Date of Award

2025

Document Type

Honors Thesis (Colby Access Only)

Department

Colby College. Physics and Astronomy Dept.

Advisor(s)

Elizabeth McGrath

Abstract

In this project, we studied active galactic nuclei (AGN) host galaxies during cosmic noon (z ∼ 2) using data from the Cosmic Evolution Early Release Science (CEERS) Survey with the James Webb Space Telescope (JWST) cross-matched with X-ray luminosity data from the Chandra X-ray Observatory. We modeled the rest 9600Å wavelength morphology using the GALFIT software that fits two models: 1) a single Sérsic component and 2) a two-component model that included a point spread function (PSF) component to better fit the central AGN. We compared the effectiveness of the two models by calculating the residual flux fraction of each galaxy with both models to create a quantitative metric. We found that about 33% were above the cut-off point, which we classified as “heavily improved”. We also calculated an AGN-Host flux ratio for each galaxy using the two-component model values for flux. Using values from our morphological fitting, we found that using a best-fit approach for each galaxy resulted in a more disk-like trend than previously observed with a single-component model, finding a median value of 3.4 for the single-component model and 2.83 for the two-component model. Additionally, we found clear relationships between AGN fraction and X-ray luminosity. Future work on this population of galaxies may include a comparison to SED plots and a broader sample size using other JWST fields matched to known X-ray sources.

Keywords

AGN, high-redshift galaxies, JWST, galaxy morphology, CEERS, galaxy evolution

Download

Share

COinS