Cosmic saga encrypted in the Cosmic Microwave Background Tarun Souradeep IUCAA, Pune 3rd National Frontiers of Science INSA, Delhi (Jan 21-22, 2009)

Cosmic Microwave Background The Isotropic Universe Cosmic Microwave Background Nobel prize 1978 Serendipitous discovery of the dominant Radiation content of the universe as an extremely isotropic, Black-body bath at temperature T0=2.725 (+/-0.002) K . “Clinching support for Hot Big Bang model”

Cosmic “Super–IMAX” theater 0.5 Mega-years 43 Billion Light-years Here & Now (14 Giga-years) Transparent universe Opaque universe

`Standard’ cosmological model: Geometry, Expansion & Matter Clustering matter Non-Clustering matter Einstein’s General relativity applied to an uniform distribution of matter on cosmic scales leads to a smooth expanding universe (FRW Cosmology)

How much do we now know about this model Universe ? lots !!!

Good old Cosmology, … New trend ! Total energy density Baryonic matter density Dark energy density Expansion rate of the universe Dark matter density Age of the universe NASA/WMAP science team

How do we know so much now about this model Universe ? Perturbed universe!

Universe is not smooth now … Fig: 2dF -GRS

Predicted as precursors to the observed large scale structure The Perturbed Universe Cosmic Microwave Background Anisotropy 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”

First detection of CMB anisotropy (1992) Nobel Prize 2006 First detection of CMB anisotropy (1992) Cosmic Background Explorer COBE George Smoot John Mather

Statistics of CMB angular power spectrum Cl CMB Anisotropy Sky map => Spherical Harmonic decomposition Gaussian CMB anisotropy completely specified by the angular power spectrum Cl

CMB physics is very well understood !!! Wayne’s talk Fig. M. White 1997 The Angular power spectrum of CMB anisotropy depends sensitively on Cosmological parameters CMB physics is very well understood !!! Wayne’s talk Hence, a powerful tool for constraining cosmological parameters. Multi-parameter Joint likelihood (MCMC)

First NASA CMB Satellite mission Second NASA CMB Satellite mission 2003

WMAP CMB mission Covers 30% sky daily, Whole sky in 6 months NASA : Launched July 2001 Covers 30% sky daily, Whole sky in 6 months

WMAP map of CMB anisotropy Saha, Jain, TS 2006 CMB temperature Tcmb = 2.725 K -200  K <  T < 200  K  Trms ¼ 70 K

WMAP: Angular power spectrum Independent, self contained analysis of WMAP multi-frequency maps Saha, Jain, Souradeep (WMAP1: Apj Lett 2006) WMAP3 2nd release : TS,Saha, Jain: Irvine proc.06 Eriksen et al. ApJ. 2006 IIT Kanpur + IUCAA Good match to WMAP team

Peaks of the angular power spectrum (48.3 1.2, 544 17) (48.8 0.9, 546 10) (41.7 1.0, 419.2 5.6) (41.0  0.5, 411.7 3.5) (74.10.3, 219.80.8) (74.7 0.5, 220.1 0.8 (Saha, Jain, Souradeep Apj Lett 2006)

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

Gravitational Instability Time  Cosmological constant + cold dark matter Standard cold dark matter (quarter size ) (half size) ( now ) expansion  (fig: Virgo simulations)

(Ostriker & Steinhardt) The Cosmic Triangle (Ostriker & Steinhardt) Curvature density Clustering matter Non-Clustering matter

`Standard’ cosmological model: Geometry, Expansion & Matter Clustering matter Non-Clustering matter

What’s the next frontier ?

Who pinged the Cosmic drum ? Quantum fluctuations super adiabatic amplified by inflation (rapid expansion) Early Universe Galaxy & Large scale Structure formation Via gravitational instability The Cosmic screen Present Universe

Early Universe in CMB … but global topology? The Background universe Homogeneous & isotropic space: Cosmological principle Flat (Euclidean) Geometry … but global topology? Underlying statistics: Gaussian Power spectrum : ‘Nearly’ Scale invariant /scale free form Spin characteristics: (Scalar) Density perturbations Type of scalar perturbation: Adiabatic -- no entropy fluctuations The nature of initial/primordial perturbations … but are there features ? … cosmic (Tensor) Gravity waves ?

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

Primordial power spectrum from WMAP WMAP-1: Shafieloo & Souradeep, PRD 2004 WMAP-3 :Shafieloo & Souradeep, PRD 2007, 2008, ongoing Horizon scale Improved Richardson-Lucy deconvolution method (Error sensitive) Recovered spectrum shows an infra-red cut-off on Horizon scale !!! Is it QG physics ? cosmic topology ? Signature of pre-inflationary phase ? String cosmology ? ….

Detecting patterns in CMB Universe on Ultra-Large scales: Beyond Cl : Detecting patterns in CMB Universe on Ultra-Large scales: Global topology Global anisotropy/rotation Breakdown of global symmetries

‘Anomalies’ in the WMAP CMB maps Cosmic topology (Poincare Dodecahedron) 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), 2006 Copi et al. 2004 (multipole vectors), … ,2006 Land & 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 Anisotropic, rotating cosmos (Bianchi VIIh) Statistical properties are not invariant under rotation of the sky Breakdown of the cosmological principle ?

Ultra Large scale structure of the universe

Planck Surveyor Satellite European Space Agency: Launch mid 2009 Planck Satellite on display at Cannes, France (Feb. 1, 2007) Capabilities: 3x angular resolution of WMAP 5 to 20 x sensitivity of WMAP

Thank you !!! ? Timeline of CMB experiments A clear niche to initiate now WMAP-5yr Planck launch Next Gen. space CMBPOL WMAP-1yr Thank you !!! A clear niche to initiate collaborative Indian experimental effort to detect the Cosmic Gravity wave background in the CMB !!! CMB Task force report 2005