IllustrisTNG模拟中的相互作用星系——第八篇：近心点恒星形成率增强由燃料增加和效率提升共同驱动
Interacting galaxies in the IllustrisTNG simulations -- VIII: Pericentric star formation rate enhancements are driven both by increased fuelling and efficiency
AI总结：
基于TNG100-1模拟，研究发现星系相互作用中近心点相遇通过同时提升气体燃料和恒星形成效率（分别贡献30%和70%）来增强中心恒星形成率，平均增强1.6倍。
摘要：
利用TNG100-1宇宙学模拟，我们探讨了星系性质（如比恒星形成率（$\rm sSFR=SFR/M_*$）、气体比例（$\rm f_{gas} \\, = \\, M_{\rm H}/M_{*}$）和恒星形成效率（$\rm SFE_{H} = SFR/M_{H}$））在星系-星系相互作用过程中的变化。我们从一组大质量星系（$\rm M_{*} > 10^{10} \\; \rm M_{\odot}$）的重建轨道中识别出18,534次不同的相遇，这些星系伴有恒星质量比在0.1到10之间的伴星系。利用这些相遇，我们研究了在红移范围$0 \leq z < 1$内，星系性质随时间的变化，以及它们接近和远离近心点相遇的过程。在宿主星系与其伴星系最接近的近心点相遇（$\leq 50$ kpc）之后，我们发现sSFR在中心恒星半质量半径（R\textsubscript{1/2}）内相对于相遇前值平均增强了$1.6 \pm 0.1$倍。我们的结果显示，从近心点到sSFR最大增强之间存在约0.1 Gyr的时间延迟，此时平均星系间距为75 kpc。我们同样发现，在相同时间尺度内，近心点相遇后$\rm f_{gas}$增强了$1.2 \pm 0.1$倍，$\rm SFE_{H}$增强了$1.4 \pm 0.1$倍。此外，通过比较中心R\textsubscript{1/2}内的$\rm f_{gas}$和金属丰度与星系外围的对应值，我们发现了气体向中心流入的证据。我们发现，峰值sSFR增强中约有70%可归因于$\rm SFE_{H}$的增加，而$\rm f_{gas}$的增加贡献了其余30%。
英文摘要：
Using the TNG100-1 cosmological simulations, we explore how galaxy properties, such as specific star formation rate ($\rm sSFR=SFR/M_*$), gas fraction ($\rm f_{gas} \,= \, M_{\rm H}/M_{*}$), and star formation efficiency ($\rm SFE_{H} = SFR/M_{H}$), change over the course of galaxy-galaxy interactions. We identify 18,534 distinct encounters from the reconstructed orbits of a sample of massive galaxies ($\rm M_{*} > 10^{10} \; \rm M_{\odot}$) with companions within a stellar mass ratio of 0.1 to 10. Using these encounters, we study the variation of galaxy properties over time as they approach and move away from pericentric encounters over a redshift range of $0 \leq z < 1$. Following the closest pericentric encounters ($\leq 50$ kpc) of a host galaxy with its companion, we find that sSFR is enhanced by a factor of $1.6 \pm 0.1$ on average within the central stellar half-mass radius (R\textsubscript{1/2}) compared to pre-encounter values. Our results show a time delay between pericentre and maximum sSFR enhancement of $\sim$0.1 Gyr with a mean galaxy separation of 75 kpc. We similarly find that $\rm f_{gas}$ is enhanced by a factor of $1.2 \pm 0.1$, and $\rm SFE_{H}$ is enhanced by a factor of $1.4 \pm 0.1$ following the pericentre of an encounter within the same timescale. Additionally, we find evidence of inflowing gas towards the centre, measured by comparing the $\rm f_{gas}$ and metallicity within the central R\textsubscript{1/2} to the galactic outskirts. We find that approximately 70 per cent of the peak sSFR enhancement can be attributed to the increase in $\rm SFE_{H}$, with the increase in $\rm f_{gas}$ contributing the remaining 30 per cent.
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