Deuterium at high redshift

Deuterium and Helium Absorption at High Redshift: Mapping the Abundance, Density and Ionization of Primordial Gas

Spectra of quasars at high redshift with high resolution and high signal-to-noise allow in favorable circumstances detection of absorption by deuterium and ultimately measurement of its primordial abundance. Ultraviolet spectra of high redshift quasars allow measurement of absorption by the most abundant cosmic absorber, singly ionized helium, thereby mapping gas even in the most rarefied cosmi...

Galaxies at High Redshift

Galaxies at High Redshift

Within just the last few years, we have advanced from knowing only a few galaxies at z > 2 to having redshifts for nearly 1000 z ∼ 2–5 objects. The majority of this sample has been detected through the photometric “dropout” technique used so successfully by Steidel and his collaborators. In addition, a handful of objects have already been detected at z > 5, and we may already have a few objects...

Clustering at High Redshift

Together with the CMB, the three sources of information that astronomers have at high redshift as probes of the formation and evolution of the LSS are QSOs, galaxies and absorbers observed in the spectrum of distant background objects. In this contribution I try to give a hint of historical perspective, following how the technological advances have driven the emphasis from one class to another,...

Old Galaxies at High Redshift

The most passive galaxies at high redshift are unlikely to be identified by either narrow-band emission-line searches, or by Lyman limit searches (both techniques which have been highlighted at this meeting) simply because such selection methods rely on the presence of a strong ultraviolet component. Selection on the basis of extreme radio power has also proved to yield optically active objects...