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Dynamical Evolution and Activities in Gas-Rich Galaxies

富含气体星系的动力学演化和活动

基本信息

批准号：
07640346
负责人：
NOGUCHI Masafumi
金额：
$ 1.41万
依托单位：
TOHOKU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07640346/
关键词：
GALAXIES INTERSTELLAR GAS DYNAMICAL EVOLUTION 恒星系力学

项目摘要

Dynamical evolution and activities of gas-rich galazies have been investigated by numerical simulations which include interstellar gas and star formation process. First, the dynamical interactions between the Galaxy, Large and Small Magellanic Clouds have been examined as a case study. Second, mergers between large elliptical galaxies and small disk galaxies have been simulated. The second half of this research project has been focused on how the gravity of the interstellar gas affects the dynamical evolution of isolated galaxies. It was found that the amount of the gas existent in the early evolutionary phase strongly affects the occurrence of non-axisymmetric structures, especially bars. The initial gas amount itself is determined by the timescale of disk formation. This result leads to a unified picture that the bars of early-type galaxies have been created by galaxy-galaxy encounters, whereas the late-type galaxies have developed their bars spontaneously by the gravitational instability of the disk. Simulations have been performed also on the collapse of protogalaxies and subsequent formation of disk galaxies. This research resulted into a new evolution model, in which the copious interstellar gas contained in the early disk forms massive clumps due to gravitational instability, and these clumps act as the major driving force of the evolution. This model explains peculiar morphology and photometric characteristics of young galaxies, and provides a new picture on the causal relationship between the emergence of activities such as quasars and the dynamical evolution of host galaxies.

通过数值模拟研究了富含气体星系的动力学演化和活动，其中包括星际气体和恒星形成过程。首先，我们将银河系、大麦哲伦星云和小麦哲伦星云之间的动态相互作用作为案例研究进行了研究。其次，模拟了大椭圆星系和小盘状星系之间的合并。该研究项目的后半部分重点研究星际气体的引力如何影响孤立星系的动力学演化。研究发现，早期演化阶段存在的气体量强烈影响非轴对称结构，尤其是棒材的出现。初始气体量本身是由圆盘形成的时间尺度决定的。这一结果得出了一个统一的结论：早期型星系的条带是由星系与星系的相遇产生的，而晚期型星系的条带是由盘的引力不稳定性自发形成的。还对原星系的塌缩和随后的盘状星系的形成进行了模拟。这项研究得出了一种新的演化模型，其中早期盘中含有的丰富的星际气体由于重力不稳定而形成巨大的团块，这些团块是演化的主要驱动力。该模型解释了年轻星系奇特的形态和光度特征，并为类星体等活动的出现与宿主星系的动力学演化之间的因果关系提供了新的图景。