The simulated 21 cm signal during the epoch of reionization : full modeling of the Ly-alpha pumping

Abstract

The 21 cm emission of neutral hydrogen is the most promising probe of the epoch of reionization(EoR). In the next few years, the SKA pathfinders will provide statistical measurements of this signal. Numerical simulations predicting these observations are necessary to optimize the design of the instruments. The main difficulty is the computation of the spin temperature of neutral hydrogen which depends on the gas kinetic temperature and on the level of the local Lyman-alpha flux. A T_s >> T_cmb assumption is usual. However, this assumption does not apply early in the reionization history, or even later in the history as long as the sources of X-rays are too weak to heat the intergalactic medium significantly. This work presents the first EoR numerical simulations including, beside dynamics and ionizing continuum radiative transfer, a self-consistent treatment of the Ly-alpha radiative transfer. This allows us to compute the spin temperature more accurately. We use two different box sizes, 20 Mpc/h and 100 Mpc/h, and a star source model. Using the redshift dependence of average quantities, maps, and power spectra, we quantify the effect of using different assumptions to compute the spin temperature and the influence of the box size. The first effect comes from allowing for a signal in absorption. The magnitude of this effect depends on the amount of heating by hydrodynamic shocks and X-rays in the intergalactic medium(IGM). The second effects comes from using the real, local, Lyman-alpha flux. This effect is important for an average ionization fraction of less than 10%: it changes the overall amplitude of the 21 cm signal, and adds its own fluctuations to the power spectrum.

20 pages, 16 figures, 2 tables, To be publish A&A. High resolution version available at http://aramis.obspm.fr/~baek/21cm_Lya.pdf

References in corpus (24)

• Wilkinson Microwave Anisotropy Probe (WMAP) Three Year Results: Implications for Cosmology
• Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Interpretation
• Observational constraints on Cosmic Reionization
• Transients from Initial Conditions in Cosmological Simulations
• 3D Lyman-alpha radiation transfer. I. Understanding Lyman-alpha line profile morphologies
• Efficient Simulations of Early Structure Formation and Reionization
• The morphology of HII regions during reionization
• 21 cm fluctuations from inhomogeneous X-ray heating before reionization
• Radiative transfer simulations of cosmic reionization I: methodology and initial results
• Simulating Cosmic Reionization at Large Scales II: the 21-cm Emission Features and Statistical Signals
• Self-regulated reionization
• Detecting the Rise and Fall of 21 cm Fluctuations with the Murchison Widefield Array
• TRAPHIC - Radiative Transfer for Smoothed Particle Hydrodynamics Simulations
• Cosmic Reionization and the 21-cm signal: Comparison between an analytical model and a simulation
• The Scattering of Lyman-series Photons in the Intergalactic Medium
• Lyman-alpha radiative transfer during the Epoch of Reionization: contribution to 21-cm signal fluctuations
• A Flat Photoionization Rate at 2<z<4.2: Evidence for a Stellar-Dominated UV Background and Against a Decline of Cosmic Star Formation Beyond z~3
• SPHRAY: A Smoothed Particle Hydrodynamics Ray Tracer for Radiative Transfer
• Higher Order Contributions to the 21 cm Power Spectrum
• Current models of the observable consequences of cosmic reionization and their detectability
• Redshifted 21 Centimeter Emission from Minihalos Before Reionization
• Detecting Early Galaxies Through Their 21-cm Signature
• Radiative Transfer Effect on Ultraviolet Pumping of the 21cm Line in the High Redshift Universe
• Radio views of cosmic reionization

Cited by in corpus (15)

• 21 cm signal from cosmic dawn: Imprints of spin temperature fluctuations and peculiar velocities
• Monte Carlo Radiative Transfer
• Emulation of reionization simulations for Bayesian inference of astrophysics parameters using neural networks
• Imaging the redshifted 21-cm pattern around the first sources during the cosmic dawn using the SKA
• 21SSD: a public database of simulated 21-cm signals from the epoch of reionization
• Probing the first galaxies with the SKA
• The reionization of galactic satellite populations
• Can the 21 cm signal probe Population III and II star formation?
• Cosmological implications of the composite spectra of galactic X-ray binaries constructed using MAXI data
• 21-cm signatures of residual HI inside cosmic HII regions during reionization
• Local reionizations histories with merger tree of HII regions
• SEURAT: SPH scheme extended with ultraviolet line radiative transfer
• Diversity of the Lyman continuum escape fractions of high-$z$ galaxies and its origins
• Gravitational Lensing Effect on the Two-Point Correlation Function of Hot Spots in 21 cm fluctuations
• Redshifted 21-cm Signals in the Dark Ages