Speaker
Andrzej Krasiński
(N. Copernicus Astronomical Center, Polish Academy of Sciences)
Description
Some light rays emitted from the Big Bang (BB) in Lemaitre - Tolman (L-T) and Szekeres (Sz) models reach all observers with an infinite blueshift. This happens when at the emission point the BB function t_B(r) has nonzero derivative and the ray propagates radially (in L-T) or along one of two preferred directions (in Sz). Consequently, some rays emitted during the last scattering period should be reaching us with a finite blueshift. This is a prediction of general relativity, which is an otherwise well-tested theory, so it should be investigated for its consequences for observations. This author recently proposed that blueshifted rays are observed as gamma-ray bursts (GRBs). In four consecutive papers it was shown that (1) L-T-based models of GRB sources successfully account for the energies of the GRBs, the large distances to them, their multitude, and for the existence of the afterglows (but not for the durations of the GRBs and of the afterglows and for their [hypothetical] collimation into narrow jets); (2) In Sz-based models large blueshifts may arise only along two opposite directions, so the collimation is immediately accounted for; (3) A Sz model generates a stronger blueshift than an L-T model with the same BB profile; (4) The short duration of the GRBs is accounted for if the blueshifted ray, on its way to the present observer, passes through another Sz region, where it undergoes the cosmic drift (i.e. a deflection by a time-dependent angle). The last two remaining problems are (i) to account for the measured durations of the afterglows and (ii) to make the angular diameters of the sources in the model compatible with the limits imposed by observations. Work on these is in progress.
