Lyα Halos around [O iii]-selected Galaxies in HETDEX

Abstract

We present extended Ly α emission out to 800 kpc of 1034 [O iii ]-selected galaxies at redshifts 1.9 < z < 2.35 using the Hobby–Eberly Telescope Dark Energy Experiment. The locations and redshifts of the galaxies are taken from the 3D-HST survey. The median-stacked surface brightness profile of the Ly α emission of the [O iii ]-selected galaxies agrees well with that of 968 bright Ly α -emitting galaxies (LAEs) at r > 40 kpc from the galaxy centers. The surface brightness in the inner parts ( r < 10 kpc) around the [O iii ]-selected galaxies, however, is 10 times fainter than that of the LAEs. Our results are consistent with the notion that photons dominating the outer regions of the Ly α halos are not produced in the central galaxies but originate outside of them.