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Evolution of Galaxies in the Young Universe

年轻宇宙中星系的演化

基本信息

批准号：
11640230
负责人：
ARIMOTO Nobuo
金额：
$ 1.86万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11640230/
关键词：
Young Universe Primeral Galaxies Starburst Galaxies Elliptical Galaxies Far-Infrared Emission Submm Star Formation History Clusters of Galaxies 遠赤外サブミリ

项目摘要

This study aimed for to investigating the spectral energy distribution (SED) of starburst galaxies to establish a way to discover efficiently primeval galaxies at cosmological distances. First we built up an evolutionary synthesis model for the SED evolution of galaxies that solves radiation field by dust and stars as well as chemical enrichment of gas-stellar system under a certain scheme of star formation history. Applying the model to UV-selected (UVSBGs) and ultra-luminous IR (ULIRGs) galaxies, we have found that although the SEDs of these galaxies show a rather wide variety, this is not due to a spread in the burst age, as was supposed before, but due to a difference in the compactness of star forming region. More active starburst regions tend to be more compact and be obscured by denser dust. We also find that starburst regions are not entirely covered by the dust, instead photons are leaking from the deep inside and influence significantly the apparent feature of SEDs. Without precise measurements of these effects, it is rather meaningless to derive age, optical depth, and size of the star forming regions. This study suggests that starbursts are bimodal. Weaker bursts should be induced by gravitational instability of gaseous disk, while very intensive bursts are likely to be triggered by external dynamical disturbances such as galaxy-galaxy mergings. It is very much plausible that starbursts in the young universe are also bimodal; thus a caution is required when we analyze the SEDs of primeval galaxies at very large redshifts. The present study will provide a fundamental insight, once observational data of high-z galaxies become available with new generation space telescopes and far-infrared, submm interferometers.

本研究旨在研究星爆星系的光谱能量分布，为在宇宙距离上有效发现原始星系提供一条途径。首先，我们建立了星系SED演化的演化综合模型，解决了一定恒星形成历史方案下尘埃和恒星的辐射场以及气体-恒星系统的化学富集问题。将该模型应用于UV-selected （UVSBGs）和ultra-luminous IR （ulrgs）星系，我们发现虽然这些星系的SEDs表现出相当广泛的变化，但这不是由于爆发年龄的分布，而是由于恒星形成区域的致密性不同。更活跃的星暴区域往往更紧凑，被更密集的尘埃所掩盖。我们还发现，星爆区域并没有完全被尘埃覆盖，相反，光子从内部深处泄漏出来，并显著影响了sed的表观特征。没有对这些效应的精确测量，推断恒星形成区域的年龄、光学深度和大小是毫无意义的。这项研究表明，星暴是双峰的。较弱的爆发应该是由气态盘的引力不稳定性引起的，而非常强烈的爆发可能是由星系-星系合并等外部动力学干扰引发的。年轻宇宙中的恒星爆发也是双峰的，这是非常合理的；因此，当我们在非常大的红移下分析原始星系的sed时，需要谨慎。一旦新一代太空望远镜和远红外、亚毫米干涉仪获得高z星系的观测数据，目前的研究将提供一个基本的见解。