arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1104.0927astro-ph.CO
收藏

在星系等级结构形成的背景下理解观测到的z=6-10星系光度函数的演化

Understanding the Observed Evolution of the Galaxy Luminosity Function from z=6-10 in the Context of Hierarchical Structure Formation

Joseph A. Muñoz

摘要:

最近对Lyman-break星系(LBG)在z~6-10的光度函数(LF)的观测表明,随着红移的增加,LBG的丰度急剧下降。然而,LF是暗物质晕(HMF)的质量函数(在这个红移范围内也急剧下降)和星系形成物理学(将晕质量映射到星系光度)的卷积。我们认为,在这种情况下,从z~6-10的LF观察到的强烈的演变,并确定它是否可以单独解释的HMF的行为。从z~6-8,我们发现星系形成的物理学中的一个残余变化对应于一个固定质量的晕的平均光度增加~0.5 dex。另一方面,我们最近的LF测量z~10的分析表明,检测到的星系的缺乏是一致的,几乎没有变化的平均光度在固定的晕质量从z~8。LF斜率也限制了这个平均值的变化,使得由相同质量的晕所承载的星系的光度都在彼此的一个数量级内。我们表明,这些结果是很好地描述了一个简单的模型,其中冷流吸积平衡恒星形成和动量驱动的外流的星系形成。如果星系形成是在质量低至10^8兆太阳的晕中进行的,那么这样的模型预测,只要聚集因子与电离逃逸分数之比C/f_esc < 10,z~10的LBG就应该能够保持电离的星系际介质。

英文摘要:

Recent observations of the Lyman-break galaxy (LBG) luminosity function (LF) from z~6-10 show a steep decline in abundance with increasing redshift. However, the LF is a convolution of the mass function of dark matter halos (HMF)--which also declines sharply over this redshift range--and the galaxy-formation physics that maps halo mass to galaxy luminosity. We consider the strong observed evolution in the LF from z~6-10 in this context and determine whether it can be explained solely by the behavior of the HMF. From z~6-8, we find a residual change in the physics of galaxy formation corresponding to a ~0.5 dex increase in the average luminosity of a halo of fixed mass. On the other hand, our analysis of recent LF measurements at z~10 shows that the paucity of detected galaxies is consistent with almost no change in the average luminosity at fixed halo mass from z~8. The LF slope also constrains the variation about this mean such that the luminosity of galaxies hosted by halos of the same mass are all within about an order-of-magnitude of each other. We show that these results are well-described by a simple model of galaxy formation in which cold-flow accretion is balanced by star formation and momentum-driven outflows. If galaxy formation proceeds in halos with masses down to 10^8 Msun, then such a model predicts that LBGs at z~10 should be able to maintain an ionized intergalactic medium as long as the ratio of the clumping factor to the ionizing escape fraction is C/f_esc < 10.

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。

↑