Probing the Intergalactic Medium with Ly$\alpha$ and 21 cm Fluctuations

Abstract

We study 21cm and Ly$\alpha$ fluctuations, as well as H$\alpha$, while distinguishing between Ly$\alpha$ emission of galactic, diffuse, and scattered intergalactic medium (IGM) origin. Cross-correlation information about the state of the IGM is obtained, testing neutral versus ionized medium cases with different tracers in a seminumerical simulation setup. In order to pave the way toward constraints on reionization history and modeling beyond power spectrum information, we explore parameter dependencies of the cross-power signal between 21cm and Ly$\alpha$, which displays a characteristic morphology and a turnover from negative to positive correlation at scales of a couple Mpc${}^{-1}$. In a proof of concept for the extraction of further information on the state of the IGM using different tracers, we demonstrate the use of the 21cm and H$\alpha$ cross-correlation signal to determine the relative strength of galactic and IGM emission in Ly$\alpha$. We conclude by showing the detectability of the 21cm and Ly$\alpha$ cross-correlation signal over more than one decade in scale at high signal-to-noise ratio for upcoming probes like SKA and the proposed all-sky intensity mapping satellites SPHEREx and CDIM, while also including the Ly$\alpha$ damping tail and 21cm foreground avoidance in the modeling.

26 pages, 18 figures, 3 tables. Accepted for publication in ApJ

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• Coupling parsec and gigaparsec scales: primordial non-Gaussianity with multi-tracer intensity mapping
• LIMFAST. II. Line Intensity Mapping as a Probe of High-Redshift Galaxy Formation
• LIMFAST. I. A Semi-Numerical Tool for Line Intensity Mapping
• The Impact of Neutral Intergalactic Gas on Lyman-$\alpha$ Intensity Mapping During Reionization
• Optimal survey parameters: Ly$\alpha$ and H$\alpha$ intensity mapping for synergy with the 21cm signal during reionization
• General Modified Gravity With 21cm Intensity Mapping: Simulations and Forecast
• Probing Population III Initial Mass Functions with He II/H$\alpha$ Intensity Mapping
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• Survey parameters for detecting 21cm - Ly$\alpha$ emitter cross correlations with the Square Kilometre Array
• Exploring the cosmic dawn and epoch of reionization with 21cm line
• The spin-temperature dependence of the 21cm -- LAE cross-correlation
• The THESAN project: Lyman-alpha emitter luminosity function calibration
• Detectability of 21cm-signal during the Epoch of Reionization with 21cm-Lyman-α emitter cross-correlation. II. Foreground contamination
• On the general nature of 21cm-Lyman-$\alpha$ emitters cross-correlations during reionisation
• Prospects for Observing the low-density Cosmic Web in Lyman-alpha Emission
• Probing the Diffuse Lyman-alpha Emission on Cosmological Scales: Lyα Emission Intensity Mapping Using the Complete SDSS-IV eBOSS Survey
• Estimating the Feasibility of 21cm-Ly$\alpha$ Synergies using the Hydrogen Epoch of Reionization Array
• Antisymmetric cross-correlation of line-intensity maps as a probe of reionization
• Predicting 21cm-line map from Lyman $\alpha$ emitter distribution with Generative Adversarial Networks
• Constraining the 21cm brightness temperature of the IGM at $z$=6.6 around LAEs with the Murchison Widefield Array
• SIMPLE: Simple Intensity Map Producer for Line Emission
• Lyman-$\alpha$ polarization from cosmological ionization fronts: II. Implications for intensity mapping
• The 21cm-galaxy cross-correlation: Realistic forecast for 21cm signal detection and reionisation constraints
• Narrowing the discovery space of the cosmological 21-cm signal using multi-wavelength constraints
• Mapping Large-Scale-Structure Evolution over Cosmic Times
• Revealing the formation histories of the first stars with the cosmic near-infrared background
• A New Boundary Condition on Reionization
• Nearest Neighbour-Based Statistics for 21cm-Galaxy Cross-Correlations in the Epoch of Reionization