Date of Award

2025

Degree Type

Dissertation

Degree Name

Doctor of Philosophy in Physics

Specialization

Astrophysics

Department

Physics

First Advisor

Douglas Gobeille

Abstract

We present a complete sample of radio-loud (P3.0 GHz = 1027.26 W/Hz) high-redshift (z ≥ 2.5) quasars in the Northern Hemisphere (δ ≥ 0). Each source was imaged with a user-defined imaging protocol developed for the Very Large Array Sky Survey. Higher-resolution images were generated from archival observations and new Enhanced Very Large Array observations (Project Code: 24B-010).  We produced 407 images of galaxies, where we are likely the first humans to see them. Twenty of these sources were high-redshift jets which increased the number of known high-redshift jets by 69%. This sample represents one of the largest and highest-resolution surveys of the high-redshift Universe to date.

We use this sample to investigate the Unified Model of Active Galactic Nuclei by examining the relationship between single- and double-lobed radio morphologies. We did this by comparing the properties of our observed sample with a population of quasars generated via Monte-Carlo approximation. Our analysis shows single-lobed galaxies are most likely explained by the orientation of the source rather than by image sensitivity limits with high confidence. We supported our claim by showing single-lobe sources are smaller than double-lobe sources confirming our projection hypothesis.  Finally, we introduced a statistical framework for estimating the probability that a source classified as single-lobed would remain so under deeper observations. We utilized simulated Next-Generation Very Large Array (ngVLA) observations showing how future telescopes will provide additional insight into our work.

Creative Commons License

Creative Commons Attribution-Noncommercial 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 4.0 License.

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