We have measured the distribution function of the flux decrement D = e−τ caused by Lyα forest absorption from intervening gas in the lines of sight to high redshift QSOs from a sample of seven high resolution QSO spectra obtained with the Keck telescope. The observed flux decrement distribution function (FDDF) is compared to the FDDF from two simulations of the Lyα forest: a ΛCDM model (with Ω ...

We derive lower bounds on the cosmic baryon density from the requirement that the high-redshift intergalactic medium (IGM) contain enough neutral hydrogen to produce the observed Lyα absorption in quasar spectra. The key theoretical assumption that leads to these analytic bounds is that absorbing structures are no more extended in redshift space than they are in real space. This assumption migh...

Aims. To understand the origin of the Lyα line profile of the prototypical Lyman break galaxy (LBG) MS 1512–cB58 and other similar objects. To attempt a consistent fit of Lyα and other UV properties of this galaxy. To understand the main physical parameter(s) responsible for the large variation of Lyα line strengths and profiles observed in LBGs. Methods. Using our 3D Lyα radiation transfer cod...

This is the first measurement and detection of coherence in the intergalactic medium (IGM) at substantially high redshift (z∼3.8) and on large physical scales (∼2.5 h 70 Mpc). We perform the measurement by presenting new observations of the high redshift quasar pair PC 1643+4631A, B and their Lyα absorber coincidences. With data collected from Keck I Low Resolution Imaging Spectrometer (LRIS) i...