Related papers: The Wouthuysen-Field effect in a clumpy intergalac…
Ly$\alpha$ intensity mapping is emerging as a new probe of faint galaxies consisting the cosmic web that elude traditional surveys. However, the resonant nature of Ly$\alpha$ radiative transfer complicates the interpretation of observed…
We calculate the intergalactic photon density as a function of both energy and redshift for 0 < z < 6 for photon energies from .003 eV to the Lyman limit cutoff at 13.6 eV in a Lambda-CDM universe with $\Omega_{\Lambda} = 0.7$ and…
The visibility of the Lyman-$\alpha$ (Ly$\alpha$) emission from reionization-epoch galaxies depends sensitively on the extent of the intrinsic \lya emission redwards of 1215.67~\AA. The prominent red peak resulting from resonant radiative…
A variety of independent observational studies have now reported a significant decline in the fraction of Lyman-break galaxies which exhibit Ly-a emission over the redshift interval z=6-7. In combination with the strong damping wing…
Cosmic rays are thought to escape their sources streaming along the local magnetic field lines. We show that this phenomenon generally leads to the excitation of both resonant and non-resonant streaming instabilities. The self-generated…
Scattering of Lyman Alpha (hereafter Lya) photons by neutral hydrogen gas in a single outflowing 'supershell' around star forming regions often explains the shape and offset of the observed Lya emission line from galaxies. We compute the…
High-redshift QSO spectra show large spatial fluctuations in the Ly-alpha opacity of the intergalactic medium on surprisingly large scales at z>~5.5. We present a radiative transfer simulation of cosmic reionization driven by galaxies that…
We report the observation of a further asymmetric, extended Lyman alpha emitting halo at z=2.63, from our ultra-deep, long-slit spectroscopic survey of faint high redshift emitters, undertaken with Magellan LDSS3 in the GOODS-S field. The…
Magnetic fields in the early universe can significantly alter the thermal evolution and the ionization history during the dark ages. This is reflected in the 21 cm line of atomic hydrogen, which is coupled to the gas temperature through…
We present an analysis of HI Lyman-alpha emission in deep VLT/MUSE observations of two highly magnified and extended galaxies at z=3.5 and 4.03, including a newly discovered, almost complete Einstein ring. While these Lyman-alpha haloes are…
The inhomogeneous cosmological reionization process leaves tangible imprints in the intergalactic medium down to z=4-5. The Lyman-alpha forest flux power spectrum provides a potentially powerful probe of the epoch of reionization. With the…
The conditions within the ionization front of a quasar during reionization (T ~ 30,000 K, neutral hydrogen fraction ~ 0.5) are ideal for producing Lyman-alpha emission via collisional excitation of hydrogen atoms. Observations of this…
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 develop an efficient method to study the effects of reionization history on the temperature-density relation of the intergalactic medium in the low density limit (overdensity less than 5). It is applied to the study of photo-reionization…
Halpha and Hbeta spectroscopy with the Wisconsin H-Alpha Mapper (WHAM) reveals a strong concentration of high velocity emission in a ~ 5 by 5 deg area centered near (l.b) = (27,-3), known as the Scutum Cloud. The high velocities imply that…
We use a large set of hydrodynamical simulations, combined with measurements of the Lyman alpha opacity of the IGM taken from the literature, to obtain robust estimates for the photoionization rate per hydrogen atom at z=5 and 6. We find…
We quantify the directional dependence of the escape fraction of Lyman-$\alpha$ (Ly$\alpha$) and non-ionising UV-continuum photons from a multiphase medium, and investigate whether there exist directional enhancements in the Ly$\alpha$…
In this work, we present for the first time the Lyman $\alpha$ intensities measured by Voyager 1/UVS in 2003-2014 (at 90-130 AU from the Sun). During this period Voyager 1 measured the Lyman $\alpha$ emission in the outer heliosphere at an…
The Maxwell-Bloch system describes a quantum two-level medium interacting with a classical electromagnetic field by mediation of the the population density. This population density variation is a purely quantum effect which is actually at…
In scattering theory, the Wigner-Smith time delay, calculated through a phaseshift derivative or its multichannel generalization, has been demonstrated to measure the amount of delay or advance experienced by colliding particles during…