Showing papers by "K. L. Thompson published in 2016"
Cardiff University1, Stanford University2, California Institute of Technology3, Harvard University4, University of Toronto5, University of Minnesota6, University of Illinois at Urbana–Champaign7, University of British Columbia8, National Institute of Standards and Technology9, University of California, San Diego10, University of Chicago11, Canadian Institute for Advanced Research12
TL;DR: An analysis of all data taken by the BICEP2 and Keck Array cosmic microwave background (CMB) polarization experiments up to and including the 2014 observing season yields an upper limit r_{0.05}<0.09 at 95% confidence, which is robust to variations explored in analysis and priors.
Abstract: We present results from an analysis of all data taken by the BICEP2 and Keck Array cosmic microwave background (CMB) polarization experiments up to and including the 2014 observing season. This includes the first Keck Array observations at 95 GHz. The maps reach a depth of 50 nK deg in Stokes Q and U in the 150 GHz band and 127 nK deg in the 95 GHz band. We take auto- and cross-spectra between these maps and publicly available maps from WMAP and Planck at frequencies from 23 to 353 GHz. An excess over lensed ΛCDM is detected at modest significance in the 95×150 BB spectrum, and is consistent with the dust contribution expected from our previous work. No significant evidence for synchrotron emission is found in spectra such as 23×95, or for correlation between the dust and synchrotron sky patterns in spectra such as 23×353. We take the likelihood of all the spectra for a multicomponent model including lensed ΛCDM, dust, synchrotron, and a possible contribution from inflationary gravitational waves (as parametrized by the tensor-to-scalar ratio r ) using priors on the frequency spectral behaviors of dust and synchrotron emission from previous analyses of WMAP and Planck data in other regions of the sky. This analysis yields an upper limit r_(0.05) <0.09 at 95% confidence, which is robust to variations explored in analysis and priors. Combining these B-mode results with the (more model-dependent) constraints from Planck analysis of CMB temperature plus baryon acoustic oscillations and other data yields a combined limit r_(0.05) <0.07 at 95% confidence. These are the strongest constraints to date on inflationary gravitational waves.
826 citations
TL;DR: In this paper, the authors present measurements of polarization lensing using the 150 GHz maps which include all data taken by the BICEP2 & Keck Array CMB polarization experiments up to and including the 2014 observing season (BK14).
Abstract: We present measurements of polarization lensing using the 150 GHz maps which include all data taken by the BICEP2 & Keck Array CMB polarization experiments up to and including the 2014 observing season (BK14). Despite their modest angular resolution ($\sim 0.5^\circ$), the excellent sensitivity ($\sim 3\mu$K-arcmin) of these maps makes it possible to directly reconstruct the lensing potential using only information at larger angular scales ($\ell\leq 700$). From the auto-spectrum of the reconstructed potential we measure an amplitude of the spectrum to be $A^{\phi\phi}_{\rm L}=1.15\pm 0.36$ (Planck $\Lambda$CDM prediction corresponds to $A^{\phi\phi}_{\rm L}=1$), and reject the no-lensing hypothesis at 5.8$\sigma$, 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 $A^{\phi\phi}_{\rm L}=1.13\pm 0.20$. These direct measurements of $A^{\phi\phi}_{\rm L}$ are consistent with the $\Lambda$CDM cosmology, and with that derived from the previously reported BK14 B-mode auto-spectrum ($A^{\rm BB}_{\rm L}=1.20\pm 0.17$). 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 ($150\lesssim\ell\lesssim 350$) 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.
96 citations
Cardiff University1, Stanford University2, SLAC National Accelerator Laboratory3, California Institute of Technology4, Harvard University5, University of Toronto6, Jet Propulsion Laboratory7, University of Minnesota8, French Alternative Energies and Atomic Energy Commission9, University of Illinois at Urbana–Champaign10, University of British Columbia11, National Institute of Standards and Technology12, University of California, San Diego13, University of Chicago14, Canadian Institute for Advanced Research15, University of California, Berkeley16
TL;DR: In this paper, the authors 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).
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 (~0o.5), the excellent sensitivity (~3μK-arcmin) of these maps makes it possible to directly reconstruct the lensing potential using only information at larger angular scales (l ⩾ 700). From the auto-spectrum of the reconstructed potential, we measure an amplitude of the spectrum to be A_L^(oo) = 1.15 ± 0.36 (Planck ΛCDM prediction corresponds to A_L^(oo) = 1) and reject the no-lensing hypothesis at 5.8σ, 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 A_L^(oo) = 1.13 ± 0.20. These direct measurements of A_L^(oo) are consistent with the ΛCDM cosmology and with that derived from the previously reported BK14 B-mode auto-spectrum (A_L^(BB) = 1.20 ± 0.17). 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 (150 ≾ l ≾ 350) 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.
85 citations
Stanford University1, Cardiff University2, Harvard University3, University of British Columbia4, University of Toronto5, California Institute of Technology6, University of Minnesota7, National Institute of Standards and Technology8, University of Chicago9, Jet Propulsion Laboratory10, University of California, San Diego11, University of California, Berkeley12
TL;DR: The Bicep3 as discussed by the authors is a 520mm aperture, compact two-lens refractor designed to observe the polarization of the cosmic microwave background (CMB) at 95 GHz.
Abstract: Bicep3 is a 520mm aperture, compact two-lens refractor designed to observe the polarization of the cosmic microwave background (CMB) at 95 GHz. Its focal plane consists of modularized tiles of antenna-coupled transition edge sensors (TESs), similar to those used in Bicep2 and the Keck Array. The increased per-receiver optical throughput compared to Bicep2/Keck Array, due to both its faster f=1:7 optics and the larger aperture, more than doubles the combined mapping speed of the Bicep/Keck program. The Bicep3 receiver was recently upgraded to a full complement of 20 tiles of detectors (2560 TESs) and is now beginning its second year of observation (and first science season) at the South Pole. We report on its current performance and observing plans. Given its high per-receiver throughput while maintaining the advantages of a compact design, Bicep3- class receivers are ideally suited as building blocks for a 3rd-generation CMB experiment, consisting of multiple receivers spanning 35 GHz to 270 GHz with total detector count in the tens of thousands. We present plans for such an array, the new "BICEP Array" that will replace the Keck Array at the South Pole, including design optimization, frequency coverage, and deployment/observing strategies.
59 citations
TL;DR: The BICEP3 as mentioned in this paper is a 520 mm aperture, compact two-lens refractor designed to observe the polarization of the cosmic microwave background (CMB) at 95 GHz.
Abstract: BICEP3 is a 520 mm aperture, compact two-lens refractor designed to observe the polarization of the cosmic microwave background (CMB) at 95 GHz. Its focal plane consists of modularized tiles of antenna-coupled transition edge sensors (TESs), similar to those used in BICEP2 and the Keck Array. The increased per-receiver optical throughput compared to BICEP2/Keck Array, due to both its faster f/1.7 optics and the larger aperture, more than doubles the combined mapping speed of the BICEP/Keck program. The BICEP3 receiver was recently upgraded to a full complement of 20 tiles of detectors (2560 TESs) and is now beginning its second year of observation (and first science season) at the South Pole. We report on its current performance and observing plans. Given its high per-receiver throughput while maintaining the advantages of a compact design, BICEP3-class receivers are ideally suited as building blocks for a 3rd-generation CMB experiment, consisting of multiple receivers spanning 35 GHz to 270 GHz with total detector count in the tens of thousands. We present plans for such an array, the new "BICEP Array" that will replace the Keck Array at the South Pole, including design optimization, frequency coverage, and deployment/observing strategies.
40 citations
Harvard University1, Cardiff University2, Stanford University3, University of British Columbia4, University of Toronto5, California Institute of Technology6, University of Minnesota7, National Institute of Standards and Technology8, University of Chicago9, Jet Propulsion Laboratory10, University of California, Berkeley11
TL;DR: The Bicep/Keck Array (BICEP3) as discussed by the authors is a small-aperture refracting cosmic microwave background (CMB) telescope designed to make sensitive polarization maps in pursuit of a potential B-mode signal from inflationary gravitational waves.
Abstract: BICEP3 is a small-aperture refracting cosmic microwave background (CMB) telescope designed to make sensitive polarization maps in pursuit of a potential B-mode signal from inflationary gravitational waves. It is the latest in the Bicep/Keck Array series of CMB experiments located at the South Pole, which has provided the most stringent constraints on inflation to date. For the 2016 observing season, BICEP3 was outfitted with a full suite of 2400 optically coupled detectors operating at 95 GHz. In these proceedings we report on the far field beam performance using calibration data taken during the 2015-2016 summer deployment season in situ with a thermal chopped source. We generate high-fidelity per-detector beam maps, show the array-averaged beam profile, and characterize the differential beam response between co-located, orthogonally polarized detectors which contributes to the leading instrumental systematic in pair differencing experiments. We find that the levels of differential pointing, beamwidth, and ellipticity are similar to or lower than those measured for Bicep2 and Keck Array. The magnitude and distribution of Bicep3’s differential beam mismatch – and the level to which temperature-to-polarization leakage may be marginalized over or subtracted in analysis - will inform the design of next-generation CMB experiments with many thousands of detectors.
18 citations
TL;DR: In this paper, a spin-2 spherical harmonics-based decomposition of a linear polarization field on the sphere was proposed to decompose an incomplete map into E and B-mode components using the pixel covariance in the observed map.
Abstract: A linear polarization field on the sphere can be uniquely decomposed into an E-mode and a B-mode component. These two components are analytically defined in terms of spin-2 spherical harmonics. Maps that contain filtered modes on a partial sky can also be decomposed into E-mode and B-mode components. However, the lack of full sky information prevents orthogonally separating these components using spherical harmonics. In this paper, we present a technique for decomposing an incomplete map into E and B-mode components using E and B eigenmodes of the pixel covariance in the observed map. This method is found to orthogonally define E and B in the presence of both partial sky coverage and spatial filtering. This method has been applied to the BICEP2 and the Keck Array maps and results in reducing E to B leakage from LCDM E-modes to a level corresponding to a tensor-to-scalar ratio of $r<1\times10^{-4}$.
17 citations
Cardiff University1, Stanford University2, California Institute of Technology3, Harvard University4, University of Toronto5, University of Minnesota6, French Alternative Energies and Atomic Energy Commission7, University of Illinois at Urbana–Champaign8, University of British Columbia9, National Institute of Standards and Technology10, University of California, San Diego11, Canadian Institute for Advanced Research12, University of Chicago13, University of California, Berkeley14
TL;DR: In this paper, a spin-2 spherical harmonics-based decomposition of a linear polarization field on the sphere is proposed to decompose an incomplete map into E and B-mode components using the pixel covariance in the observed map.
Abstract: A linear polarization field on the sphere can be uniquely decomposed into an E-mode and a B-mode component. These two components are analytically defined in terms of spin-2 spherical harmonics. Maps that contain filtered modes on a partial sky can also be decomposed into E-mode and B-mode components. However, the lack of full sky information prevents orthogonally separating these components using spherical harmonics. In this paper, we present a technique for decomposing an incomplete map into E and B-mode components using E and B eigenmodes of the pixel covariance in the observed map. This method is found to orthogonally define E and B in the presence of both partial sky coverage and spatial filtering. This method has been applied to the Bicep2 and the Keck Array maps and results in reducing E to B leakage from ΛCDM E-modes to a level corresponding to a tensor-to-scalar ratio of r < 1 x 10^(-4).
15 citations
TL;DR: In this article, the authors report on the far field beam performance using calibration data taken during the 2015-2016 summer deployment season in situ with a thermal chopped source, and show the array-averaged beam profile, and characterize the differential beam response between co-located, orthogonally polarized detectors.
Abstract: BICEP3 is a small-aperture refracting cosmic microwave background (CMB) telescope designed to make sensitive polarization maps in pursuit of a potential B-mode signal from inflationary gravitational waves. It is the latest in the BICEP/Keck Array series of CMB experiments at the South Pole, which has provided the most stringent constraints on inflation to date. For the 2016 observing season, BICEP3 was outfitted with a full suite of 2400 optically coupled detectors operating at 95 GHz. In these proceedings we report on the far field beam performance using calibration data taken during the 2015-2016 summer deployment season in situ with a thermal chopped source. We generate high-fidelity per-detector beam maps, show the array-averaged beam profile, and characterize the differential beam response between co-located, orthogonally polarized detectors which contributes to the leading instrumental systematic in pair differencing experiments. We find that the levels of differential pointing, beamwidth, and ellipticity are similar to or lower than those measured for BICEP2 and Keck Array. The magnitude and distribution of BICEP3's differential beam mismatch - and the level to which temperature-to-polarization leakage may be marginalized over or subtracted in analysis - will inform the design of next-generation CMB experiments with many thousands of detectors.
6 citations