MUSEQuBES: characterizing the circumgalactic medium of redshift ≈3.3 Lyα emitters

We present the first characterization of the circumgalactic medium of Ly alpha emitters (LAEs), using a sample of 96 z approximate to 3.3 LAEs detected with the VLT/MUSE in fields centred on eight bright background quasars. The LAEs have low Ly alpha luminosities (similar to 10(42) erg s(-1)) and star formation rates (SFRs) similar to 1 M-circle dot yr(-1), which for main-sequence galaxies correspond to stellar masses of only similar to 10(8.6)M(circle dot). 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 Hi and Civ absorption near the LAEs out to 500 kms(-1) and at least approximate to 250 pkpc (corresponding to approximate to 7 virial radii). At less than or similar to 30 kms(-1) from the galaxies, the median HI and CIV optical depths are enhanced by an order of magnitude. The absorption is significantly stronger around the approximate to 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 HI or CIV absorption on transverse distance (over the range approximate to 50-250 pkpc), redshift, or the properties of the Ly alpha emission line (luminosity, full width at half-maximum, or equivalent width). However, for HI, but not CIV, the absorption at less than or similar to 100 kms(-1) from the LAE does increase with the SFR. This suggests that LAEs surrounded by more Hi tend to have higher SFRs.