Cosmic Microwave background: a brief review

1. PNC – Orsay, November 2005 Cosmic Microwave background: a brief review Simon Prunet IAP

2. Outline • Theoretical aspects, cosmological parameters: a brief reminder • Observation: what have we learned so far, and how ? • Observation: what do we hope to learn, and how ?

3. Theory: a brief reminder Calculation of Theoretical Cl (e.g. CMBFAST) Boltzmann transport equation describes the evolution of the photon distribution function Collisional part describes the scattering of the photons with electrons Gravitational part describes the motion of the photons in the perturbed background Differential form in Fourier space

4. Determining basic parameters Effect of curvature: geometry http://background.uchicago.edu/~whu/

5. Determining basic parameters Gravity vs sound: baryon content Also measured by D/H ratio http://background.uchicago.edu/~whu/

6. Determining basic parameters Effect of potential decay: matter vs radiation domination http://background.uchicago.edu/~whu/

7. Geometrical degeneracy Models with same Rand same matter content have very close spectra except at low l Efstathiou & Bond 1999

8. What have we learned so far ? TERRA INCOGNITA 1992 State COBE FIRAS: Black body spectrum DMR: anisotropy on large scales Anisotropy level: T/T ~ 10-5 Spectrum index ns ~1

9. Changing detector technology • Spider web bolometers (JPL/Berkeley) • Very sensitive calorimeters • Work at low temperature (< 300 mK) • Need complex cryogenics • Noise properties are complicated • Needed for balloon-borne missions Late 1999 stage

10. Unveiling the acoustic peaks… Boomerang second release “Big” data set: New, fast analyses techniques needed Faster and (slightly) suboptimalis much better than Slower and optimal Systematics are the new enemy !! • The Boomerang example: • 4 frequency bands (90,150,240, 400 GHz) • 16 detectors (bolometers) • Sensitivity per pixel ~ Planck • 10 days antarctic flight @ 37 km altitude And also Maxima, DASI, VSA … Map of the 150 GHz best channel

11. … and the diffusion scale (May 2002, as VSA) • The CBI example: • Atacama desert • Interferometer (13 antennas) • 10 frequency bands (26-36 GHz) • Noise properties simpler (no drift scan) • Ground effects, point sources … 6x7 field mosaic map Also BIMA …

12. Archeops: a (mainly) french experiment 7 February 2002 flight 12.5 hours of night data covering ~30% of sky 6 best channels at 143 and 217 GHz Measurements well confirmed later with WMAP 1st year results A technological validation of Planck Tristram et al. 2005 (latest analysis)

13. WMAP • Satellite at Lagrange L2 point • Differential measurement • Passive cooling • HEMT detectors :robust, sensitivity ~ 1.5 • 5 freq. bands: 23,33,41,61,94 GHz • FWHM from 30’ down to 10’ • 4 years of observations funded Self-consistent (low-frequency) foreground removal

14. WMAP main results

15. Effect of reionisation on polarisation Effect of reionisation: rescattering of CMB photons http://background.uchicago.edu/~whu/

16. E and B modes of polarisation Scalar quantity Pseudo-scalar quantity Scalar perturbations cannot produce B modes B modes are model-independent tracers of tensor perturbations

17. Polarisation of the CMB: present status • Detected by DASI in 2002 • Confirmed (TE) by WMAP in 2003 • New measurements by CBI, CAPMAP and Boom03 • B modes still undetected … Piacentini et al. 2005 TE cross-correlation Montroy et al. 2005 EE power spectrum

18. Cosmological consistency WMAP TT+TE CBI+B03+DASI EE+TE WMAP TT+TE + CBI+B03+DASI TT+TE+EE Sievers et al. 2005

19. Polarisation: on-going BICEP QUAD

20. Polarisation: testing inflation predictions Generic predictions “to lowest order in slow-roll parameters” Tensor/scalar ratio “Consistency relation” “Theoretical uncertainty window” (coming from N uncertainty) Kinney & Riotto 2005

21. Polarisation: constraining isocurvature modes Bucher, Moodley, Turok 2001

22. Planck: agenda • CQM • Calibration (IAS, Nov 2004) • Integration with payload (Cannes) • Cryogenic test at CSL (Liege, June->Oct 2005) • Post-test review: this week • PFM • Final choice of bolometers: this week • Calibration (IAS, starting Jan. 2006) • Integration with LFI for tests (Liege, end 2006) Integration at CSL

23. Planck: TE and EE forecasts

24. B03 Deep survey A foretaste of Planck-HFI @ 145 GHz but: • wI =82μK.arcmin, while HFI goal is wI =42μK.arcmin @ 143GHz • Planck has matching sensitivities in 9 frequency bands, e.g. 65 μK.arcmin @ 100 & 217 GHz • 90 deg2, i.e. 0.2% of the sky covered, instead of 100% (and deep surveys in Planck too) Masi et al. astroph/0507509 Jan6 2003 + 10 days

25. Why bother ? WMAP 4 years (94 GHz) Planck 1 year (143 GHz) Bond et al. 2004

26. Conclusions • Polarization is the next frontier -> early universe connection cf N. Ponthieu’s presentation

27. Conclusions • Polarization is the next frontier -> early universe connection cf N. Ponthieu’s presentation • Weak-lensing on the CMB: signal AND contamination ! (cf N. Ponthieu and Weak lensing session)

28. Conclusions • Polarization is the next frontier -> early universe connection cf N. Ponthieu’s presentation • Weak-lensing on the CMB: signal AND contamination ! (cf N. Ponthieu and Weak lensing session) • Secondary anisotropies: non-linear physics, galaxy cluster physics, reionisation: dedicated experiments coming online soon (APEX, AMI, AMIBA, ACT, SPT, etc.) (cf M. Douspis, D. Yvon and A. da Silva’s presentations)

29. Conclusions • Polarization is the next frontier -> early universe connection cf N. Ponthieu’s presentation • Weak-lensing on the CMB: signal AND contamination ! (cf N. Ponthieu and Weak lensing session) • Secondary anisotropies: non-linear physics, galaxy cluster physics, reionisation: dedicated experiments coming online soon (APEX, AMI, AMIBA, ACT, SPT, etc.) (cf M. Douspis, D. Yvon and A. da Silva’s presentations) • Polarized foregrounds: could be a killer for B-modesGastrophysical insight needed