Gravitational lensing of a quasar by a spiral galaxy should often be accompanied by damped Ly alpha absorption and dust extinction due to the intervening gaseous disk. In nearly edge-on configurations, the surface mass ...

SN 1998bw is the most luminous radio supernova ever observed. Previous discussions argued that its exceptional radio luminosity, similar to 4 x 10(38) ergs s(-1), must originate from a highly relativistic shock that is ...

Cosmic microwave background (CMB) anisotropies probe the primordial density field at the edge of the observable Universe. There is a limiting precision (''cosmic variance'') with which anisotropies can determine the amplitude ...

Gamma-ray bursts (GRBs) are thought to originate at cosmological distances from the most powerful explosions in the universe. If GRBs are not beamed, then the distribution of their number as a function of gamma-ray flux ...

High-resolution, deep-imaging surveys are instrumental in setting constraints on semianalytical structure formation models in cold dark matter (CDM) cosmologies. We show here that the lack of unresolved B-band "dropouts" ...

The degree of beaming in gamma-ray bursts (GRBs) is currently unknown. The uncertainty in the gamma-ray-beaming angle, theta(b), leaves the total energy release (proportional to theta(b)(2)) and the event rate per galaxy ...

The redshift of all cosmological sources drifts by a systematic velocity of order a few meters per second over a century as a result of the deceleration of the universe. The specific functional dependence of the predicted ...

During the period of reionization, the universe was filled with a cosmological background of ionizing radiation. By that time a significant fraction of the cosmic gas had already been incorporated into collapsed galactic ...

We calculate the prompt X-ray emission as a function of the viewing angle for beamed gamma-ray burst (GRB) sources. Prompt X-rays are inevitable owing to the less highly blueshifted photons emitted at angles greater than ...

The redshift at which the universe was reionized is currently unknown. We examine the optimal strategy for extracting this redshift, z(reion), from the spectra of early sources. For a source located at a redshift z(s) ...