An Analysis of the Relationship between Color and Morphology of Galaxies with Redshift

The research topic derives from my deep curiosity in galaxy evolution. I am asking if there is a correlation between the distance to a galaxy (measured by its redshift) and its color, measured by u-v (ultraviolet magnitude subtracted by visible light magnitude) color index, for galaxies of various morphological types (spirals, ellipticals or irregular shapes). Astronomical data such as redshifts, morphological types, and color indices were queried from the database SIMBAD. Python was used to perform data analysis and to graph data. The best fit function was deployed for polynomial regression with different polynomial degrees to determine the best fitting trend. One-directional trending was not seen throughout, rather, a complex pattern roughly represented by y = -0.027x^4 + 0.150x^3 + 0.053x^2 - 0.453x + 1.192 was identified. The downward trend was present only in the redshift ranges z < 1 and z > 3. The study showed that for each morphological type, there is not a simple correlation between a galaxy’s distance and its color index. However, a cross-morphological type comparison indicated irregular shaped galaxies are bluer than spirals, and spirals are bluer than ellipticals, which was the case throughout the entire redshift range.