LIGO Seminar
https://caltech.zoom.us/j/87546916051?pwd=aTByZU5WamhUKzlkRVY2bW05bytDdz09
Speaker: Anya Nugent
Title: Dwarf Galaxies, Neutron Star Mergers, and Heavy Elements
The astrophysical sites for heavy "r-process" (A > 130; e.g., gold, platinum, uranium) elements are heavily debated. While neutron star (NS) mergers are currently the only confirmed source of r-process elements, it is contentious if they produced the r-process enrichment observed in Local Group dwarf galaxies and Galactic metal poor stars. Specifically, it is assumed that NS systems have too long of merger timescales to pollute these environments. To resolve this paradigm, we can observe the population of short gamma-ray bursts (SGRBs; z~0.1-3), which originate from NS mergers, and their host galaxies to understand the necessary environmental conditions under which these systems can form, their merger timescales, and pre-merger binary properties. As SGRBs are both detected and associated to host galaxies far more frequently than the population detected through gravitational waves and extend to much further redshifts, their host population currently provides the most information on the formation and evolution of these systems. Here, I discuss building the largest catalog of SGRB host galaxy observations and stellar population properties, including redshifts, stellar masses, ages, metallicities and star formation rates. To understand how NS mergers depend on their environment over cosmic time, I showcase the SGRB host stellar populations in the context of the field galaxy population and compare them to well-known galaxy relations. I also discuss the implications for the distribution of NS merger timescales. I further present a population of ultra-faint SGRB hosts which thus far had unknown redshifts and luminosities, but provide strong discriminating power on their NS merger timescale distributions and chemical enrichment of the Universe. I conclude by discussing recent results to measure their stellar mass and redshifts. Finally, I note how using spaced based missions, such as JWST, will push our understanding of these fantastic events.