The impact of source and survey modelling on the connection between [O III] emitters and Ly α forest transmission at z ~ 6

James Webb Space Telescope (JWST) surveys of [O III]-emitting galaxies are offering fresh insight into the connection between galaxies and the intergalactic medium at redshift z ~ 6. Recent measurements of the cross-correlation between [O III]-emitting galaxies and Ly α forest transmission point to excess Ly α transmission at a scale (r ≈ 30 cMpc) and amplitude (roughly twice the global mean) that is not seen in numerical models. Here we improve upon previous theoretical work by constructing an empirical model that connects haloes with the observed population of [O III] emitters and incorporates the geometry and depth of the JWST surveys into mock galaxy survey catalogues. We compare these mocks to recent measurements of [O III] emitter clustering, the one-dimensional galaxy–Ly α transmission cross-correlation, and the relation between galaxy surface density and Ly α effective optical depth. The large scatter in our mock survey measurements of the cross-correlation means there is no significant tension with the observational data, albeit the peak of the one dimensional correlation in our mocks occurs at a scale ≈ 10 cMpc below that observed. Though further studies of the effect of different ionising source models will be useful, the large scatter implies that, at present, current galaxy-IGM observations may struggle to rule out a broad range of such models. We anticipate that further progress will strongly benefit from increased observational sample sizes, as well as simulations performed in box sizes > 250 cMpc that use a variety of source models.