Year: 2026
Type: preprint
Abstract: We present deep, >10 hr, JWST NIRSpec G140M and G395M observations of a previously known galaxy C3PO-8447 at z=8.99781. Our new NIRSpec data from the Carbon-3 plus Oxygen (C3PO) survey detect Lyα emission with an escape fraction of 1.5±0.3% and a velocity offset of 210±80 km s⁻¹, making C3PO-8447 the third Lyα emitting galaxy confirmed at z≳9. The galaxy has a low stellar mass of 2.2±0.1×10⁷ M⊙, a young stellar age of 1.6±0.2 Myr, and a low oxygen abundance of 12+log(O/H)=7.50±0.08. UV diagnostic diagrams incorporating the C IV, O III], and C III] emission lines indicate that the ionization of C3PO-8447 is dominated by the recent starburst. The low Lyα escape fraction of C3PO-8447 implies that C3PO-8447 resides in a small ionized bubble with radius R∼0.07 to 0.20 pMpc, which can be produced by C3PO-8447 alone. We find no evidence for either a large-scale galaxy overdensity around C3PO-8447 or a significant contribution from nearby galaxies to its ionizing photon budget. Taken together, these results suggest that C3PO-8447 likely represents an ionized bubble powered by a single low-mass, vigorously star-forming galaxy during the early stages of cosmic reionization.
Source: arXiv (Cornell University)
DOI: 10.13016/m2amqw-t7hn
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7208774119