发表机构
Hebei Normal University; University of Chinese Academy of Sciences (UCAS); Dalian University of Technology; Shanghai Astronomical Observatory, Chinese Academy of Sciences（河北师范大学; 中国科学院大学; 大连理工大学; 中国科学院上海天文台）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究结合星系对间距、形态扰动与近期恒星形成历史，揭示近距星系相遇触发强恒星形成，中等间距星系的恒星形成演化存在时间差，为星系并合序列的恒星形成演化提供观测证据。
AI 中文摘要
星系间的相互作用可以增强恒星形成，但观测对星系相互作用期间恒星形成如何演化的约束仍十分有限。我们结合星系对间距、形态扰动以及近期恒星形成历史来研究这种演化。我们利用DESI Legacy Surveys的深场图像，通过形状不对称参数（$A_{\rm shape}$）测量形态扰动，并以Galaxy Zoo DESI分类作为独立检验。我们通过将追踪当前恒星形成的恒星形成率（SFR）和Hα等值宽度（EW(Hα)），与对更长时间尺度上形成的恒星族敏感的Hδ_A等值宽度（EW(Hδ_A)）和$D_n4000$进行比较，来推断近期恒星形成历史。在小投影间距下，受强烈扰动的星系表现出最强的SFR和EW(Hα)增强，表明近距相遇会触发强烈的恒星形成。在中等间距（$d_{\rm p}\backsim100\rm{\thinspace kpc}$）下，这些星系的当前恒星形成仅适度增强，但它们的EW(Hδ_A)增强最强，这表明在过去约0.1至1 Gyr期间，更强恒星形成过程中形成的中等年龄恒星贡献更大。TNG100分析显示，这种模式源于近距相遇前后SFR的快速变化：SFR在相遇期间急剧上升，随着星系相互远离而下降，而潮汐扰动仍可见；当短寿命大质量恒星消失，中等年龄的A型星开始主导光谱时，EW(Hδ_A)的增强峰值晚于SFR的增强峰值。我们的结果为并合序列中SFR的演化提供了重要观测证据。
英文摘要
Galaxy interactions can enhance star formation, but how star formation evolves during galaxy interactions remains poorly constrained by observations. We combine pair separation, morphological disturbance, and recent star formation history to study this evolution. We measure morphological disturbance with the shape asymmetry parameter ($A_{\rm shape}$) using deep images from the DESI Legacy Surveys, and use Galaxy Zoo DESI classifications as an independent test. We infer recent star formation histories by comparing SFR and $\mathrm{EW}(\mathrm{H}α)$, which trace current star formation, with $\mathrm{EW}(\mathrm{H}δ_A)$ and $D_n4000$, which are sensitive to stellar populations formed over longer timescales. At small projected separations, strongly disturbed galaxies show the strongest enhancements in SFR and $\mathrm{EW}(\mathrm{H}α)$, indicating that close encounters trigger strong star formation. At intermediate separations ($d_{\rm p}\sim100\,\mathrm{kpc}$), their current star formation is only moderately enhanced, but their $\mathrm{EW}(\mathrm{H}δ_A)$ enhancement is the strongest. This indicates a larger contribution from intermediate-age stars formed during stronger star formation in the past $\sim0.1$--$1\,\mathrm{Gyr}$. The TNG100 analysis shows that this pattern results from rapid changes in SFR around close passage. SFR rises sharply during the encounter and declines as the galaxies move apart, while tidal disturbances remain visible. As short-lived massive stars disappear and intermediate-age A-type stars begin to dominate the spectrum, the $\mathrm{EW}(\mathrm{H}δ_A)$ enhancement peaks later than the SFR enhancement. Our results provide important observational evidence for the evolution of SFR along the merger sequence.
Comments20 pages, 8 figures; accepted for publication in The Astrophysical Journal
