Physics & Astronomy ETDs

Publication Date

Fall 11-15-2020


We can use the 21 cm neutral hydrogen (HI) emission line to detect galaxies in optically obscured regions, but it is also a faint line that is difficult to detect at higher redshifts. This work presents two HI surveys. The ALFAZOA Survey maps new and predicted large-scale structure across the Galactic plane, and finds a total of 217 completely new galaxies across both of the survey phases. The completeness limits for ALFAZOA Shallow and Deep are presented. Follow-up observations of confused galaxies in ALFAZOA using the VLA determine that confusion in this survey will not cause significant deviations for the measurement of the HI mass function. The other survey, CHILES, is trying to detect HI sources in emission out to a redshift of z=0.5 to see how galaxies evolve across cosmic time. We use artificial sources to test the detection limit in the survey and the completeness for the SoFiA source finding program.

Degree Name


Level of Degree


Department Name

Physics & Astronomy

First Committee Member (Chair)

Patricia Henning

Second Committee Member

Ylva Pihlstrom

Third Committee Member

Richard Rand

Fourth Committee Member

Emmanuel Momjian




extragalactic neutral hydrogen, large-scale structure

Document Type