在z=0.6的大质量星系中，只有不到10%的恒星形成是由主要的相互作用引发的。
Less than 10 percent of star formation in z=0.6 massive galaxies is triggered by major interactions
摘要：
观测和模拟都表明，富含气体的星系之间的主要潮汐相互作用或合并可能导致恒星形成的强烈爆发。然而，恒星形成率（SFR）在主要合并的平均增强和这些事件对宇宙SFR的贡献没有得到很好的估计。在这里，我们使用光度红移，恒星质量和紫外SFR从COMBO-17，24微米SFR从斯皮策和形态从两个深HST宇宙学调查领域（ECDFS/GEMS和A901/STAGES）研究SFR的增强作为一个功能的投影星系分离。我们应用两点投影关联函数技术，我们用形态学上选择的非常接近的对（分离<2 arcsec）和来自HST成像的合并残余来增强该技术。我们的分析证实，最强烈的恒星形成系统确实在相互作用或合并。然而，对于质量（M* > 10^10 Msun）的恒星形成星系，在0.4<z<0.8时，我们发现经历主要相互作用（质量比<1：4，分离< 40 kpc）的星系的SFR仅比非相互作用星系的SFR高1.80 +/- 0.30倍，当平均到所有相互作用和相互作用的所有阶段时，与其他观测工作非常一致。我们证明，这些结果意味着在0.4 < z < 0.8时，小于10%的恒星形成是由主要的合并和相互作用直接触发的;由于z=1，这些事件不是恒星质量积累的重要因素。
英文摘要：
Both observations and simulations show that major tidal interactions or mergers between gas-rich galaxies can lead to intense bursts of starformation. Yet, the average enhancement in star formation rate (SFR) in major mergers and the contribution of such events to the cosmic SFR are not well estimated. Here we use photometric redshifts, stellar masses and UV SFRs from COMBO-17, 24 micron SFRs from Spitzer and morphologies from two deep HST cosmological survey fields (ECDFS/GEMS and A901/STAGES) to study the enhancement in SFR as a function of projected galaxy separation. We apply two-point projected correlation function techniques, which we augment with morphologically-selected very close pairs (separation <2 arcsec) and merger remnants from the HST imaging. Our analysis confirms that the most intensely star-forming systems are indeed interacting or merging. Yet, for massive (M* > 10^10 Msun) star-forming galaxies at 0.4<z<0.8, we find that the SFRs of galaxies undergoing a major interaction (mass ratios <1:4 and separations < 40 kpc) are only 1.80 +/- 0.30 times higher than the SFRs of non-interacting galaxies when averaged over all interactions and all stages of the interaction, in good agreement with other observational works. We demonstrate that these results imply that <10% of star formation at 0.4 < z < 0.8 is triggered directly by major mergers and interactions; these events are not important factors in the build-up of stellar mass since z=1.
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