February
2026
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2026ApJ...998..175M
Authors
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Morishita, Takahiro
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Stiavelli, Massimo
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Mason, Charlotte A.
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Tripodi, Roberta
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Chiaberge, Marco
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Schuldt, Stefan
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Willott, Chris J.
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Zhang, Yechi
Abstract
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We report the detection of Lyα in CANUCS-LRD-z8.6, a recently discovered active galactic nucleus (AGN) at z = 8.63 by R. Tripodi et al. (2025), in new NIRSpec/MSA G140H/F070LP observations. We detect broad Lyα emission (FWHM = 1540 ± 260 km s−1) near the systemic velocity, which suggests a large ionizing bubble, considering that the Universe is almost fully neutral at the redshift. Through Lyα line-shape modeling assuming a Strömgren sphere, we find a large bubble radius, Rb = 1.5−0.2+0.3 pMpc, and a moderately high Lyα escape fraction, fesc = 11% ± 3%. The intrinsic line width is inferred to be broad (2200 ± 280 km s−1), likely originating in the broad-line region. Existing data indicate that CANUCS-LRD-z8.6 is within a mild overdensity, δ = 1.8−0.6+3.0 , suggesting that other galaxies in its proximity might have contributed to the formation of the bubble. The high N IV]λ1488/C IVλ1548 and N IV]λ1488/O III]λ1661 line ratios measured in existing NIRSpec/PRISM data indicate nitrogen enrichment in this metal-poor, low-luminosity AGN. The spectroscopic features are overall similar to those of other nitrogen-rich galaxies discovered in the literature, such as GN-z11 and GHZ2/GLASSz12. This suggests that CANUCS-LRD-z8.6 may represent one of the evolutionary phases of those nitrogen-rich galaxies.
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