MUSEQuBES: characterizing the circumgalactic medium of redshift ≈3.3 Ly α emitters
Sowgat Muzahid, Joop Schaye, Sebastiano Cantalupo, R. A. Marino, N. Bouché, Sean D. Johnson, Michael V. Maseda, Martin Wendt, L. Wisotzki, Johannes Zabl
Abstract
ABSTRACT We present the first characterization of the circumgalactic medium of Ly α emitters (LAEs), using a sample of 96 z ≈ 3.3 LAEs detected with the VLT/MUSE in fields centred on eight bright background quasars. The LAEs have low Ly α luminosities ($\sim 10^{42}\, \text{erg}\, \text{s}^{-1}$) and star formation rates (SFRs) $\sim 1~\text{M}_\odot \, \text{yr}^{-1}$, which for main-sequence galaxies correspond to stellar masses of only $\sim 10^{8.6}\, \text{M}_\odot$. 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 $\text{km}\, \text{s}^{-1}$ and at least ≈250 pkpc (corresponding to ≈7 virial radii). At $\lesssim 30~\text{km}\, \text{s}^{-1}$ 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 Ly α emission line (luminosity, full width at half-maximum, or equivalent width). However, for H i, but not C iv, the absorption at $\lesssim 100\, \text{km}\, \text{s}^{-1}$ from the LAE does increase with the SFR. This suggests that LAEs surrounded by more H i tend to have higher SFRs.