## Theses and Dissertations

#### Title

Exploring Star Formation In Cluster Galaxies

January 2018

Dissertation

#### Degree Name

Doctor of Philosophy (PhD)

#### Department

Physics & Astrophysics

Galaxy clusters are the most dense virialized environments in the known Universe. Hence they are the best locations to study the effect of the high-density environment on the evolution of galaxies. The intracluster medium (ICM) plays an important role in galaxy evolution. The goal of this dissertation is to study the effect of the ICM on galaxy evolution using star formation. A sample of 10 galaxy clusters were observed through the $r$-band and redshifted $H\alpha$ narrow-band filters using the Mayall 4-m telescope at the Kitt Peak National Observatory. Continuum image subtraction was used to measure H$\alpha$ flux to quantify star formation. Cluster galaxies were selected using the red-sequence method. The radial dependence ($0.0\leq (r/r_{200})\leq 1.0$) of the star formation rate (SFR), equivalent width (EW), and specific star formation rate (SSFR) were measured for the cluster galaxy sample. Evidence for quenching of star formation towards the cluster center was found at all radii using the SFR, EW, and SSFR to estimate star formation activity. Results suggest that both galaxy harassment and ram pressure stripping help to quench star formation in the low-density cluster outskirts, while ram pressure stripping plays a more important role towards the high-density cluster center. The cluster galaxy sample was divided into giant (high-mass) and dwarf (low-mass) galaxies. It was found that dwarfs are more susceptible to ram pressure stripping than the giant systems. The effect of the cluster environment on different morphological types, such as elliptical and spiral galaxies, was studied and it was determined that ram pressure and galaxy harassment have similar effects on the SFR for both morphological types.