The Impact of Neutral Intergalactic Gas on Lyman-$\alpha$ Intensity Mapping During Reionization

Abstract

We present the first simulations of the high-redshift Ly$\alpha$ intensity field that account for scattering in the intergalactic medium (IGM). Using a 3D Monte Carlo radiative transfer code, we find that Ly$\alpha$ scattering smooths spatial fluctuations in the Ly$\alpha$ intensity on small scales and that the spatial dependence of this smoothing depends strongly on the mean neutral fraction of the IGM. Our simulations find a strong effect of reionization on $k=0.1-1\mathrm{Mp}{\mathrm{c}}^{-1}$, with $P_{\mathrm{Ly}\alpha }\propto k^{-1.75}$ for ${\bar{x}}_{\mathrm{HI}}=0.63$ and $P_{\mathrm{Ly}\alpha }\propto k^{-2.2}$ for ${\bar{x}}_{\mathrm{HI}}=0.86$ in contrast to $P_{\mathrm{Ly}\alpha }\propto k^{-1.5}$ after reionization. At wavenumbers of $k>1\mathrm{Mp}{\mathrm{c}}^{-1}$, we find that the signal is sensitive to the emergent Ly$\alpha$ line profiles from galaxies. We also demonstrate that the cross-correlation between a Ly$\alpha$ intensity map and a future galaxy redshift survey could be detected on large scales by an instrument similar to SPHEREx, and over a wide range of scales by a hypothetical intensity mapping instrument in the vein of CDIM.

7 pages, 4 figures, submitted to ApJL

References in corpus (7)

• UV Luminosity Functions at redshifts z~4 to z~10: 10000 Galaxies from HST Legacy Fields
• A galaxy at a redshift z = 6.96
• 21 cm fluctuations from inhomogeneous X-ray heating before reionization
• Systematic Identification of LAEs for Visible Exploration and Reionization Research Using Subaru HSC (SILVERRUSH). I. Program Strategy and Clustering Properties of ~2,000 Lya Emitters at z=6-7 over the 0.3-0.5 Gpc${}^2$ Survey Area
• Can the intergalactic medium cause a rapid drop in Lyman alpha emission at z>6?
• Lyman-alpha emitters gone missing: evidence for late reionization?
• Lyman alpha Resonant Scattering in Young Galaxies - Predictions from Cosmological Simulations

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