The 4th Conference of the Polish Society on Relativity

Session

Cosmology I

25 Sept 2017, 14:50

Kazimierz Dolny, Poland

66. Averaging of disturbed Friedmann--Lemaitre cosmological model

Krzysztof Głód (Astronomical Observatory of the Jagiellonian University)

25/09/2017, 14:50

Oral presentation (preferred)

We examine a naive perturbative generalization of the Friedmann--Lemaitre cosmological model. We introduce at the metric level parameters which control basic properties of inhomogeneities, their profile, growth rate and density contrast. We give conditions under which the model can be considered reasonable and comment limitations of this approach. Finally, we perform an averaging procedure of...

51. A possible connection of blueshifts in the Lemaitre - Tolman and Szekeres models with the gamma-ray bursts

Andrzej Krasiński (N. Copernicus Astronomical Center, Polish Academy of Sciences)

25/09/2017, 15:10

Oral presentation (preferred)

As known since 1980, some light rays emitted from the Big Bang (BB) in a
Lemaitre - Tolman (L-T) model 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. Some authors portrayed the existence
of blueshifts as a disaster disqualifying the L-T models. This author recently
proposed...

74. Cosmological backreaction conjecture: recent developments

Jan Ostrowski (CRAL)

25/09/2017, 15:30

Oral presentation (preferred)

Inhomogeneous, relativistic cosmology has recently observed a rise in popularity among the cosmologists. In particular, the scalar averaging approach (Buchert formalism) has been intensively examined
both analytically and numerically, giving some new insights
into the problem of cosmological backreaction i.e. the conjectured influence of small scale density inhomogeneities on the large scale...

36. Formation of the first molecules in early Universe beyond the $\Lambda$CDM model

Olga Sergijenko (Ivan Franko National University of Lviv)

25/09/2017, 15:50

Oral presentation (preferred)

We study the formation of first molecules H$_2$ and HD, negative Hydrogen ions H$^-$, molecular ions H$_2^+$ and HeH$^+$ in the pre-reionization Universe. The cosmological recombination is described within the framework of modified model of the effective 3-level atom [Seager, Sasselov $\&$ Scott, 1999; Wong, Moss $\&$ Scott, 2008], while for the kinetics of chemical reactions we restrict...

20. Simple inhomogeneous cosmological model in the context of back reaction

Szymon Sikora (Jagiellonian University)

25/09/2017, 16:10

Oral presentation (preferred)

I present the cosmological model which approximates the periodically distributed dust overdensities on the Einstein-de Sitter background.
The model construction enables application of the Green-Wald averaging scheme and the Buchert averaging technique simultaneously.
The comparison of the angular diameter distance obtained within the presented model and the angular diameter distances for the...