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Register a new userMeasurements of Sub-degree B-mode Polarization in the Cosmic Microwave Background from 100 Square Degrees of SPTpol Data
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We present a measurement of the $B$-mode polarization power spectrum (the $BB$ spectrum) from 100 $mathrm{deg}^2$ of sky observed with SPTpol, a polarization-sensitive receiver currently installed on the South Pole Telescope. The observations used in this work were taken during 2012 and early 2013 and include data in spectral bands centered at 95 and 150 GHz. We report the $BB$ spectrum in five bins in multipole space, spanning the range $300 le ell le 2300$, and for three spectral combinations: 95 GHz $times$ 95 GHz, 95 GHz $times$ 150 GHz, and 150 GHz $times$ 150 GHz. We subtract small ($< 0.5 sigma$ in units of statistical uncertainty) biases from these spectra and account for the uncertainty in those biases. The resulting power spectra are inconsistent with zero power but consistent with predictions for the $BB$ spectrum arising from the gravitational lensing of $E$-mode polarization. If we assume no other source of $BB$ power besides lensed $B$ modes, we determine a preference for lensed $B$ modes of $4.9 sigma$. After marginalizing over tensor power and foregrounds, namely polarized emission from galactic dust and extragalactic sources, this significance is $4.3 sigma$. Fitting for a single parameter, $A_mathrm{lens}$, that multiplies the predicted lensed $B$-mode spectrum, and marginalizing over tensor power and foregrounds, we find $A_mathrm{lens} = 1.08 pm 0.26$, indicating that our measured spectra are consistent with the signal expected from gravitational lensing. The data presented here provide the best measurement to date of the $B$-mode power spectrum on these angular scales.
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We report a B-mode power spectrum measurement from the cosmic microwave background (CMB) polarization anisotropy observations made using the SPTpol instrument on the South Pole Telescope. This work uses 500 deg$^2$ of SPTpol data, a five-fold increase over the last SPTpol B-mode release. As a result, the bandpower uncertainties have been reduced by more than a factor of two, and the measurement extends to lower multipoles: $52 < ell < 2301$. Data from both 95 and 150 GHz are used, allowing for three cross-spectra: 95 GHz x 95 GHz, 95 GHz x 150 GHz, and 150 GHz x 150 GHz. B-mode power is detected at very high significance; we find $P(BB < 0) = 5.8 times 10^{-71}$, corresponding to a $18.1 sigma$ detection of power. An upper limit is set on the tensor-to-scalar ratio, $r < 0.44$ at 95% confidence (the expected $1 sigma$ constraint on $r$ given the measurement uncertainties is 0.22). We find the measured B-mode power is consistent with the Planck best-fit $Lambda$CDM model predictions. Scaling the predicted lensing B-mode power in this model by a factor Alens, the data prefer Alens = $1.17 pm 0.13$. These data are currently the most precise measurements of B-mode power at $ell > 320$.
We present measurements of $E$-mode polarization and temperature-$E$-mode correlation in the cosmic microwave background (CMB) using data from the first season of observations with SPTpol, the polarization-sensitive receiver currently installed on the South Pole Telescope (SPT). The observations used in this work cover 100~sqdeg of sky with arcminute resolution at $150,$GHz. We report the $E$-mode angular auto-power spectrum ($EE$) and the temperature-$E$-mode angular cross-power spectrum ($TE$) over the multipole range $500 < ell leq5000$. These power spectra improve on previous measurements in the high-$ell$ (small-scale) regime. We fit the combination of the SPTpol power spectra, data from planck, and previous SPT measurements with a six-parameter LCDM cosmological model. We find that the best-fit parameters are consistent with previous results. The improvement in high-$ell$ sensitivity over previous measurements leads to a significant improvement in the limit on polarized point-source power: after masking sources brighter than 50,mJy in unpolarized flux at 150,GHz, we find a 95% confidence upper limit on unclustered point-source power in the $EE$ spectrum of $D_ell = ell (ell+1) C_ell / 2 pi < 0.40 mu{mbox{K}}^2$ at $ell=3000$, indicating that future $EE$ measurements will not be limited by power from unclustered point sources in the multipole range $ell < 3600$, and possibly much higher in $ell.$
We present a measurement of the cosmic microwave background (CMB) gravitational lensing potential using data from the first two seasons of observations with SPTpol, the polarization-sensitive receiver currently installed on the South Pole Telescope (SPT). The observations used in this work cover 100 deg$^2$ of sky with arcminute resolution at 150 GHz. Using a quadratic estimator, we make maps of the CMB lensing potential from combinations of CMB temperature and polarization maps. We combine these lensing potential maps to form a minimum-variance (MV) map. The lensing potential is measured with a signal-to-noise ratio of greater than one for angular multipoles between $100< L <250$. This is the highest signal-to-noise mass map made from the CMB to date and will be powerful in cross-correlation with other tracers of large-scale structure. We calculate the power spectrum of the lensing potential for each estimator, and we report the value of the MV power spectrum between $100< L <2000$ as our primary result. We constrain the ratio of the spectrum to a fiducial $Lambda$CDM model to be $A_{rm MV}=0.92 pm 0.14 {rm, (Stat.)} pm 0.08 {rm, (Sys.)}$. Restricting ourselves to polarized data only, we find $A_{rm POL}=0.92 pm 0.24 {rm, (Stat.)} pm 0.11 {rm, (Sys.)}$. This measurement rejects the hypothesis of no lensing at $5.9 sigma$ using polarization data alone, and at $14 sigma$ using both temperature and polarization data.
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 ($sigma_8 = 0.77 pm 0.02$).
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.
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