S. J. Melhuish

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.

A Broadband WR10 Turnstile Junction Orthomode Transducer

We present a broadband waveguide ortho-mode transducer for the WR10 band that was designed for CLOVER, an astrophysics experiment aiming to characterize the polarization of the cosmic microwave background radiation. The design, based on a turnstile junction, was manufactured and then tested using a millimeter-wave vector network analyzer. The average measured return loss and isolation were -22 dB and -45 dB, respectively, across the entire WR10 band

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.

QUIJOTE scientific results – I. Measurements of the intensity and polarisation of the anomalous microwave emission in the Perseus molecular complex

In this paper, we present Q-U-I JOint Tenerife Experiment (QUIJOTE) 10-20 GHz observations (194 h in total over ???250 deg2) inintensity and polarisation of G159.6-18.5, one of the most widelystudied regions harbouring anomalous microwave emission (AME). Bycombining with other publicly available intensity data, we achieve themost precise spectrum of the AME measured to date in an individualregion, with 13 independent data points between 10 and 50 GHz beingdominated by this emission. The four QUIJOTE data points provide thefirst independent confirmation of the downturn of the AME spectrum atlow frequencies, initially unveiled by the COSMOlogical Structures OnMedium Angular Scales experiment in this region. Our polarisation maps,which have an angular resolution of ???1?? and a sensitivity of ???25 ??K beam-1, are consistent with zero polarisation. Weobtain upper limits on the polarisation fraction of ?? {\textless} 6.3 and{\textless}2.8 per cent (95 per cent C.L.), respectively, at 12 and 18 GHz(??AME {\textless} 10.1 and {\textless}3.4 per cent with respect to theresidual AME intensity), a frequency range where no AME polarisationobservations have been reported to date. The combination of theseconstraints with those from other experiments confirm that all themagnetic dust models based on single-domain grains, and most of thoseconsidering randomly oriented magnetic inclusions, predict higherpolarisation levels than is observed towards regions with AME. Also,neither of the two considered models of electric dipole emission seemsto be compatible with all the observations together. More stringentconstraints of the AME polarisation at 10-40 GHz are necessary todisentangle between different models, to which future QUIJOTE data willcontribute.

The QUIJOTE-CMB experiment: studying the polarisation of the galactic and cosmological microwave emissions

The QUIJOTE (Q-U-I JOint Tenerife) CMB Experiment will operate at the Teide Observatory with the aim of characterizing the polarisation of the CMB and other processes of Galactic and extragalactic emission in the frequency range of 10-40GHz and at large and medium angular scales. The first of the two QUIJOTE telescopes and the first multi-frequency (10-30GHz) instrument are already built and have been tested in the laboratory. QUIJOTE-CMB will be a valuable complement at low frequencies for the Planck mission, and will have the required sensitivity to detect a primordial gravitational-wave component if the tensor-to-scalar ratio is larger than r = 0.05.

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.