Accompanying data for "Deep JWST spectroscopy of galaxies in a candidate ionized bubble at z=8.7: probing reionization at pMpc scales with Lyα emission"

Strong Lyα emission observed from galaxies when the Universe is expected to be highly neutral is thought to trace large ionized regions that facilitate the transmission of Lyα through the IGM. In this work, we use deep JWST Lyα spectroscopy to constrain the size of a candidate ionized bubble at z∼8.7 in the EGS field, with a potential radius of Rb=2 physical Mpc (pMpc) or larger. We measure a photometric galaxy density and find that the volume is a factor of ∼2.5−3.6 overdense, suggesting that there may be a large population of galaxies capable of creating an Rb∼2 pMpc bubble. Then, we infer the Lyα transmission through the IGM for galaxies in the EGS volume using our deep spectroscopy, finding IGM=0.26+0.25−0.14. This transmission is consistent with the average at z∼9 and is mildly inconsistent with the transmission expected for an Rb∼2 pMpc bubble (IGM,2pMpc=0.53−0.63), implying that such a large bubble is unlikely to be present. However, the photometric galaxy density in the EGS field is larger than in several other deep fields. This overdensity and the moderate Lyα transmission may be consistent with smaller, Rb∼0.5−1 pMpc bubbles in EGS. This additionally motivates the need for future wider area Lyα spectroscopy in EGS and other fields to obtain a more representative understanding of the sizes of ionized bubbles in the early stages of reionization, and the properties of the galaxies that create them.