Author ORCID Identifier

https://orcid.org/0000-0002-3758-2492

Semester

Spring

Date of Graduation

2024

Document Type

Dissertation

Degree Type

PhD

College

Eberly College of Arts and Sciences

Department

Physics and Astronomy

Committee Chair

Loren Anderson

Committee Member

Duncan Lorimer

Committee Member

Sarah Burke-Spolaor

Committee Member

Anish Roshi

Abstract

The star formation rate (SFR) of the Milky Way is poorly understood in comparison to the SFR of other galaxies. In order to better find the Galaxy's place in the universe, it is imperative to understand the star formation activity occurring within it. We characterize the Galactic \hii\ region luminosity function (LF) at multiple infrared and radio wavelengths using a sample of 797 first Galactic quadrant \hii regions compiled from the WISE Catalog of Galactic \hii Regions. This sample is statistically complete for all regions powered by single stars of type O9.5V and earlier.

We find that neither a single nor a double power law model is favored over the other for describing the LF. We find that the form of the LF depends on the location and physical size of \hii\ regions, but that there is no variation in the LF as a function of wavelength. This suggests that observations at relatively unextincted infrared and radio wavelengths can be used for studying the LF instead of H$\alpha$.

We use these results in conjunction with the contributions of point sources, diffuse gas, and supernova remnants to determine the total luminosity and the SFR of the Galaxy. We find that although the SFRs exhibit a significant level of inter-wavelength variation, the intra-wavelength consistency is high. In addition, the SFRs found at the wavelengths thought to most accurately track star formation are the closest to the value of $\sim$\,1--2\,M$_{\odot}$\,yr$^{-1}$ found in the literature. Our analysis supports the conclusion that the Milky Way is a normal disk galaxy with a slightly lower-than-average level of star formation.

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