LAUSR

We present the first characterization of the circumgalactic medium of Lyα emitters (LAEs), using a sample of 96 z ≈ 3.3 LAEs detected with the VLT/MUSE in fields centered on 8 bright background quasars. The LAEs have low Lyα luminosities (∼1042 erg s−1) and star formation rates (SFRs) ∼1 M⊙ yr−1, which for main sequence galaxies corresponds to stellar masses of only ∼108.6 M⊙. The median transverse distance between the LAEs and the quasar sightlines is 165 proper kpc (pkpc). We stacked the high-resolution quasar spectra and measured significant excess H i and C iv absorption near the LAEs out to 500 km s−1 and at least ≈250 pkpc (corresponding to ≈7 virial radii). At ≲ 30 km s−1 from the galaxies the median H i and C iv optical depths are enhanced by an order of magnitude. The absorption is significantly stronger around the ≈1/3 of our LAEs that are part of ‘groups’, which we attribute to the large-scale structures in which they are embedded. We do not detect any strong dependence of either the H i or C iv absorption on transverse distance (over the range ≈50 − 250 pkpc), redshift, or the properties of the Lyα emission line (luminosity, full width at half maximum, or equivalent width). However, for H i, but not C iv, the absorption at ≲ 100 km s−1 from the LAE does increase with the SFR. This suggests that LAEs surrounded by more H i tend to have higher SFRs.