Cosmic Reionization On Computers. Mean and Fluctuating Redshifted 21 cm Signal

Abstract

We explore the mean and fluctuating redshifted 21 cm signal in numerical simulations of cosmic reionization from the Cosmic Reionization On Computers (CROC) project. We find that the mean signal varies between about $\pm 20\mathrm{mK}$. Most significantly, we find that the negative pre-reionization dip at $z\sim 10-15$ only extends to $⟨\Delta T_B⟩\sim -20\mathrm{mK}$, in agreement with prior simulation results and in significant contrast to Pritchard & Loeb analytical model, requiring substantially higher sensitivity from global signal experiments that operate in this redshift range (EDGES-II, LEDA, SCI-HI, and DARE). We also explore the role of dense substructure (filaments and embedded galaxies) in the formation of 21 cm power spectrum. We find that by neglecting the semi-neutral substructure inside ionized bubbles, the power spectrum can be mis-estimated by 25-50\% at scales $k\sim 0.1-1h{\mathrm{Mpc}}^{-1}$. This scale range is of a particular interest, because the upcoming 21 cm experiments (MWA, PAPER, HERA) are expected to be most sensitive within it.

8 pages, 8 figures

References in corpus (8)

• Evolution of the 21 cm signal throughout cosmic history
• Cosmic Reionization On Computers I. Design and Calibration of Simulations
• Detecting the Rise and Fall of 21 cm Fluctuations with the Murchison Widefield Array
• BIGHORNS - Broadband Instrument for Global HydrOgen ReioNisation Signal
• Cosmic Reionization On Computers II. Reionization History and Its Back Reaction on Early Galaxies
• Multi-redshift limits on the 21cm power spectrum from PAPER
• SARAS measurement of the Radio Background at long wavelengths
• Low-mass galaxy formation and the ionizing photon budget during reionization

Cited by in corpus (9)

• Introducing the THESAN project: radiation-magnetohydrodynamic simulations of the epoch of reionization
• Results from EDGES High-Band: I. Constraints on Phenomenological Models for the Global $21$ cm Signal
• Emulating Simulations of Cosmic Dawn for 21cm Power Spectrum Constraints on Cosmology, Reionization, and X-ray Heating
• Calibration of the EDGES High-Band Receiver to Observe the Global 21-cm Signature from the Epoch of Reionization
• The THESAN project: predictions for multi-tracer line intensity mapping in the epoch of reionization
• Robust Velocity-induced Acoustic Oscillations at Cosmic Dawn
• Models of the Cosmological 21 cm Signal from the Epoch of Reionization Calibrated with Lyman-alpha and CMB Data
• An Effective Bias Expansion for 21 cm Cosmology in Redshift Space
• On improving analytical models of cosmic reionization for matching numerical simulation