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Published November 1, 2009 | Published
Journal Article Open

Improved Measurements of the Temperature and Polarization of the Cosmic Microwave Background from QUaD


We present an improved analysis of the final data set from the QUaD experiment. Using an improved technique to remove ground contamination, we double the effective sky area and hence increase the precision of our cosmic microwave background (CMB) power spectrum measurements by ~30% versus that previously reported. In addition, we have improved our modeling of the instrument beams and have reduced our absolute calibration uncertainty from 5% to 3.5% in temperature. The robustness of our results is confirmed through extensive jackknife tests, and by way of the agreement that we find between our two fully independent analysis pipelines. For the standard six-parameter ΛCDM model, the addition of QUaD data marginally improves the constraints on a number of cosmological parameters over those obtained from the WMAP experiment alone. The impact of QUaD data is significantly greater for a model extended to include either a running in the scalar spectral index, or a possible tensor component, or both. Adding both the QUaD data and the results from the Arcminute Cosmology Bolometer Array Receiver experiment, the uncertainty in the spectral index running is reduced by ~25% compared to WMAP alone, while the upper limit on the tensor-to-scalar ratio is reduced from r < 0.48 to r < 0.33 (95% c.l.). This is the strongest limit on tensors to date from the CMB alone. We also use our polarization measurements to place constraints on parity-violating interactions to the surface of last scattering, constraining the energy scale of Lorentz violating interactions to <1.5 × 10^(–43) GeV (68% c.l.). Finally, we place a robust upper limit on the strength of the lensing B-mode signal. Assuming a single flat band power between ℓ = 200 and ℓ = 2000, we constrain the amplitude of B-modes to be <0.57 μK^2 (95% c.l.).

Additional Information

© 2009 The American Astronomical Society. Received 2009 June 5; accepted 2009 August 31; published 2009 October 16. QUaD is funded by the National Science Foundation in the USA through grants ANT-0338138, ANT-0338335, and ANT- 0338238, by the Science and Technology Facilities Council (STFC) in the UK and by the Science Foundation Ireland. The BOOMERanG collaboration kindly allowed the use of their CMB maps for our calibration purposes. P.G.C. acknowledges funding from the Portuguese FCT. S.E.C. acknowledges support from a Stanford Terman Fellowship. J.R.H. acknowledges the support of an NSF Graduate Research Fellowship, a Stanford Graduate Fellowship and a NASA Postdoctoral Fellowship. Y.M. acknowledges support from a SUPA Prize studentship. C.P. acknowledges partial support from the Kavli Institute for Cosmological Physics through the grant NSF PHY-0114422. E.Y.W. acknowledges receipt of an NDSEG fellowship. M.Z. acknowledges support from a NASA Postdoctoral Fellowship. Part of the analysis described in this paper was carried out on the University of Cambridge's distributed computing facility, CAMGRID. We acknowledge the use of the FFTW (Frigo & Johnson 2005), CAMB (Lewis et al. 2000), CosmoMC (Lewis & Bridle 2002), and HEALPix (G´orski et al. 2005) packages. We acknowledge the use of the Legacy Archive for Microwave Background Data Analysis (LAMBDA). Support for LAMBDA is provided by the NASA Office of Space Science.

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