21cm Absorption Lines at High Redshift from Intervening Galaxies

Galaxies , Intergalactic Absorption Lines , and Feedback at High Redshift

The galaxy-IGM part of the Lyman-break survey currently consists of measured redshifts for more than 1000 galaxies with redshift 1.5 < ∼ z < ∼ 3.5 along the sightlines to 25 background QSOs. One of the goals of the survey was to measure the influence on the intergalactic medium of energetic feedback from star and black-hole formation. This talk begins with a description of the observed correlat...

Molecular Absorption Lines at High Redshift

The four known molecular absorption line systems at redshifts z=0.25–0.89 are discussed. Two of the systems originate in the galaxy hosting the ‘background’ AGN, while in two cases the absorption occurs in truely intervening galaxies. Indirect evidence for the existence of very small scale structure in the molecular ISM is presented. A new absorption line at z=0.89 towards PKS1830–211 opens up ...

The Connection between Galaxies and Intergalactic Absorption Lines at Redshift

Absorption-line spectroscopy of 23 background QSOs and numerous background galaxies has let us measure the spatial distribution of metals and neutral hydrogen around 1044 UV-selected galaxies at redshifts 1.8 < ∼ z < ∼ 3.3. The typical galaxy is surrounded to radii r ∼ 40 proper kpc by gas that has a large velocity spread (∆v > 260 km s) and produces very strong absorption lines (NCIV ≫ 10 14 c...

High Redshift Hi 21cm Absorption toward Red Quasars

We have searched for redshifted absorption in the 21 cm line of neutral hydrogen toward 'red quasars', which are extragalactic radio sources with a steep spectral drop between optical and infrared wavelengths. The success rate for detecting HI 21cm absorption toward a representative sample of such sources is 80%. This compares to the much lower success rate of 11% for detecting HI 21cm absorpti...

Galaxies at High Redshift