Collaborative Research: First Light and Reionization with Lyman Alpha Galaxies

University Of California-Riverside, Riverside CA

Investigators

Abstract

The team will use ground-based telesopes, kitted out with special purpose filters, to hunt for the most distant galaxies in the Universe. These galaxies were the first to form and are probably responsible for radically transforming the matter in the young Universe from a neutral to an ionized state. That state-altering transition sent the young Universe down a path that led to the rich panoply of galaxies, stars, and planets in today's mature Universe. The data acquired for the research will exhibit rich patterns in the strength of the signal as a function of its electromagnetic frequency. As part of a novel outreach effort, the team will sonify these data, that is, convert them to audible frequencies and imprint them with rich patterns in the loudness of the signal. This allows the human ear to "detect" the most distant galaxies known. MP3 files will be developed and released along with explanatory material. The aim of the project is to investigate when and how the early Universe became reionized, a key unsolved problem in cosmology. A staged observational approach will be taken. In the first stage, data from narrow-band surveys will be acquired to find candidate Lyman-alpha-emitting galaxies at redshifts of 7.7 and 8.8. In the second stage, spectroscopic follow-up of the candidates will be done to confirm their high redshifts and form a luminosity function of Lyman-alpha-emitting galaxies. That function will yield constraints on the degree of ionization of the intergalactic medium (IGM) at those redshifts. The team pioneered this luminosity-function approach, using it to show for the first time that the IGM is largely ionized at a redshift of 6.5. The team's new work will place the first constrains on the degree of ionization of the IGM at even more extreme redshifts. The spectroscopy will also be used to study other IGM properties. The spectroscopic data acquired for the research will exhibit rich patterns in the strength of the signal as a function of its electromagnetic frequency. As part of a novel outreach effort, the team will sonify these data, that is, convert them to audible frequencies and imprint them with rich patterns in the loudness of the signal. This allows the human ear to emulate a spectrograph. MP3 files will be developed and released along with explanatory material.