Abstract

We stack thousands of spectra of LAEs from HETDEX Data Release 3 to analyze the typical Lya profile at z ~ 2-3. We find significant ~ 3000 km/s absorption wings around Lya in stacks at varying redshift, counterpart magnitude, and Lya luminosity. Via comparisons to far-UV spectra of nearby ( z < 0.2) LAEs in the CLASSY treasury and optical/near-IR spectra of 2.8 < z < 5 LAEs in the MUSE-Wide survey, we find some similar profiles at low and higher redshift. We then show that basic simulations of Lya radiative transfer are able to produce troughs in a manner similar to a damped Lyman alpha system. We postulate that these troughs could be attributed to UV background absorption by HI gas in the halo of the LAE and/or from a cosmic web filament.