The Dark Ages' 21-cm Trispectrum

Abstract

We investigate tomography of 21-cm brightness temperature fluctuations during the Dark Ages as a probe for constraining primordial non-Gaussianity. We expand the 21- cm brightness temperature up to cubic order in perturbation theory and improve previous models of the signal by including the effect of the free electron fraction. Using modified standard perturbation theory methods that include baryonic pressure effects we derive an improved secondary bispectrum and for the first time derive the secondary trispectrum of 21-cm brightness temperature fluctuations. We then forecast the amount of information available from the Dark Ages to constrain primordial non-Gaussianity, including the imprints of massive particle exchange during inflation and we determine how much signal is lost due to secondary non-Gaussianity. We find that although secondary non-Gaussianity swamps the primordial signal, primordial non-Gaussianity can still be extracted with signal-to-noise ratios that surpass current and future CMB experiments by several orders of magnitude, depending on the experimental setup. Furthermore, we conclude that for the bi- and trispectra of massive particle exchange marginalizing over other primordial shapes affects signal-to-noise ratios more severely than secondary shapes. Baryonic pressure effects turn out to have a negligible impact on our forecasts, even at scales close to the Jeans scale. The results of this work reinforce the prospects of 21-cm brightness temperature fluctuations from the Dark Ages as the ultimate probe for primordial non-Gaussianity.

47 pages, 20 figures, code available at https://github.com/tsfloss/21-cm-Dark-Ages-Fisher-Forecast. v2: minor typos corrected. v3: matches published version

References in corpus (17)

• Cosmology at Low Frequencies: The 21 cm Transition and the High-Redshift Universe
• The Effective Field Theory of Inflation
• The Epoch of Reionization Window: I. Mathematical Formalism
• Cosmological Collider Physics
• Non-Gaussianity in the modulated reheating scenario
• The Epoch of Reionization Window: II. Statistical Methods for Foreground Wedge Reduction
• Adaptive Multidimensional Integration: VEGAS Enhanced
• The 21cm angular-power spectrum from the dark ages
• 21-cm Background Anisotropies Can Discern Primordial Non-Gaussianity
• The bispectrum of redshifted 21-cm fluctuations from the dark ages
• Standard Clock in Primordial Density Perturbations and Cosmic Microwave Background
• Third-order Perturbation Theory With Non-linear Pressure
• Primordial Non-Gaussianity
• Deconvolving the Wedge: Maximum-Likelihood Power Spectra via Spherical-Wave Visibility Modeling
• Optimal analysis of the CMB trispectrum
• Linear effects of perturbed recombination
• Exploring the Cosmic Dawn with NenuFAR

Cited by in corpus (11)

• Large Spin-2 Signals at the Cosmological Collider
• Prospects for precision cosmology with the 21 cm signal from the dark ages
• Primordial non-Gaussianity and non-Gaussian Covariance
• How informative are summaries of the cosmic 21-cm signal?
• Improving constraints on primordial non-Gaussianity using neural network based reconstruction
• Cosmology in nonlocal gravity
• Cosmic mysteries and the hydrogen 21-cm line: bridging the gap with lunar observations
• Non-Gaussianities in generalized non-local $R^2$-like inflation
• Modes of the Dark Ages 21cm field accessible to a lunar radio interferometer
• The impact of lunar topography on the 21-cm power spectrum for grid-based arrays : Insights for the Dark-ages EXplorer (DEX)
• Primordial black holes and the velocity acoustic oscillations features in 21 cm signals from the cosmic Dark Ages