Context. Among the different observational techniques used to select high-redshift galaxies, the hydrogen recombination line Lymanalpha (Lyα) is of particular interest because it gives access to the measurement of cosmological quantities such as the star formation rate (SFR) of distant galaxy populations. However, interpreting this line and calibrating such observables are still subject to seri...

Context. Among the different observational techniques used to select high-redshift galaxies, the hydrogen recombination line Lymanalpha (Lyα) is of particular interest as it gives access to the measurement of cosmological quantities such as the star formation rate of distant galaxy populations. However, the interpretation of this line and the calibration of such observables is still subject to ...

Knowledge of the evolution of the low column density end of the Lyα forest (12.8 < log NHI < 16.0 cm ) can provide substantial insight for models of structure formation and studies of the evolution of the ionizing background. Here we describe the evolution of the b values and column densities of forest clouds over the redshift range 2 < z < 4. While the distribution function for clouds with col...

The thermal evolution of the intergalactic medium (IGM) depends on the reionization history of the universe. Numerical simulations indicate that the low density IGM, which is responsible for the low column density Lyα forest, follows a well defined temperature-density relation. This results in a cut-off in the distribution of line widths as a function of column density. We use hydrodynamic simu...

We propose a new method of analysis for the Lyα forest, namely to measure the 1-point and 2-point joint probability distribution of the transmitted flux. The results for a sample of seven observed quasars and from two simulations of structure formation are shown and compared. Statistically significant differences in the 2-point function between the results of the numerical simulations and the o...

Lam Hui, Nickolay Y. Gnedin and Yu Zhang Absorption lines in the Lyα forest can be thought of as peaks in neutral hydrogen density along lines of sight. The column density distribution (the number density of absorption lines as a function of column density) is then a statistic of density peaks, which contains information about the underlying power spectrum. In particular, we show that the slope...

At redshifts beyond z ∼> 6, as the mean fraction of neutral hydrogen 〈xHI〉 in the intergalactic medium (IGM) increases, the line flux of Lyα emitters can be significantly suppressed, which can result in a decrease in the observed number of emitters at a given Lyα flux. However, cosmological HII regions surrounding the Lyα emitting galaxies alleviate these effects. We use simple models of the Ly...

I discuss the properties of gas-rich forming galaxies. I particularly emphasize the latest results on Lyα emission that are relevant to the search of distant young galaxies. The interdependance of the Lyα escape with the properties of the ISM in starburst galaxies is outlined. A new model from G. Tenorio-Tagle and his collaborators explain Lyα profiles in starburst galaxies from the hydrodynami...