Impact of Galactic dust non-Gaussianity on searches for B-modes from inflation

Abstract

A key challenge in the search for primordial B-modes is the presence of polarized Galactic foregrounds, especially thermal dust emission. Power-spectrum-based analysis methods generally assume the foregrounds to be Gaussian random fields when constructing a likelihood and computing the covariance matrix. In this paper, we investigate how non-Gaussianity in the dust field instead affects CMB and foreground parameter inference in the context of inflationary B-mode searches, capturing this effect via modifications to the dust power-spectrum covariance matrix. For upcoming experiments such as the Simons Observatory, we find no dependence of the tensor-to-scalar ratio uncertainty $\sigma (r)$ on the degree of dust non-Gaussianity or the nature of the dust covariance matrix. We provide an explanation of this result, noting that when frequency decorrelation is negligible, dust in mid-frequency channels is cleaned using high-frequency data in a way that is independent of the spatial statistics of dust. We show that our results hold also for non-zero levels of frequency decorrelation that are compatible with existing data. We find, however, that neglecting the impact of dust non-Gaussianity in the covariance matrix can lead to inaccuracies in goodness-of-fit metrics. Care must thus be taken when using such metrics to test B-mode spectra and models, although we show that any such problems can be mitigated by using only cleaned spectrum combinations when computing goodness-of-fit statistics.

16 pages, 8 figures, accepted version

References in corpus (40)

• The NumPy array: a structure for efficient numerical computation
• Three Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Polarization Analysis
• A Joint Analysis of BICEP2/Keck Array and Planck Data
• BICEP / Keck XIII: Improved Constraints on Primordial Gravitational Waves using Planck, WMAP, and BICEP/Keck Observations through the 2018 Observing Season
• SPT-3G: A Next-Generation Cosmic Microwave Background Polarization Experiment on the South Pole Telescope
• Improved limits on the tensor-to-scalar ratio using BICEP and Planck
• Planck intermediate results. XXII. Frequency dependence of thermal emission from Galactic dust in intensity and polarization
• CLASS: The Cosmology Large Angular Scale Surveyor
• Mapping the Magnetic Interstellar Medium in Three Dimensions Over the Full Sky with Neutral Hydrogen
• On the assumption of Gaussianity for cosmological two-point statistics and parameter dependent covariance matrices
• Statistical properties of dust far-infrared emission
• Polarized CMB power spectrum estimation using the pure pseudo-cross-spectrum approach
• Planck intermediate results. L. Evidence for spatial variation of the polarized thermal dust spectral energy distribution and implications for CMB $B$-mode analysis
• Cosmic shear power spectra in practice
• Forecasting performance of CMB experiments in the presence of complex foreground contaminations
• Evidence for Line-of-Sight Frequency Decorrelation of Polarized Dust Emission in $Planck$ Data
• Measurement of CIB power spectra over large sky areas from Planck HFI maps
• A 3-D model of polarised dust emission in the Milky Way
• The Simons Observatory: Constraining inflationary gravitational waves with multi-tracer B-mode delensing
• Statistical description of dust polarized emission from the diffuse interstellar medium -- A RWST approach
• The Simons Observatory: gain, bandpass and polarization-angle calibration requirements for B-mode searches
• Simulated forecasts for primordial B-mode searches in ground-based experiments
• Component separation with flexible models. Application to the separation of astrophysical emissions
• Frequency dependence of the thermal dust $E/B$ ratio and $EB$ correlation: insights from the spin-moment expansion
• BICEP / Keck XVI: Characterizing Dust Polarization through Correlations with Neutral Hydrogen
• Full-sky, arcminute-scale, 3D models of Galactic microwave foreground dust emission based on filaments
• Dust polarization spectral dependence from Planck HFI data. Turning point on CMB polarization foregrounds modelling
• Delensing the CMB with the cosmic infrared background: the impact of foregrounds
• Determination of Polarization Angles in CMB Experiments and Application to CMB Component Separation Analyses
• A practical guide to Basic Statistical Techniques for Data Analysis in Cosmology
• Estimating the tensor-to-scalar ratio and the effect of residual foreground contamination
• Morphological Analysis of the Polarized Synchrotron Emission with WMAP and Planck
• A hybrid map-$C_{\ell }$ component separation method for primordial CMB $B$-mode searches
• Foreground Bias From Parametric Models of Far-IR Dust Emission
• Characterizing line-of-sight variability of polarized dust emission with future CMB experiments
• Testing for spectral index variations in polarised CMB foregrounds
• B-mode constraints from Planck low multipole polarisation data
• Mitigating Bias in CMB B-modes from Foreground Cleaning Using a Moment Expansion
• Prescription for Cosmic Information Extraction from Multiple Sky Maps
• Characterization of the polarized synchrotron emission from Planck and WMAP data

Cited by in corpus (3)

• How bad could it be? Modelling the 3D complexity of the polarised dust signal using moment expansion
• The Simons Observatory: Assessing the Impact of Dust Complexity on the Recovery of Primordial $B$-modes
• ForSE+: Simulating non-Gaussian CMB foregrounds at 3 arcminutes in a stochastic way based on a generative adversarial network