Journal of Physical Studies 26(2), Article 2901 [7 pages] (2022)
DOI: https://doi.org/10.30970/jps.26.2901

ADVANCED MORPHOLOGY OF VIPERS GALAXIES

O. Gugnin{1} , A. Tugay{1} , N. Pulatova{2,3} , L. Zadorozhna{1,4} 

{1}Taras Shevchenko National University of Kyiv, 4, Glushkova ave., Kyiv, UA–03127, Ukraine,
{2}Main Astronomical Observatory of National Academy of Science of Ukraine, 27, Akademika Zabolotnoho St., Kyiv, UA–03143, Ukraine,
{3}Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg, Germany,
{4}Faculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University, 30-348 Kraków, Poland

Received 10 December 2021; in final form 22 February 2022; accepted 05 April 2022; published online 14 June 2022

We calculated morphological parameters for a test sample of 4659 galaxies from VIPERS (spectroscopic galaxy survey performed on VIMOS spectroscope at VLT). These parameters include Gini, $\operatorname{M_{20}}$, Concentration, Asymmetry, and Smoothness, also known as CAS parameters. The results correlate with the distribution of these parameters for other simulated and observed samples. We also studied the dependence of these parameters with the Sersic power index of the radial distribution of the surface brightness of the galaxy image. Our aim was to find a clear division of VIPERS galaxies into elliptical and spiral. This is necessary for testing the method of the Sersic index (ns) calculation in the statmorph program. To find such bimodality, we use B-V color index from VIPERS database.

To perform the error analysis of morphological parameters, we simulated galaxy images with a random background of different magnitudes and estimated the errors as the dispersion of the parameters. We also found asymptotic values of errors of morphological parameters by increasing the numbers of mock images.

To analyse the possible variation of each morphological parameter during the convolution of close galactic images, we have simulated them to research. As a result of this investigation, we have analysed the dependence of every morphological parameter from CAS and Gini-$\operatorname{M_{20}}$ statistics, from the distance between galactic centers.

The differences between our results for VIPERS and Gini-$\operatorname{M_{20}}$ distribution for PanStarrs galaxies at $z < 0.5$ could be explained by cosmological evolution of galaxies. We found out that in modern Universe there are many more elliptical galaxies than at $z > 0.5$ which corresponds to VIPERS sample. Also we concluded that galaxy mergers were more frequent in the early Universe.

Key words: Galaxies: photometry, cosmology: large-scale structure of Universe.

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