星系合并推动电离态增强
Galaxy mergers drive enhancements in ionization states
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中文总结 AI 辅助
研究星系合并对电离态的影响，通过分析斯隆数字巡天数据，发现合并使\(\rm{O}_{32}\)增加，尤其在首次近心点通过后，低质量合并贡献大，表明合并增强电离态，还推断绿豌豆星系是低质量星系合并。
中文摘要 AI 辅助
近期研究表明星系合并可能有助于推动电离光子从星系逃逸。然而，合并星系的电离特性尚未在一个大型、明确的样本中，针对整个合并序列进行系统研究。本文研究合并对追踪电离态的线比\(\rm{O}_{32}\)的影响，并研究其作为合并进程函数的演化。利用斯隆数字巡天数据发布17中具有稳健（\(\rm{SNR}>3\)）发射线通量的星系合并，通过光谱对分析和参与式科学实验“宇宙迪斯科：表征星系碰撞”的视觉分类，识别出7641个星系合并。发现\(\rm{O}_{32}\)随合并进程持续增加，在合并后达到峰值。与孤立星系的对照样本相比，首次近心点通过后的合并中\(\rm{O}_{32}\)显著增强。研究\(\rm{O}_{32}>3\)的星系合并特性，发现主要是接近合并的低质量合并。在这个群体中，大的\(\rm{O}_{32}\)值是由于合并导致特定恒星形成率同时增加和金属丰度降低。因此，星系合并增强了星系的电离态，可能促进电离辐射从星系逃逸，甚至在低恒星质量时也是如此。最后推断，以高\(\rm{O}_{32}\)为特征的绿豌豆星系是合并时的低质量星系合并，这一情景调和了环境和干涉21厘米研究的结果。
英文摘要
Recent studies have suggested that galaxy mergers may help drive the escape of ionizing photons from galaxies. However, the ionization properties of merging galaxies have not yet been systematically studied across the full merger sequence in a large, well-defined sample. Here, we investigate the impact of mergers on the line ratio $\rm{O}_{32}$ tracing the ionization state and study its evolution as a function of merger progression. We identify 7641 galaxy mergers with robust ($\rm{SNR}>3$) emission line fluxes from the Sloan Digital Sky Survey Data Release 17, using spectroscopic pair analysis and visual classifications from the participatory science experiment "Cosmic Disco: Characterizing Galaxy Collisions". We find a continuous increase in $\rm{O}_{32}$ as a function of merger progression traced by pair separation and visual merger stages, with median and 90th percentile peaking post-coalescence. $\rm{O}_{32}$ is significantly enhanced in mergers past the first pericenter passage as compared to a control sample of isolated galaxies. We investigate the properties of galaxy mergers with $\rm{O}_{32}>3$ and find that these are mainly low-mass ($\widetilde{\rm{M}_{*}}=6\times 10^{8}\,\rm{M}{_\odot}$) mergers close to coalescence. In this population, large $\rm{O}_{32}$ values are due to mergers driving a simultaneous increase in specific star formation rate and decrease in metallicity. Thus, galaxy mergers enhance the ionization state of galaxies and likely facilitate the escape of ionizing radiation from galaxies, even at low stellar masses. Finally, we infer that Green Pea galaxies, a population characterized by high $\rm{O}_{32}$ , are low-mass galaxy mergers at coalescence, a scenario that reconciles findings from environmental and interferometric 21cm studies.
