arXivDaily arXiv每日学术速递 周一至周五更新
arXiv astro-ph/0103485astro-ph
收藏

阻尼Lyman $α$系统的恒星形成和化学演化

Star formation and chemical evolution of damped Lyman $α$ systems

J. Ma, C. G. Shu

备注：
7 pages, 6 figures, will appear in MNRAS, 2001 (21 April), 322, 927-932
发表信息：
Mon.Not.Roy.Astron.Soc. 322 (2001) 927
阅读 PDF
arXiv 页面 ↗HTML 原文 ↗

摘要：

本文基于Mo，Mao & White提出的盘状星系形成模型，研究了阻尼Lyman- $α$系统（DLAs）的恒星形成和化学演化。我们认为DLAs是红移为$z\sim 3$的质量较小的暗晕的中心星系，它们应该居住在中等低圆速度的暗晕中。恒星形成率的经验施密特定律，和封闭的盒子模型的化学演化，被称为瞬时再循环的近似假设，被采用。在我们的模型中，当计算DLAs的金属丰度的预测分布时，考虑了两种情况。一种是利用闭箱模型、经验施密特定律和恒星形成时间直接计算金属丰度分布。另一个是，当考虑Toomre首先讨论的薄等温气体盘的简单引力不稳定性时，恒星形成只发生在气体表面密度满足临界值的区域，而不是气体盘的任何地方。我们假设恒星形成在每个DLA持续一个周期的1 Gyr的红移$z=3$。在我们的模型中只有一个输出参数，即恒星产额，它与恒星形成历史的时间有关，是通过将预测的金属丰度分布归一化为Pettini等人提出的1/13 $Z_{\odot}$的平均值而得到的，预测的金属丰度分布与目前（相当有限的）观测数据是一致的。考虑到星系盘的随机分布。

英文摘要：

In this paper, we investigate the star formation and chemical evolution of damped Lyman-$α$ systems (DLAs) based on the disc galaxy formation model which is developed by Mo, Mao & White. We propose that the DLAs are the central galaxies of less massive dark haloes present at redshifts $z\sim 3$, and they should inhabit haloes of moderately low circular velocity. The empirical Schmidt law of star formation rates, and closed box model of chemical evolution that an approximation known as instantaneous recycling is assumed, are adopted. In our models, when the predicted distribution of metallicity for DLAs is calculated, two cases are considered. One is that, using the closed box model, empirical Schmidt law and star formation time, the distribution of metallicity can be directly calculated. The other is that, when the simple gravitational instability of a thin isothermal gas disc as first discussed by Toomre is considered, the star formation occurs only in the region where the surface density of gas satisfies the critical value, not everywhere of a gas disc. We assume that star formation in each DLA lasts for a period of 1 Gyr from redshifts $z=3$. There is only one output parameter in our models, i.e. the stellar yield, which relates to the time of star formation history and is obtained by normalizing the predicted distribution of metallicity to the mean value of 1/13 $Z_{\odot}$ as presented by Pettini et al. The predicted metallicity distribution is consistent with the current (rather limited) observational data. A random distribution of galactic discs is taken into account.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

↑