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Title: New constraints on cosmic polarization rotation from B-mode polarization in the cosmic microwave background

Abstract

SPTpol, POLARBEAR, and BICEP2 have recently measured the cosmic microwave background (CMB) B-mode polarization in various sky regions of several tens of square degrees and obtained BB power spectra in the multipole range 20-3000, detecting the components due to gravitational lensing and to inflationary gravitational waves. We analyze jointly the results of these three experiments and propose modifications to their analyses of the spectra to include in the model, in addition to the gravitational lensing and the inflationary gravitational wave components, and also the effects induced by the cosmic polarization rotation (CPR), if it exists within current upper limits. Although in principle our analysis would also lead to new constraints on CPR, in practice these can only be given on its fluctuations (δα{sup 2}), since constraints on its mean angle are inhibited by the derotation which is applied by current CMB polarization experiments, in order to cope with the insufficient calibration of the polarization angle. The combined data fits from all three experiments (with 29% CPR-SPTpol correlation, depending on the theoretical model) gives the constraint (δα{sup 2}){sup 1/2} < 27.3 mrad (1.°56), with r = 0.194 ± 0.033. These results show that the present data are consistent with no CPRmore » detection and the constraint on CPR fluctuation is about 1.°5. This method of constraining the CPR is new, is complementary to previous tests, which use the radio and optical/UV polarization of radio galaxies and the CMB E-mode polarization, and adds a new constraint for the sky areas observed by SPTpol, POLARBEAR, and BICEP2.« less

Authors:
 [1]; ;  [2]
  1. INAF—Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5, I-50125 Firenze (Italy)
  2. Department of Physics, National Tsing Hua University, Hsinchu, Taiwan 30013 (China)
Publication Date:
OSTI Identifier:
22365219
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 792; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BACKGROUND RADIATION; CALIBRATION; CORRELATIONS; DETECTION; FLUCTUATIONS; GRAVITATIONAL LENSES; GRAVITATIONAL WAVES; INFLATIONARY UNIVERSE; POLARIZATION; RADIO GALAXIES; RELICT RADIATION; ROTATION; SPECTRA; UNIVERSE

Citation Formats

Alighieri, Sperello di Serego, Ni, Wei-Tou, and Pan, Wei-Ping, E-mail: sperello@arcetri.astro.it, E-mail: weitou@gmail.com, E-mail: d9722518@oz.nthu.edu.tw. New constraints on cosmic polarization rotation from B-mode polarization in the cosmic microwave background. United States: N. p., 2014. Web. doi:10.1088/0004-637X/792/1/35.
Alighieri, Sperello di Serego, Ni, Wei-Tou, & Pan, Wei-Ping, E-mail: sperello@arcetri.astro.it, E-mail: weitou@gmail.com, E-mail: d9722518@oz.nthu.edu.tw. New constraints on cosmic polarization rotation from B-mode polarization in the cosmic microwave background. United States. doi:10.1088/0004-637X/792/1/35.
Alighieri, Sperello di Serego, Ni, Wei-Tou, and Pan, Wei-Ping, E-mail: sperello@arcetri.astro.it, E-mail: weitou@gmail.com, E-mail: d9722518@oz.nthu.edu.tw. Mon . "New constraints on cosmic polarization rotation from B-mode polarization in the cosmic microwave background". United States. doi:10.1088/0004-637X/792/1/35.
@article{osti_22365219,
title = {New constraints on cosmic polarization rotation from B-mode polarization in the cosmic microwave background},
author = {Alighieri, Sperello di Serego and Ni, Wei-Tou and Pan, Wei-Ping, E-mail: sperello@arcetri.astro.it, E-mail: weitou@gmail.com, E-mail: d9722518@oz.nthu.edu.tw},
abstractNote = {SPTpol, POLARBEAR, and BICEP2 have recently measured the cosmic microwave background (CMB) B-mode polarization in various sky regions of several tens of square degrees and obtained BB power spectra in the multipole range 20-3000, detecting the components due to gravitational lensing and to inflationary gravitational waves. We analyze jointly the results of these three experiments and propose modifications to their analyses of the spectra to include in the model, in addition to the gravitational lensing and the inflationary gravitational wave components, and also the effects induced by the cosmic polarization rotation (CPR), if it exists within current upper limits. Although in principle our analysis would also lead to new constraints on CPR, in practice these can only be given on its fluctuations (δα{sup 2}), since constraints on its mean angle are inhibited by the derotation which is applied by current CMB polarization experiments, in order to cope with the insufficient calibration of the polarization angle. The combined data fits from all three experiments (with 29% CPR-SPTpol correlation, depending on the theoretical model) gives the constraint (δα{sup 2}){sup 1/2} < 27.3 mrad (1.°56), with r = 0.194 ± 0.033. These results show that the present data are consistent with no CPR detection and the constraint on CPR fluctuation is about 1.°5. This method of constraining the CPR is new, is complementary to previous tests, which use the radio and optical/UV polarization of radio galaxies and the CMB E-mode polarization, and adds a new constraint for the sky areas observed by SPTpol, POLARBEAR, and BICEP2.},
doi = {10.1088/0004-637X/792/1/35},
journal = {Astrophysical Journal},
number = 1,
volume = 792,
place = {United States},
year = {Mon Sep 01 00:00:00 EDT 2014},
month = {Mon Sep 01 00:00:00 EDT 2014}
}
  • We present a measurement of the B-mode polarization power spectrum (the BB spectrum) from 100more » $${\mathrm{deg}}^{2}$$ 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 $$300\leqslant {\ell }\leqslant 2300$$, and for three spectral combinations: 95 GHz × 95 GHz, 95 GHz × 150 GHz, and 150 GHz × 150 GHz. We subtract small (<0.5σ 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 4.9σ. After marginalizing over tensor power and foregrounds, namely, polarized emission from galactic dust and extragalactic sources, this significance is 4.3σ. 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.« less
  • The effect of weak gravitational lensing on the cosmic microwave background (CMB) temperature anisotropies and polarization will provide access to cosmological information that cannot be obtained from the primary anisotropies alone. We compare the information content of the lensed B-mode polarization power spectrum, properly accounting for the non-Gaussian correlations between the power on different scales, with that of the unlensed CMB fields and the lensing potential. The latter represent the products of an (idealized) optimal analysis that exploits the lens-induced non-Gaussianity to reconstruct the fields. Compressing the non-Gaussian lensed CMB into power spectra is wasteful and leaves a tight degeneracymore » between the equation of state of dark energy and neutrino mass that is much stronger than in the more optimal analysis. Despite this, a power-spectrum analysis will be a useful first step in analyzing future B-mode polarization data. For this reason, we also consider how to extract accurate parameter constraints from the lensed B-mode power spectrum. We show with simulations that for cosmic-variance-limited measurements of the lensed B-mode power, including the non-Gaussian correlations in existing likelihood approximations gives biased parameter results. We develop a more refined likelihood approximation that performs significantly better. This new approximation should also be of more general interest in the wider context of parameter estimation from Gaussian CMB data.« less
  • We present a measurement of themore » $B$-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.« less
  • We present a measurement of themore » $B$-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.« less
  • We reconsider the pixel-based, 'template' polarized foreground removal method within the context of a next-generation, low-noise, low-resolution (0.{sup 0}5 FWHM) space-borne experiment measuring the cosmological B-mode polarization signal in the cosmic microwave background (CMB). This method was first applied to polarized data by the Wilkinson Microwave Anisotropy Probe (WMAP) team and further studied by Efstathiou et al. We need at least three frequency channels: one is used for extracting the CMB signal, whereas the other two are used to estimate the spatial distribution of the polarized dust and synchrotron emission. No extra data from non-CMB experiments or models are used.more » We extract the tensor-to-scalar ratio (r) from simulated sky maps outside the standard polarization mask (P06) of WMAP consisting of CMB, noise (2 {mu}K arcmin), and a foreground model, and find that, even for the simplest three-frequency configuration with 60, 100, and 240 GHz, the residual bias in r is as small as {Delta}r {approx} 0.002. This bias is dominated by the residual synchrotron emission due to spatial variations of the synchrotron spectral index. With an extended mask with f{sub sky} = 0.5, the bias is reduced further down to <0.001.« less