The rich complexity of 21-cm fluctuations produced by the first stars

Abstract

We explore the complete history of the 21-cm signal in the redshift range z = 7-40. This redshift range includes various epochs of cosmic evolution related to primordial star formation, and should be accessible to existing or planned low-frequency radio telescopes. We use semi-numerical computational methods to explore the fluctuation signal over wavenumbers between 0.03 and 1 Mpc${}^{-1}$, accounting for the inhomogeneous backgrounds of Ly-$\alpha$, X-ray, Lyman-Werner and ionizing radiation. We focus on the recently noted expectation of heating dominated by a hard X-ray spectrum from high-mass X-ray binaries. We study the resulting delayed cosmic heating and suppression of gas temperature fluctuations, allowing for large variations in the minimum halo mass that contributes to star formation. We show that the wavenumbers at which the heating peak is detected in observations should tell us about the characteristic mean free path and spectrum of the emitted photons, thus giving key clues as to the character of the sources that heated the primordial Universe. We also consider the line-of-sight anisotropy, which allows additional information to be extracted from the 21-cm signal. For example, the heating transition at which the cosmic gas is heated to the temperature of the cosmic microwave background should be clearly marked by an especially isotropic power spectrum. More generally, an additional cross-power component $P_X$ directly probes which sources dominate 21-cm fluctuations. In particular, during cosmic reionization (and after the just-mentioned heating transition), $P_X$ is negative on scales dominated by ionization fluctuations and positive on those dominated by temperature fluctuations.

Accepted for publication in MNRAS, 13 pages, 7 figures, 2 tables

References in corpus (10)

• Cosmology at Low Frequencies: The 21 cm Transition and the High-Redshift Universe
• Effect of Primordial Black Holes on the Cosmic Microwave Background and Cosmological Parameter Estimates
• The Global 21 Centimeter Background from High Redshifts
• The CMBR fluctuations from HI perturbations prior to reionization
• Large-scale BAO signatures of the smallest galaxies
• The First Stars in The Universe
• The nature of dark matter from the global high redshift HI 21 cm signal
• The 21 cm Signature of Cosmic String Wakes
• Detecting Early Galaxies Through Their 21-cm Signature
• Will Nonlinear Peculiar Velocity and Inhomogeneous Reionization Spoil 21cm Cosmology from the Epoch of Reionization?

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