Impact of reionization history on constraining primordial gravitational waves in future all-sky cosmic microwave background experiments

Abstract

We explore the impact of the reionization history on examining the shape of the power spectrum of the primordial gravitational waves (PGWs) with the cosmic microwave background (CMB) polarization. The large-scale CMB generated from the reionization epoch is important in probing the PGWs from all-sky experiments, such as LiteBIRD. The reionization model has been constrained by several astrophysical observations. However, its uncertainty could impact constraining models of the PGWs if we use large-scale CMB polarization. Here, by expanding the analysis of Mortonson & Hu (2007), we estimate how reionization uncertainty impacts constraints on a generic primordial tensor power spectrum. We assume that CMB polarization is measured by a LiteBIRD-like experiment and the tanh model is adopted for a theoretical template when we fit data. We show that constraints are almost unchanged even if the true reionization history is described by an exponential model, where all parameters are within 68% Confidence Level (CL). We also show an example of the reionization history that the constraints on the PGWs are biased more than 68% CL. Even in that case, using E-mode power spectrum on large scales would exclude such a scenario and make the PGW constraints robust against the reionization uncertainties.

arXiv comment10 pages, 6 figures

References in corpus (50)

• emcee: The MCMC Hammer
• Seven-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Interpretation
• Efficient Computation of CMB anisotropies in closed FRW models
• The Cosmic Linear Anisotropy Solving System (CLASS) II: Approximation schemes
• An All-Sky Analysis of Polarization in the Microwave Background
• Statistics of Cosmic Microwave Background Polarization
• Signature of Gravity Waves in Polarization of the Microwave Background
• BICEP / Keck XIII: Improved Constraints on Primordial Gravitational Waves using Planck, WMAP, and BICEP/Keck Observations through the 2018 Observing Season
• Reconstructing the Inflaton Potential --- an Overview
• A Probe of Primordial Gravity Waves and Vorticity
• Planck 2015 results. XI. CMB power spectra, likelihoods, and robustness of parameters
• A Survey of z>5.7 Quasars in the Sloan Digital Sky Survey IV: Discovery of Seven Additional Quasars
• The Quest for B Modes from Inflationary Gravitational Waves
• Hydrogen reionisation ends by $z=5.3$: Lyman-$\alpha$ optical depth measured by the XQR-30 sample
• The Universe Was Reionized Twice
• Improved limits on the tensor-to-scalar ratio using BICEP and Planck
• Likelihood Analysis of CMB Temperature and Polarization Power Spectra
• Measuring Polarization In Cosmic Microwave Background
• Cosmological parameters derived from the final (PR4) Planck data release
• Observations of the Lyman-$\alpha$ Universe
• Cosmic Microwave Background Probes Models of Inflation
• Efficient Cosmological Parameter Estimation from Microwave Background Anisotropies
• Maximum Likelihood algorithm for parametric component separation in CMB experiments
• Cosmological parameters from WMAP 5-year temperature maps
• Model-Independent Reionization Observables in the CMB
• Peeling off foregrounds with the constrained moment ILC method to unveil primordial CMB $B$-modes
• The Cosmic Microwave Background and the Ionization History of the Universe
• Simple foreground cleaning algorithm for detecting primordial B-mode polarization of the cosmic microwave background
• Complete Reionization Constraints from Planck 2015 Polarization
• Reionization inference from the CMB optical depth and E-mode polarization power spectra
• Cosmic Microwave Background Constraints in Light of Priors Over Reionization Histories
• Probing dark energy and neutrino mass from upcoming lensing experiments of CMB and galaxies
• The Simons Observatory: Constraining inflationary gravitational waves with multi-tracer B-mode delensing
• Measuring the reionization optical depth without large-scale CMB polarization
• Likelihood methods for CMB experiments
• Impact of reionization on CMB polarization tests of slow-roll inflation
• Retrieving cosmological information from small-scale CMB foregrounds II. The kinetic Sunyaev Zel'dovich effect
• Cosmic Reionization May Still Have Started Early and Ended Late: Confronting Early Onset with CMB Anisotropy and 21 cm Global Signals
• LiteBIRD Science Goals and Forecasts. A Case Study of the Origin of Primordial Gravitational Waves using Large-Scale CMB Polarization
• Multi-Clustering Needlet-ILC for CMB B-modes component separation
• LiteBIRD Science Goals and Forecasts: Improving Sensitivity to Inflationary Gravitational Waves with Multitracer Delensing
• The Dark Ages of the Universe and Hydrogen Reionization
• Reconstruction of primordial tensor power spectra from B-mode polarization of the cosmic microwave background
• Is patchy reionization an obstacle in detecting the primordial gravitational wave signal?
• Beyond optical depth: Future determination of ionization history from the CMB
• Reionization in the dark and the light from Cosmic Microwave Background
• Constraining the reionization history with CMB and spectroscopic observations
• Probing the Early History of Cosmic Reionization by Future Cosmic Microwave Background Experiments
• A framework to mitigate patchy reionization contamination on the primordial gravitational wave signal
• Cosmic microwave background constraints on the tensor-to-scalar ratio