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. DOI: 10.1103/PhysRevLett.116.031302 PRL 116, 031302 (2016) P H Y S I C A L R E V I E W L E T T E R S week ending 22 JANUARY 20160031-9007=16=116(3)=031302 (9) 031302-1 © 2016 American Physical SocietyIntroduction.-Measurements of the cosmic microwave background (CMB) [1] are one of the observational pillars of the standard cosmological model (ΛCDM) and constrain its parameters to high precision (see most recently Ref. [2]). This model extrapolates the Universe back to very high temperatures (≫10 12 K) and early times (≪ 1 s). Observations indicate that conditions at these early times are described by an almost uniform plasma with a nearly scale invariant spectrum of adiabatic density perturbations. However, ΛCDM itself offers no explanation for how these conditions occurred. The theory of inflation is an extension to the standard model, which postulates a phase of exponential expansion at a still earlier epoch (∼10 −35 s) that precedes ΛCDM and produces the required initial conditions (see Ref.[3] for a recent review and citations to the original literature).There is widespread support for the claim that existing observations already indicate that some version of inflation probably did occur, but there are also skeptics [4,5]. As well as the specific form of the initial density perturbations, there is an additional relic which inflation predicts, and which one can attempt to detect....

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We present results from an analysis of all data taken by the BICEP2/Keck CMB polarization experiments up to and including the 2015 observing season. This includes the first Keck Array observations at 220 GHz and additional observations at 95 & 150 GHz. The Q/U maps reach depths of 5.2, 2.9 and 26 µKcmb arcmin at 95, 150 and 220 GHz respectively over an effective area of ≈ 400 square degrees. The 220 GHz maps achieve a signal-to-noise on polarized dust emission approximately equal to that of Planck at 353 GHz. We take auto-and cross-spectra between these maps and publicly available WMAP and Planck maps at frequencies from 23 to 353 GHz. We evaluate the joint likelihood of the spectra versus a multicomponent model of lensed-ΛCDM+r+dust+synchrotron+noise. The foreground model has seven parameters, and we impose priors on some of these using external information from Planck and WMAP derived from larger regions of sky. The model is shown to be an adequate description of the data at the current noise levels. The likelihood analysis yields the constraint r0.05 < 0.07 at 95% confidence, which tightens to r0.05 < 0.06 in conjunction with Planck temperature measurements and other data. The lensing signal is detected at 8.8σ significance. Running maximum likelihood search on simulations we obtain unbiased results and find that σ(r) = 0.020. These are the strongest constraints to date on primordial gravitational waves.

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 .

Gravitational lensing due to the large-scale distribution of matter in the cosmos distorts the primordial Cosmic Microwave Background (CMB) and thereby induces new, small-scale B -mode polarization. This signal carries detailed information about the distribution of all the gravitating matter between the observer and CMB last scattering surface. We report the first direct evidence for polarization lensing based on purely CMB information, from using the four-point correlations of even-and odd-parity E -and B -mode polarization mapped over ∼ 30 square degrees of the sky measured by the Polarbear experiment. These data were analyzed using a blind analysis framework and checked for spurious systematic contamination using null tests and simulations. Evidence for the signal of polarization lensing and lensing B -modes is found at 4.2σ (stat.+sys.) significance. The amplitude of matter fluctuations is measured with a precision of 27%, and is found to be consistent with the Lambda Cold Dark Matter (ΛCDM) cosmological model. This measurement demonstrates 2 a new technique, capable of mapping all gravitating matter in the Universe, sensitive to the sum of neutrino masses, and essential for cleaning the lensing B -mode signal in searches for primordial gravitational waves.Introduction: As Cosmic Microwave Background (CMB) photons traverse the Universe, their paths are gravitationally deflected by large-scale structures. By measuring the resulting changes in the statistical properties of the CMB anisotropies, maps of this gravitational lensing deflection, which traces large-scale structure, can be reconstructed. Gravitational lensing of the CMB has been detected in the CMB temperature anisotropy in several ways: in the smoothing of the acoustic peaks of the temperature power spectrum [1-3], in cross-correlations with tracers of the large-scale matter distribution [4][5][6][7][8][9][10], and in the four-point correlation function of CMB temperature maps [11][12][13][14].The South Pole Telescope (SPT) collaboration recently reported a detection of lensed polarization using the cross-correlation between maps of CMB polarization and sub-mm maps of galaxies from Herschel/SPIRE [15]. A companion paper to this one has also shown the evidence of the CMB lensing-Cosmic Infrared Background crosscorrelation results using Polarbear data [16], finding good agreement with the SPT measurements. This crosscorrelation is immune to several instrumental systematic effects but the cosmological interpretation of this measurement requires assumptions about the relation of submm galaxies to the underlying mass distribution [17].In this Letter, we present the first direct evidence for gravitational lensing of the polarized CMB using data from the Polarbear experiment. We present power spectra of the lensing deflection field for two four-point estimators using only CMB polarization data, and tests for spurious systematic contamination of these estimators. We combine the two estimators to increase the signal-to-noise of the lensing detection.CMB lens...