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

2. 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”

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

4. `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)

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

6. 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

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

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

9. 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”

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

11. 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

12. 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)

13. First NASA CMB Satellite mission
Second NASA CMB Satellite mission
2003

14. 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

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

17. 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

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

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

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

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

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

23. What’s the next frontier ?

24. 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

25. 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 ?

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

27. 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 ? ….

28. 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

29. ‘Anomalies’ in the WMAP CMB maps
Cosmic topology
(Poincare Dodecahedron)
North-South asymmetry
Eriksen, et al. 2004,2006; Hansen et al (in local power)
Larson & Wandelt … , Park 2004 (genus stat.) .
Special directions (“Axis of Evil”)
Tegmark et al (l=2,3 aligned), 2006
Copi et al (multipole vectors), … ,2006
Land & Magueijo (cubic anomalies), …
Prunet et al., 2004 (mode coupling)
Bernui et al (separation histogram)
Wiaux et al
Underlying patterns
T.Jaffe et al ,2006
Anisotropic, rotating cosmos
(Bianchi VIIh)
Statistical properties are not invariant under rotation of the sky
Breakdown of the cosmological principle ?

30. Ultra Large scale structure of the universe

31. 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

32. 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