We search for the signature of parity-violating physics in the cosmic microwave background, called cosmic birefringence, using the Planck data release 4. We initially find a birefringence angle of ...β=0.30°±0.11° (68% C.L.) for nearly full-sky data. The values of β decrease as we enlarge the Galactic mask, which can be interpreted as the effect of polarized foreground emission. Two independent ways to model this effect are used to mitigate the systematic impact on β for different sky fractions. We choose not to assign cosmological significance to the measured value of β until we improve our knowledge of the foreground polarization.
We present constraints on the tensor-to-scalar ratio
r
using
Planck
data. We use the latest release of
Planck
maps, processed with the
NPIPE
code, which produces calibrated frequency maps in ...temperature and polarisation for all
Planck
channels from 30 GHz to 857 GHz using the same pipeline. We computed constraints on
r
using the
BB
angular power spectrum, and we also discuss constraints coming from the
TT
spectrum. Given
Planck
’s noise level, the
TT
spectrum gives constraints on
r
that are cosmic-variance limited (with
σ
r
= 0.093), but we show that the marginalised posterior peaks towards negative values of
r
at about the 1.2
σ
level. We derived
Planck
constraints using the
BB
power spectrum at both large angular scales (the ‘reionisation bump’) and intermediate angular scales (the ‘recombination bump’) from
ℓ
= 2 to 150 and find a stronger constraint than that from
TT
, with
σ
r
= 0.069. The
Planck
BB
spectrum shows no systematic bias and is compatible with zero, given both the statistical noise and the systematic uncertainties. The likelihood analysis using
B
modes yields the constraint
r
< 0.158 at 95% confidence using more than 50% of the sky. This upper limit tightens to
r
< 0.069 when
Planck
EE
,
BB
, and
EB
power spectra are combined consistently, and it tightens further to
r
< 0.056 when the
Planck
TT
power spectrum is included in the combination. Finally, combining
Planck
with BICEP2/Keck 2015 data yields an upper limit of
r
< 0.044.
The measurement of the large-scale B-mode polarization in the cosmic microwave background (CMB) is a fundamental goal of future CMB experiments. However, because of unprecedented sensitivity, future ...CMB experiments will be much more sensitive to any imperfect modelling of the Galactic foreground polarization in the reconstruction of the primordial B-mode signal. We compare the sensitivity to B-modes of different concepts of CMB satellite missions (LiteBIRD, COrE, COrE+, PRISM, EPIC, PIXIE) in the presence of Galactic foregrounds. In particular, we quantify the impact on the tensor-to-scalar parameter of incorrect foreground modelling in the component separation process. Using Bayesian fitting and Gibbs sampling, we perform the separation of the CMB and Galactic foreground B-modes. The recovered CMB B-mode power spectrum is used to compute the likelihood distribution of the tensor-to-scalar ratio. We focus the analysis to the very large angular scales that can be probed only by CMB space missions, i.e. the reionization bump, where primordial B-modes dominate over spurious B-modes induced by gravitational lensing. We find that fitting a single modified blackbody component for thermal dust where the ‘real’ sky consists of two dust components strongly bias the estimation of the tensor-to-scalar ratio by more than 5σ for the most sensitive experiments. Neglecting in the parametric model the curvature of the synchrotron spectral index may bias the estimated tensor-to-scalar ratio by more than 1σ. For sensitive CMB experiments, omitting in the foreground modelling a 1 per cent polarized spinning dust component may induce a non-negligible bias in the estimated tensor-to-scalar ratio.
In a trial involving over 9000 patients with coronary artery disease who were assigned to receive either contemporary drug-eluting stents or bare-metal stents, there was no significant between-group ...difference in a composite outcome of death from any cause or nonfatal MI at 6 years.
Percutaneous coronary intervention (PCI) with implantation of drug-eluting or bare-metal stents has become one of the most frequently performed therapeutic procedures in medicine.
1
Each year, millions of patients are treated worldwide.
1
,
2
The use of drug-eluting stents has been shown to be more effective in the prevention of restenosis than the use of bare-metal stents,
1
and the use of newer-generation drug-eluting stents, as compared with first-generation devices,
3
,
4
may also reduce the rate of stent thrombosis.
5
–
8
It has been suggested that the benefits associated with the use of newer-generation drug-eluting stents may translate into reduced rates of death and . . .
We perform a metastudy of recently published redshift space distortion (RSD) measurements of the cosmological growth rate, f(z)σ8(z). We analyze the latest results from the 6dFGS, BOSS, LRG, WiggleZ, ...and VIPERS galaxy redshift surveys, and compare the measurements to expectations from Planck. In this Letter we point out that the RSD measurements are consistently lower than the values expected from Planck, and the relative scatter between the RSD measurements is lower than expected. A full resolution of this issue may require a more robust treatment of nonlinear effects in RSD models, although the trend for a low σ8 agrees with recent constraints on σ8 and Ω(m) from Sunyaev-Zeldovich cluster counts identified in Planck.
We present constraints on the tensor-to-scalar ratio r using a combination of BICEP/Keck 2018 (BK18) and Planck PR4 data allowing us to fit for r consistently with the six parameters of the ΛCDM ...model. We discuss the sensitivity of constraints on r to uncertainties in the ΛCDM parameters as defined by the Planck data. In particular, we are able to derive a constraint on the reionization optical depth τ and thus propagate its uncertainty into the posterior distribution for r. While Planck sensitivity to r is slightly lower than the current ground-based measurements, the combination of Planck with BK18 and baryon-acoustic-oscillation data yields results consistent with r=0 and tightens the constraint to r<0.032 at 95% confidence.
We report on the results from two independent but complementary statistical analyses of the Wilkinson Microwave Anisotropy Probe (WMAP) first- year data, based on the power spectrum and N-point ...correlation functions. We focus on large and intermediate scales (larger than about 3 degree ) and compare the observed data against Monte Carlo ensembles with WMAP-like properties. In both analyses, we measure the amplitudes of the large-scale fluctuations on opposing hemispheres and study the ratio of the two amplitudes. The power- spectrum analysis shows that this ratio for WMAP, as measured along the axis of maximum asymmetry, is high at the 95%-99% level (depending on the particular multipole range included). The axis of maximum asymmetry of the WMAP data is weakly dependent on the multipole range under consideration but tends to lie close to the ecliptic axis. In the N-point correlation-function analysis, we focus on the northern and southern hemispheres defined in ecliptic coordinates, and we find that the ratio of the large-scale fluctuation amplitudes is high at the 98%-99% level. Furthermore, the results are stable with respect to choice of Galactic cut and also with respect to frequency band. A similar asymmetry is found in the COBE Differential Microwave Radiometer (DMR) map, and the axis of maximum asymmetry is close to the one found in the WMAP data.
If a single line of sight (LOS) intercepts multiple dust clouds with different spectral energy distributions and magnetic field orientations, then the frequency scaling of each of the Stokes
Q
and
U
...parameters of the thermal dust emission may be different, a phenomenon we refer to as LOS frequency decorrelation. We present first evidence for LOS frequency decorrelation in
Planck
data using independent measurements of neutral-hydrogen (H
I
) emission to probe the 3D structure of the magnetized interstellar medium (ISM). We use H
I
-based measurements of the number of clouds per LOS and the magnetic field orientation in each cloud to select two sets of sightlines: (i) a target sample of pixels that are likely to exhibit LOS frequency decorrelation and (ii) a control sample of pixels that lack complex LOS structure. We test the null hypothesis that LOS frequency decorrelation is not detectable in
Planck
353 and 217 GHz polarization data at high Galactic latitudes. We reject the null hypothesis at high significance based on data that show that the combined effect of polarization angle variation with frequency and depolarization are detected in the target sample. This detection is robust against the choice of cosmic microwave background (CMB) map and map-making pipeline. The observed change in polarization angle due to LOS frequency decorrelation is detectable above the
Planck
noise level. The probability that the detected effect is due to noise alone ranges from 5 × 10
−2
to 4 × 10
−7
, depending on the CMB subtraction algorithm and treatment of residual systematic errors; correcting for residual systematic errors consistently increases the significance of the effect. Within the target sample, the LOS decorrelation effect is stronger for sightlines with more misaligned magnetic fields, as expected. With our sample, we estimate that an intrinsic variation of ~15% in the ratio of 353 to 217 GHz polarized emission between clouds is sufficient to reproduce the measured effect. Our finding underlines the importance of ongoing studies to map the three-dimensional structure of the magnetized and dusty ISM that could ultimately help component separation methods to account for frequency decorrelation effects in CMB polarization studies.
ABSTRACT
We repeat and extend the analysis of Eriksen et al. and Hansen et al., testing the isotropy of the cosmic microwave background fluctuations. We find that the hemispherical power asymmetry ...previously reported for the largest scales ℓ = 2–40 extends to much smaller scales. In fact, for the full multipole range ℓ = 2–600, significantly more power is found in the hemisphere centered at (θ = 107° ± 10°, ϕ = 226° ± 10°) in galactic co-latitude and longitude than in the opposite hemisphere, consistent with the previously detected direction of asymmetry for ℓ = 2–40. We adopt a model selection test where the direction and amplitude of asymmetry, as well as the multipole range, are free parameters. A model with an asymmetric distribution of power for ℓ = 2–600 is found to be preferred over the isotropic model at the 0.4% significance level, taking into account the additional parameters required to describe it. A similar direction of asymmetry is found independently in all six subranges of 100 multipoles between ℓ = 2–600. None of our 9800 isotropic simulated maps show a similarly consistent direction of asymmetry over such a large multipole range. No known systematic effects or foregrounds are found to be able to explain the asymmetry.
We describe and implement an exact, flexible, and computationally efficient algorithm for joint component separation and CMB power spectrum estimation, building on a Gibbs sampling framework. Two ...essential new features are (1) conditional sampling of foreground spectral parameters and (2) joint sampling of all amplitude-type degrees of freedom (e.g., CMB, foreground pixel amplitudes, and global template amplitudes) given spectral parameters. Given a parametric model of the foreground signals, we estimate efficiently and accurately the exact joint foreground-CMB posterior distribution and, therefore, all marginal distributions such as the CMB power spectrum or foreground spectral index posteriors. The main limitation of the current implementation is the requirement of identical beam responses at all frequencies, which restricts the analysis to the lowest resolution of a given experiment. We outline a future generalization to multiresolution observations. To verify the method, we analyze simple models and compare the results to analytical predictions. We then analyze a realistic simulation with properties similar to the 3 yr WMAP data, downgraded to a common resolution of 3 degree FWHM. The results from the actual 3 yr WMAP temperature analysis are presented in a companion Letter.
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