Frequency dependence of the thermal dust $E/B$ ratio and $EB$ correlation: insights from the spin-moment expansion

Abstract

The change of physical conditions across the turbulent and magnetized interstellar medium (ISM) induces a 3D spatial variation of the properties of Galactic polarized emission. The observed signal results from the averaging of different spectral energy distributions (SED) and polarization angles, along and between lines of sight. As a consequence, the total Stokes parameters $Q$ and $U$ will have different distorted SEDs, so that the polarization angle becomes frequency dependent. In the present work, we show how this phenomenon similarly induces a different distorted SED for the three polarized angular power spectra $EE$, $BB$ and $EB$, implying a variation of the $EE/BB$ ratio with frequency. We demonstrate how the previously introduced spin-moment formalism provides a natural framework to grasp these effects, allowing us to derive analytical predictions for the spectral behaviors of the polarized spectra, focusing here on the example of thermal dust polarized emission. After a quantitative discussion based on a model combining emission from a filament with its background, we further reveal that the spectral complexity implemented in the dust models commonly used by the cosmic microwave background (CMB) community produce such effects. This new understanding is crucial for CMB component separation, in which an extreme accuracy is required in the modeling of the dust signal to allow for the search of the primordial imprints of inflation or cosmic birefringence. For the latter, as long as the dust $EB$ signal is not measured accurately, great caution is required about the assumptions made to model its spectral behavior, as it may not simply follow from the other dust angular power spectra.

Published in A&A. Last version here includes minor typo corrections

References in corpus (15)

• Planck intermediate results. XXII. Frequency dependence of thermal emission from Galactic dust in intensity and polarization
• Planck intermediate results. XX. Comparison of polarized thermal emission from Galactic dust with simulations of MHD turbulence
• Cosmic Birefringence from Planck Data Release 4
• Improved Constraints on Cosmic Birefringence from the WMAP and Planck Cosmic Microwave Background Polarization Data
• Mapping the Magnetic Interstellar Medium in Three Dimensions Over the Full Sky with Neutral Hydrogen
• Modeling the Anomalous Microwave Emission with Spinning Nanoparticles: No PAHs Required
• Planck intermediate results. L. Evidence for spatial variation of the polarized thermal dust spectral energy distribution and implications for CMB $B$-mode analysis
• Evidence for Line-of-Sight Frequency Decorrelation of Polarized Dust Emission in $Planck$ Data
• A 3-D model of polarised dust emission in the Milky Way
• High precision modeling of polarized signals: Moment expansion method generalized to spin-2 fields
• Dust polarization spectral dependence from Planck HFI data. Turning point on CMB polarization foregrounds modelling
• Characterizing line-of-sight variability of polarized dust emission with future CMB experiments
• Polarization power spectra and dust cloud morphology
• Mitigating Bias in CMB B-modes from Foreground Cleaning Using a Moment Expansion
• The Python Sky Model 3 software

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• A New Solution for the Observed Isotropic Cosmic Birefringence Angle and its Implications for the Anisotropic Counterpart through a Boltzmann Approach
• Mitigating the impact of the CIB on galaxy cluster SZ detection with spectrally constrained matched filters
• Modeling parity-violating spectra in Galactic dust polarization with filaments and its applications to cosmic birefringence searches
• Optical modeling of systematic uncertainties in detector polarization angles for the Atacama Cosmology Telescope
• Absolute reference for microwave polarization experiments -- The COSMOCal project and its proof of concept
• Impact of Galactic dust non-Gaussianity on searches for B-modes from inflation
• How bad could it be? Modelling the 3D complexity of the polarised dust signal using moment expansion
• Cosmoglobe DR1. III. First full-sky model of polarized synchrotron emission from all WMAP and Planck LFI data
• The Simons Observatory: Assessing the Impact of Dust Complexity on the Recovery of Primordial $B$-modes
• High-precision polarization measurements with Lumped Element Kinetic Inductance Detectors