Tarun Souradeep

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Cosmology: towards ‘ observing ’ the early universe. 1 st Asian Winter School Pheonix Park, Korea (Jan 17, 2007). Tarun Souradeep. I.U.C.A.A, Pune, India. Good old Cosmology, … New trend !. Total energy density. Dark energy density. Baryonic matter density. Dawn of - PowerPoint PPT Presentation

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  • Tarun SouradeepI.U.C.A.A, Pune, India 1st Asian Winter SchoolPheonix Park, Korea(Jan 17, 2007)Cosmology: towards observing the early universe

  • NASA/WMAP science teamTotal energy density Baryonic matter density Dawn of Precision cosmology !!Dark energy density Good old Cosmology, New trend !

  • Planck Surveyor SatelliteEuropean Space Agency: Launch 2008

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

  • Who ordered Dark Energy? Is it the Cosmological constant? Interestingly enough, current cosmological observations are consistent with it being the L term blunder in GR!!!

  • Number count of clusters vs. redshift (dN/dz)Near future : SZ Cluster surveys (SPT,ACT) CMB Task force report 2005

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

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

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

  • 2-point correlation of density contrast Acoustic Baryon oscillations in the matter correlation function !! The same CMB oscillations at low redshifts !!!SDSS survey(astro-ph/0501171)

    Undeniable proof ofGravitational instability mechanism for structure formation (from adiabatic initial perturbations) !!!

    150 Mpc. (Einsentein et al. 2005)105 h-1 150

  • Ripples in the different constituents

  • Whats the next frontier ?

  • Thompson scattering at redshift z=1100 (surface of last scattering) generates a linear polarization pattern in the CMB sky.Two polarization modes E&B Four CMB spectra : ClTT, ClEE,ClBB,ClTE Density (scalar) perturbations generate only E mode polarization. E-mode 5 --10 K Gravitational waves generate both the modes in comparable amounts . B-mode 0.05 0.1 KB-mode measures cosmic gravity wave background.CMB Polarization

  • Thompson scattering of the CMB anisotropy quadrupole at the surface of last scattering generates a linear polarization pattern in the CMB.(Fig:Hu & White , 97)

  • E modes(Gradient)B modes(Curl)

  • Polarization: E modes and B modesE Modes: Gradient of the polarization Produced by both scalar andtensor modes Have been detected

    B Modes: Curl of the polarization Produced only by tensor modes ...or gravitational lensing ...or foregrounds ...or systematics Expected from inflation Have not been detected

    A detection of primordial sourced B modes would provideimportant evidence for, and determine the energy scale of Inflation EB

  • NASA/WMAP science team 2006

  • (Boomerang 2003, WMAP-3)

    Out of phase location of peaks in EE, TE relative to TT implies adiabatic initial perturbations !!! Proof of inflation !Null BB: Awaiting direct signature of tensor perturbations, a.k.a. cosmic gravity waves !!! Current status of CMB Spectra

  • CMB Task force report 2005

  • CMB Task force report 2005

  • CMB Task force report 2005Timeline of CMB experiments

  • Early UniversePresent UniverseThe Cosmic screenWho pinged the Cosmic drum ?

  • String theory Landscape: Non trivial skiing slopes

  • A scalar field displaced from the minima of its potentialLindes chaotic inflation

  • A scalar field displaced from the minima of its potential

  • timeHubble RadiusA phase of rapid expansion in the scale factor of the universe

  • (Souradeep, Thesis 1995)

  • Generation of fluctuations

  • The inhomogeneous scale factor on which the space creation rate is constant is a measure of adiabatic scalar perturbations It is equivalent to the Gauge invariant Bardeen potentialon super-Hubble radius scales Adiabatic scalar perturbations

  • Reconstructing the inflaton potential from the primordial power spectrum

  • Energy scale and Model of inflation(Souradeep & Sahni, 1992, Souradeep, Ph.D.thesis, 1995)COBE-DMR normalized Hubble parameter during inflation

  • Scalar & Tensor perturbations(Fig:Souradeep, Thesis 1995)

  • Power spectra of perturbations Evaluate the mode functions at freeze out values on super-Hubble-radius scales.

  • Scale Invariant perturbation spectraIdeal case: Never exactly possible for inflation!!Requires No end to dS phase Scale free perturbation spectraVery specific model : Power law inflation Scalar & tensor spectra have the same shapeRelative amplitude and spectral index determined by

  • Power spectrumNearly Scale invariant /scale free form( but are there features ?) Spin characteristics Scalar --- Density perturbations

    Tensor --- Gravity waves Type of scalar perturbations Adiabatic --- no entropy fluctuations Isocurvature -- no curvature fluctuations Underlying statistics Gaussian Non-GaussianThe nature of initial/primordial perturbationsThe Background universe Homogeneous & isotropic: Cosmological principle Flat (Euclidean) Geometry ( but topology ? )

  • Detecting the relicGW background : Energy scale of inflation

  • Tensor to scalar ratio is crucial discriminant of EU scenariosScalar --- Density perturbations Large scale structure in galaxy clustering Tensor --- Gravitational waves Relic stochastic GW backgroundVector --- rotational modes Perhaps unimportant, but primordial magnetic field Tensor to scalarratio in the CMB(Souradeep & Sahni, 1992, Souradeep, Ph.D.thesis, 1995)COBEWMAPWMAP+SDSS

  • CMB Task force report 2005

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

  • Cosmic Gravity wave background from inflationFirst COBE-DMR normalized prediction of inflationary GW background spectrum(GW energy density per log interval in wavenumber)(Souradeep & Sahni, 1992, Souradeep, Ph.D.thesis, 1995)

  • Cosmic Gravity wave background from inflation CMB Task force report 2005Coveted Goal

  • Measuring the primordial power spectrum: Features as signatures of new physics

  • Primordial spectra with features

  • Dynamics of slow roll parameters(Souradeep, Thesis 1995)

  • Breaking Scale Invariance of spectraTwo distinct approaches:1. Vary H during inflationChanges both scalar & tensor spectra2. Vary effective massChanges only scalar spectra(Zelnikov & Mukhanov)

  • Breaking Scale Invariance of spectraResponse to `delta function effective mass : (Starobinsky 1992)Transfer function on the scalar spectra(Memari, TS 2003)

  • Breaking Scale Invariance of spectraResponse to `delta function effective mass : (Starobinsky 1992)Transfer function on the scalar spectra(Memari, TS 2003)

  • CMB anisotropy has two independent aspects:Post recombination Radiation transport in a given cosmologyPrimordial power spectrum from Early universe

  • *Assume model initial power spectrum+* CMB anisotropy dataCosmological parameters +Power spectrumInitial power spectrum* CMB anisotropy data+* Cosmological parameters.Forward (model comparsion):Reverse (direct deconvolution):Determining P(k)(Kogo et al. 03, 04, Matsumiya et al. 02, Tegmark & Zaldariagga 97, ..)

  • (Shafieloo & Souradeep, 2004 PRD )Recovered spectrum shows an infra-red cut-off on Horizon scale !!! Is it QG physics ? cosmic topology ? Signature of pre-inflationary phase ? String cosmology ? . Primordial power spectrum from WMAPHorizon scaleCited in WMAP-3 paper

  • Wavelet Decomposition of features(TS+ Rangarajan, Panigrahi, Manimaran: astro-ph/0611352 )

  • (AS,TS+ Rangarajan, Panigrahi, Manimaran: astro-ph/0611352 )Wavelet Decomposition of features

  • Recovery of the primordial power spectrum (Tocchini-Vaentini, Hoffman, Silk astro-ph/0509478)A reconfirmation of our results using different deconvolution method !

  • The Grand program :Primordial power spectra from Early universePost recombination Radiative transport kernels in a given cosmology

  • Beyond Cl : Measuring correlation patterns in CMB(BiPS: Bipolar power spectra)

  • Statistical properties are not invariant under rotation of the sky Breakdown of the cosmological principle ?North-South asymmetry Eriksen, et al. 2004,2006; Hansen et al. 2004 (in local power)Larson & Wandelt 2004 , Park 2004 (genus stat.)..

    Special directions (Axis of Evil)Tegmark et al. 2004 (l=2,3 aligned), 2006Copi et al. 2004 (multipole vectors), ,2006Land & Magueijo 2004 (cubic anomalies), Prunet et al., 2004 (mode coupling)Bernui et al. 2005 (separation histogram)Wiaux et al. 2006

    Underlying patterns T.Jaffe et al. 2005,2006..

    Anomalies in the WMAP CMB maps

  • Can we measure correlation patterns?the COSMIC CATCH is Beautiful Correlation patterns could underlie the CMB tapestry Figs. J. Levin

  • T(n) : smooth Gaussian random function on a sphere (sky map), i.e., Completely specified by the two-point correlationAdvanced Statistics of CMBStatistical isotropy implies Cl is sufficientMost general, Bipolar Spherical HarmonicExpansion

  • BiPS:rotationally invariantBiPoSH coefficients : Complete,Independent linear combinations of off-diagonal correlations.Recall: Coupling of angular momentum states

  • Bipolar spherical harmonics Spherical harmonicsBipolar Power spectrum (BiPS) :A Generic Measure of Statistical Anisotropy

    Spherical Harmonic coefficentsBiPoSH coefficents

    Angular pow