Semester

Summer

Date of Graduation

2022

Document Type

Dissertation

Degree Type

PhD

College

Eberly College of Arts and Sciences

Department

Physics and Astronomy

Committee Chair

Daniel Pisano

Committee Co-Chair

Loren Anderson

Committee Member

Loren Anderson

Committee Member

Duncan Lorimer

Committee Member

Jacqueline van Gorkom

Committee Member

Adam Kobelski

Abstract

A current open question in the evolution of galaxies, is what are the physical mechanisms that cut off galaxies from their primordial gas reservoirs, resulting in the end of their star-formation capabilities? Recent observational programs have shown that the properties of galaxies show dependencies on their placement within the large-scale structure (LSS) of the universe. These observations have motivated recent developments in theoretical work that have shown how a galaxy's interaction with the LSS may impact its connection to primordial gas supply, and ability to continue to accrete gas, the fundamental ingredient in star-formation.

In order to investigate the role of LSS in galaxy evolution, we use data from the COSMOS HI Large Extragalactic Survey (CHILES), a single pointing of the Very Large Array in the COSMOS field with the ability to detect HI in galaxies out to a redshift 0.45. We introduce a fast imaging pipeline that is able to produce science-ready image cubes of the CHILES data in a reasonable turnover time. This pipeline is applied to the full CHILES database and produces data of excellent sensitivity with minimal imaging artefacts. Additionally, we introduce the CHILES Continuum Polarization Survey (CHILES Con Pol), which is the most sensitive 1.4 GHz radio continuum survey, to date, at 4.5" resolution. We discuss the survey design, data processing, and comparison to other surveys taken in the COSMOS field and discuss their complementary aspects.

Using these high quality sensitive radio data, and ancillary data from the COSMOS survey, we investigate neutral hydrogen content and relative star-formation rate for blue, lower mass spiral galaxies as a function of their placement in their LSS, for two redshift bins. We find that the neutral hydrogen content for galaxies not near the spine of filaments, more than 2 Mpc away, is lower in our low-z bin. We place this result in the context of recent theoretical work and speculate that we are observing recent cosmic web detachment events for galaxies of these types, that result in the cutting-off of galaxies from their primordial gas supply.

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