Moreom Akter

Date of Award

January 2025

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Physics & Astrophysics

First Advisor

Wayne W. Barkhouse

Abstract

We investigate the influence of Active Galactic Nuclei (AGN) feedback on star formation in spiral galaxies by analyzing a sample of 324 red and 273 blue spiral galaxies from 115 low-redshift galaxy clusters. The multi-wavelength dataset combines optical emission line data from the Sloan Digital Sky Survey (SDSS), X-ray luminosity from the Chandra X-ray & XMM-Newton observatories, and ultraviolet (UV) and infrared (IR) measurements from GALEX and WISE. Using diagnostic emission line ratios, we constructed Baldwin, Phillips, and Terlevich (BPT) diagrams to classify galaxies based on nuclear activity. Our analysis reveals that most of the red spirals have AGNs and LINER signatures in optical data, based on BPT and other diagrams. This proves thepresence of AGNs and (negative) feedback from AGNs quenching star formation. Conversely, X-ray analysis show that many blue spirals have high X-ray luminosities and are also located in the AGN regions of the BPT and other diagrams, suggesting that AGN-driven positive feedback may be enhancing star formation. Specific star formation rates and Dn(4000) also support this dual role, with blue spirals showing younger stellar populations and higher star formation efficiency. This thesis results support that AGN feedback plays a key role in the evolutionary pathway of spiral galaxies, particularly in quenching star formation and driving the transition from blue to red spiral populations.

Download

Share

COinS