Prospects of a statistical detection of the 21-cm forest and its potential to constrain the thermal state of the neutral IGM during reionization

Abstract

The 21-cm forest signal is a promising probe of the Epoch of Reionization complementary to other 21-cm line observables and Ly$\alpha$ forest signal. Prospects of detecting it have significantly improved in the last decade thanks to the discovery of more than 30 radio-loud quasars at these redshifts, upgrades to telescope facilities, and the notion that neutral hydrogen islands persist down to $z\lesssim 5.5$. We forward-model the 21-cm forest signal using semi-numerical simulations and incorporate various instrumental features to explore the potential of detecting the 21-cm forest at $z=6$, both directly and statistically, with the currently available (uGMRT) and forthcoming (SKA1-low) observatories. We show that it is possible to detect the 1D power spectrum of the 21-cm forest spectrum, especially at large scales of $k\lesssim 8.5\mathrm{MH}{\mathrm{z}}^{-1}$ with the $500\mathrm{hr}$ of the uGMRT time and $k\lesssim 32.4\mathrm{MH}{\mathrm{z}}^{-1}$ with the SKA1-low over $50\mathrm{hr}$ if the intergalactic medium (IGM) is $25\%$ neutral and these neutral hydrogen regions have a spin temperature of $\lesssim 30\mathrm{K}$. On the other hand, we infer that a null-detection of the signal with such observations of 10 radio-loud sources at $z\approx 6$ can be translated into constraints on the thermal and ionization state of the IGM which are tighter than the currently available measurements. Moreover, a null-detection of the 1D 21-cm forest power spectrum with only $50\mathrm{hr}$ of the uGMRT observations of 10 radio-loud sources can already be competitive with the Ly$\alpha$ forest and 21-cm tomographic observations in disfavouring models of significantly neutral and cold IGM at $z=6$.

15 pages, 16 figures. Accepted for publiction in MNRAS

References in corpus (30)

• Array Programming with NumPy
• Cosmology at Low Frequencies: The 21 cm Transition and the High-Redshift Universe
• The LOFAR Two-metre Sky Survey - I. Survey Description and Preliminary Data Release
• Model-independent evidence in favor of an end to reionization by z~6
• Evidence of patchy hydrogen reionization from an extreme Ly$\alpha$ trough below redshift six
• Improved upper limits on the 21-cm signal power spectrum of neutral hydrogen at $\mathbf{z}\approx 9.1$ from LOFAR
• The Global 21 Centimeter Background from High Redshifts
• Deep multi-redshift limits on Epoch of Reionisation 21cm Power Spectra from Four Seasons of Murchison Widefield Array Observations
• The low-frequency environment of the Murchison Widefield Array: radio-frequency interference analysis and mitigation
• 21cmFAST v3: A Python-integrated C code forgenerating 3D realizations of the cosmic 21cm signal
• Constraining the radio-loud fraction of quasars at z>5.5
• The LOFAR Two Metre Sky Survey: Deep Fields Data Release 1 -- III. Host-galaxy identifications and value added catalogues
• Anticipated Performance of the Square Kilometre Array -- Phase 1 (SKA1)
• The PHLEK Survey: A New Determination of the Primordial Helium Abundance
• The discovery of a highly accreting, radio-loud quasar at z=6.82
• Modelling the observed luminosity function and clustering evolution of Lyman-$\alpha$ emitters: growing evidence for late reionization
• Damping Wing-Like Features in the Stacked Ly$\alpha$ Forest: Potential Neutral Hydrogen Islands at $z<6$
• Probing small-scale cosmological fluctuations with the 21 cm forest: effects of neutrino mass, running spectral index and warm dark matter
• Detecting ionized bubbles in redshifted 21 cm maps
• Constraining the quasar radio-loud fraction at $z\sim 6$ with deep radio observations
• Discovery of 24 radio-bright quasars at $4.9\le z\le 6.6$ using low-frequency radio observations
• Radio Detection of VIK J2318$-$3113, the Most Distant Radio-Loud Quasar ($z$=6.44)
• The earliest galaxies seen in 21 cm line absorption
• A search for HI 21cm absorption toward the highest redshift radio loud objects
• The detectability of strong 21 centimetre forest absorbers from the diffuse intergalactic medium in late reionisation models
• Statistical Detection of IGM Structures during Cosmic Reionization using Absorption of the Redshifted 21 cm line by HI against Compact Background Radio Sources
• 21cm forest probes on the axion dark matter in the post-inflationary Peccei-Quinn symmetry breaking scenarios
• No strong radio absorption detected in the low-frequency spectra of radio-loud quasars at z > 5.6
• Forecasting constraints on the high-z IGM thermal state from the Lyman-$\alpha$ forest flux auto-correlation function
• Cospatial 21 cm and metal-line absorbers in the epoch of reionization -- I : Incidence and observability