College of Science and Health Theses and Dissertations

Date of Award

Spring 6-10-2023

Degree Type


Degree Name

Master of Science (MS)



First Advisor

Sangeeta Malhotra, PhD

Second Advisor

Anuj Sarma, PhD

Third Advisor

Jesus Pando, PhD


In this thesis, I am investigating the optical variability of Green Pea galaxies (GPs). GPs are good analogs to high-redshift galaxies, enabling us to learn more about the first galaxies in the universe. One of their key properties is their strong emission lines, some of which indicate the presence of an active galactic nucleus (AGN). An effective way to identify AGN is to look for stochastic variability in the optical light from the galaxy. Finding AGN in these galaxies would help us learn more about the formation and evolution of the supermassive black holes that power AGN. In this thesis, I analyzed 317 observations of 216 GPs taken with the Transiting Exoplanet Survey Satellite (TESS). These data are comprised of nearly continuous observations of the GP on a 27-day timescale. I used these data to create light curves and used the inverse von Neumann ratio (1/η) to quantify the variability. Considering sectors with a value of 1/ η > 0.588 as having a high confidence of variability, 11 sectors showed indications of variability and 3 of those sectors had significant variability when compared to other nearby TESS pixels. Since those 3 sectors correspond to 2 GPs, we conclude that 2 GPs (GP# 41 and GP# 219) show significant optical variability on 30-day time scales, therefore likely containing AGN. This is supported by other independent methods for finding AGN such as mid-infrared colors and X-ray luminosity for one of these two GPs (GP# 219).

SLP Collection


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Physics Commons