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arXiv 1006.0230astro-ph.CO
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亚毫米星系在等级星系形成中的作用

The role of submillimetre galaxies in hierarchical galaxy formation

Juan E. Gonzalez, C. G. Lacey, C. M. Baugh, C. S. Frenk

摘要:

我们研究了在λ冷暗物质宇宙学中亚毫米星系(SMG)在星系形成过程中的作用。我们使用Baugh等人(2005)的半分析模型,该模型通过假设星系合并引发的爆发中的头重脚轻的初始质量函数(IMF)来匹配观测到的SMG数计数和红移分布。我们建立星系合并树,并遵循SMG及其后代的演化和属性。我们的SMG模型的主要样本由星系,其中有850亩通量比5 mJy在一些红移z>1。我们的模型预测,这些SMG的后代恒星质量范围很广,约为10^{10} - 10^{12} Msun/h,中位数约为10^{11} Msun/h,并且这些后代中有70%以上是膨胀主导的。目前超过50%的恒星质量大于7 x 10^{11} Msun/h的星系被预测为这种SMG的后代。我们发现,虽然SMG对z~2处的恒星形成速率有重要贡献,但在亚毫米阶段产生的最终恒星质量仅占现今恒星质量的0.2%,占SMG后代恒星质量的2%,这与SMG阶段产生了现今大质量椭圆星系的大部分质量的流行观点形成了鲜明的对比。

英文摘要:

We study the role of submillimetre galaxies (SMGs) in the galaxy formation process in the Lambda Cold Dark Matter cosmology. We use the Baugh et al. (2005) semi-analytical model, which matches the observed SMG number counts and redshift distribution by assuming a top-heavy initial mass function (IMF) in bursts triggered by galaxy mergers. We build galaxy merger trees and follow the evolution and properties of SMGs and their descendants. Our primary sample of model SMGs consists of galaxies which had 850 mu fluxes brighter than 5 mJy at some redshift z>1. Our model predicts that the present-day descendants of such SMGs cover a wide range of stellar masses ~ 10^{10} - 10^{12} Msun/h, with a median ~ 10^{11} Msun/h, and that more than 70% of these descendants are bulge-dominated. More than 50% of present day galaxies with stellar masses larger than 7 x 10^{11} Msun/h are predicted to be descendants of such SMGs. We find that although SMGs make an important contribution to the total star formation rate at z~2, the final stellar mass produced in the submillimetre phase contributes only 0.2% of the total present-day stellar mass, and 2% of the stellar mass of SMG descendants, in stark contrast to the popular picture in which the SMG phase marks the production of the bulk of the mass of present day massive ellipticals.

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。

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