9 research outputs found
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The QUaD Galactic Plane Survey. I. Maps and Analysis of Diffuse Emission
We present a survey of ~800 deg of the galactic plane observed with the QUaD telescope. The primary products of the survey are maps of Stokes I, Q, and U parameters at 100 and 150 GHz, with spatial resolution of 5' and 3'.5, respectively. Two regions are covered, spanning approximately 245°-295° and 315°-5° in the galactic longitude l and –4° < b < +4° in the 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 α = 2.35 ± 0.01(stat) ± 0.02(sys) for |b| ≤ 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 the WMAP five-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 (|b| ≤ 1°) yields mean spectral indices of α s = –0.32 ± 0.03 and α = 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 largely attributed 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 the WMAP W band, the latter giving 1.1% ± 0.4%.Astronom
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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 k = 0.013 Mpc to be {hΩ, hΩ, H, A, n, τ} = {0.113, 0.0224, 70.6, 2.29 × 10, 0.960, 0.086}.Astronom
The status of the Quijote multi-frequency instrument
The QUIJOTE-CMB project has been described in previous publications. Here we present the current status of the QUIJOTE multi-frequency instrument (MFI) with five separate polarimeters (providing 5 independent sky pixels): two which operate at 10-14 GHz, two which operate at 16-20 GHz, and a central polarimeter at 30 GHz. The optical arrangement includes 5 conical corrugated feedhorns staring into a dual reflector crossed-draconian system, which provides optimal cross-polarization properties (designed to be < -35 dB) and symmetric beams. Each horn feeds a novel cryogenic on-axis rotating polar modulator which can rotate at a speed of up to 1 Hz. The science driver for this first instrument is the characterization of the galactic emission. The polarimeters use the polar modulator to derive linear polar parameters Q, U and I and switch out various systematics. The detection system provides optimum sensitivity through 2 correlated and 2 total power channels. The system is calibrated using bright polarized celestial sources and through a secondary calibration source and antenna. The acquisition system, telescope control and housekeeping are all linked through a real-time gigabit Ethernet network. All communication, power and helium gas are passed through a central rotary joint. The time stamp is synchronized to a GPS time signal. The acquisition software is based on PLCs written in Beckhoffs TwinCat and ethercat. The user interface is written in LABVIEW. The status of the QUIJOTE MFI will be presented including pre-commissioning results and laboratory testing
QUBIC:Exploring the primordial universe with the Q&U bolometric interferometer
In this paper we describe QUBIC, an experiment that will observe the
polarized microwave sky with a novel approach, which combines the sensitivity
of state-of-the art bolometric detectors with the systematic effects control
typical of interferometers. QUBIC unique features are the so-called
"self-calibration", a technique that allows us to clean the measured data from
instrumental effects, and its spectral imaging power, i.e. the ability to
separate the signal in various sub-bands within each frequency band. QUBIC will
observe the sky in two main frequency bands: 150 GHz and 220 GHz. A
technological demonstrator is currently under testing and will be deployed in
Argentina during 2019, while the final instrument is expected to be installed
during 2020.Comment: Proceedings of the 2018 ICNFP conference, Crete. Published by
Universe arXiv admin note: text overlap with arXiv:1801.0373