Morphology and star formation in IllustrisTNG: the build-up of spheroids and discs
Morphology and star formation in IllustrisTNG: the build-up of spheroids and discs
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DOI：
10.1093/mnras/stz1657
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发表时间：
2019-04
影响因子：
4.8
通讯作者：
S. Tacchella;B. Diemer;L. Hernquist;S. Genel;F. Marinacci;D. Nelson;A. Pillepich;V. Rodriguez-Gomez-V.-Rodriguez
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文献类型：
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作者：
S. Tacchella;B. Diemer;L. Hernquist;S. Genel;F. Marinacci;D. Nelson;A. Pillepich;V. Rodriguez-Gomez-V.-Rodriguez
使用IllustrisTNG模拟，我们调查的星系形态和星星形成之间的连接，在中央星系的恒星质量范围在109-1011.5 M。我们通过将恒星分量运动学分解为球体和盘分量（球体与总比，S/T）以及恒星质量密度分布（C82）的浓度来量化星系形态。S/T与恒星质量和星星形成活动有关，而C 82只与恒星质量有关。总的来说，我们发现S/T和C82的观测估计值很好的协议。低质量和高质量星系主要由随机恒星运动控制，而只有中等质量星系（M 1010-1010.5 M）主要由有序旋转控制。高质量星系是典型的高浓度球状体，而低质量星系则是低浓度球状体，这说明星系的形成通道不同。虽然我们发现S/T和星星形成活动之间的相关性，在TNG模型中，星系不一定改变它们的形态时，他们通过绿色过渡或当他们停止他们的星星形成，这取决于星系恒星质量和形态估计。相反，形态（S/T和C82）通常在星系的恒星形成阶段设定。S/T和星星形成之间的明显相关性是因为早期形成的星系在给定的恒星质量下平均具有较高的S/T。此外，我们还发现，合并驱动了中等质量星系中的原位球核形成，并对M_（10）> 1011 M_（11）的大质量星系中最近的球状质量组装负责。特别是，这些大质量星系在恒星形成时聚集了大约一半的球状体质量，另一半则是在静止时通过合并。
Using the IllustrisTNG simulations, we investigate the connection between galaxy morphology and star formation in central galaxies with stellar masses in the range 109–1011.5 M⊙. We quantify galaxy morphology by a kinematical decomposition of the stellar component into a spheroidal and a disc component (spheroid-to-total ratio, S/T) and by the concentration of the stellar mass density profile (C82). S/T is correlated with stellar mass and star formation activity, while C82 correlates only with stellar mass. Overall, we find good agreement with observational estimates for both S/T and C82. Low- and high-mass galaxies are dominated by random stellar motion, while only intermediate-mass galaxies (M⋆ ≈ 1010–1010.5 M⊙) are dominated by ordered rotation. Whereas higher mass galaxies are typical spheroids with high concentrations, lower mass galaxies have low concentration, pointing to different formation channels. Although we find a correlation between S/T and star formation activity, in the TNG model galaxies do not necessarily change their morphology when they transition through the green valley or when they cease their star formation, this depending on galaxy stellar mass and morphological estimator. Instead, the morphology (S/T and C82) is generally set during the star-forming phase of galaxies. The apparent correlation between S/T and star formation arises because earlier forming galaxies had, on average, a higher S/T at a given stellar mass. Furthermore, we show that mergers drive in situ bulge formation in intermediate-mass galaxies and are responsible for the recent spheroidal mass assembly in the massive galaxies with M⋆ > 1011 M⊙. In particular, these massive galaxies assemble about half of the spheroidal mass while star-forming and the other half through mergers while quiescent.