An examination of the spin vector orientation of r-magnitude SDSS DR-15 galaxies within the redshift range of 0.50 to 0.60

Abstract

This study explores the spatial orientations of a large sample of 483,899 galaxies selected from the SDSS DR-15 catalog with redshifts ranging from 0.50 to 0.60. The primary objective is to examine the spin vector orientations of these galaxies in the context of three galaxy evolution models: the Pancake Model, the Hierarchy Model, and the Primordial Vorticity Model. To achieve this, the observed two-dimensional parameters, including celestial coordinates, position angles, and inclination angles, are transformed into three-dimensional spin vector orientations, represented by the polar and azimuthal angles, using the Flin--Godlowski transformation. Expected isotropic distribution curves are generated by accounting for selection biases through Monte Carlo simulations of 10⁷ virtual galaxies. The observed and expected distributions are then compared using three statistical tests: the chi-square test, autocorrelation analysis, and Fourier analysis. The dataset is divided into 17 distinct samples for detailed investigation. The results predominantly support the Hierarchy Model, while a few samples exhibit signatures consistent with the Primordial Vorticity Model. The analysis is carried out in the equatorial coordinate system, and local effects are identified through graphical features such as humps and dips in the angular distributions.