COLIBRE模拟中星系相互作用对恒星形成率的影响
The effect of galaxy interactions on star formation rates in the COLIBRE simulations
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中文总结 AI 辅助
本研究利用COLIBRE模拟探究红移z≈0处星系相互作用对恒星形成率的影响，发现相互作用会提升恒星形成率，提升程度与间距、分辨率、恒星质量等相关，结果与SDSS观测基本吻合，且该提升贡献了约2%的宇宙恒星形成率密度。
中文摘要 AI 辅助
观测与理论表明，星系相互作用会提升恒星形成率（SFR），但不同研究中这种提升的程度及其对相互作用星系属性的依赖关系存在差异。本研究利用星系形成的COLIBRE模拟，探究红移z≈0处恒星形成星系的相互作用对其SFR的影响。COLIBRE模拟捕捉了星际介质的多相特性，在m6分辨率（气体与暗物质粒子质量约10^6 M⊙）下体积达200^3立方百万秒差距，在m7分辨率（约10^7 M⊙）下体积达400^3立方百万秒差距。在构建恒星质量、大小尺度环境及红移均匹配的相互作用星系样本（质量比>0.1）与孤立对照样本后，结果显示，当星系对间距约10千秒差距时，相互作用星系的平均恒星形成率（sSFR）提升幅度可达约2倍；这种提升随星系对间距增大而减弱，但在间距约200千秒差距时仍显著。提升幅度随数值分辨率提高而增大，在星系中心区域更明显，且在固定间距下随恒星质量增大而减小；质量比更高的并合会引发更强的sSFR提升。将结果与SDSS观测数据对比发现，平均sSFR提升随间距的依赖关系吻合良好，但模拟对其归一化的预测值偏低约2倍。最后，研究表明，已分辨相互作用的并合前sSFR提升贡献了z≈0处宇宙SFR密度的约2%。
英文摘要
Observations and theory indicate that galaxy interactions enhance star formation rates (SFRs). However, the degree of enhancement and its dependence on the properties of the interacting galaxies vary across different studies. In this work, we use the COLIBRE simulations of galaxy formation to investigate the effect of interactions on the SFRs of star-forming galaxies at redshift $z\approx0$. The COLIBRE simulations capture the multiphase nature of the interstellar medium and have volumes up to $200^3$ and $400^3$ cMpc$^3$ at m6 (gas and dark-matter particle mass $\sim10^6~\mathrm{M_\odot}$) and m7 ($\sim10^7~\mathrm{M_\odot}$) resolutions, respectively. After constructing samples of interacting galaxies (with mass ratios $>0.1$) and isolated controls, matched in stellar mass, large- and small-scale environment, and redshift, we show that the average specific SFR (sSFR) of interacting galaxies is enhanced by up to a factor of $\approx2$ for separations of $\approx10$ kpc. The enhancement decreases with pair separation but remains significant out to $\approx200$ kpc. The enhancement increases with increasing numerical resolution, is more pronounced in the central regions of galaxies, and decreases with increasing stellar mass at fixed separation. Mergers with higher mass ratios induce stronger sSFR enhancement. We compare our results with observational data from the SDSS, finding good agreement in the dependence of the mean sSFR enhancement on separation, but underpredicting its normalisation by a factor of $\approx2$. Finally, we show that the pre-merger sSFR enhancement of resolved interactions accounts for $\approx2$ per cent of the $z\approx0$ cosmic SFR density.
