about 1.�2, the true spectral resolution is around 8 Å, consistent with the measured width of the spectral features. The average line profile, constructed from the Fe II lines above 6000 Å, appears unresolved. This implies that the absorbing clouds have a velocity dispersion of less than 100 km s �1 in the rest frame. The observed BATSE gamma-ray fluence of GRB 990123 is 5.09 � 0.02 � 10 –4 erg cm –2 for energies above 20 keV (14). In Table 2 we give the luminosity distance and the inferred isotropic energy output in various cosmologies for z � 1.600. A lower limit to the isotropic energy release in gamma-rays alone is obtained in an

Abstract By matching across a surface of constant time, it is demon-strated that the spacetime for a radiation-dominated Einstein-de Sitter universe can be directly matched to the spacetime for a matter-dominated Einstein-de Sitter universe. Thus, this can serve as a model of a universe filled

A family of cosmological models is considered which in a certain synchronized system of reference possess flat slices t = const. They are generated from the EINSTEIN-DE SITTER universe by a suitable transformation. Under physically reasonable presumptions these transformed models fulfil certain

dilation factors are also corrected for energy stretching and similar effects. Within an Einstein-de Sitter cosmology, we place strong bounds on the evolution of the bursts, and these bounds are incompatible with a homogeneous population, assuming a power law spectrum and no luminosity evolution

thetemperaturedistributionfunction(TDF)ofX{ray clustersofgalaxiesisexaminedintermsoftheamplitudetobegiventotheprimevalmatteructuationsfor consistencywithpresentobservations. TheTDFofclustersisderivedfordierentnormalizationsoftheHDMpowerspectruminanEinstein-deSitter universe(0

We describe similarity solutions that characterize the collapse of collisional gas onto scalefree perturbations in an Einstein-de Sitter universe. We consider the effects of radiative cooling and derive self-similar solutions under the assumption that the

We consider the effect of inhomogeneities on the expansion of the Einstein-de Sitter universe. We find that the backreaction of linear scalar metric perturbations results in apparent dark energy with a mixture of equations of state between 0 and –4/3. We discuss the possibility that backreaction

whose radius remains strictly constant during the expansion. In the Einstein-de Sitter universe approximate calculations show that the atom expands, but at a rate which is negligible compared with the general cosmic expansion.

The well-known self-similar solution for the two-point correlation function of the density field is valid only in an Einstein – de Sitter universe. We attempt to extend the solution for non – Einstein – de Sitter universes. For this purpose we introduce an idea of quasi-self-similar evolution

The evolution of a planar perturbation in a Einstein-de Sitter Universe is studied using a previously introduced Lagrangian scheme. An approximate discrete dynamical system is derived, which describes the mass agglomeration process qualitatively. Quantitative predictions for the late density