AI 中文总结
本研究发现宇宙大爆炸后5亿年的并合星系Gz9p3正处于无反馈星暴向重子循环转变的阶段，通过JWST光谱揭示其冷外流气体电子密度等关键特征，证实反馈调控再循环在再电离纪元已存在。
AI 中文摘要
恒星反馈作为星系生长调控因子的出现，标志着宇宙历史中的一次基本转变。在早期，快速的气体吸积与坍缩可能会在反馈生效前引发剧烈的恒星形成，产生无反馈星暴。这类星暴随后何时以及如何发展为自我调控的重子循环，观测上尚不明确。本研究显示，在宇宙大爆炸后仅5亿年，处于z=9.311的并合星系Gz9p3正处于这一转变阶段。深度詹姆斯·韦布空间望远镜（JWST）光谱揭示，其并合驱动的潮汐结构中存在大量中性气体储库，且存在多相外流。精细结构吸收首次直接测量到高红移冷外流气体的电子密度约为17 cm⁻³，得出的质量加载因子是同恒星质量星系中迄今测得的最高值之一。剧烈星暴后这类高效反馈的出现，与无反馈星暴模型中预期的反馈延迟起始一致。冷外流气体不太可能逃离宿主暗物质晕，意味着大量富金属物质可能仍可通过星系周介质进行未来的再循环。因此，Gz9p3提供了重子循环通过并合驱动气体重分布、爆发式恒星形成与恒星反馈相互作用建立的早期视图，表明反馈调控的再循环在再电离纪元已开始塑造星系生长。
英文摘要
The emergence of stellar feedback as a regulator of galaxy growth marks a fundamental transition in cosmic history. At early times, rapid gas accretion and collapse may induce intense star formation before feedback becomes effective, producing feedback-free starbursts. When and how such bursts subsequently develop into self-regulated baryon cycles remain observationally unknown. Here we show that Gz9p3, a merging galaxy at $z=9.311$, is caught in this transition only 500 million years after the Big Bang. Deep JWST spectroscopy reveals a substantial neutral-gas reservoir along its merger-driven tidal structure and a multiphase outflow. Fine-structure absorption provides the first direct measurement of the electron density of the cool outflowing gas at high redshift ($\approx\,17\,{\rm cm^{-3}}$), yielding a mass-loading factor among the highest yet measured for galaxies of comparable stellar mass. The emergence of such efficient feedback after an intense burst is consistent with the delayed onset of feedback expected in feedback-free starburst models. The cool outflowing gas is unlikely to escape the host halo, implying that much of this metal-enriched material may remain available for future recycling through the circumgalactic medium. Gz9p3 therefore provides an early view of a baryon cycle being established through the interplay of merger-driven gas redistribution, bursty star formation and stellar feedback, suggesting that feedback-regulated recycling was already shaping galaxy growth during the epoch of reionization.
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