Molecular Gas and Star Formation in Nearby Starburst Galaxy Mergers
Molecular Gas and Star Formation in Nearby Starburst Galaxy Mergers
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DOI：
10.3847/1538-4357/acca76
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发表时间：
2023-01
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影响因子：
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通讯作者：
Hao He;C. Bottrell;Christine Wilson;J. Moreno;B. Burkhart;C. Hayward;L. Hernquist;Angela A. Twum
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文献类型：
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作者：
Hao He;C. Bottrell;Christine Wilson;J. Moreno;B. Burkhart;C. Hayward;L. Hernquist;Angela A. Twum
我们采用真实环境反馈（FIRE-2）物理模型来研究星系合并过程中巨分子云（GMCs）的性质如何演化。我们在模拟的控制星系和星系主要合并中进行分子气体性质的逐像素分析。在控制星系中模拟的GMC像素在速度色散（σ v）与气体表面密度（μ mol）的关系图中遵循与在邻近星系高角分辨率物理学（PHANGS）巡天中在本地螺旋星系中观察到的趋势相似的趋势。对于模拟合并中的GMC像素，我们看到σ v和σ v都显著增加了5 - 10倍，这使得这些像素在σ v与σ v图中高于PHANGS星系的趋势。这种偏离可能表明，与维里参数（α vir）达到10 - 100的模拟控制星系相比，模拟合并中的GMC的引力束缚要小得多。此外，我们发现α vir的增加与全球星星形成率的增加同时发生，这表明恒星反馈是分散气体的原因。我们还发现，气体耗尽时间是显着较低的高α vir GMC在一个星暴事件。这与简单的物理图像形成对比，低α vir GMC更容易在较短的耗尽时间内坍缩并形成恒星。这可能表明，除了自引力之外，还有其他一些物理机制帮助GMC在恒星爆发合并中坍塌并形成恒星。
We employ the Feedback In Realistic Environments (FIRE-2) physics model to study how the properties of giant molecular clouds (GMCs) evolve during galaxy mergers. We conduct a pixel-by-pixel analysis of molecular gas properties in both the simulated control galaxies and galaxy major mergers. The simulated GMC pixels in the control galaxies follow a similar trend in a diagram of velocity dispersion (σ v ) versus gas surface density (Σmol) to the one observed in local spiral galaxies in the Physics at High Angular resolution in Nearby GalaxieS (PHANGS) survey. For GMC pixels in simulated mergers, we see a significant increase of a factor of 5–10 in both Σmol and σ v , which puts these pixels above the trend of PHANGS galaxies in the σ v versus Σmol diagram. This deviation may indicate that GMCs in the simulated mergers are much less gravitationally bound compared with simulated control galaxies with virial parameters (α vir) reaching 10–100. Furthermore, we find that the increase in α vir happens at the same time as the increase in global star formation rate, which suggests that stellar feedback is responsible for dispersing the gas. We also find that the gas depletion time is significantly lower for high-α vir GMCs during a starburst event. This is in contrast to the simple physical picture that low-α vir GMCs are easier to collapse and form stars on shorter depletion times. This might suggest that some other physical mechanisms besides self-gravity are helping the GMCs in starbursting mergers collapse and form stars.