29 June 2006Bernard's Cosmic Stories1 1 st results from the QUaD CMB polarisation experiment Michael Brown (University of Edinburgh)

29 June 2006Bernard's Cosmic Stories2 Polarisation of the CMB Temperature Polarisation Temperature Polarisation Matrix: P = Q + U

29 June 2006Bernard's Cosmic Stories3 The E/B Decomposition Can decompose Q & U into: E-modes (even-parity): (or grad) B-modes (odd-parity): (or curl) Density perturbations produce only E-modes. Gravitational waves produce both E & B-modes. B E B E Cold Spot: Hot Spot:

29 June 2006Bernard's Cosmic Stories4 The CMB Power Spectra Have 4 possible spectra: TT, TE, EE, BB (TB = EB = 0). Primary effects Secondary effects Reionisation Gravitational Lensing Diffusion Damping Sachs-Wolfe Acoustic Oscillations Gravitational Wave `Bump’ QUaD l-range

29 June 2006Bernard's Cosmic Stories5 The QUaD experiment QUaD is the QUEST telescope installed on the DASI mount at the South Pole. 2.6 m primary mirror. 31 pixel polarisation sensitive bolometer (PSB) camera. 100GHz and 150GHz observing frequencies. Secondary supported on foam cone. DASI infrastructure re-used for QUaD. Extended ground shield.

29 June 2006Bernard's Cosmic Stories6 QUaD people Cardiff: Peter Ade, Walter Gear, Simon Melhuish, Angiola Orland, Lucio Piccirillo, Nutan Rajguru, Mike Zemcov. Caltech: Andrew Lange, Jamie Bock, John Kovac, Ken Ganga (Paris). Chicago: John Carlstrom, Tom Culverhouse, Robert Friedmann, Eric Leitch (JPL), Clem Pryke, Robert Schwarz (South Pole). Edinburgh: Michael Brown, Patricia Castro, Andy Taylor Maynooth: Gary Cahill, Anthony Murphy, Fabio Noviello, Creidhe O’Sullivan. Stanford: Melanie Bowden, Sarah Church, Jamie Hinderks, Ben Rusholme, Keith Thompson, Ed Wu.

29 June 2006Bernard's Cosmic Stories7 QUaD in extended ground shield:

29 June 2006Bernard's Cosmic Stories8 Focal plane: GHz (6 arcmin), 19 feeds at 150GHz (4 arcmin).

29 June 2006Bernard's Cosmic Stories9 1 st season’s observations Each hour of observations is split between a lead and trail field – separated by 0.5 hrs (7.5°) in RA – exact same scan pattern with respect to ground. Two 8-hour CMB runs/day: 2 nd run repeats same scan pattern as 1 st with telescope rotated 60° about line of sight axis (deck angle rotation). Relative calibration from source (RCW38) + “el- nods” (small el scan to inject atmospheric ramp). 99 days of CMB data taken in 1 st season covering a 10°×6° patch of the B03 (low-foreground) deep field region.

29 June 2006Bernard's Cosmic Stories10 Beams measured from RCW38 Used to construct a T-dependent beam model for each detector.

29 June 2006Bernard's Cosmic Stories11 1 st year T maps: 100 GHz:150 GHz:. Inverse-variance weighted maps. 3 rd order polynomial removed from each az-scan.

29 June 2006Bernard's Cosmic Stories12 1 st year Q/U maps at 150GHz: Smoothed at scale ~5 arcmin in attempt to bring out structure. Q: U:

29 June 2006Bernard's Cosmic Stories13 T, Q & U jacknife maps: 100 GHz T 150 GHz U 150 GHz Q 150 GHz T

29 June 2006Bernard's Cosmic Stories14 Field differencing Difference lead & trail fields to remove possible ground signal (sensitivity hit: S/N ↓ by √2). 100 GHz T150 GHz T 150 GHz Q150 GHz U

29 June 2006Bernard's Cosmic Stories15 Simulations: Using Monte-Carlo based power spectrum estimator so need to simulate the experiment extremely accurately: Measure auto- and cross-spectra of time-ordered data (TOD) for each pair of PSBs. Using these, inject correlated noise into simulations in fourier space. Add a CMB signal convolved with a temperature-dependent beam model measured for each bolometer. Process simulated TOD in exact same way as the real data. Simulations → noise bias, beam/filtering transfer functions, errors & covariances.

29 June 2006Bernard's Cosmic Stories16 Simulated maps: 100 GHz T 150 GHz U 150 GHz Q 150 GHz T

29 June 2006Bernard's Cosmic Stories17 Jacknife power spectra – 150 GHz real /sims

29 June 2006Bernard's Cosmic Stories18 Weiner filtered E and B maps

29 June 2006Bernard's Cosmic Stories19 Power spectra from simulations

29 June 2006Bernard's Cosmic Stories20 Conclusions 1 st season completed, 2 nd season underway. Measuring polarisation from ground is hard!!! Field-difference to remove ground contamination. QUaD will run for 3 years, funding permitted (lensing of CMB, isocurvature modes, non-trivial test of ΛCDM model. Possible detection of lensing B- modes). Upcoming ground & balloon-borne experiments (Clover, Ebex, Spider etc. ~2008/09) will search for gravitational wave signature of inflation. Planck may measure large-angle B-mode polarisation.