利用JWST发现$z=3.33$处极低质量比并合诱导的恒星形成团块
Discovery of Very Minor Merger-Induced Star-forming Clumps at $z=3.33$ with JWST
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- Department of Physics and Astronomy, University of California（加州大学物理与天文学系）
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中文总结 AI 辅助
利用JWST观测发现，一个恒星质量比低约28倍的伴星系与宿主星系相互作用，在$z=3.33$处形成了恒星形成团块，表明低质量比并合是高红移团块形成的重要机制。
中文摘要 AI 辅助
高红移星系通常含有“团块”：致密的、约千秒差距尺度的强烈恒星形成区域。这些子结构占其宿主星系质量和恒星形成率的显著比例，并预计会影响宿主星系的形态，例如通过构建核球。因此，研究团块可以为星系演化的理论模型提供信息。目前提出了两种主要的形成机制：盘不稳定性引起的气体碎裂，以及与其他星系引力相互作用过程中气体的压缩。在后一种机制中，仅考虑了质量比大于1:10的并合。在此，我们报告詹姆斯·韦伯太空望远镜对JADES 1034862的光谱和成像观测，这是一个位于$z_{\textrm{spec}} = 3.33$的星系，其宿主一个在与伴星系相互作用期间形成的团块，该伴星系的恒星质量比宿主低约28倍。通过对团块和伴星系的光谱能量分布进行拟合，发现两者的恒星形成历史在最近的100-300百万年内急剧上升，在此期间团块形成了约$10^{7.2} \\ M_{\odot}$的恒星，目前占其宿主总恒星形成率的约10%。鉴于低质量比（<1:10）并合的发生频率高于高质量比并合，我们推断高红移团块的相当大一部分可能是通过弱引力相互作用形成的。
英文摘要
High-redshift galaxies often contain ''clumps:'' compact, $\sim$kpc-scale regions of intense star formation. These substructures make up significant fractions of the masses and star-formation rates of their host galaxies and are expected to affect the morphologies of their hosts, such as by building up bulges. Studying clumps can therefore inform theoretical models of galaxy evolution. Two main mechanisms have been proposed for their formation: gas fragmentation from disk instabilities and compression of gas during gravitational interactions with other galaxies. In the latter, only mergers with mass ratios greater than 1:10 have been considered. Here, we report James Webb Space Telescope spectroscopy and imaging of JADES 1034862, a galaxy at $z_{\textrm{spec}} = 3.33$, which hosts a clump that formed during an interaction with a companion with a stellar mass that is $\approx28$ times lower than the host. From fits to the spectral energy distributions of the clump and the companion, it is found that both of their star-formation histories rose sharply in the most recent 100-300 Myr, during which the clump formed $\sim10^{7.2} \ M_{\odot}$ in stars and currently makes up $\approx10\%$ of the total star-formation rate of its host. Given the higher frequency of mergers with low mass ratios ($<1:10$) to those with higher ratios, we infer that a substantial fraction of high-redshift clumps could have formed through weak gravitational interactions.
