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Arxiv: Late-end reionization with ATON-HE: towards constraints from Lyman-α emitters observed with JWST Published: 4/9/2024 9:01:13 PM Updated: 9/10/2024 8:15:28 PM

Paper abstract: We present a new suite of late-end reionization simulations performed withATON-HE, a revised version of the GPU-based radiative transfer code ATON thatincludes helium. The simulations are able to reproduce the Ly\alpha fluxdistribution of the E-XQR-30 sample of QSO absorption spectra at 5 <~ z<~ 6.2, and show that a large variety of reionization models areconsistent with these data. We explore a range of variations in source modelsand in the early-stage evolution of reionization. Our fiducial reionizationhistory has a midpoint of reionization at z = 6.5, but we also explore an`Early' reionization history with a midpoint at z = 7.5 and an `ExtremelyEarly' reionization history with a midpoint at z = 9.5. Haloes massive enoughto host observed Ly\alpha emitters are highly biased. The fraction of suchhaloes embedded in ionized bubbles that are large enough to allow highLy\alpha transmission becomes close to unity much before the volume fillingfactor of ionized regions. For our fiducial reionization history this happensat z = 8, probably too late to be consistent with the detection by JWST ofabundant Ly\alpha emission out to z = 11. A reionization history in our`Early' model or perhaps even our `Extremely Early' model may be required,suggesting a Thomson scattering optical depth in tension with that reported byPlanck, but consistent with recent suggestions of a significantly higher value.