Hydrodynamical simulations of the triggering of nuclear activities by minor mergers of galaxies
Hydrodynamical simulations of the triggering of nuclear activities by minor mergers of galaxies
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DOI：
10.1088/1674-4527/19/12/177
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发表时间：
2019-12
影响因子：
1.8
通讯作者：
Chao-Chin Yang;J. Ge;Youjun Lu
中科院分区：
文献类型：
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作者：
Chao-Chin Yang;J. Ge;Youjun Lu
星系的重大合并被认为是触发活动星系核的有效方式，并被认为是类星体现象的罪魁祸首。然而，最近观测到大量低亮度的活动星系核在低红移(z≲1)，但没有明显的主要合并特征，这一点受到了挑战。人们经常提出小合并来解释这些活跃星系核的存在。在这篇文章中，我们进行了九个小星系合并的高分辨率流体动力学模拟，并通过设置小合并的前驱星系的各种属性来研究小合并是否能有效地触发核活动。我们发现，小星系合并可以激活主星系中的大质量黑洞，其爱丁顿比为Fedd>；0.01和>；0.05(或测辐射光度为>；1043和>；1044erg S−1)，持续时间分别为2.71和0.49 Gyr(或2.69和0.19 Gyr)。原星系的核活动强烈地依赖于核的分离，因此当两个核相互接近时，核更活跃。虽然双活动星系的持续时间仅为∼0.011 Gyr和∼0.017 Gyr，爱丁顿比值为Fedd>；0.05，测辐射热光度&Gt；1044erg S−1，但仍有可能由星系的次要合并形成双活动星系系统。
Major mergers of galaxies are considered to be an efficient way to trigger Active Galactic Nuclei and are thought to be responsible for the phenomenon of quasars. This has however recently been challenged by observations of a large number of low luminosity Active Galactic Nuclei at low redshift (z ≲ 1) without obvious major merger signatures. Minor mergers are frequently proposed to explain the existence of these Active Galactic Nuclei. In this paper, we perform nine high resolution hydrodynamical simulations of minor galaxy mergers, and investigate whether nuclear activities can be efficiently triggered by minor mergers, by setting various properties for the progenitor galaxies of those mergers. We find that minor galaxy mergers can activate the massive black hole in the primary galaxy with an Eddington ratio of fEdd > 0.01 and > 0.05 (or a bolometric luminosity >1043 and >1044 erg s−1) with a duration of 2.71 and 0.49Gyr (or 2.69 and 0.19Gyr), respectively. The nuclear activity of the primary galaxy strongly depends on the nucleus separation, such that the nucleus is more active as the two nuclei approach each other. Dual Active Galactic Nuclei systems can still possibly be formed by minor mergers of galaxies, though the time duration for dual Active Galactic Nuclei is only ∼ 0.011 Gyr and ∼ 0.017 Gyr with Eddington ratio of fEdd > 0.05 and bolometric luminosity >1044 erg s−1. This time period is typically shorter than that of dual Active Galactic Nuclei induced by major galaxy mergers.