1. Cosmology : Cosmic Microwave Background & Large scale structure & Large scale structure Cosmology : Cosmic Microwave Background & Large scale structure & Large scale structure Tarun Souradeep I.U.C.A.A. Cosmology IUCAA VSP program (May 18-22, 2012) Lec. 4: Current frontiers

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

3. Baryon acoustic oscillations

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

5. Ripples in the different constituents

6. 2-point correlation of density contrast Acoustic Baryon oscillations in the matter correlation function !! The same CMB oscillations at low redshifts !!! SDSS survey Undeniable proof of Gravitational instability mechanism for structure formation (from adiabatic initial perturbations) !!! BAO: Emerging as a obs. probe of nature of Dark Energy 150 Mpc. (Einsentein et al. 2005) 105 h -1 ~ 150 Mpc.

7. Sensitivity to Baryonic matter fraction

8. Towards ‘Observing’ the Early Universe

9. Simple … yet, an exotic universe 95% of the energy of the universe is in some exotic form Dark Matter: we cannot see it directly, only via its gravitational affect. Dark Energy: smooth form of energy which acts repulsively under gravity. Some new Ultra-high energy (possibly, fundamental) physics for generating primordial perturbations.

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

11. Cosmic Microwave Background XR H /33

12. time Hubble Radius A phase of rapid expansion in the scale factor of the universe Inflation a paradigm in search of a model

13. A scalar field displaced from the minima of its potential Linde’s chaotic inflation Generic Inflation model

14. Generation of fluctuations

15. 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 The Background universe Homogeneous & isotropic space: Cosmological principle Flat (Euclidean) Geometry … cosmic (Tensor) Gravity waves ? Early Universe in CMB

16. CMB Polarization

17. 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 : C l TT, C l EE,C l BB,C l TE 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  K B-mode measures cosmic gravity wave background. CMB Polarization

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

19. E modes (Gradient) B modes (Curl)

20. First detection of CMB Polarization DASI ( Degree Angular scale Interferometer) in 2002

21. NASA/WMAP science team 2006

22. (BICEP 2010, QUAD 2010) 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 !!! r < 0.72 (BICEP 2010) Current status of CMB Spectra

23. Cosmic Gravity wave background CMB Task force report 2005 Spectral Energy Density Amplitude sets the energy scale of Inflation

24. CMB space missions 1991-94 2001-2010 2009-2011

25. Planck Satellite on display at Cannes, France (Feb. 1, 2007) Capabilities: 3x angular resolution of WMAP 5 to 20 x sensitivity of WMAP Promises : Cosmic Variance limited primary C l T T Polarization C l EE as good WMAP C l T T Unlikely, but may be lucky with C l BB Planck Surveyor Satellite European Space Agency: Launched May 14, 2009

26. Testing fundamental tenets of cosmology

27. 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 The Background universe Homogeneous & isotropic space: Cosmological principle Flat (Euclidean) Geometry … but global topology ? Parity? … but are there features ? … cosmic (Tensor) Gravity waves ? Early Universe in CMB

28. Assuming an infinite universe may be similar to assuming the Earth is flat Recall, explorers were feared to have sailed off the edge In a finite universe, explorers in space may end where they began ! Is the Universe Finite ?

29. Simple Toroidal space … more complicated space

30. Simple Torus (Euclidean) Compact hyperbolic space Multiply connected Spherical space (Poincare dodecahedron) Is the Universe Compact ? Post WMAP Nature article (Luminet et al 2003)

31. BiPS signature of a “soccer ball” universe (Hajian, Pogosyan, TS, Contaldi, Bond : in progress.) Ideal, noise free maps predictions

32. BiPS signature of Flat Torus spaces Hajian & Souradeep (astro-ph/0301590) Ongoing research: Nidhi Joshi, Sanjay Jhingan BiPS  Spectroscopy of Cosmic topology !?!

33. Tuhin Ghosh, Amir Hajian & Tarun Souradeep (PRD 2007) Hunting Correlation patterns in the CMB Anisotropy

34. BiPS of random CMB maps plus Bianchi pattern (Tuhin Ghosh, Hajian, Souradeep, PRD 2007)

35. Ultra Large scale structure of the universe Thank you !!!