Mass supply to active galactic nuclei by self-gravitational instability of gas

提出活动星系核释放的巨大能量来自于气体吸积到大质量黑洞的引力能。然而，由于气体主要分布在银河系中心之外，因此需要气体的角动量转移来将气体从银河系中心外部供应到银河中心。核星暴星系需要类似的质量供应机制。在这项研究中，我研究了弱棒势和FAS的自引力对银河系中心区气体运动的影响，表明这些效应带来的角动量转移是非常有效的。第一年，我用数值流体力学的方法研究了具有弱棒成分的固定星系势中的自引力气体运动。数值结果表明，气体积累到Lindblad内共振半径后，由于自引力不稳定性而形成气团，由于这些气团之间的碰撞造成能量损失和角动量损失，气体供应到银心。第二年，我将研究扩展到自引力气体和恒星的双分量模型，因为对于恒星系统来说，气体的自引力是不可忽略的。起初，我假设恒星系统是自洽的，微弱的棒势，并研究气体和恒星运动。数值结果表明，气体通过Lindblad内共振积累后，中心质量浓度改变了恒星结构，气体与恒星相互作用使弱势垒结构变弱。这些结果表明，当足够多的气体集中到银河系中心时，很难探测到棒状结构。我已经将这项研究的一些部分作为科学论文发表了，我准备为另一部分提交一篇论文。

It is proposed that huge energy released in active galactic nuclei comes from gravitational energy of gas accreting into massive black hole. However, since gas distributes mainly outside a galactic center, angular momentum transfer from gas is needed to supply gas from the outside galactic center to the galactic center. Similar mass supply mechanism is needed in nuclear starburst galaxies.In this research, I study the effects of weak bar potential and self-gravity of fas on the gas motion in galactic central region to show that angular momentum transfer by these effects is very effect.In the first year, I study self-gravitational gas motion in a fixed galaxy potential with weak bar component by numerical hydrodynamics. I got the numerical results that, after gas is accumulated into the radius of the inner Lindblad resonance, gas clumps are formed by self-gravitational instablility and gas supply into the galactic center due to the energy loss and angular momentum loss by collisions between these clumps.In the second year, I extend the study to the two-component model of self-gravitational gas and stars, since self-gravity of gas can not be neglected for stellar system. Initially I assumed self-consistent, weak bar potential of a stellar system and study gas and stellar motion. Our numerical results show that, after gas is accumulated by the inner Lindblad resonance, central mass concentration changes the stellar structure and weak barred structure become weaker by the gas and stellar interaction. These results indicate that, when sufficient gas concentrates into the galactic center, it is gard to detect bar structure.I have already published some parts of this study as scientific papers and I prepare to submit a paper for the other part.