arXivDaily arXiv每日学术速递 周一至周五更新
arXiv周末暂无论文更新,休息一下吧,周末愉快~~
arXiv 0912.0075astro-ph.CO
收藏

团星系冲压压力剥离产生的热分子氢尾

A Warm Molecular Hydrogen Tail Due to Ram Pressure Stripping of a Cluster Galaxy

Suresh Sivanandam, Marcia J. Rieke, George H. Rieke

摘要:

我们在Abell 3627星系团的一个螺旋星系ESO 137-001中发现了一个显著的热(130-160 K)氢分子尾,其H_2质量约为4*10^7太阳质量,延伸距离为20 kpc。至少有一半的气体会永久地流失到团内介质中,因为尾部延伸到星系的潮汐半径之外。我们还检测到一个热(400-550 K)组件的尾巴,约1%的质量。在尾部的大的H_2线与红外连续光谱的光度比表明,恒星形成不是主要的激发源,气体可能是激波加热的。这一发现证实了该星系目前正在经历冲压压力剥离,正如之前发现的X射线和Halalpha尾巴所表明的那样。我们估计银河系正在以每年约2-3个太阳质量的速度失去其温暖的H_2气体。如果我们考虑冷的分子气体和原子气体,真实的质量损失率可能更高。我们预测,星系将在一次通过核心的过程中失去大部分气体,并在1 Gyr的冲压压力时间尺度上设置一个强大的上限。我们还研究了星系及其尾部的恒星形成特性。我们确定了大多数以前发现的外部Halpha源在我们的8微米的数据,但不是在我们的3.6微米的数据的尾巴; IRS光谱的区域包含这些Halpha源还揭示了芳香族功能通常与恒星形成。从这些HII区域的位置来看,恒星的形成似乎并不是发生在整个氢分子尾部,而是发生在星系的下游。其中一些HII区域位于星系潮汐半径之外,表明冲压压力剥离可能是星团内恒星的来源。

英文摘要:

We have discovered a remarkable warm (130-160 K) molecular hydrogen tail with a H_2 mass of approximately 4*10^7 solar masses extending 20 kpc from a cluster spiral galaxy, ESO 137-001, in Abell 3627. At least half of this gas is lost permanently to the intracluster medium, as the tail extends beyond the tidal radius of the galaxy. We also detect a hot (400-550 K) component in the tail that is approximately 1% of the mass. The large H_2 line to IR continuum luminosity ratio in the tail indicates that star formation is not a major excitation source and that the gas is possibly shock-heated. This discovery confirms that the galaxy is currently undergoing ram-pressure stripping, as also indicated by its X-ray and Halpha tails found previously. We estimate the galaxy is losing its warm H_2 gas at a rate of ~ 2-3 solar masses per year. The true mass loss rate is likely higher if we account for cold molecular gas and atomic gas. We predict that the galaxy will lose most of its gas in a single pass through the core and place a strong upper limit on the ram-pressure timescale of 1 Gyr. We also study the star-forming properties of the galaxy and its tail. We identify most of the previously discovered external Halpha sources within the tail in our 8 um data but not in our 3.6 um data; IRS spectroscopy of the region containing these Halpha sources also reveals aromatic features typically associated with star formation. From the positions of these HII regions, it appears that star formation is not occurring throughout the molecular hydrogen tail but only immediately downstream of the galaxy. Some of these HII regions lie outside the tidal radius of the galaxy, indicating that ram-pressure stripping can be a source of intracluster stars.

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。

↑