UNCOVER: A NIRSpec Census of Lensed Galaxies at z = 8.50–13.08 Probing a High-AGN Fraction and Ionized Bubbles in the Shadow

UNCOVER: A NIRSpec Census of Lensed Galaxies at z = 8.50–13.08 Probing a High-AGN Fraction and Ionized Bubbles in the Shadow

We present JWST NIRSpec prism spectroscopy of lensed galaxies at z ≳ 9 found behind the massive galaxy cluster Abell 2744 in the UNCOVER Cycle 1 Treasury Program. We confirm the redshift via emission lines and/or the Ly α break for 10 galaxies at z = 8.50–13.08 down to M _V = −17.3. We achieve a 100...

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Main Authors: Seiji Fujimoto, Bingjie Wang, John R. Weaver, Vasily Kokorev, Hakim Atek, Rachel Bezanson, Ivo Labbe, Gabriel Brammer, Jenny E. Greene, Iryna Chemerynska, Pratika Dayal, Anna de Graaff, Lukas J. Furtak, Pascal A. Oesch, David J. Setton, Sedona H. Price, Tim B. Miller, Christina C. Williams, Katherine E. Whitaker, Adi Zitrin, Sam E. Cutler, Joel Leja, Richard Pan, Dan Coe, Pieter van Dokkum, Robert Feldmann, Yoshinobu Fudamoto, Andy D. Goulding, Gourav Khullar, Danilo Marchesini, Michael Maseda, Themiya Nanayakkara, Erica J. Nelson, Renske Smit, Mauro Stefanon, Andrea Weibel
Format: Article
Language:English
Published: IOP Publishing 2024-01-01
Series:The Astrophysical Journal
Subjects:
High-redshift galaxies
Early universe
Luminosity function
Reionization
Active galactic nuclei
Online Access:https://doi.org/10.3847/1538-4357/ad9027
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Summary:We present JWST NIRSpec prism spectroscopy of lensed galaxies at z ≳ 9 found behind the massive galaxy cluster Abell 2744 in the UNCOVER Cycle 1 Treasury Program. We confirm the redshift via emission lines and/or the Ly α break for 10 galaxies at z = 8.50–13.08 down to M _V = −17.3. We achieve a 100% confirmation rate for z > 9 candidates reported in H. Atek et al. Using six sources with multiple line detections, we find that offsets in redshift estimates between the lines and the Ly α break alone can be ±0.2, raising caution in designing future follow-up spectroscopy for the break-only sources with the Atacama Large Millimeter/submillimeter Array. With spec- z -confirmed sources in UNCOVER and the literature, we derive lower limits on the rest-frame ultraviolet (UV) luminosity function (LF) at z ≃ 9–12 and find that these lower limits agree with recent photometric measurements. We identify at least two unambiguous and several possible active galactic nucleus (AGN) systems based on X-ray, broad H β , high ionization lines, and excess in the UV LF. This requires the AGN LFs at z ≃ 9–10 to be comparable or even higher than the X-ray AGN LF estimated at z ∼ 6 and suggests a plausible cause of the high abundance of z > 9 galaxies claimed in the recent photometric measurements is AGNs. One UV-luminous source is confirmed at the same redshift as a broad-line AGN at z = 8.50 with a physical separation of 380 kpc in the source plane. These two sources show emission blueward of Ly α , indicating a giant ionized bubble enclosing them with a radius of 7.69 ± 0.18 pMpc. Our results imply that AGNs have a nonnegligible contribution to cosmic reionization.
ISSN:1538-4357

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