arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1202.5903astro-ph.CO
收藏

早型星系的中心质量密度和由内向外生长

On the central stellar mass density and the inside-out growth of early-type galaxies

P. Saracco, A. Gargiulo, M. Longhetti

摘要:

[摘要]在本文中,我们推导出一个完整的样本的34 ETG形态选择在0.9< z_{spec} <2的中心恒星质量密度在一个固定的半径和有效半径内的有效恒星质量密度,并比较它们与样本的900个本地ETG在相同的质量范围。我们发现高z ETG的中心恒星质量密度跨越了一个数量级,与以往研究中发现的局域ETG的中心恒星质量密度相近,而高z ETG的有效恒星质量密度跨越了三个数量级,与本地ETG完全一样,并且它与本地ETG的有效恒星质量密度相似,表明它自z~1.5以来没有变化,在过去的9-10 Gyr。因此,观测到的有效恒星质量密度在z~1.5的范围内的广泛分布,一定是在z>2时开始的。此外,我们表明,小分散的ETGs的中心质量密度相比,大分散的有效质量密度仅仅是一个独特的功能的Sersic的配置文件,因此,独立的红移和任何组装的历史所经历的星系。因此,它与ETG可能的由内而外的增长无关。最后,我们发现ETG的中心恒星质量密度与恒星总质量之间存在紧密的相关性,即中心质量密度随质量的增加而增加,M^{~0.6}。这意味着ETG的中心恒星质量的分数随着星系的质量而减少。这些相关性是有效的,为整个人口的ETG考虑独立的红移,这表明他们起源于其形成的早期阶段。

英文摘要:

[Abridged] In this paper we derive the central stellar mass density within a fixed radius and the effective stellar mass density within the effective radius for a complete sample of 34 ETGs morphologically selected at 0.9<z_{spec}<2 and compare them with those derived for a sample of ~900 local ETGs in the same mass range. We find that the central stellar mass density of high-z ETGs spans just an order of magnitude and it is similar to the one of local ETGs as actually found in previous studies.However, we find that the effective stellar mass density of high-z ETGs spans three orders of magnitude, exactly as the local ETGs and that it is similar to the effective stellar mass density of local ETGs showing that it has not changed since z~1.5, in the last 9-10 Gyr. Thus, the wide spread of the effective stellar mass density observed up to z~1.5 must originate earlier, at z>2. Also, we show that the small scatter of the central mass density of ETGs compared to the large scatter of the effective mass density is simply a peculiar feature of the Sersic profile hence, independent of redshift and of any assembly history experienced by galaxies. Thus, it has no connection with the possible inside-out growth of ETGs. Finally, we find a tight correlation between the central stellar mass density and the total stellar mass of ETGs in the sense that the central mass density increases with mass as M^{~0.6}. This implies that the fraction of the central stellar mass of ETGs decreases with the mass of the galaxy. These correlations are valid for the whole population of ETGs considered independently of their redshift suggesting that they originate in the early-phases of their formation.

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。

↑