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Advances in Cosmic Microwave Background Polarization Observations: CBI Insights (2000-2004)

This document outlines critical advancements in polarization observations of the Cosmic Microwave Background (CMB) during the years 2000 to 2004, primarily focusing on the work conducted by the Cosmic Background Imager (CBI). It highlights techniques, including very close matched filtering for E-mode polarization signals, significant findings related to gravitational waves and lensing impacts on B-mode polarization, and the collaboration of numerous scientists and institutions, culminating in a celebration event in Moscow in December 2004. The results underscore the importance of CMB research in understanding the early universe.

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Advances in Cosmic Microwave Background Polarization Observations: CBI Insights (2000-2004)

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  1. 1-year Polarization Observations 2003+2004 2-year Total Intensity Observations 2000+2001 Cosmic Background Imager Tony Readhead Zeldovich celebration Moscow December 2004

  2. Caltech: (Cartwright*) Dickinson (Keeney) (Mason) (Padin (project scientist)) Pearson Readhead (Schaal) (Shepherd) (Sievers*) (Udomprasert*) (Yamasaki) NRAO: Myers CITA: Bond Contaldi (Pen) Pogosyan (Prunet) U. de Chile: Achermann* (Altamirano) Bronfman Casassus May Oyarce Chicago: Carlstrom Kovac* Leitch Pryke Berkeley: (Halverson*) (Holzapfel) MSFC: (Joy) U. de Concepcion Bustos* Reeves* Torres * students altitude 16,800 feet

  3. Polarization Observations Pablo Altamirano, Ricardo Bustos, John Kovac Rodrigo Reeves, Cristobal Achermann

  4. APEX CBI, 5080 m

  5. CBI Configuration for Polarization Observations Very close to a perfect matched filter to the expected polarization signal 1 meter LCP RCP vl ul

  6. p/2 _i e cmb temperature variations DT(x) to celestial signal D sin q =l u.x q D cos q D=ul E2(t) E1(t) complex correlator Re Im V(u)

  7. North . e2piu x -U U Q -Q CBI: 78 baselines 10 frequency channels = 780 separate interferometers Thomson scattering gives rise to E-mode (curl-free) polarization (~10 % of DT) Gravitational waves and lensing also give rise to B-mode polarization (<1 % of DT)

  8. Page et al. ApJ 2003, 148, 39 CBI Flux Density scale is tied to the WMAP Flux Density scale, absolute uncertainty = 1.3%

  9. Silk damping

  10. CBI Polarization EE Observations

  11. strategy: size of mosaics chosen so that at the end of 3-4 years the cosmic variance will equal the thermal noise in the center of the CBI l-range

  12. If point sources were a factor we would see a l(l +1)xCl dependence in both EE and BB

  13. simulations with realistic point source contributions show that the first two bins are expected to change by < 4 mK2

  14. 2.1-s 3.4-s 1.6-s significance of shaped fit is 8.9-s without point source projection, or 7.0-s with point source projection

  15. CBI EE Polarization Phase • Parameterization 1: envelope plus shiftable sinusoid • fit to “WMAP+ext” fiducial spectrum using rational functions

  16. slice at: a=1 =25°±33° rel. phase 7.0-s to 8.9-s detection in amplitude of EE-mode polarization and 3-s rejection of “in phase” EE-TT spectra

  17. Example: Acoustic Overtone Pattern • Sound crossing angular size at photon decoupling • Overtone pattern • TT extrema spaced at j intervals • EE spaced at j+1/2 (plus corrections)

  18. CBI EE Polarization Phase • Parameterization 2: • Scaling model: spectrum shifts by scaling l • allow amplitude a and scale lto vary best fit: a=0.93 slice along a=1: /0=1.02±0.04 (Dc2=1)

  19. overtone 0.67 island: a=0.69±0.03 excluded by TT and other priors other overtone islands also excluded • Scaling model: spectrum shifts by scaling l • allow amplitude a and scale lto vary

  20. a=0.5, 0.67 overtone islands: suppressed by DASI DASI phase lock: /0=0.94±0.06 a=0.5 (low DASI) • DASI EE 5-bin bandpowers (Leitch et al. 2004) • bin-bin covariance matrix plus approximate window functions

  21. CBI a=0.67 overtone island: suppressed by DASI data CBI+DASI phase lock: /0=1.00±0.03 a=0.78±0.15 (low DASI) other overtone islands also excluded

  22. slice at: a=1 =25°±33° rel. phase 7.0-s to 8.9-s detection in amplitude of EE-mode polarization and 3-s rejection of “in phase” EE-TT spectra a marginal result? I don’t think so! apples & oranges: known uncertainties vs.blue-sky predictions of new technologies

  23. x a b y polarizers Ga Ea2 Gb Eb2 Ex Ey OMT ± Polarimetry Techniques Ex ~Ea+Eb Ey ~Ea - Eb Gx Gy (ExEy) ~ Gx Gy (Ea2-Eb2 ) Differencing Bolometers Correlation Polarimetry

  24. WMAP BICEP QUIET1 QUEST (QUaD) Planck QUIET2 synchrotron 100 GHz synchrotron 100 GHz dust 100 GHz dust 100 GHz Hivon

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