Award Date

5-15-2025

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Physics and Astronomy

First Committee Member

Bing Zhang

Second Committee Member

Paul La Plante

Third Committee Member

George Rhee

Fourth Committee Member

Bryar Shareef

Number of Pages

57

Abstract

The Epoch of Reionization (EoR) marks a critical phase in cosmic history, during which time the first stars and galaxies ionized the surrounding neutral hydrogen gas. A powerful way to probe this period is by cross-correlating the 21 cm signal from neutral hydrogen with high-redshift galaxy distributions. In this study, we analyze the 21 cm-galaxy cross-power spectrum using simulated sky maps and explore its redshift evolution, revealing a transition from positive correlation at early times (high redshift) to anti-correlation at later stages of reionization (low redshift). Our results highlight the sensitivity of the cross-power spectrum to the evolving ionized structure of the universe. We compute the auto-angular power spectra C` of the 21 cm brightness temperature, and galaxy distributions, as well as their cross-power spectrum, across multiple redshifts. The cross-power spectrum transitions from positive at higher redshifts (z > 9.5), where neutral hydrogen closely traces the large-scale structure, to negative at lower redshifts (7.5 < z < 8.5), where ionized bubbles surround galaxies and suppress the 21 cm signal. These results demonstrate that 21 cm-galaxy cross-correlations are a powerful tool for understanding reionization and large-scale structure formation. Future observational efforts, including measurements from the Hydrogen Epoch of Reionization Array (HERA) and galaxy surveys from NASA’s Nancy Grace Roman Space Telescope (Roman), will enable direct comparisons with these theoretical predictions, improving constraints on the timing and topology of reionization.

Keywords

Astrophysics; Cosmology; Galaxies; Modeling; Neutral Hydrogen; Simulations

Disciplines

Astrophysics and Astronomy

File Format

pdf

File Size

6700 KB

Degree Grantor

University of Nevada, Las Vegas

Language

English

Rights

IN COPYRIGHT. For more information about this rights statement, please visit http://rightsstatements.org/vocab/InC/1.0/

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