Identifying lyman α emitters powered by AGNs

Abstract

Lyman α emitters (LAEs) are usually thought to be powered by star formation. It has been recently reported that a fraction of LAEs at redshift z ̃ 3-4 host an active galactic nuclei (AGNs). If an AGN is present, it could be obscured and undetectable in X-rays, but yet dominate the Lya luminosity. We examine the properties of these AGN-powered LAEs at high redshift (z ≥ 6) using radiative transfer cosmological simulations and obtain a reliable criterion to identify them from their observed Lya line and surface brightness. We find that these sources should have (a) negative lineweighted skewness, S