Date of Award
Doctor of Philosophy (PhD)
Physics & Astrophysics
Galaxy clusters are one of the most massive structures in the Universe, consisting of hundreds to thousands of galaxies bound together by gravity. They are important laboratories for the study of the formation and evolution of galaxies over the age of the Universe. The high-density cluster environment affects the physical and morphological properties of cluster galaxies. The main goal of this dissertation is to study the effect of the cluster environment on galaxy evolution using the star-formation rate (SFR) of cluster galaxies. Multi-wavelength data at ultraviolet, u-band, and infrared wavelengths for a sample of 74 low-redshift (0.022 < z < 0.184 ) galaxy clusters were used for the analysis of this study. WIYN 0.9m+HDI telescope/detector at the Kitt Peak National Observatory was used to obtain u-band measurements of 14 galaxy clusters. This dataset was supplemented by 18 clusters from the study of Barkhouse et al. (2007), 10 clusters from Omizzolo et al. (2014), 13 clusters from Rude et al. (2020), and 19 clusters from Valentinuzzi et al. (2011). Archival data from the GALaxy Evolution EXplorer (GALEX) and the Wide-field Infrared Survey Explorer (WISE) satellites were used for ultraviolet and IR analysis, respectively. Redshifts of galaxies were obtained from SDSS spectroscopy data and were used to select cluster galaxies. The dispersion of the background-corrected red-sequence was used to separate cluster galaxies based on color into red and blue systems. A dynamical radius, r200, was calculated for each cluster using the cluster velocity dispersion, and used as a normalization factor to compare cluster characteristics. For each passband, the radial dependence (0.0 < r/r200 < 1.0) of the SFR was measured for all cluster galaxies. Evidence for the quenching of star formation towards the cluster center was found for both red and blue galaxies, with the blue galaxy SFR decreasing more than for the red galaxies. The cluster galaxy sample was divided into giant (high-mass) and dwarf (low-mass) galaxies using their absolute r-band magnitude. It was found that dwarfs are more susceptible to environmental effects compared to giant systems. These results are consistent for all multi-wavelength data used in this study. While ram pressure stripping plays a more important role in quenching star formation towards the cluster core, other mechanisms, such as galaxy harassment and starvation, were found to be more effective in the cluster outskirts.
Gamage, Gihan Lakmal, "Multi-Wavelength Analysis Of Star Formation In Galaxy Clusters" (2022). Theses and Dissertations. 4260.