Reconstructing the nature of the first cosmic sources from the anisotropic 21-cm signal

Abstract

The redshifted 21-cm background is expected to be a powerful probe of the early Universe, carrying both cosmological and astrophysical information from a wide range of redshifts. In particular, the power spectrum of fluctuations in the 21-cm brightness temperature is anisotropic due to the line-of-sight velocity gradient, which in principle allows for a simple extraction of this information in the limit of linear fluctuations. However, recent numerical studies suggest that the 21-cm signal is actually rather complex, and its analysis likely depends on detailed model fitting. We present the first realistic simulation of the anisotropic 21-cm power spectrum over a wide period of early cosmic history. We show that on observable scales, the anisotropy is large and thus measurable at most redshifts, and its form tracks the evolution of 21-cm fluctuations as they are produced early on by Lyman-a radiation from stars, then switch to X-ray radiation from early heating sources, and finally to ionizing radiation from stars. In particular, we predict a redshift window during cosmic heating (at z ~ 15), when the anisotropy is small, during which the shape of the 21-cm power spectrum on large scales is determined directly by the average radial distribution of the flux from X-ray sources. This makes possible a model-independent reconstruction of the X-ray spectrum of the earliest sources of cosmic heating.

arXiv commentAccepted for publication in PRL, 6 pages, 2 figures

References in corpus (27)

• In the Beginning: The First Sources of Light and the Reionization of the Universe
• 21-cm Tomography of the Intergalactic Medium at High Redshift
• 21cmFAST: A Fast, Semi-Numerical Simulation of the High-Redshift 21-cm Signal
• Cosmological Parameter Estimation Using 21 cm Radiation from the Epoch of Reionization
• What Next-Generation 21 cm Power Spectrum Measurements Can Teach Us About the Epoch of Reionization
• Reionization and the Cosmic Dawn with the Square Kilometre Array
• Four Fundamental Foreground Power Spectrum Shapes for 21 cm Cosmology Observations
• Unusually Large Fluctuations in the Statistics of Galaxy Formation at High Redshift
• The Global 21 Centimeter Background from High Redshifts
• Detecting the Earliest Galaxies Through Two New Sources of 21cm Fluctuations
• The Epoch of Reionization Window: I. Mathematical Formalism
• New Limits on 21cm EoR From PAPER-32 Consistent with an X-Ray Heated IGM at z=7.7
• 21 cm fluctuations from inhomogeneous X-ray heating before reionization
• A Method for Separating the Physics from the Astrophysics of High-Redshift 21cm Fluctuations
• Stellar black holes at the dawn of the universe
• Energy Feedback from X-ray Binaries in the Early Universe
• The CMBR fluctuations from HI perturbations prior to reionization
• The impact of point source subtraction residuals on 21 cm Epoch of Reionization estimation
• The observable signature of late heating of the Universe during cosmic reionization
• Opening the 21cm EoR Window: Measurements of Foreground Isolation with PAPER
• The X-ray spectra of the first galaxies: 21cm signatures
• Redshift Space Distortion of the 21cm Background from the Epoch of Reionization I: Methodology Re-examined
• Probing reionization with LOFAR using 21-cm redshift space distortions
• The rich complexity of 21-cm fluctuations produced by the first stars
• The First Stars in the Universe and Cosmic Reionization
• Light cone anisotropy in 21 cm signal from the epoch of reionization
• Will Nonlinear Peculiar Velocity and Inhomogeneous Reionization Spoil 21cm Cosmology from the Epoch of Reionization?

Cited by in corpus (26)

• Eliminating the optical depth nuisance from the CMB with 21 cm cosmology
• Quantifying the non-Gaussianity in the EoR 21-cm signal through bispectrum
• The Rise of the First Stars: Supersonic Streaming, Radiative Feedback, and 21-cm Cosmology
• Constraining the redshifted 21-cm signal with the unresolved soft X-ray background
• Robust Velocity-induced Acoustic Oscillations at Cosmic Dawn
• 21cm-line bispectrum as method to probe Cosmic Dawn and Epoch of Reionization
• A Standard Ruler at Cosmic Dawn
• 21-cm signal from cosmic dawn - II: Imprints of the light-cone effects
• Supermassive Black Holes in the Early Universe
• Charting the Parameter Space of the 21-cm Power Spectrum
• Statistics of the epoch of reionization 21-cm signal - I. Power spectrum error-covariance
• Redshifted 21-cm Bispectrum I: Impact of the Redshift Space Distortions on the Signal from the Epoch of Reionization
• Redshift-space distortions in simulations of the 21-cm signal from the cosmic dawn
• Redshifted 21-cm bispectrum II: Impact of the spin temperature fluctuations and redshift space distortions on the signal from the Cosmic Dawn
• Effects of the sources of reionization on 21-cm redshift-space distortions
• An Effective Bias Expansion for 21 cm Cosmology in Redshift Space
• 21cm Global Signal Extraction: Extracting the 21cm Global Signal using Artificial Neural Networks
• Photoevaporation of Minihalos during Cosmic Reionization: Primordial and Metal-Enriched Halos
• An Analytic Formulation of 21-cm Signal from Early Phase of Epoch of Reionization
• Extracting the Global Signal from 21-cm Fluctuations: the Multi-Tracer Approach
• Cosmic mysteries and the hydrogen 21-cm line: bridging the gap with lunar observations
• Line of sight anisotropies in the Cosmic Dawn and EoR 21-cm power spectrum
• Analytic Formulation of 21 cm Signal from Cosmic Dawn: Ly$\alpha$ Fluctuations
• In Search of Global 21-cm Signal using Artificial Neural Network in light of ARCADE 2
• Impact of anisotropic photon emission from sources during the epoch of reionisation
• Probing dark energy using anisotropies in the clustering of post-EoR HI distribution