Planck intermediate results. XXXVIII. E- and B-modes of dust polarization from the magnetized filamentary structure of the interstellar medium

Abstract

The quest for a B-mode imprint from primordial gravity waves on the polarization of the cosmic microwave background (CMB) requires the characterization of foreground polarization from Galactic dust. We present a statistical study of the filamentary structure of the 353 GHz Planck Stokes maps at high Galactic latitude, relevant to the study of dust emission as a polarized foreground to the CMB. We filter the intensity and polarization maps to isolate filaments in the range of angular scales where the power asymmetry between E-modes and B-modes is observed. Using the Smoothed Hessian Major Axis Filament Finder, we identify 259 filaments at high Galactic latitude, with lengths larger or equal to 2° (corresponding to 3.5 pc in length for a typical distance of 100 pc). These filaments show a preferred orientation parallel to the magnetic field projected onto the plane of the sky, derived from their polarization angles. We present mean maps of the filaments in Stokes I, Q, U, E, and B, computed by stacking individual images rotated to align the orientations of the filaments. Combining the stacked images and the histogram of relative orientations, we estimate the mean polarization fraction of the filaments to be 11 %. Furthermore, we show that the correlation between the filaments and the magnetic field orientations may account for the E and B asymmetry and the $C_{\ell }^{TE}/C_{\ell }^{EE}$ ratio, reported in the power spectra analysis of the Planck 353 GHz polarization maps. Future models of the dust foreground for CMB polarization studies will need to take into account the observed correlation between the dust polarization and the structure of interstellar matter.

18 pages, 15 figures. A&A accepted. Corresponding author: T. Ghosh

References in corpus (8)

• A Joint Analysis of BICEP2/Keck Array and Planck Data
• Planck intermediate results. XXXV. Probing the role of the magnetic field in the formation of structure in molecular clouds
• Planck intermediate results. XIX. An overview of the polarized thermal emission from Galactic dust
• 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
• Planck intermediate results. XXI. Comparison of polarized thermal emission from Galactic dust at 353 GHz with interstellar polarization in the visible
• Polarised radio filaments outside the Galactic plane
• Planck 2015 results. VII. HFI TOI and beam processing

Cited by in corpus (17)

• The link between turbulence, magnetic fields, filaments, and star formation in the Central Molecular Zone cloud G0.253+0.016
• Planck 2018 results. XI. Polarized dust foregrounds
• Mapping the Magnetic Interstellar Medium in Three Dimensions Over the Full Sky with Neutral Hydrogen
• IMAGINE: A comprehensive view of the interstellar medium, Galactic magnetic fields and cosmic rays
• Matching dust emission structures and magnetic field in high-latitude cloud L1642: comparing Herschel and Planck maps
• The Origin of Parity Violation in Polarized Dust Emission and Implications for Cosmic Birefringence
• Planck intermediate results. L. Evidence for spatial variation of the polarized thermal dust spectral energy distribution and implications for CMB $B$-mode analysis
• Polarized galactic synchrotron and dust emission and their correlation
• Modelling and simulation of large-scale polarized dust emission over the southern Galactic cap using the GASS HI data
• Magnetic fields in the Milky Way from pulsar observations: effect of the correlation between thermal electrons and magnetic fields
• Statistical properties of galactic CMB foregrounds: dust and synchrotron
• Planck intermediate results. XLIV. The structure of the Galactic magnetic field from dust polarization maps of the southern Galactic cap
• A new perspective on turbulent Galactic magnetic fields through comparison of linear polarisation decomposition techniques
• Real-space computation of $E$/$B$-mode maps I: Formalism, Compact Kernels, and Polarized Filaments
• Detection and Removal of B-mode Dust Foregrounds with Signatures of Statistical Anisotropy
• Statistical properties of polarized CMB foreground maps
• The Galactic interstellar medium has a preferred handedness of magnetic misalignment