Claire Bolda, “Lyman-α Emission and Large-Scale Structure in Galaxies at z = 2.3”
Mentor: Dawn Erb, Physics
Poster #2

Galaxies interact with their environment through inflows and outflows of gas consisting mostly of hydrogen. On the galactic scale, star formation and other stellar processes within star-forming galaxies at high redshift (i.e., very distant) produce photons which illuminate extended halos of hydrogen gas surrounding them. We can observe this phenomenon through the double peaked Lyman-α spectral emission line in the emission spectrum of hydrogen, which enables us to learn more about the interactions between galaxies and their environment. Here we present measurements of the spatially resolved Lyman-α spectral emission from two neighboring galaxies in a large-scale structure at redshift z = 2.3 using observations from the Keck Cosmic Web Imager, an integral field spectrograph on the Keck II Telescope. By fitting double Gaussian best fit models to the Lyman-α emission in various regions of these galaxies, we have obtained measurements of the Lyman-α emission’s spatially varying velocity structure and intensity. We find that the Lyman-α spectral lines from these galaxies indicate the presence of abnormally prominent inflows of gas which are likely caused by the accretion of cold hydrogen gas from the intergalactic medium or a galaxy merger between the neighboring galaxies. Additionally, we find that these galaxies are aligned with a filament containing thirteen galaxies within this large-scale structure, which we expect will eventually evolve into a galaxy cluster. Examining the Lyman-α emission from these galaxies and their relationship with this nearby galaxy filament helps us to observe how galaxies accrete matter to fuel star formation and how large-scale structures form.