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arXiv 2501.07151astro-ph.GA
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动力学热核球中恒星的多样物理起源:CALIFA vs. IllustrisTNG

The diverse physical origins of stars in the dynamically hot bulge: CALIFA vs. IllustrisTNG

Le Zhang, Ling Zhu, Annalisa Pillepich, Min Du, Fangzhou Jiang, Jesús Falcón-Barroso

AI总结:

通过对比TNG50/TNG100模拟与CALIFA巡天数据,研究了动力学热核球中恒星的物理起源,发现热恒星的形成受初始圆度分布、长期演化加热和合并过程共同影响,且内部热核球不能反映合并历史。

摘要:

我们比较了TNG50和TNG100模拟中中心星系的内部恒星结构与CALIFA巡天中场星系的结构。TNG50和TNG100星系中动力学冷、温和热组分的光度分数与CALIFA星系中观测到的结果表现出总体一致性。例如,它们都在中等恒星质量的星系中表现出动力学热组分的最小光度分数,并且TNG50和TNG100星系中各轨道组分的形态与CALIFA星系中发现的非常相似。因此,我们利用这些模拟来量化不同组分的物理起源,重点关注TNG50中的动力学热组分。我们确定了三种主要情形及其对应的物理过程:(1)在未经历大合并的低质量星系中,恒星诞生时具有很宽的圆度分布,并且直到今天保持相对不变。因此,此类星系在红移0处的热恒星主要是天生热的。(2)在缺乏大合并的较高质量星系中,大多数恒星最初冷诞生,但随后通过长期演化被加热。(3)在横跨整个质量范围的星系中,如果发生合并,会显著增加热轨道分数。因此,现代星系在有效半径$R_e$内的动力学热核球并不能指示它们过去的合并历史;相反,外部区域的热恒星大多是被合并加热或吸积的,从而指示了星系合并历史。大质量星系最初诞生时具有冷的、旋转支撑的结构,这与詹姆斯·韦伯空间望远镜(JWST)关于高红移星系的近期观测一致。

英文摘要:

We compare the internal stellar structures of central galaxies in the TNG50 and TNG100 simulations and field galaxies in the CALIFA survey. The luminosity fractions of the dynamically cold, warm, and hot components in both TNG50 and TNG100 galaxies exhibit general consistency with those observed in CALIFA galaxies. For example, they all exhibit a minimum luminosity fraction of the dynamically hot component in galaxies with intermediate stellar masses, and the morphology of each orbital component in the TNG50 and TNG100 galaxies closely resembles that found in the CALIFA galaxies. We therefore use the simulations to quantify the physical origins of the different components, focusing on the dynamically hot component in TNG50. We identify three primary regimes and thus physical processes: (1) in low mass galaxies that have not experienced major mergers, stars are born with a wide range of circularity distributions and have remained relatively unchanged until the present day. Consequently, hot stars in such galaxies at redshift 0 are predominantly born hot. (2) In higher mass galaxies lacking major mergers, most stars are initially born cold but are subsequently heated through secular evolution. (3) In galaxies across the entire mass range, mergers, if they occurred, significantly increased the hot orbital fraction. As a result, the dynamically hot bulge within $R_e$ of present-day galaxies does not indicate their past merger histories; instead, the hot stars in the outer regions are mostly heated or accreted by mergers, thus indicating galaxy merger history. The massive galaxies are initially born with cold, rotationally supported structures, consistent with recent observations from the James Webb Space Telescope (JWST) regarding high-redshift galaxies.

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