agreement with ΛCDM: flat universe, made of baryons, cold dark matter and dark energy • Excellent agreement with other data ITF Colloquium

  11. Third year spectra • Reduced errors, third peak • Octupole (l=3) • Reionization • E-E spectrum ITF Colloquium

  12. N 2 2 R f ( j ) ( g ) h h d d ­ ­ H L < > ® ® ¾ ® ¿ p n ® ® = b i i 0 8 m s ; ; ; ; ; Cosmological parameters • Parameter estimation: • Best fit: 6 parameter ΛCDM • Bayesian statistics, uniform priors • Markov Monte Carlo chains: exploring likelihood surface • Mean vs maximum likelihood ITF Colloquium

  13. Departures from best fit • No urgent reason to add more parameters ITF Colloquium

  14. Combined constraints • Bottomline: consistent numbers ITF Colloquium

  15. ³ ´ 2 0 0 ³ ´ 2 V 2 M 0 M V ´ l P ´ ´ ² l P V V 2 Inflationary parameters • Some models constrained, but still lots of room • Constraints on tensor-scalar ratio ITF Colloquium

  16. Dark Energy and Neutrinos • Flat universe, WMAP + SNLS: w=-0.97(+0.07, -0.09) • True cosmological constant? ITF Colloquium

  17. Other features • No sign of non-gaussiannities • No sign of modulations due to initial state modifications (“wiggles”, potentially probing the string scale) ITF Colloquium

  18. The Future • Holy grail: B-mode polarization • Tensor perturbations: scale of inflation • Testing inflation • Non-gaussiannities • Surprising features (string theory?) • ESA Planck satellite (not optimized for polarization), expected to launch in 2008 • Ground-based/balloon missions • USA: CMBPOL (before 2020) • Galaxy surveys, gravitational lensing, 21 cm radiation D. Spergel: ultimately one might reach 10-6 level precision ITF Colloquium

  19. Conclusions • Unprecedented data • Rigorous test of Standard Model of Cosmology • Closing in on a cosmological constant • First hint of departure from scale invariance, as predicted by inflation • What about low multipole (l=2) anomaly? • “Axis of evil” ? ITF Colloquium

  20. WMAP three-year papers: Three-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Beam Profiles, Data Processing, Radiometer Characterization and Systematic Error LimitsN. Jarosik, et.al., submitted Three-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Temperature ResultsG. Hinshaw, et.al., submitted Three-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Polarization AnalysisL. Page, et.al., submitted Three-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Implications for CosmologyD.N. Spergel, et.al., submitted, astro-ph/0302209 Three-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Three Year Explanatory SupplementM. Limon, et.al., The WMAP Science Team is acknowledged for providing most of the figures ITF Colloquium

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