Related papers: Fluctuations in the High-Redshift Lyman-Werner and…
The first generation of stars produces a background of Lyman-Werner (LW) radiation which can photo-dissociate molecular hydrogen, increasing the mass of dark matter halos required to host star formation. Previous studies have determined the…
The earliest generation of stars and black holes must have established an early 'Lyman-Werner' background (LWB) at high redshift, prior to the epoch of reionization. Because of the long mean free path of photons with energies E<13.6 eV, the…
The first galaxies that formed at a redshift ~20-30 emitted continuum photons with energies between the Lyman-alpha and Lyman limit wavelengths of hydrogen, to which the neutral universe was transparent except at the Lyman-series…
The Lyman-Werner (LW) radiation field is a key ingredient in the chemo-thermal evolution of gas in the Early Universe, as it dissociates H2 molecules, the primary cooling channel in an environment devoid of metals and dust. Despite its…
The spectra of the first galaxies and quasars in the Universe should be strongly absorbed shortward of their rest-frame Lyman-alpha wavelength by neutral hydrogen (HI) in the intervening intergalactic medium. However, the Lyman-alpha line…
The Lyman alpha line is a robust tracer of high redshift galaxies. We present estimates of Lyman alpha emission from a protogalactic halo illuminated by UV background radiation fields with various intensities. For this purpose, we performed…
We explore the complete history of the 21-cm signal in the redshift range z = 7-40. This redshift range includes various epochs of cosmic evolution related to primordial star formation, and should be accessible to existing or planned…
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…
We consider the evolution of the sky-averaged 21 cm background during the early phases of structure formation. Using simple analytic models, we calculate the thermal and ionization histories, assuming that stellar photons dominate the…
Prior to the epoch of reionisation, the 21-cm signal of the cosmic dawn is dominated by the Lyman-$\alpha$ coupling and gas temperature fluctuations caused by the first sources of radiation. While early efforts to model this epoch relied on…
Before reionization, the intergalactic medium (IGM) may have been sufficiently cold for low-mass "minihalos" to condense out of the gas and subsequently affect reionization. Previous work has shown that minihalos generate reasonably large…
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…
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 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 present the first complete calculation of the history of the inhomogeneous 21-cm signal from neutral hydrogen during the era of the first stars. We use hybrid computational methods to capture the large-scale distribution of the first…
Some Lyman continuum photons are likely to escape from most galaxies, and these can play an important role in ionizing gas around and between galaxies, including gas that gives rise to Lyman alpha absorption. Thus the gas surrounding…
We present a suite of zoom-in cosmological hydrodynamical simulations of dwarf galaxies using the LYRA galaxy formation model with an extremely high mass resolution of $4\, \mathrm{M_{\odot}}$, evolved to $z=0$. The suite contains 65 haloes…
The observed scatter in intergalactic Lyman-$\alpha$ opacity at $z \lesssim 6$ requires large-scale fluctuations in the neutral fraction of the intergalactic medium (IGM) after the expected end of reionization. Post-reionization models that…
The first, self-consistent calculations are presented of the cosmological, H2-dissociating UV background produced during the epoch of reionization by the sources of reionization. Large-scale radiative transfer simulations of reionization…
The high-redshift 21-cm signal of neutral hydrogen is expected to be observed within the next decade and will reveal epochs of cosmic evolution that have been previously inaccessible. Due to the lack of observations, many of the…