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Arxiv: A SPectroscopic survey of biased halos In the Reionization Era (ASPIRE): JWST Supports Earlier Reionization around [OIII] Emitters Published: 10/2/2024 11:22:36 AM Updated: 10/2/2024 11:22:36 AM

Paper abstract: Understanding when and how reionization happened is crucial for studying theearly structure formation and the properties of first galaxies in the Universe.At z>5.5, the observed IGM optical depth shows a significant scatter,indicating an inhomogeneous reionization process. However, the nature of theinhomogeneous reionization remains debated. ASPIRE is a JWST Cycle 1 programthat has spectroscopically identified >400 [OIII] emitters in 25 quasarfields at z>6.5. Combined with deep ground-based optical spectroscopy ofASPIRE quasars, ASPIRE program provides the current largest sample forIGM-galaxy connection studies during cosmic reionization. We present the firstresults of IGM effective optical depth measurements around [OIII] emittersusing 14 ASPIRE quasar fields. We find the IGM transmission is tightly relatedwith reionization-era galaxies to the extent that significant excess ofLy\alpha transmission exists around [OIII] emitters. We measure the stackedIGM effective optical depth of IGM patches associated with [OIII] emitters andfind they reach the same IGM effective optical depth at least dz~0.1 ahead ofthose IGM patches where no [OIII] emitters are detected, supporting earlierreionization around [OIII] emitters. Our results indicate an enhancement in IGMLy\alpha transmission around [OIII] emitters at scales beyond 25 h^{-1}cMpc, consistent with the predicted topology of reionization from fluctuatingUV background (UVB) models.