We report results from the BICEP2 experiment, a cosmic microwave background (CMB) polarimeter specifically designed to search for the signal of inflationary gravitational waves in the B-mode power ...spectrum around ℓ∼80. The telescope comprised a 26 cm aperture all-cold refracting optical system equipped with a focal plane of 512 antenna coupled transition edge sensor 150 GHz bolometers each with temperature sensitivity of ≈300 μK(CMB)√s. BICEP2 observed from the South Pole for three seasons from 2010 to 2012. A low-foreground region of sky with an effective area of 380 square deg was observed to a depth of 87 nK deg in Stokes Q and U. In this paper we describe the observations, data reduction, maps, simulations, and results. We find an excess of B-mode power over the base lensed-ΛCDM expectation in the range 30 < ℓ < 150, inconsistent with the null hypothesis at a significance of >5σ. Through jackknife tests and simulations based on detailed calibration measurements we show that systematic contamination is much smaller than the observed excess. Cross correlating against WMAP 23 GHz maps we find that Galactic synchrotron makes a negligible contribution to the observed signal. We also examine a number of available models of polarized dust emission and find that at their default parameter values they predict power ∼(5-10)× smaller than the observed excess signal (with no significant cross-correlation with our maps). However, these models are not sufficiently constrained by external public data to exclude the possibility of dust emission bright enough to explain the entire excess signal. Cross correlating BICEP2 against 100 GHz maps from the BICEP1 experiment, the excess signal is confirmed with 3σ significance and its spectral index is found to be consistent with that of the CMB, disfavoring dust at 1.7σ. The observed B-mode power spectrum is well fit by a lensed-ΛCDM+tensor theoretical model with tensor-to-scalar ratio r = 0.20_(-0.05)(+0.07), with r = 0 disfavored at 7.0σ. Accounting for the contribution of foreground, dust will shift this value downward by an amount which will be better constrained with upcoming data sets.
Measurements of the cosmic microwave background (CMB) radiation can reveal with remarkable precision the conditions of the Universe when it was approximately 400,000 years old. The three most ...fundamental properties of the CMB are its frequency spectrum (which determines the temperature), and the fluctuations in both the temperature and polarization across a range of angular scales. The frequency spectrum has been well determined, and considerable progress has been made in measuring the power spectrum of the temperature fluctuations. But despite many efforts to measure the polarization, detection of this property of the CMB has hitherto been beyond the reach of even the most sensitive observations. Here we describe the Degree Angular Scale Interferometer (DASI), an array of radio telescopes, which for the past two years has conducted polarization-sensitive observations of the CMB from the Amundsen-Scott South Pole research station.
Microwave Multiplexing on the Keck Array Cukierman, A.; Ahmed, Z.; Henderson, S. ...
Journal of low temperature physics,
05/2020, Letnik:
199, Številka:
3-4
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We describe an on-sky demonstration of a microwave-multiplexing readout system in one of the receivers of the Keck Array, a polarimetry experiment observing the cosmic microwave background at the ...South Pole. During the austral summer of 2018–2019, we replaced the time-division multiplexing readout system with microwave-multiplexing components including superconducting microwave resonators coupled to radio frequency superconducting quantum interference devices at the sub-Kelvin focal plane, coaxial-cable plumbing and amplification between room temperature and the cold stages, and a SLAC Microresonator Radio Frequency system for the warm electronics. In the range 5–6 GHz, a single coaxial cable reads out 528 channels. The readout system is coupled to transition-edge sensors, which are in turn coupled to 150-GHz slot-dipole phased-array antennas. Observations began in April 2019, and we report here on an initial characterization of the system performance.
A blind H i survey in the Canes Venatici region Kovač, K.; Oosterloo, T. A.; Van Der Hulst, J. M.
Monthly Notices of the Royal Astronomical Society,
December 2009, Letnik:
400, Številka:
2
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We have carried out a blind H i survey using the Westerbork Synthesis Radio Telescope to make an inventory of objects with small H i masses (between 106 and 108 M⊙) and to constrain the low-mass end ...of the H i mass function. The survey has been conducted in a part of the volume containing the nearby Canes Venatici groups of galaxies. The surveyed region covers an area on the sky of about 86 deg2 and a range in velocity from about −450 to about 1330 km s−1. We find 70 sources in the survey by applying an automated searching algorithm. Two of the detections have not been catalogued previously, but they can be assigned an optical counterpart, based on visual inspection of the second-generation Digital Sky Survey images. Only one of the H i detections is without an optical counterpart. This object is detected in the vicinity of NGC 4822, and it has been already detected in previous H i studies. 19 of the objects have been detected for the first time in the 21-cm emission line in this survey. The distribution of the H i properties of our detections confirms our ability to find low-mass objects. 86 per cent of the detections have profile widths less than 130 km s−1, and they can be considered dwarf galaxy candidates. The H i fluxes measured imply that this survey goes about 10 times deeper than any previous blind H i survey. The H i mass function and the optical properties of the detected sources will be discussed in future papers.
The inner regions of the solar corona from 1-2.5 Rsun are poorly sampled both from the ground and space telescopes. A solar eclipse reduces the sky scattered background intensity by a factor of about ...10,000 and opens a window to view this region directly. The goal of the Citizen Continental-America Telescopic Eclipse (CATE) Experiment is to take a 90-minute time sequence of calibrated white-light images of this coronal region using 60 identical telescopes spread from Oregon to South Carolina during the 2017 August 21 total solar eclipse. Observations that can address questions of coronal dynamics in this region can be collected with rather modest telescope equipment, but the large dynamic range of the coronal brightness requires careful camera control. The instruments used for test runs on the Faroe Islands in 2015 and at five sites in Indonesia in 2016 are described. Intensity calibration of the coronal images is done and compared with previous eclipse measurements from November & Koutchmy and Bazin et al. The change of coronal brightness with distance from the Sun seen in the 2016 eclipse agrees with observations from the 1991 eclipse, but differ substantially from the 2010 eclipse. The 2015 observations agree with 2016 and 1991 solar radii near the Sun, but are fainter at larger distances. Problems encountered during these test runs are discussed as well the solutions which will be implemented for the 2017 eclipse experiment.
Abstract Background The purpose of this study was to test the accuracy of a single synovial fluid biomarker, α-defensin, in diagnosing periprosthetic joint infection in revision total hip and ...revision total knee arthroplasty. Methods A total of 102 patients comprising 116 revision total hip arthroplasty and revision total knee arthroplasty procedures performed between May 2013 and March 2014 were prospectively evaluated. Cases were categorized as infected or notinfected using Musculoskeletal Infection Society criteria. Synovial fluid was obtained and tested for α-defensin using a commercially available kit (Synovasure CD Diagnostics, Baltimore, Maryland). Results For first-stage and single-stage revisions, the α-defensin test had a sensitivity of 100% (95% confidence interval CI, 86%-100%) and a specificity of 98% (95% CI, 90%-100%) with a positive predictive value of 96% (95% CI, 80%-99%) and negative predictive value of 100% (95% CI, 93%-100%). Conclusion A positive α-defensin test result was significantly more sensitive and specific for predicting infection than current diagnostic testing and should be considered when managing periprosthetic joint infection. Level of Evidence: Level III, Study of Diagnostic Test.
Background & Aims Barrett's esophagus (BE) increases the risk of esophageal adenocarcinoma (EAC). We found the risk to be BE has been associated with single nucleotide polymorphisms (SNPs) on ...chromosome 6p21 (within the HLA region) and on 16q23, where the closest protein-coding gene is FOXF1 . Subsequently, the Barrett's and Esophageal Adenocarcinoma Consortium (BEACON) identified risk loci for BE and esophageal adenocarcinoma near CRTC1 and BARX1 , and within 100 kb of FOXP1 . We aimed to identify further SNPs that increased BE risk and to validate previously reported associations. Methods We performed a genome-wide association study (GWAS) to identify variants associated with BE and further analyzed promising variants identified by BEACON by genotyping 10,158 patients with BE and 21,062 controls. Results We identified 2 SNPs not previously associated with BE: rs3072 (2p24.1; odds ratio OR = 1.14; 95% CI: 1.09–1.18; P = 1.8 × 10−11 ) and rs2701108 (12q24.21; OR = 0.90; 95% CI: 0.86–0.93; P = 7.5 × 10−9 ). The closest protein-coding genes were respectively GDF7 (rs3072), which encodes a ligand in the bone morphogenetic protein pathway, and TBX5 (rs2701108), which encodes a transcription factor that regulates esophageal and cardiac development. Our data also supported in BE cases 3 risk SNPs identified by BEACON (rs2687201, rs11789015, and rs10423674). Meta-analysis of all data identified another SNP associated with BE and esophageal adenocarcinoma: rs3784262, within ALDH1A2 (OR = 0.90; 95% CI: 0.87–0.93; P = 3.72 × 10−9 ). Conclusions We identified 2 loci associated with risk of BE and provided data to support a further locus. The genes we found to be associated with risk for BE encode transcription factors involved in thoracic, diaphragmatic, and esophageal development or proteins involved in the inflammatory response.
ABSTRACT We present measurements of polarization lensing using the 150 GHz maps, which include all data taken by the BICEP2 and Keck Array Cosmic Microwave Background polarization experiments up to ...and including the 2014 observing season (BK14). Despite their modest angular resolution ( ), the excellent sensitivity (∼3 K-arcmin) of these maps makes it possible to directly reconstruct the lensing potential using only information at larger angular scales ( ). From the auto-spectrum of the reconstructed potential, we measure an amplitude of the spectrum to be (Planck ΛCDM prediction corresponds to ) and reject the no-lensing hypothesis at , which is the highest significance achieved to date using an EB lensing estimator. Taking the cross-spectrum of the reconstructed potential with the Planck 2015 lensing map yields . These direct measurements of are consistent with the ΛCDM cosmology and with that derived from the previously reported BK14 B-mode auto-spectrum ( ). We perform a series of null tests and consistency checks to show that these results are robust against systematics and are insensitive to analysis choices. These results unambiguously demonstrate that the B modes previously reported by BICEP/Keck at intermediate angular scales ( ) are dominated by gravitational lensing. The good agreement between the lensing amplitudes obtained from the lensing reconstruction and B-mode spectrum starts to place constraints on any alternative cosmological sources of B modes at these angular scales.
BICEP2. II. EXPERIMENT AND THREE-YEAR DATA SET Ade, P A R; Aikin, R W; Amiri, M ...
Astrophysical journal/The Astrophysical journal,
09/2014, Letnik:
792, Številka:
1
Journal Article
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We report on the design and performance of the BICEP2 instrument and on its three-year data set. BICEP2 was designed to measure the polarization of the cosmic microwave background (CMB) on angular ...scales of 1degrees-5degrees(scriptl = 40-200), near the expected peak of the B-mode polarization signature of primordial gravitational waves from cosmic inflation. Measuring B-modes requires dramatic improvements in sensitivity combined with exquisite control of systematics. The BICEP2 telescope observed from the South Pole with a 26 cm aperture and cold, on-axis, refractive optics. BICEP2 also adopted a new detector design in which beam-defining slot antenna arrays couple to transition-edge sensor (TES) bolometers, all fabricated on a common substrate. The antenna-coupled TES detectors supported scalable fabrication and multiplexed readout that allowed BICEP2 to achieve a high detector count of 500 bolometers at 150 GHz, giving unprecedented sensitivity to B-modes at degree angular scales. After optimization of detector and readout parameters, BICEP2 achieved an instrument noise-equivalent temperature of 15.8 mu Kradicals. The full data set reached Stokes Q and U map depths of 87.2 nK in square-degree pixels (5'.2 mu K) over an effective area of 384 deg super(2) within a 1000 deg super(2) field. These are the deepest CMB polarization maps at degree angular scales to date. The power spectrum analysis presented in a companion paper has resulted in a significant detection of B-mode polarization at degree scales.
In order to study inflationary cosmology and the Milky Way Galaxy's composition and magnetic field structure, Stokes I, Q, and U maps of the Galactic plane covering the Galactic longitude range 260 ...degree < l < 340 degree in three atmospheric transmission windows centered on 100, 150, and 220 GHz are presented. The maps sample an optical depth 1 less than or equal to AV less than or equal to 30, and are consistent with previous characterizations of the Galactic millimeter-wave frequency spectrum and the large-scale magnetic field structure permeating the interstellar medium. The polarization angles in all three bands are generally perpendicular to those measured by starlight polarimetry as expected and show changes in the structure of the Galactic magnetic field on the scale of 60 degree . The frequency spectrum of degree-scale Galactic emission is plotted between 23 and 220 GHz (including WMAP data) and is fit to a two-component (synchrotron and dust) model showing that the higher frequency BICEP data are necessary to tightly constrain the amplitude and spectral index of Galactic dust. Polarized emission is detected over the entire region within two degrees of the Galactic plane, indicating the large-scale magnetic field is oriented parallel to the plane of the Galaxy. A trend of decreasing polarization fraction with increasing total intensity is observed, ruling out the simplest model of a constant Galactic magnetic field orientation along the line of sight in the Galactic plane. A generally increasing trend of polarization fraction with electromagnetic frequency is found, varying from 0.5%-1.5% at frequencies below 50 GHz to 2.5%-3.5% above 90 GHz. The effort to extend the capabilities of BICEP by installing 220 GHz band hardware is described along with analysis of the new band.
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