Pseudo-Evolution of Galaxies in LCDM Cosmology
Abstract
Our knowledge about galaxy evolution comes from transforming observed galaxy properties at different redshifts to co-moving physical scales. This transformation depends on using a cosmological model. Here the effects of unintentional mixing of two different cosmological models on the size evolution of galaxies is studied. As a gedanken experiment, a galaxy of fixed proper size and luminosity is moved across different redshifts. The apparent size of this galaxy is then interpreted with a cosmological model presumed by the observer, which is different compared to the cosmology exhibited by the Universe. In such a case, a spurious size evolution of the galaxy is observed. A galaxy behaving according to the R_h=ct and Neumann's cosmology, when interpreted with the LCDM cosmological model, shows an increase in size by a factor of 1.1 and 1.3 from z=7.5 to z approx. 0, respectively. The apparent size of a galaxy in a static Euclidean cosmology, when interpreted in the LCDM model, shows a factor of 23.8 increase in size between z=7.5 to z approx. 0. This is in close agreement with the observational data with a size increase of a factor of 6.8 between z=3.2 to z approx. 0. Furthermore, using the apparent size data, it is shown that the difference between the derived proper sizes in R_h=ct, Neumann's and LCDM cosmological models are minimal.
Cite
@article{arxiv.1907.09486,
title = {Pseudo-Evolution of Galaxies in LCDM Cosmology},
author = {Vasanth Balakrishna Subramani and Pavel Kroupa and Hossein Shenavar and Vyoma Muralidhara},
journal= {arXiv preprint arXiv:1907.09486},
year = {2019}
}
Comments
accepted for publication by MNRAS, pdflatex, 9 figures, 8 pages; replacement only includes additional references