Towards simulating and quantifying the light-cone EoR 21-cm signal

Abstract

The light-cone (LC) effect causes the Epoch of Reionization (EoR) 21-cm signal $T_{\mathrm{b}}(\hat{\mathbf{n}},\nu )$ to evolve significantly along the line of sight (LoS) direction $\nu$. In the first part of this paper, we present a method to properly incorporate the LC effect in simulations of the EoR 21-cm signal that include peculiar velocities. Subsequently, we discuss how to quantify the second order statistics of the EoR 21-cm signal in the presence of the LC effect. We demonstrate that the 3D power spectrum $P(\mathbf{k})$ fails to quantify the entire information because it assumes the signal to be ergodic and periodic, whereas the LC effect breaks these conditions along the LoS. Considering a LC simulation centered at redshift $8$ where the mean neutral fraction drops from $0.65$ to $0.35$ across the box, we find that $P(\mathbf{k})$ misses out $\sim 40\%$ of the information at the two ends of the $17.41\mathrm{MHz}$ simulation bandwidth. The multi-frequency angular power spectrum (MAPS) ${\mathcal{C}}_{\ell }({\nu }_1,{\nu }_2)$ quantifies the statistical properties of $T_{\mathrm{b}}(\hat{\mathbf{n}},\nu )$ without assuming the signal to be ergodic and periodic along the LoS. We expect this to quantify the entire statistical information of the EoR 21-cm signal. We apply MAPS to our LC simulation and present preliminary results for the EoR 21-cm signal.

Published in Monthly Notices of the Royal Astronomical Society (MNRAS). Available at http://dx.doi.org/10.1093/mnras/stx2888

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Cited by in corpus (3)

• The impact of non-Gaussianity on the error covariance for observations of the Epoch of Reionization 21-cm power spectrum
• Deconvolving the Wedge: Maximum-Likelihood Power Spectra via Spherical-Wave Visibility Modeling
• A Tapered Gridded Estimator (TGE) for the Multi-Frequency Angular Power Spectrum (MAPS) and the Cosmological HI 21-cm Power Spectrum