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arXiv 1812.05613astro-ph.GA
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宇宙学流体动力学模拟中恒星形成规定的观测检验

An observational test for star formation prescriptions in cosmological hydrodynamical simulations

Tobias Buck, Aaron A. Dutton, Andrea V. Macciò

摘要:

最先进的星系形成的宇宙流体动力学模拟已经达到了这样一个程度,即它们的结果导致星系更加真实。尽管如此,所采用的子网格模型包括几个自由参数,如密度阈值,$n$,本地化的恒星形成气体。在这项工作中,我们调查的可能性,利用所观察到的集群性质的恒星形成(SF),以完善SF处方和约束的密度阈值参数。为此,我们测量的集群强度,相关长度和幂律指数的两点关联函数的年轻($τ<50$ MYR)恒星粒子和比较我们的结果从HST遗产河外紫外线巡天(LEGUS)的观测。我们的模拟揭示了一个明显的趋势,较大的聚类信号和幂律指数和较低的相关长度的SF阈值增加,只有轻微的依赖于星系的属性,如恒星质量或特定的恒星形成率。总之,我们发现,所观察到的SF的聚类与SF的低阈值($n<1$ cm $^{-3}$)不一致,并且强烈支持SF的密度阈值($n>10$ cm $^{-3}$)的高值,例如在NIHAO项目中采用的。

英文摘要:

State-of-the-art cosmological hydrodynamical simulations of galaxy formation have reached the point at which their outcomes result in galaxies with ever more realism. Still, the employed sub-grid models include several free parameters such as the density threshold, $n$, to localize the star-forming gas. In this work, we investigate the possibilities to utilize the observed clustered nature of star formation (SF) in order to refine SF prescriptions and constrain the density threshold parameter. To this end, we measure the clustering strength, correlation length and power-law index of the two-point correlation function of young ($τ<50$ Myr) stellar particles and compare our results to observations from the HST Legacy Extragalactic UV Survey (LEGUS). Our simulations reveal a clear trend of larger clustering signal and power-law index and lower correlation length as the SF threshold increases with only mild dependence on galaxy properties such as stellar mass or specific star formation rate. In conclusion, we find that the observed clustering of SF is inconsistent with a low threshold for SF ($n<1$ cm$^{-3}$) and strongly favours a high value for the density threshold of SF ($n>10$ cm$^{-3}$), as for example employed in the NIHAO project.

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