Recent numerical simulations show that many Lyα absorption lines of column densities NHI < ∼ 10 15 cm are produced in transient, mini pancakes. Such pancakes are modeled here, approximating the initial perturbation leading to the formation of the pancake as a single sinusoidal wave. The density and temperature profiles of the gas in the pancake are determined in the case where cooling and heati...

The metal absorption lines found in association with Lyα absorbers of moderate to high HI column density contain valuable information about the metallicity and ionization conditions within the absorbers and offer a stronger test of models of the intergalactic medium at z ∼ 3 than HI absorption lines alone. We have developed a method to predict the strengths of metal absorption lines within the ...

We report the discovery of an extremely long (∼110Mpc h−1) and dark (τ eff 7) Lyα trough extending down to z 5.5 towards the zem 6.0 quasar ULAS J0148+0600. We use these new data in combination with Lyα forest measurements from 42 quasars at 4.5 ≤ zem ≤ 6.4 to conduct an updated analysis of the line-of-sight variance in the intergalactic Lyα opacity over 4 ≤ z ≤ 6. We find that the scatter in t...

Recovery of the mass power spectrum from the Ly-α forest: The effect of ionizing background fluctuations from discrete QSO sources. Abstract. In gravitational instability models, there is a close relationship between most Lyα absorption and the matter density along the line of sight. Croft et al. (1997) have shown that it is possible to use this relationship with some additional assumptions (su...

ABSTRACT We use the Sherwood–Relics suite of hybrid hydrodynamical and radiative transfer simulations to model effect inhomogeneous reionization on 1D power spectrum Lyman α (Lyα) forest transmitted flux at redshifts 4.2 ≤ z 5. Relative models that assume a homogeneous ultraviolet background, suppresses small scales, k ∼ 0.1 km−1 s, by ∼10 per cent because spatial variations in thermal broadeni...

We measure the filling factor, correlation function, and power spectrum of transmitted flux in a large sample of Lyα forest spectra, comprised of 30 Keck HIRES spectra and 23 Keck LRIS spectra. We infer the linear matter power spectrum P (k) from the flux power spectrum PF (k), using an improved version of the method of Croft et al. (1998) that accounts for the influence of redshift-space disto...

We develop a prescription for characterizing the strengths of metal lines associated with Lyα forest absorbers (LYFAs) of a given neutral hydrogen column density NHI and metallicity [O/H]. This Line Observability Index (LOX) is line-specific and translates, for weak lines, into a measure of the equivalent width. It can be evaluated quickly for thousands of transitions within the framework of a ...

Using stacks of Lyα images of 2128 Lyα emitters (LAEs) and 24 protocluster UVselected galaxies (LBGs) at z = 3.1, we examine the surface brightness profiles of Lyα haloes around high-z galaxies as a function of environment and UV luminosity. We find that the slopes of the Lyα radial profiles become flatter as the Mpc-scale LAE surface densities increase, but they are almost independent of the c...

We present here new GHRS observations of Lyα absorption lines associated with groups or clusters toward the QSOs 1545+2101 and 0850+4400. In the first case we have identified at least eight distinct Lyα absorption features, with a mean redshift of < z >= 0.2648 ± 0.0002 and a velocity dispersion of 163 ± 57 km s −1. We have also identified a group or cluster of galaxies in the vicinity of this ...