Linear Polarization of the 21 cm Line from the Epoch of Reionization

Abstract

The 21 cm linear polarization due to Thomson scattering off free electrons can probe the distribution of neutral hydrogen in the intergalactic medium during the epoch of reionization, complementary to the 21 cm temperature fluctuations. Previous study (Babich & Loeb 2005) estimated the strength of polarization with a toy model and claimed that it can be detected with 1-month observation of the Square Kilometre Array (SKA). Here we revisit this investigation with account of nonlinear terms due to inhomogeneous reionization, using seminumerical reionization simulations to provide the realistic estimation of the 21 cm TE and EE angular power spectra ($C_{\ell }^{\mathrm{TE}}$ and $C_{\ell }^{\mathrm{EE}}$). We find that (1) both power spectra are enhanced on sub-bubble scales but suppressed on super-bubble scales, compared with previous results; (2) $C_{\ell }^{\mathrm{TE}}$ displays a zero-crossing at $\ell <100$, and its angular scale is sensitive to the scale-dependence of H I bias on large scales; (3) the ratios of the power spectrum to its maximum value during reionization at a given $\ell$, i.e. $C_{\ell }^{\mathrm{TE}}/C_{\ell ,\max }^{\mathrm{TE}}$ and $C_{\ell }^{\mathrm{EE}}/C_{\ell ,\max }^{\mathrm{EE}}$, show robust correlations with the global ionized fraction. However, measurement of this signal will be very challenging not only because the overall strength is weaker than the sensitivity of SKA, but also because of the polarized foregrounds from diffuse synchrotron emission, and Faraday rotation which modifies the observed polarization. Nevertheless, the 21 cm linear polarization signal may still likely be detectable through other approaches, e.g. its cross-correlation with other probes.

21 pages, 11 figures, Published in ApJ

References in corpus (30)

• Cosmic Reionization and Early Star-Forming Galaxies: A Joint Analysis of New Constraints from Planck and Hubble Space Telescope
• Model-independent evidence in favor of an end to reionization by z~6
• Efficient Simulations of Early Structure Formation and Reionization
• Evidence of patchy hydrogen reionization from an extreme Ly$\alpha$ trough below redshift six
• The morphology of HII regions during reionization
• Conditions for Reionizing the Universe with A Low Galaxy Ionizing Photon Escape Fraction
• Improved upper limits on the 21-cm signal power spectrum of neutral hydrogen at $\mathbf{z}\approx 9.1$ from LOFAR
• The Global 21 Centimeter Background from High Redshifts
• How accurately can 21 cm tomography constrain cosmology?
• The Epoch of Reionization Window: I. Mathematical Formalism
• Radiative transfer simulations of cosmic reionization I: methodology and initial results
• Deep multi-redshift limits on Epoch of Reionisation 21cm Power Spectra from Four Seasons of Murchison Widefield Array Observations
• The CMBR fluctuations from HI perturbations prior to reionization
• Detecting the Rise and Fall of 21 cm Fluctuations with the Murchison Widefield Array
• Testing General Relativity with 21 cm intensity mapping
• The 21cm angular-power spectrum from the dark ages
• 21cmFAST v3: A Python-integrated C code forgenerating 3D realizations of the cosmic 21cm signal
• Three-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Foreground Polarization
• Revisiting the radio interferometer measurement equation. II. Calibration and direction-dependent effects
• The multi-frequency angular power spectrum of the epoch of reionization 21 cm signal
• The simulated 21 cm signal during the epoch of reionization : full modeling of the Ly-alpha pumping
• Low frequency observations of linearly polarized structures in the interstellar medium near the south Galactic pole
• The challenges of low-frequency radio polarimetry: lessons from the Murchison Widefield Array
• Towards simulating and quantifying the light-cone EoR 21-cm signal
• Spherical Harmonic Analyses of Intensity Mapping Power Spectra
• The Signature of Patchy Reionization in the Polarization Anisotropy of the CMB
• Diffuse polarized emission in the LOFAR Two-meter Sky Survey
• The POlarised GLEAM Survey (POGS) II: Results from an All-Sky Rotation Measure Synthesis Survey at Long Wavelengths
• Spatially Extended 21 cm Signal from Strongly Clustered UV and X-Ray Sources in the Early Universe
• Standard Model Prediction for Cosmological 21cm Circular Polarization

Cited by in corpus (1)

• Cross-correlation of the Polarizations of the 21-cm and Cosmic Microwave Backgrounds