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WMAP – 3-year results

WMAP – 3-year results. Fabio Finelli. Lauro Moscardini. INAF/OAB & INAF/IASF-BO. Dip. Astronomia UniBo. SOURCES. 1. WMAP 1st year papers 2. WMAP 3rd papers 3. A. Lewis, astro-ph/0603753 4. Planck Bluebook, astro-ph/0604069 5. Wayne Hu’s webpage: http://background.uchicago.edu/whu.

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WMAP – 3-year results

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  1. WMAP – 3-year results Fabio Finelli Lauro Moscardini INAF/OAB & INAF/IASF-BO Dip. Astronomia UniBo

  2. SOURCES 1. WMAP 1st year papers 2. WMAP 3rd papers 3. A. Lewis, astro-ph/0603753 4. Planck Bluebook, astro-ph/0604069 5. Wayne Hu’s webpage: http://background.uchicago.edu/whu

  3. WMAP • WMAP: spinning (~0.5 rpm), precessing satellite orbiting L2 • dual Gregorian (1.4×1.6m) mirror system • passively cooled to <95K • radiometers measuring phase and amplitude of incoming waves • Proposed in 1995; selected in 1996; launched in june 2001; possibly 8-years mission • 13 papers in 2003, 7311 citations up today • 4 new papers in march 2006, 160 citations up today

  4. Channels • frequencies: 22, 30, 40, 60, 90 GHz (3.3 to 13.6 mm wavelength) • resolution: 0.23-0.93 degrees • sensitivity: ~35µK per 0.3×0.3 degree pixel

  5. Channels • frequencies: 22, 30, 40, 60, 90 GHz (3.3 to 13.6 mm wavelength) • resolution: 0.23-0.93 degrees • sensitivity: ~35µK per 0.3×0.3 degree pixel

  6. Sky Maps foregrounds: synchrotron, dust, free-free emission

  7. Temperature Map • foreground subtraction: spectra differ from the CMB's Planck spectrum • comparison of signals from different channels • fitting of foreground templates

  8. Power-Spectrum Analysis • subtraction of mean temperature; relative temperature fluctuations • expansion into spherical harmonics; coefficients alm • power spectrumCl=<|alm|2> , related to the matter power spectrum P(k) • principal effects: • Sachs-Wolfe effect • acoustic oscillations • Silk damping

  9. Courtesy by W. Hu

  10. Mechanisms for anisotropies gravity: gravitational red- or blue-shift density: adiabatic process  compression increases T, while expansion decreases T velocity: Doppler effect Different contributions must be summed up Primary anisotropies: produced on the last scattering surface Secondary anisotropies: produced along the trajectory to the observer

  11. On scales larger than the horizon (i.e. large angles, small l) Velocity can be neglected (dipole), microphysics too, gravity wins against density! Temperature fluctuations are directly proportional to the gravitational potential: Sachs-Wolfe effect Notice: overdensity are colder than average! Already observed by COBE in 1991! Good estimates for amplitude and slope of P(k), but problems of cosmic variance

  12. The cosmological parameters (I):the density parameters i • Matter:  m • Dark energy:  DE (w  P/ c2=-1 is the cosmological constant  ; w  -1 is the quintessence) • Baryons:  b • Curvature:  K=1 -   i • Total:  0 =1-  K

  13. The cosmological parameters (II):the spectral parameters Standard inflationary models predict that primordial fluctuations are • Gaussian • Adiabatic • Scale invariant, i.e. with logarithmic slope of the power spectrum n=1: P(k)=A kn The amplitude A is usually expressed in terms of the variance computed on a scale of 8 Mpc/h: 8

  14. The cosmological parameters (III):the other ones • The Hubble constant H0and its redshift evolution: measures the expansion rate of the universe and enters the distance definitions • The optical depth  : it is related to the probability that a CMB photon with an electron along the trajectory: dP=ne T c dt=-d  If there is re-ionization at a given redshift zre, photons are diffuse  there is a suppression of fluctuations on scales smaller than the horizon scale at zre (warning: degeneracy with spectral index n). The higher is zre, the smaller is the angular scale involved by diffusion.

  15. Power Spectra and Cosmological Parameters Varying the baryonic density

  16. Power Spectra and Cosmological Parameters Varying the Hubble constant

  17. Power Spectra and Cosmological Parameters Varying the matter density

  18. Power Spectra and Cosmological Parameters Varying the total density

  19. CMB Polarisation • CMB photons have last been Thomson scattered • directional dependence of Thomson cross section imprints polarisation • polarisation pattern has similar, but shifted power spectrum

  20. Polarisation and Reionisation • Universe recombined when CMB formed • hydrogen was later reionised • ionised hydrogen damps primordial fluctuations • creates secondary polarisation • constraints on reionisation from temperature-polarisation and polarisation power spectra

  21. Where were we? CMB anisotropies WMAP 1st year results (Feb.03): TT & TE EE detection by DASI (02), CBI (04), CAPMAP (05), Boomerang (05) Galaxy surveys 2dF: Percival et al. (02), Cole et al. (05). SDSS: Tegmark et al. (04), Seljak et al. (05). Ly used heavily in WMAP1, but not in WMAP3: “… further study is needed if the new values are consistent with Ly data.” See however Viel et al. (06), Seljak et al. (06) for WMAP3 + Ly

  22. Issues after WMAP 1st year High value for  Sticky points out of the CDM fit Low amplitude for low multipoles of the Cl pattern Weird alignment of the l=2,3 of alm Evidence of running of the spectral index ?

  23. Will these “waves” in 1st year data persist?

  24. Temperature WMAP3 plus small scale CMB data The spectrum is cosmic variance limited to l=400 (354 1st year)and S/N>1 up to l=850 (658 1st year)

  25. Red: WMAP1 Black: WMAP3 Points: ratio of WMAP3 over WMAP1 value Red line: ratio of window function WMAP1 over WMAP3 Red: WMAP1 with 06 analysis and 06 windows function Black: WMAP3

  26. WMAP1 WMAP3 Anomaly on the octupole alleviated; quadrupole remains low TE in better agreement with CDM;  is almost half of 1st yr value Some (but not all) of the sticky points remain

  27. Lines: Red: WMAP1 Orange: WMAP1 + CBI +ACBAR Black: WMAP3 Points: Grey: WMAP1 Black: WMAP3

  28. CDM plus  constraints courtesy from Spergel et al., 2006

  29. CDM plus  is a good fit to WMAP courtesy from Hinshaw et al., 2006

  30. CMB Polarization Polarization only useful for measuring tau for near future Polarization probably best way to detect tensors

  31. Cosmological Parameters: Main WMAP3 parameter results rely on polarization courtesy from A. Lewis, 2006

  32. WMAP3 TT with tau = 0.10 ± 0.03 prior (equiv to WMAP EE) Black: TT+priorRed: full WMAP courtesy from A. Lewis, 2006

  33. Implications for Nucleosynthesis

  34. From =0.170.04 (1st year) To =0.090.03 (3 years) courtesy from Page et al., 2006

  35. 1 e 2 contours: Light Blue: WMAP1 Red: WMAP1 + CBI +ACBAR Blue: WMAP3 courtesy from Spergel et al., 2006

  36. Is Harrison-Zeldovich Ruled out? ns < 1 or tau is high or there are tensors or the model is wrong or we are quite unlucky ns =1 So:

  37. Dark Energy: wDE≠ w = -1 for CMB anisotropies we needDE perturbations wDE constant in time cDE =1 (pDE=c2DE DE+…).

  38. WMAP 3 years results without DE perturbations are flawed Effect known since Caldwell,Dave, Steinhardt PRL 1998 Abramo, Finelli, Pereira PRD 2004

  39. Massive Neutrinos courtesy from Spergel et al., 2006

  40. Curvature K≠0 courtesy from Spergel et al., 2006

  41. Curvature K≠0 plus Dark Energy courtesy from Spergel et al., 2006

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