G. Cahill

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.).

Second and Third Season QUaD Cosmic Microwave Background Temperature and Polarization Power Spectra

We report results from the second and third seasons of observation with the QUaD experiment. Angular power spectra of the cosmic microwave background are derived for both temperature and polarization at both 100 GHz and 150 GHz, and as cross-frequency spectra. All spectra are subjected to an extensive set of jackknife tests to probe for possible systematic contamination. For the implemented data cuts and processing technique such contamination is undetectable. We analyze the difference map formed between the 100 and 150 GHz bands and find no evidence of foreground contamination in polarization. The spectra are then combined to form a single set of results which are shown to be consistent with the prevailing LCDM model. The sensitivity of the polarization results is considerably better than that of any previous experiment—for the first time multiple acoustic peaks are detected in the E-mode power spectrum at high significance.

First Season QUaD CMB Temperature and Polarization Power Spectra

QUaD is a bolometric CMB polarimeter sited at the South Pole, operating at frequencies of 100 and 150 GHz. In this paper we report preliminary results from the first season of operation (austral winter 2005). All six CMB power spectra are presented derived as cross spectra between the 100 and 150 GHz maps using 67 days of observation in a low foreground region of approximately 60 deg2. These data are a small fraction of the data acquired to date. The measured spectra are consistent with the ΛCDM cosmological model. We perform jackknife tests that indicate that the observed signal has negligible contamination from instrumental systematics. In addition, by using a frequency jackknife we find no evidence for foreground contamination.

Parity Violation Constraints Using Cosmic Microwave Background Polarization Spectra from 2006 and 2007 Observations by the QUaD Polarimeter

(The QUaD Collaboration) Kavli Institute for Particle Astrophysics and Cosmology and Department of Physics, Stanford University, Stanford, CA 94305, USA. School of Physics and Astronomy, Cardiff University, Cardiff CF24 3AA, UK. California Institute of Technology, Pasadena, CA 91125, USA. Jet Propulsion Laboratory, Pasadena, CA 91109, USA. School of Physics and Astronomy, Cardiff University, Queen’s Buildings, The Parade, Cardiff CF24 3AA, UK. Cavendish Laboratory, University of Cambridge, Cambridge CB3 OHE, UK. Department of Experimental Physics, National University of Ireland Maynooth, Maynooth, Co. Kildare, Ireland. CENTRA, Departamento de Fisica, Universidade Tecnica de Lisboa, 1049-001 Lisboa, Portugal. Institute for Astronomy, University of Edinburgh, Edinburgh EH9 3HJ, UK. Kavli Institute for Cosmological Physics, Department of Astronomy & Astrophysics, Enrico Fermi Institute, University of Chicago,Chicago, IL 60637, USA. Laboratoire APC/CNRS, Bâtiment Condorcet, 75205 Paris Cedex 13, France. School of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK.

Scientific optimization of a ground-based CMB polarization experiment

We investigate the science goals achievable with the upcoming generation of ground-based cosmic microwave background polarization experiments, focusing on one particular experiment, QUaD [QUEST (Q and U Extragalactic Submillimetre Telescope) and DASI (Degree Angular Scale Interferometer)], a proposed bolometric polarimeter operating from the South Pole. We calculate the optimal sky coverage for this experiment, including the effects of foregrounds and gravitational lensing. We find that an E-mode measurement will be sample-limited, whereas a B-mode measurement will be detector-noise-limited. We conclude that a 300 deg2 survey is an optimal compromise for a 2-yr experiment to measure both E and B modes, and that a ground-based polarization experiment can make an important contribution to B-mode surveys. QUaD can make a high significance measurement of the acoustic peaks in the E-mode spectrum, over a multipole range of 25 < ? < 2500, and will be able to detect the gravitational lensing signal in the B-mode spectrum. Such an experiment could also directly detect the gravitational wave component of the B-mode spectrum if the amplitude of the signal is close to current upper limits. We also investigate how QUaD can improve constraints on the cosmological parameters. We estimate that combining two years of QUaD data with the 4-yr Wilkinson Microwave Anisotropy Probe (WMAP) data can improve constraints on ?bh2, ?mh2, h, r and ns by a factor of 2. If the foreground contamination can be reduced, the measurement of r can be improved by up to a factor of 6 over that obtainable from WMAP alone. These improved accuracies will place strong constraints on the potential of the inflaton field.

COSMOLOGICAL PARAMETERS FROM THE QUAD CMB POLARIZATION EXPERIMENT

In this paper, we present a parameter estimation analysis of the polarization and temperature power spectra from the second and third season of observations with the QUaD experiment. QUaD has for the first time detected multiple acoustic peaks in the E-mode polarization spectrum with high significance. Although QUaD-only parameter constraints are not competitive with previous results for the standard six-parameter ΛCDM cosmology, they do allow meaningful polarization-only parameter analyses for the first time. In a standard six-parameter ΛCDM analysis, we find the QUaD TT power spectrum to be in good agreement with previous results. However, the QUaD polarization data show some tension with ΛCDM. The origin of this 1σ-2σ tension remains unclear, and may point to new physics, residual systematics, or simple random chance. We also combine QUaD with the five-year WMAP data set and the SDSS luminous red galaxies 4th data release power spectrum, and extend our analysis to constrain individual isocurvature mode fractions, constraining cold dark matter density, αcdmi < 0.11 (95% confidence limit (CL)), neutrino density, αndi < 0.26 (95% CL), and neutrino velocity, αnvi < 0.23 (95% CL), modes. Our analysis sets a benchmark for future polarization experiments.

Characterization of the Millimeter-Wave Polarization of Centaurus A with QUaD

Centaurus (Cen) A represents one of the best candidates for an isolated, compact, highly polarized source that is bright at typical cosmic microwave background (CMB) experiment frequencies. We present measurements of the 4° × 2° region centered on Cen A with QUaD, a CMB polarimeter whose absolute polarization angle is known to an accuracy of 0fdg5. Simulations are performed to assess the effect of misestimation of the instrumental parameters on the final measurement and systematic errors due to the fields background structure and temporal variability from Cen As nuclear region are determined. The total (Q, U) of the inner lobe region is (1.00 ± 0.07(stat.) ± 0.04(sys.), – 1.72 ± 0.06 ± 0.05) Jy at 100 GHz and (0.80 ± 0.06 ± 0.06, – 1.40 ± 0.07 ± 0.08) Jy at 150 GHz, leading to polarization angles and total errors of –30fdg0 ± 1fdg1 and –29fdg1 ± 1fdg7. These measurements will allow the use of Cen A as a polarized calibration source for future millimeter experiments.

THE QUaD GALACTIC PLANE SURVEY. I. MAPS AND ANALYSIS OF DIFFUSE EMISSION

We present a survey of 800 square degrees of the galactic plane observed with the QUaD telescope. The primary product of the survey are maps of Stokes I, Q and U parameters at 100 and 150 GHz, with spatial resolution 5 and 3.5 arcminutes respectively. Two regions are covered, spanning approximately 245- 295 and 315- 5 in galactic longitude l, and -4< b< +4 in galactic latitude b. At 0:02 square pixel size, the median sensitivity is 74 and 107 kJy/sr at 100 GHz and 150 GHz respectively in I, and 98 and 120 kJy/sr for Q and U. In total intensity, we find an average spectral index of = 2:35 0:01(stat) 0:02(sys) forjbj 1 , indicative of emission components other than thermal dust. A comparison to published dust, synchrotron and free-free models implies an excess of emission in the 100 GHz QUaD band, while better agreement is found at 150 GHz. A smaller excess is observed when comparing QUaD 100 GHz data to WMAP 5-year W band; in this case the excess is likely due to the wider bandwidth of QUaD. Combining the QUaD and WMAP data, a two-component spectral fit to the inner galactic plane (jbj 1 ) yields mean spectral indices of s = -0:32 0:03 and d = 2:84 0:03; the former is interpreted as a combination of the spectral indices of synchrotron, free-free and dust, while the second is attributed largely to the thermal dust continuum. In the same galactic latitude range, the polarization data show a high degree of alignment perpendicular to the expected galactic magnetic field direction, and exhibit mean polarization fraction 1:38 0:08(stat) 0:1(sys)% at 100 GHz and 1:70 0:06(stat) 0:1(sys)% at 150 GHz. We find agreement in polarization fraction between QUaD 100 GHz and WMAP W band, the latter giving 1:1 0:4%. Subject headings: Surveys — Submillimeter — cosmic microwave background polarization — cosmology: observations — diffuse radiation — Galaxy: structure — Galaxy: disk — ISM: structure

PARAMETER ESTIMATION FROM IMPROVED MEASUREMENTS OF THE COSMIC MICROWAVE BACKGROUND FROM QUaD

We evaluate the contribution of cosmic microwave background (CMB) polarization spectra to cosmological parameter constraints. We produce cosmological parameters using high-quality CMB polarization data from the ground-based QUaD experiment and demonstrate for the majority of parameters that there is significant improvement on the constraints obtained from satellite CMB polarization data. We split a multi-experiment CMB data set into temperature and polarization subsets and show that the best-fit confidence regions for the ΛCDM six-parameter cosmological model are consistent with each other, and that polarization data reduces the confidence regions on all parameters. We provide the best limits on parameters from QUaD EE/BB polarization data and we find best-fit parameters from the multi-experiment CMB data set using the optimal pivot scale of kp = 0.013 Mpc-1 to be {h 2Ω c , h 2Ω b , H 0, As , ns , τ} = {0.113, 0.0224, 70.6, 2.29 × 10-9, 0.960, 0.086}.

THE QUaD GALACTIC PLANE SURVEY. II. A COMPACT SOURCE CATALOG

We present a catalog of compact sources derived from the QUaD Galactic Plane Survey. The survey covers ~800 deg^2 of the inner galaxy (|b| < 4°) in Stokes I, Q, and U parameters at 100 and 150 GHz, with angular resolutions of 5 and 3.5 arcmin, respectively. Five hundred and twenty-six unique sources are identified in I, of which 239 are spatially matched between frequency bands, with 53 (234) detected at 100 (150) GHz alone; 170 sources are identified as ultracompact H II regions. Approximating the distribution of total intensity source fluxes as a power law, we find a slope of γ_(S,100) = –1.8 ± 0.4 at 100 GHz and γ_(S,150) = –2.2 ± 0.4 at 150 GHz. Similarly, the power-law index of the source two-point angular correlation function is γ_(θ,100) = –1.21 ± 0.04 and γ_(θ,150) = –1.25 ± 0.04. The total intensity spectral index distribution peaks at α_I ~ 0.25, indicating that dust emission is not the only source of radiation produced by these objects between 100 and 150 GHz; free-free radiation is likely significant in the 100 GHz band. Four sources are detected in polarized intensity P, of which three have matching counterparts in I. Three of the polarized sources lie close to the Galactic center, Sagittarius A^*, Sagittarius B2, and the Galactic Radio Arc, while the fourth is RCW 49, a bright H II region. An extended polarized source, undetected by the source extraction algorithm on account of its ~0°5 size, is identified visually, and is an isolated example of large-scale polarized emission oriented distinctly from the bulk Galactic dust polarization.