Pilot Study: Correlating Galaxy Properties to Lyman-alpha Emission strength in the TESLA survey

Understanding the role that galaxies played during reionization is something that is still not well understood. One reason for this is that directly measuring the evolution of the intergalactic medium Hydrogen neutral fraction during the epoch of reionization is limited. To measure this quantity we need to compare the emergent Lyman-alpha strength, post ISM pre CGM, to that of what we observe. However, getting an accurate measure of the emergent Lyman-alpha strength during the epoch of reionization has been difficult to acquire due to neutral hydrogen absorbing Lyman-alpha and destroying the emergent lyman alpha strength information of a galaxy. We set out to study the correlation of emergent Lyman-alpha strength to galaxy properties by using a sample of galaxies at z ~ 2-3 where the IGM is transparent to Lyman alpha, found from the Texas Euclid Survey for Lyman Alpha (TESLA) survey. TESLA uses the Visible Integral-Field Replicable Unit Spectrographs (VIRUS) on the Hobby Eberly Telescope to spectroscopically identify Lyman-alpha emitters (LAEs) between redshifts 1.9 < z < 3.5. TESLA targets the North Ecliptic Pole (NEP), and will ultimately cover the full 10 deg² area of the Euclid deep survey in this region. Photometry is provided by the H20 Hyper Suprime-Cam (HSC) survey, acts as a secondary constraint on the redshift of the detected emission line from VIRUS and helps in validating our selection of LAE sources. We show preliminary results using BAGPIPES, a Bayesian SED fitting code, on correlations between the strength of Lyman alpha emission to various galaxy properties, with the eventual goal of making predictive estimates of the Lyman-alpha emission that are based on a galaxy’s individual properties. The predictive model will tell us for a given set of galaxy properties what the emergent strength of Lyman alpha should be and, as a result, improve calculation of the neutral fraction during the epoch of reionization.