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Register a new userA measurement of the CMB E-mode angular power spectrum at subdegree scales from 670 square degrees of POLARBEAR data
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We report a measurement of the E-mode polarization power spectrum of the cosmic microwave background (CMB) using 150 GHz data taken from July 2014 to December 2016 with the POLARBEAR experiment. We reach an effective polarization map noise level of $32,mumathrm{K}$-$mathrm{arcmin}$ across an observation area of 670 square degrees. We measure the EE power spectrum over the angular multipole range $500 leq ell <3000$, tracing the third to seventh acoustic peaks with high sensitivity. The statistical uncertainty on E-mode bandpowers is $sim 2.3 mu {rm K}^2$ at $ell sim 1000$ with a systematic uncertainty of 0.5$mu {rm K}^2$. The data are consistent with the standard $Lambda$CDM cosmological model with a probability-to-exceed of 0.38. We combine recent CMB E-mode measurements and make inferences about cosmological parameters in $Lambda$CDM as well as in extensions to $Lambda$CDM. Adding the ground-based CMB polarization measurements to the Planck dataset reduces the uncertainty on the Hubble constant by a factor of 1.2 to $H_0 = 67.20 pm 0.57 {rm km,s^{-1} ,Mpc^{-1}}$. When allowing the number of relativistic species ($N_{eff}$) to vary, we find $N_{eff} = 2.94 pm 0.16$, which is in good agreement with the standard value of 3.046. Instead allowing the primordial helium abundance ($Y_{He}$) to vary, the data favor $Y_{He} = 0.248 pm 0.012$. This is very close to the expectation of 0.2467 from Big Bang Nucleosynthesis. When varying both $Y_{He}$ and $N_{eff}$, we find $N_{eff} = 2.70 pm 0.26$ and $Y_{He} = 0.262 pm 0.015$.
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We present a measurement of the $B$-mode polarization power spectrum of the cosmic microwave background (CMB) using taken from July 2014 to December 2016 with the POLARBEAR experiment. The CMB power spectra are measured using observations at 150 GHz with an instantaneous array sensitivity of $mathrm{NET}_mathrm{array}=23, mu mathrm{K} sqrt{mathrm{s}}$ on a 670 square degree patch of sky centered at (RA, Dec)=($+0^mathrm{h}12^mathrm{m}0^mathrm{s},-59^circ18^prime$). A continuously rotating half-wave plate is used to modulate polarization and to suppress low-frequency noise. We achieve $32,mumathrm{K}$-$mathrm{arcmin}$ effective polarization map noise with a knee in sensitivity of $ell = 90$, where the inflationary gravitational wave signal is expected to peak. The measured $B$-mode power spectrum is consistent with a $Lambda$CDM lensing and single dust component foreground model over a range of multipoles $50 leq ell leq 600$. The data disfavor zero $C_ell^{BB}$ at $2.2sigma$ using this $ell$ range of POLARBEAR data alone. We cross-correlate our data with Planck high frequency maps and find the low-$ell$ $B$-mode power in the combined dataset to be consistent with thermal dust emission. We place an upper limit on the tensor-to-scalar ratio $r < 0.90$ at 95% confidence level after marginalizing over foregrounds.
We report an improved measurement of the cosmic microwave background (CMB) $B$-mode polarization power spectrum with the POLARBEAR experiment at 150 GHz. By adding new data collected during the second season of observations (2013-2014) to re-analyzed data from the first season (2012-2013), we have reduced twofold the band-power uncertainties. The band powers are reported over angular multipoles $500 leq ell leq 2100$, where the dominant $B$-mode signal is expected to be due to the gravitational lensing of $E$-modes. We reject the null hypothesis of no $B$-mode polarization at a confidence of 3.1$sigma$ including both statistical and systematic uncertainties. We test the consistency of the measured $B$-modes with the $Lambda$ Cold Dark Matter ($Lambda$CDM) framework by fitting for a single lensing amplitude parameter $A_L$ relative to the Planck best-fit model prediction. We obtain $A_L = 0.60 ^{+0.26} _{-0.24} ({rm stat}) ^{+0.00} _{-0.04}({rm inst}) pm 0.14 ({rm foreground}) pm 0.04 ({rm multi})$, where $A_{L}=1$ is the fiducial $Lambda$CDM value, and the details of the reported uncertainties are explained later in the manuscript.
We report a measurement of the B-mode polarization power spectrum in the cosmic microwave background (CMB) using the POLARBEAR experiment in Chile. The faint B-mode polarization signature carries information about the Universes entire history of gravitational structure formation, and the cosmic inflation that may have occurred in the very early Universe. Our measurement covers the angular multipole range 500 < l < 2100 and is based on observations of an effective sky area of 25 square degrees with 3.5 arcmin resolution at 150 GHz. On these angular scales, gravitational lensing of the CMB by intervening structure in the Universe is expected to be the dominant source of B-mode polarization. Including both systematic and statistical uncertainties, the hypothesis of no B-mode polarization power from gravitational lensing is rejected at 97.1% confidence. The band powers are consistent with the standard cosmological model. Fitting a single lensing amplitude parameter A_BB to the measured band powers, A_BB = 1.12 +/- 0.61 (stat) +0.04/-0.12 (sys) +/- 0.07 (multi), where A_BB = 1 is the fiducial WMAP-9 LCDM value. In this expression, stat refers to the statistical uncertainty, sys to the systematic uncertainty associated with possible biases from the instrument and astrophysical foregrounds, and multi to the calibration uncertainties that have a multiplicative effect on the measured amplitude A_BB.
We present measurements of the $E$-mode polarization angular auto-power spectrum ($EE$) and temperature-$E$-mode cross-power spectrum ($TE$) of the cosmic microwave background (CMB) using 150 GHz data from three seasons of SPTpol observations. We report the power spectra over the spherical harmonic multipole range $50 < ell leq 8000$, and detect nine acoustic peaks in the $EE$ spectrum with high signal-to-noise ratio. These measurements are the most sensitive to date of the $EE$ and $TE$ power spectra at $ell > 1050$ and $ell > 1475$, respectively. The observations cover 500 deg$^2$, a fivefold increase in area compared to previous SPTpol analyses, which increases our sensitivity to the photon diffusion damping tail of the CMB power spectra enabling tighter constraints on LCDM model extensions. After masking all sources with unpolarized flux $>50$ mJy we place a 95% confidence upper limit on residual polarized point-source power of $D_ell = ell(ell+1)C_ell/2pi <0.107,mu{rm K}^2$ at $ell=3000$, suggesting that the $EE$ damping tail dominates foregrounds to at least $ell = 4050$ with modest source masking. We find that the SPTpol dataset is in mild tension with the $Lambda CDM$ model ($2.1,sigma$), and different data splits prefer parameter values that differ at the $sim 1,sigma$ level. When fitting SPTpol data at $ell < 1000$ we find cosmological parameter constraints consistent with those for $Planck$ temperature. Including SPTpol data at $ell > 1000$ results in a preference for a higher value of the expansion rate ($H_0 = 71.3 pm 2.1,mbox{km},s^{-1}mbox{Mpc}^{-1}$ ) and a lower value for present-day density fluctuations ($sigma_8 = 0.77 pm 0.02$).
In the context of cosmic microwave background (CMB) data analysis, we compare the efficiency at large scale of two angular power spectrum algorithms, implementing, respectively, the quadratic maximum likelihood (QML) estimator and the pseudo spectrum (pseudo-Cl) estimator. By exploiting 1000 realistic Monte Carlo (MC) simulations, we find that the QML approach is markedly superior in the range l=[2-100]. At the largest angular scales, e.g. l < 10, the variance of the QML is almost 1/3 (1/2) that of the pseudo-Cl, when we consider the WMAP kq85 (kq85 enlarged by 8 degrees) mask, making the pseudo spectrum estimator a very poor option. Even at multipoles l=[20-60], where pseudo-Cl methods are traditionally used to feed the CMB likelihood algorithms, we find an efficiency loss of about 20%, when we considered the WMAP kq85 mask, and of about 15% for the kq85 mask enlarged by 8 degrees. This should be taken into account when claiming accurate results based on pseudo-Cl methods. Some examples concerning typical large scale estimators are provided.
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