Toward First-Principle Simulations of Galaxy Formation: I. How Should We Choose Star-Formation Criteria in High-Resolution Simulations of Disk Galaxies?
Toward First-Principle Simulations of Galaxy Formation: I. How Should We Choose Star-Formation Criteria in High-Resolution Simulations of Disk Galaxies?
复制标题
走向星系形成的第一原理模拟：一、盘状星系高分辨率模拟中我们应该如何选择恒星形成标准？
DOI：
--
复制
发表时间：
2008
期刊：
影响因子：
--
通讯作者：
N. Yoshida
中科院分区：
文献类型：
--
作者：
Takayuki R.Saitoh;H. Daisaka;E. Kokubo;J. Makino;T. Okamoto;K. Tomisaka;K. Wada;N. Yoshida
我们进行了三维N体/SPH模拟，研究了质量分辨率和其他模型参数，如恒星形成效率参数C和恒星形成的阈值密度nth对星系气体/恒星盘结构的影响。我们使用106-107个粒子来分解冷相(T 100 cm�3)以及扩散相和热相。我们发现星际介质(ISM)的结构和年轻恒星的分布对假设的nth值很敏感。当nth=100cmISM3的高第n个模型在�中产生块状多相特征。年轻恒星分布在一个薄盘中，其半质量尺度高度为10-30pC。在宇宙星系形成模拟中通常采用的nth=0.1cm.nth的低第n个模型中，气盘看起来更光滑，恒星盘被发现比高第n个模型厚几倍。为了再现气盘的复杂结构，需要进行高n阶高分辨率的模拟。当我们调整CSO的值时，低n次模型中星系的整体成星性质，如恒星形成历史，与高n次模型中的类似，从而再现了观测到的表面气体密度与表面成星率密度之间的关系。然而，我们强调，无论C�的值如何，高n阶模型都会自动再现这种关系。在C�值不同的情况下，ISM的结构、相分布和年轻恒星形成区的分布非常相似。我们发现，从水库(NH�1c m�3)到恒星形成区(NH&100 cm�3)的流动的时间尺度大约是当地动力时间的5倍，并且这种演化时间尺度是独立的
We performed three-dimensional N -body/SPH simulations to study how mass resolution and other model param- eters, such as the star-formation efficiency parameter, Cand the threshold density for star formation, nth affect structures of the galactic gaseous/stellar disk. We employed 10 6 -10 7 particles to resolve a cold ( T 100 cm � 3 ) phase as well as diffuse, hot phases. We found that structures of the interstellar medium (ISM) and the distribution of young stars were sensitive to the assumed values of nth. High-nth models with nth = 100 cm � 3 yielded clumpy multi-phase features in the ISM. Young stars were distributed in a thin disk, of which the half-mass scale height was 10-30 pc. In low-nth models with nth = 0.1 cm � 3 , which is usually employed in cosmological galaxy-formation simulations, the gas disk appears to be smoother and the stellar disk is found to be several-times thicker than the high-nth models. A high-resolution simulation with high-nth is necessary to reproduce the complex structure of the gas disk. The global star-formation properties of galaxies, such as the star-formation history, in low-nth models are similar to those in high-nth models when we tune the value of Cso that they repro- duce the observed relation between the surface gas density and the surface star-formation rate density. We however emphasize that high-nth models automatically reproduce the relation, regardless of the values of C� .T he ISM structure, phase distribution and distributions of young star-forming regions are quite similar in runs with different values of C� . We found that the timescale of the flow from the reservoir (nH � 1c m � 3 ) to the star-forming regions (nH & 100cm � 3 ) is about five-times as long as the local dynamical time, and this evolution timescale is independent