2-year Total Intensity Observations year Polarization Observations Cosmic Background Imager Tony Readhead Zeldovich celebration Moscow December 2004

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

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

CBI, 5080 m APEX

1 meter CBI Configuration for Polarization Observations Very close to a perfect matched filter to the expected polarization signal LCP RCP v u

D cos  D sin   u.x  D=u E 1 (t) E 2 (t)  /2 complex correlator Im Re to celestial signal cmb temperature variations  T(x) V(u)V(u) _i_i e

e 2  iu x. Q U Thomson scattering gives rise to E-mode (curl-free) polarization (~10 % of  T) Gravitational waves and lensing also give rise to B-mode polarization (<1 % of  T) North -Q -U CBI: 78 baselines 10 frequency channels = 780 separate interferometers

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

Silk damping

CBI Polarization EE Observations

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 -range

If point sources were a factor we would see a ( +1) x C dependence in both EE and BB

simulations with realistic point source contributions show that the first two bins are expected to change by < 4  K 2

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

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

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

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)

CBI EE Polarization Phase Parameterization 2: Scaling model: spectrum shifts by scaling l –allow amplitude a and scale l to vary best fit: a=0.93 slice along a=1: / 0 = 1.02±0.04 (   2 =1)

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

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

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

slice at: a=1  = 25°±33° rel. phase 7.0-  to 8.9-  detection in amplitude of EE-mode polarization and 3-  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

E y ~ E a - E b E x ~ E a + E b G x G y (E x E y ) ~ G x G y ( E a 2 - E b 2 ) polarizers G a E a 2 G b E b 2 x y ab EyEy ExEx ± OMT Correlation Polarimetry Differencing Bolometers Polarimetry Techniques

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