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Cosmology with CMB anisotropy

Cosmology with CMB anisotropy. Tarun Souradeep. I.U.C.A.A, Pune. WHEPP-9 (Jan 10, 2005). The Isotropic Universe . Cosmic Microwave Background.

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Cosmology with CMB anisotropy

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  1. Cosmology with CMB anisotropy Tarun Souradeep I.U.C.A.A, Pune WHEPP-9 (Jan 10, 2005)

  2. The Isotropic Universe Cosmic Microwave Background Serendipitous discovery of the dominant Radiation content of the universe as an extremely isotropic, Black-body bath at temperature T0=2.725§0.002K . “Clinching support for Hot Big Bang model”

  3. Cosmic Microwave Background The dominant radiation component in the universe ~ 400 CMB photons per cubic cm. (D. Scott ’99)

  4. Cosmic Microwave Background The most perfect Black-Body spectrum in nature COBE –FIRAS The CMB temperature – A single number characterizes the radiation content of the universe!! COBE website

  5. 60 Ghz 10 Ghz 30Ghz Cosmic Microwave Background COBE-FIRAS results strongly constrain any Energy input into the CMB in the not-so-early universe 600 Ghz (figs: Bond, 1996) ARCADE 2004

  6. The Perturbed Universe The Isotropic Universe Cosmic Microwave Background Anisotropy Cosmic Microwave Background Isotropy Predicted as precursors to the observed large scale structure After 25 years of intense search, tiny variations (~10 p.p.m.) of CMB temperature sky map finally discovered. “Holy grail of structure formation”

  7. Cosmic Microwave Background – a probe beyond the cosmic horizon Pristine relic of a hot, dense & smooth early universe - Hot Big Bang model Pre-recombination : Tightly coupled to, and in thermal equilibrium with, ionized matter. Post-recombination :Freely propagating through (weakly perturbed) homogeneous & isotropic cosmos. CMB anisotropy is related to the tiny primordial fluctuations which formed the Large scale Structure through gravitational instability Simple linear physics allows for accurate predictions Consequently a powerful cosmological probe

  8. Gravitational Instability Mildly Perturbed universe at z=1100 Present universe at z=0 Cosmic matter content

  9. Cosmological Parameters Multi-parameter (7-11) joint estimation (complex covariance, degeneracies, priors,…  marginal distributions) Strategies to search & Locate best parameters: Markov Chain Monte Carlo Dark energy Cosmic age Dark matter Optical depth Baryonic matter Expansion rate Fig.:R.Sinha, TS

  10. Statistics of CMB CMB Anisotropy Sky map => Spherical Harmonic decomposition Gaussian CMB anisotropy completely specified by the angular power spectrum IF Statistical isotropy (=> Correlation function C(n,n’)=hDT DTi is rotationally invariant)

  11. Fig. M. White 1997 The Angular power spectrum of the CMB anisotropy depends sensitively on the present matter current of the universe and the spectrum of primordial perturbations The Angular power spectrum of CMB anisotropy is considered a powerful tool for constraining cosmological parameters.

  12. Dissected CMB power spectrum • Moderate multipole : Acoustic “Doppler” peaks • High multipole : Damping tail • Low multipole : Sachs-Wolfe plateau CMB physics is very well understood !!!

  13. Angular power spectrum Sensitive to curvature Fig:Hu & Dodelson 2002

  14. Angular power spectrum Sensitive to Baryon density Fig:Hu & Dodelson 2002

  15. Post-COBE Ground & Balloon Experiments Python-V 1999, 2003 Boomerang 1998 DASI 2002 (Degree Angular scale Interferometer) Archeops 2002

  16. Highlights of CMB Anisotropy Measurements (1992- 2002)

  17. CMB space mission-II : WMAP WilkinsonMicrowave Anisotropy Probe NASA Launched July 2001 First year data results announced on Feb. 11, 2003 !

  18. WMAP: Full sky coverage 30% sky daily, Whole sky every 6 months

  19. WMAP multi-frequency maps 10 independent Difference assemblies over 5 frequencies Ka band 33 GHz (1 DA) K band 23 GHz (1 DA) CMB anisotropy signal Q band 41 GHz (2 DA) W band 94 GHz (4 DA) V band 61 GHz (2 DA) NASA/WMAP science team

  20. dus saal baad ….

  21. WMAP: Angular power spectrum NASA/WMAP science team

  22. WMAP: Angular power spectrum Independent, self contained analysis of WMAP multi-frequency maps Only input : CMB anisotropy is achromatic (frequency independent) No extraneous foreground info. ! I.e., free of uncertainty of foreground modeling IIT Kanpur + IUCAA Black: IITK+IUCAA Red : WMAP team Saha, Jain,Souradeep 2005 (astro-ph/0508383)

  23. Controlling other Systematics Eg.,Non-circular beam effect in CMB measurements WMAP Q beam Eccentricity =0.7 (S. Mitra, A. Sengupta, Souradeep, PRD 2004) Close to the corrections expected in the WMAP 2nd data release

  24. (74.40.3, 220.80.8) (74.7 0.5, 220.1 0.8) Saha, Jain,Souradeep 2005 (astro-ph/0508383) (49.6 1.2, 545 17) (48.8 0.9, 546 10) (42.2 0.9, 418.7 5.5) (41.0  0.5, 411.7 3.5) Peaks of the Angular Power spectrum

  25. Power spectrum of mass distribution ( Tegmark et al. 2004)

  26. (Fig: Tegmark) CMB + LSS (WMAP+SDSS analysis: Tegmark et al. 2004)

  27. Near future : High resolution Cl(SPT) CMB Task force report 2005

  28. Gravitational Instability Mildly Perturbed universe at z=1100 Present universe at z=0 Cosmic matter content

  29. Present distribution of matter Few Gpc. SLOAN DIGITAL SKY SURVEY (SDSS)

  30. 150 Mpc. One little telltale bump !! A small excess in correlation at 150 Mpc.! SDSS survey (astro-ph/0501171) (Einsentein et al. 2005)

  31. 150 Mpc. Acoustic Baryon oscillations!! (Einsentein et al. 2005)

  32. Acoustic Baryon oscillations in the matter correlation function !! 150 Mpc. 105 h-1¼ 150 2-point correlation of density contrast The same CMB oscillations at low redshifts !!! SDSS survey (astro-ph/0501171) Strong evidence of Gravitational instability mechanism for structure formation (from adiabatic initial perturbations) !!! (Einsentein et al. 2005)

  33. Quantum fluctuations super adiabatic amplified by inflation (rapid expansion) PARAMETERS OF THE INITIAL CONDITIONS FROM EARLY UNIVERSE COSMOLOGICAL PARAMETERS Galaxy & Large scale Structure formation Via gravitational instability Early Universe The Cosmic screen Present Universe

  34. Early universe in CMB Anisotropy The nature of initial/primordial perturbations • Power spectrum ‘Nearly’ Scale invariant /scale free form ( for the Geometry & Topology of the universe) • Spin characteristics Scalar --- Density perturbations Tensor --- Gravity waves Vector --- rotational modes • Type of scalar perturbations Adiabatic --- no entropy fluctuations Isocurvature -- no curvature fluctuations • Underlying statistics Gaussian Non-Gaussian

  35. CMB Polarization Thompson scattering of the CMB anisotropy quadrupole at the surface of last scattering generates a linear polarization pattern in the CMB. • Three additional Power spectra (ClTT +.. ): • two polarization modes (ClEE , ClBB ) • cross correlation with temperature anisotropy ClTE . (Fig:Hu & White , 97) • Initial metric perturbation mix correspondence : • Scalar perturbations predominantly generate the Electric (E) polarization mode. • Vector perturbations predominantly generate the magnetic (B) polarization mode . • Tensor perturbations generate the both modes in comparable amounts . • Temperature anisotropy Cross-correlation only with the E-mode.

  36. CMB Polarization spectra First detection by DASI (2002) l =220-400 ClTT ClEE Regularly updated Sept 2004: CBI, DASI,CAPMAP July 2005: Boomerang ClTE

  37. WMAP : Polarization cross correlation Proof of inflation? Anti-correlation peak Adiabatic IC TE peak out of phase NASA/WMAP science team

  38. Boomerang : CMB Polarization spectra (MacTavish et al. astro-ph/0507503) Null BB: Awaiting direct signature of tensor perturbations, a.k.a. gravity waves !!! Out of phase location of peaks in EE, TE relative to TT implies adiabatic initial perturbations!!!

  39. Boomerang 2003 flight: parameter estimates (MacTavish et al. astro-ph/0507503) BUT, please read the fine print ! Data combos, priors, parameterization,… BUT, please read the fine print ! Data combos, priors, parameterization

  40. Boomerang 2003 flight (MacTavish et al. astro-ph/0507503)

  41. Boomerang 2003 flight (MacTavish et al. astro-ph/0507503) • The curvature (density) of the Universe WK=-0.037§0.04 WK=-0.027§0.016 WK=-0.022§0.017

  42. Boomerang 2003 flight (MacTavish et al. astro-ph/0507503) • Cosmological constraints on n mass • 3-ndegenerate mass • Wn = 3 mn /(94.0 eV) • fn= Wn/WDM (95% CL) mn < 1.0 eV mn < 0.4 eV mn < 0.16 eV

  43. Boomerang 2003 flight (MacTavish et al. astro-ph/0507503) • The nature of dark energy Constant equation of state, w w=-0.86§0.4 w=-0.94§0.1

  44. Boomerang 2003 flight (MacTavish et al. astro-ph/0507503) Tensor to scalar ratio is a crucial discriminant of EU scenarios Tensor to scalar ratio AT/AS < 0.71 AT/AS < 0.36

  45. CMB Task force report 2005

  46. CMB Task force report 2005

  47. 10-3 : reasonable low end of inflationary possibilities Courtesy: A. Coorey (EPIC)

  48. PARAMETERS OF THE INITIAL CONDITIONS FROM EARLY UNIVERSE COSMOLOGICAL PARAMETERS Early Universe The Cosmic screen Present Universe

  49. Primordial power spectrum ? CMB anisotropy has two independent aspects: Post recombination Radiation transport in a given cosmology Primordial power spectrum from Early universe (Tegmark & Zaldariagga 97, Gawaiser & Silk ’00, Matsumiya et al. ’02..)

  50. WMAP: Angular power spectrum Suppression of power on low multipoles (l=2,3) NASA/WMAP science team

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