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Are γ -ray bursts at cosmological distances optically thin?
(American Physical Society, 1993)
The observed spatial distribution of gamma-ray bursts indicates that they probably originate at cosmological distances. At this distance scale their variability time scale and flux above MeV imply an initial optical depth ...
X-Ray Absorption by the Hot Intergalactic Medium
(American Astronomical Society, 1998)
The current census of observed baryons in the local universe is still missing a significant fraction of them according to standard big bang nucleosynthesis. Numerical simulations predict that most of the missing baryons ...
Observational Signatures of the First Quasars
(American Astronomical Society, 1998)
We study the observational signatures of a potential population of low-luminosity quasars at high redshifts in a ACDM cosmology. We derive the evolution of the quasar luminosity function at fainter luminosities and higher ...