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arXiv 2108.01671astro-ph.GAastro-ph.HE
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大质量分子气体作为星系核反馈的燃料箱

Massive Molecular Gas as a Fuel Tank for Active Galactic Nuclei Feedback in Central Cluster Galaxies

Yutaka Fujita, Nozomu Kawakatu, Hiroshi Nagai

摘要:

在星系团中心的巨大椭圆星系中发现了大量的分子气体。为了揭示它在这些星系的活动星系核(AGN)反馈中的作用,我们构造了一个气体环流的半解析模型。该模型特别关注大质量分子气体(星际冷气体,尺度约为10 kpc)和环核盘(约< 0.5 kpc)。我们考虑了恒星形成对星际冷气体的破坏和环核盘的引力不稳定性。我们的模型可以再现星际冷气体和环核盘的基本性质,例如它们的质量。我们还发现,环核盘往往停留在稳定和不稳定状态之间的边界。这就像一个“调节阀”,调节着向超大质量黑洞的质量增长。另一方面,星际冷气体在活动星系核反馈中充当“燃料箱”。即使银河系热气体的冷却被阻止,星际冷气体也可以维持活动星系核的活动~> 0.5 Gyr。我们还证实了小熵的热气体(~< 30 keV cm ^2)或短的冷却时间(~< 1 Gyr)是星系中存在大量分子气体的临界条件。星际冷气体的消散时间可能与临界冷却时间有关。星系的行为被描述为一个简单的关系之间的磁盘稳定性,云耗散时间,和气体冷却速率。

英文摘要:

Massive molecular gas has been discovered in giant elliptical galaxies at the centers of galaxy clusters. To reveal its role in active galactic nucleus (AGN) feedback in those galaxies, we construct a semianalytical model of gas circulation. This model especially focuses on the massive molecular gas (interstellar cold gas on a scale of ~ 10 kpc) and the circumnuclear disk (~< 0.5 kpc). We consider the destruction of the interstellar cold gas by star formation and the gravitational instability for the circumnuclear disk. Our model can reproduce the basic properties of the interstellar cold gas and the circumnuclear disk, such as their masses. We also find that the circumnuclear disk tends to stay at the boundary between stable and unstable states. This works as an 'adjusting valve' that regulates mass accretion toward the supermassive black hole. On the other hand, the interstellar cold gas serves as a 'fuel tank' in the AGN feedback. Even if the cooling of the galactic hot gas is prevented, the interstellar cold gas can sustain the AGN activity for ~> 0.5 Gyr. We also confirm that the small entropy of the hot gas (~< 30 keV cm^2) or the short cooling time (~< 1 Gyr) is a critical condition for the existence of the massive amounts of molecular gas in the galaxy. The dissipation time of the interstellar cold gas may be related to the critical cooling time. The galaxy behavior is described by a simple relation among the disk stability, the cloud dissipation time, and the gas cooling rate.

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。

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