The stellar population of a <i>z</i> ∼ 3.25 Ly<i>α</i>-emitting group associated with a damped Ly<i>α</i> absorber

We present near-infrared observations, acquired with the Wide Field Camera 3 (WFC3) on board the Hubble Space Telescope (HST), of a Ly α -emitting double-clumped nebula at z ≈ 3.25 associated with a damped Ly α absorber (DLA). With the WFC3/F160W data we observe the stellar continuum around 3600 Å in the rest frame of a galaxy embedded in the west clump of the nebula, G W , for which we estimate a star formation rate (SFR) of SFR G W = 5.0 ± 0.4 M ⊙ yr −1 and a maximum stellar mass M G W &lt; 9.9 ± 0.7 × 10 9 M ⊙ . With the enhanced spatial resolution of HST, we discover the presence of an additional faint source, G E , in the center of the east clump, with SFR G E = 0.70 ± 0.20 M ⊙ yr −1 and a maximum stellar mass M G E &lt; 1.4 ± 0.4 × 10 9 M ⊙ . We show that the Ly α emission in the two clumps can be explained by recombination following in situ photoionization by the two galaxies, assuming escape fractions of ionizing photons of ≲0.24 for G W and ≲0.34 for G E . The fact that G W is offset by ≈8 kpc from the west clump means we cannot fully rule out the presence of additional fainter star-forming sources, which would further contribute to the photon budget inside this ≈10 12 M ⊙ galaxy group that extends over a region of 30 × 50 kpc.