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