MIDIS: Unveiling the Role of Strong Hα Emitters During the Epoch of Reionization with JWST

Rinaldi, P.; Caputi, K. I.; Iani, E.; Costantin, L.; Gillman, S.; Perez Gonzalez, P. G.; Östlin, G.; Colina, L.; Greve, T. R.; Nørgard-Nielsen, H. U.; Wright, G. S.; Álvarez-Márquez, J.; Eckart, A.; García-Marín, M.; Hjorth, J.; Ilbert, O.; Kendrew, S.; Labiano, A.; Le Fèvre, O.; Pye, J.; Tikkanen, T.; Walter, F.; van der Werf, P.; Ward, M.; Annunziatella, M.; Azzollini, R.; Bik, A.; Boogaard, L.; Bosman, S. E. I.; Crespo Gómez, A.; Jermann, I.; Langeroodi, D.; Melinder, J.; Meyer, R. A.; Moutard, T.; Peissker, F.; van Dishoeck, E.; Güdel, M.; Henning, Th.; Lagage, P.-O.; Ray, T.; Vandenbussche, B.; Waelkens, C.; Dayal, Pratika

Abstract

By using an ultradeep JWST/MIRI image at 5.6 μm in the Hubble eXtreme Deep Field, we constrain the role of strong Hα emitters (HAEs) during “cosmic reionization” at z ≃ 7-8. Our sample of HAEs is comprised of young (<35 Myr) galaxies, except for one single galaxy (≈300 Myr), with low stellar masses (≲109 M☉). These HAEs show a wide range of rest-frame UV continuum slopes (β), with a median value of β = -2.15 ± 0.21, which broadly correlates with stellar mass. We estimate the ionizing photon production efficiency (ξion,0) of these sources (assuming fesc,LyC = 0%), which yields a median value log10(xion,0 (Hz erg-1)) = 25.50-+0.120.10. We show that ξion,0 positively correlates with Hα equivalent width and specific star formation rate. Instead ξion,0 weakly anticorrelates with stellar mass and β. Based on the β values, we predict fesc,LyC = 4%-+23, which results in log10(xion (Hz erg-1)) = 25.55-+0.130.11. Considering this and related findings from the literature, we find a mild evolution of ξion with redshift. Additionally, our results suggest that these HAEs require only modest escape fractions (fesc,rel) of 6%-15% to reionize their surrounding intergalactic medium. By only considering the contribution of these HAEs, we estimated their total ionizing emissivity (N(Equation presented)ion) as N(Equation presented)ion = 1050.53±0.45 s-1Mpc-3. When comparing their N(Equation presented)ion with non-HAE galaxies across the same redshift range, we find that that strong, young, and low-mass emitters may have played an important role during cosmic reionization.

Citation

Rinaldi, P., Caputi, K. I., Iani, E., Costantin, L., Gillman, S., Perez Gonzalez, P. G., Östlin, G., Colina, L., Greve, T. R., Nørgard-Nielsen, H. U., Wright, G. S., Álvarez-Márquez, J., Eckart, A., García-Marín, M., Hjorth, J., Ilbert, O., Kendrew, S., Labiano, A., Le Fèvre, O., Pye, J., …Dayal, P. (2024). MIDIS: Unveiling the Role of Strong Hα Emitters During the Epoch of Reionization with JWST. Astrophysical Journal, 969(1), 12. https://doi.org/10.3847/1538-4357/ad4147

• Journal Article Type: Article
• Acceptance Date: Apr 15, 2024
• Online Publication Date: Jun 21, 2024
• Publication Date: Jul 1, 2024
• Deposit Date: Aug 5, 2024
• Publicly Available Date: Aug 5, 2024
• Journal: The Astrophysical Journal
• Print ISSN: 0004-637X
• Electronic ISSN: 1538-4357
• Publisher: American Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 969
• Issue: 1
• Pages: 12
• DOI: https://doi.org/10.3847/1538-4357/ad4147
• Public URL: https://durham-repository.worktribe.com/output/2740801