发表机构
Scuola Normale Superiore; Università di Pisa; INAF/OAS Bologna（高等师范学院; 比萨大学; 意大利国家天体物理研究所博洛尼亚天文台）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过辐射流体动力学模拟发现，超级早期星系中致密恒星团块可由气体盘碎裂原位形成，反馈调控其质量与演化，贡献随时间显著下降。
AI 中文摘要
（删节版）JWST 揭示了红移 z>6 的星系中极其致密的恒星团块，但其形成机制及后续演化仍不确定。我们研究此类系统是否可以通过早期星系盘的碎裂在原位形成，以及恒星反馈如何调控其性质。我们针对一个孤立星系（“Ninfea_blu”）进行了一组辐射流体动力学模拟，其 $\rm M_{vir}=1.5\times10^{10} M_\rm{\odot}$，从 z=16 演化至 z=12.5，历时 100 Myr，最大空间分辨率为 3.6 pc。在所有情况下，气体迅速形成旋转支撑的盘，达到峰值恒星形成率 $10-15\rm M_\rm{\odot} yr^{-1}$，并碎裂成致密的恒星团块。Toomre 不稳定区域（$Q_{\rm gas}<1$）在恒星形成开始之前出现，第一批恒星结构优先在这些区域内形成，支持了类似 Toomre 的引力碎裂路径。团块的恒星质量为 $10^6-2\times10^8\\,M_\rm{\odot}$，有效半径为 7-50 pc，表面密度为 $0.2-3\times10^4\rm M_\rm{\odot} pc^{-2}$，与观测到的 z>6 团块所占参数空间的大部分重叠。反馈使累积恒星质量减少 30-40%，使团块内保留的气体质量降低约 1 dex，并抑制其高质量端，但不阻止其初始形成。团块随后迁移、相互作用、经历潮汐剥离并消散。团块质量函数产生幂律斜率 -1.88，与观测结果高度吻合。此外，它们对恒星质量和固有紫外光度的贡献分别从 20 Myr 时的 0.41 和 0.40 下降到 100 Myr 时的 0.13 和 0.10。我们得出结论：致密、富含气体的盘的碎裂为早期宇宙中观测到的许多致密恒星系统提供了可行的起源，而反馈和内部动力学主要调控其生长和命运。
英文摘要
(Abridged) JWST has revealed extremely compact stellar clumps in galaxies at z>6, but their formation mechanism and subsequent evolution remain uncertain. We investigate whether such systems can form in-situ through the fragmentation of an early galactic disk and how stellar feedback regulates their properties. We perform a suite of radiation-hydrodynamical simulations of an isolated galaxy ("Ninfea_blu"), with $\rm M_{vir}=1.5\times10^{10} M_\odot$, evolved for 100 Myr from z=16 to 12.5 with a maximum spatial resolution of 3.6 pc. In all cases, the gas rapidly forms a rotationally supported disk, reaches a peak star formation rate of $10-15\rm M_\odot yr^{-1}$, and fragments into dense stellar clumps. Toomre-unstable regions ($Q_{\rm gas}<1$) appear before the onset of star formation, and the first stellar structures form preferentially within these regions, supporting a Toomre-like gravitational fragmentation pathway.The clumps have stellar masses of $10^6-2\times10^8\,M_\odot$, effective radii of 7-50 pc, and surface densities of $0.2-3\times10^4\rm M_\odot pc^{-2}$, overlapping much of the parameter space occupied by observed z>6 clumps. Feedback reduces the cumulative stellar mass by 30-40%, lowers the gas mass retained within clumps by ~1 dex, and suppresses their high-mass tail without preventing their initial formation. Clumps subsequently migrate, interact, undergo tidal stripping, and disperse. The clump mass function produces a power law slope of -1.88, which aligns closely with observations. Moreover, their contributions to the stellar mass and intrinsic UV luminosity decline from 0.41 and 0.40 at 20 Myr to 0.13 and 0.10 at 100 Myr, respectively. We conclude that fragmentation of compact, gas-rich disks provides a viable origin for many of the dense stellar systems observed in the early Universe, while feedback and internal dynamics primarily regulate their growth and fate.
Comments19 pages, 15 figures
