Related papers: Wouthuysen-Field Coupling in the 21 cm Region Arou…
We study the Wouthuysen-Field coupling at early universe with numerical solutions of the integrodifferential equation describing the kinetics of photons undergoing resonant scattering. The numerical solver is developed based on the weighted…
The first UV sources in the universe are expected to have coupled the HI spin temperature to the gas kinetic temperature via scattering in the Lyman-alpha resonance [the Wouthuysen-Field (WF) effect]. By establishing an HI spin temperature…
We examine the effect of Lyman continuum photons on the 21 cm background in the high-redshift universe. The brightness temperature of this transition is determined by the spin temperature T_s, which describes the relative populations of the…
We develop a numerical solver for the integral-differential equations, which describes the radiative transfer of photon distribution in the frequency space with resonant scattering of Lyalpha photons by hydrogen gas in the early universe.…
Lyman-$\alpha$ photons enable the cosmic dawn 21-cm signal through a process called the Wouthuysen-Field effect. An accurate model of the signal in this epoch hinges on the accuracy of the computation of the Ly$\alpha$ coupling, which…
The scattering of Ly$\alpha$ photons from the first radiating sources in the Universe plays a pivotal role in 21-cm radio detections of Cosmic Dawn and the Epoch of Reionization through the Wouthuysen-Field effect. New data from JWST show…
We show that, due to the high optical depth of the intergalactic medium to Lyman-alpha photons before the Epoch of Reionization, the Lyman-alpha scattering rate responsible for the Wouthuysen-Field effect from an isolated source will be…
The EDGES experiment recently announced evidence for a broad absorption feature in the sky-averaged radio spectrum around 78 MHz, as may result from absorption in the 21 cm line by neutral hydrogen at z~15-20. If confirmed, one implication…
Observations of the redshifted 21 cm line with upcoming radio telescopes promise to transform our understanding of the cosmic reionization. To unravel the underlying physical process, we investigate the 21 cm structures of three different…
During the epoch of reionization the 21cm signal is sensitive to the scattering rate of the ultraviolet photons, redshifting across the Lyman_alpha resonance. Here we calculate the photon scattering rate profile for a single ultraviolet…
We investigate the interaction of Lyman alpha photons produced by the first stars in the universe with the intergalactic medium (IGM) prior to reionization. The background Lyman alpha spectral profile is obtained by solving a Fokker-Planck…
We use a new method to model fluctuations of the Lyman-Werner (LW) and Lyman-alpha radiation backgrounds at high redshift. At these early epochs the backgrounds are symptoms of a universe newly lit with its first stars. LW photons…
The formation of the first stars is an exciting frontier area in astronomy. Early redshifts z ~ 20 have become observationally promising as a result of a recently recognized effect of a supersonic relative velocity between the dark matter…
Lyman-alpha (Ly{\alpha}) photons from ionizing sources and cooling radiation undergo a complex resonant scattering process that generates unique spectral signatures in high-redshift galaxies. We present a detailed Ly{\alpha} radiative…
A formal derivation is presented of the energy transfer rate between radiation and matter due to the scattering of an isotropic distribution of resonant photons. The derivation is developed in the context of the two-level atom in the…
The 21-cm signal in the vicinity of the first stars is expected to reflect properties of the first stars. In this study we pay special attention to tracing the time evolution of the ionizing photons' escape fraction, which affects the…
During the epoch of reionization, Ly-alpha photons emitted by the first stars can couple the neutral hydrogen spin temperature to the kinetic gas temperature, providing the opportunity to observe the gas in emission or absorption in the…
The tentative detection by the EDGES experiment of a global 21-cm absorption trough centered at redshift 17 opens up the opportunity to study the birth of the first luminous sources, the intensity of radiation backgrounds at cosmic dawn,…
We review some of the fundamental physics necessary for computing the highly-redshifted spin-flip background. We first discuss the radiative transfer of the 21-cm line and define the crucial quantities of interest. We then review the…
A crucial physical quantity in determining the 21-cm signal during cosmic dawn is the inhomogeneous background of Ly$\alpha$ photons originating from the first galaxies. As these photons travel through the intergalactic medium, their…