As of September 2015, gravitational waves established themselves as a new way to observe the universe. Sources of these waves could now be detected and contribute to our understanding of the stellar world. Currently, all of these waves have been attributed to be a result of compact binary coalescences (CBC). However, these waves share a very close profile with another potential, currently undetected, source: cosmic string cusps. This raises questions as to whether any of these detections have been misidentified. For this talk, I will discuss the ability to distinguish between CBCs and cosmic string cusps, and the likelihood of misidentified events. 

Understanding how galaxies evolve across cosmic time is especially pressing during the age of the James Webb Space Telescope (JWST). In its first year of observations, JWST has observed the highest redshift galaxies to date (z~13 at the time of this writing) and has shown that they are more “evolved” than we expected them to be. Tracing the chemical enrichment (what we call "metallicity") of galaxies is critical to understand the process of galaxy formation and evolution. Metallicity "diagnostics" have been developed using the strong emission lines observable in galactic spectra to estimate the metallicity of galaxies when direct detections are difficult. However, there is a need for a diagnostic suitable for low-resolution observations, for example one that can be applied to JWST's NIRISS, or the upcoming Euclid surveys and Nancy Roman Observatory. In this talk, I will present my results from my summer at the Center for Astrophysics | Harvard & Smithsonian, where we propose a new metallicity diagnostic that can be used on low-resolution observations of galaxies across cosmic time.