Probing Direct Contributions of Galaxies and Active Galactic Nuclei to Cosmic Reionization in a Quasar Field J0226+0302 with JWST/NIRCam and NIRSpec

@article{jin2026probing,
  title = {{Probing Direct Contributions of Galaxies and Active Galactic Nuclei to Cosmic Reionization in a Quasar Field J0226+0302 with JWST/NIRCam and NIRSpec}},
  author = {Xiangyu Jin and Jinyi Yang and Feige Wang and Koki Kakiichi and Xiaohui Fan and Enrico Garaldi and Jaclyn B. Champagne and George D. Becker and Yongda Zhu and Yunjing Wu and Marianne Vestergaard and Huanqing Chen and Valentina D’Odorico and Anna-Christina Eilers and Jiamu Huang and Hyunsung D. Jun and Mingyu Li and Maria Pudoka and Wei Leong Tee and Minghao Yue and Huanian Zhang and Siwei Zou},
  journal = {The Astrophysical Journal},
  year = {2026},
  month = oct,
  doi = {10.3847/1538-4357/aea55d},
  url = {https://iopscience.iop.org/article/10.3847/1538-4357/aea55d},
  note = {CC BY 4.0},
}

TY  - JOUR
TI  - Probing Direct Contributions of Galaxies and Active Galactic Nuclei to Cosmic Reionization in a Quasar Field J0226+0302 with JWST/NIRCam and NIRSpec
AU  - Xiangyu Jin
AU  - Jinyi Yang
AU  - Feige Wang
AU  - Koki Kakiichi
AU  - Xiaohui Fan
AU  - Enrico Garaldi
AU  - Jaclyn B. Champagne
AU  - George D. Becker
AU  - Yongda Zhu
AU  - Yunjing Wu
AU  - Marianne Vestergaard
AU  - Huanqing Chen
AU  - Valentina D’Odorico
AU  - Anna-Christina Eilers
AU  - Jiamu Huang
AU  - Hyunsung D. Jun
AU  - Mingyu Li
AU  - Maria Pudoka
AU  - Wei Leong Tee
AU  - Minghao Yue
AU  - Huanian Zhang
AU  - Siwei Zou
PY  - 2026
DA  - 2026/10/21
JO  - The Astrophysical Journal
DO  - 10.3847/1538-4357/aea55d
UR  - https://iopscience.iop.org/article/10.3847/1538-4357/aea55d
AB  - We present JWST Cycle 2 NIRCam and NIRSpec observations of a quasar field J0226+0302 at z = 6.5412 to probe the direct connections between the intergalactic medium (IGM), galaxies, and active galactic nuclei (AGN) during reionization. This field was previously observed by the JWST ASPIRE program, detecting eight [O III ]-emitting galaxies at 5.3 < z < 6.4 with a single NIRCam pointing. Using new NIRCam and NIRSpec observations, we identify 65 additional line-emitting galaxies at 5.3 < z < 6.4. The IGM–galaxy cross-correlation function shows an ∼2 σ excess IGM transmission at ∼10–40 cMpc from galaxies, suggesting a significant contribution from regions traced by star-forming galaxies to the local ionizing background. The IGM–galaxy cross-correlation function in this field is consistent with THESAN simulations for an IGM neutral fraction of 5%–7% and an average galaxy ionizing escape fraction f esc of 6%, although a single field is subject to substantial cosmic variance and cannot constrain these quantities independently. Among 49 line-emitting galaxies observed by NIRSpec, we identify four AGN with broad H α emission lines, resulting in an AGN fraction of 8% ± 4%. From the IGM effective optical depth and the IGM–AGN cross-correlation function, we find that the IGM transmission is higher within 5 h ⁻¹ cMpc of four AGN than around the majority of [O iii ] emitters. We interpret the excess transmission as resulting from the local radiation enhancement by the AGN, and estimate AGN f esc ∼ 50%–100%, based on our illustrative model for the IGM–AGN cross-correlation function. Future JWST/NIRSpec observations of quasar fields will yield a more constraining IGM–AGN cross-correlation function, providing further insights into the roles of galaxies and AGN in reionization.
SN  - 0004-637X
SN  - 1538-4357
ER  -