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

有人提出，活动星系核释放的巨大能量来自于气体吸积成大质量黑洞的引力能。然而，由于气体主要分布在星系中心外，因此需要气体的角动量传递才能将气体从星系外中心输送到星系中心。在核星爆星系中也需要类似的质量供应机制。在本研究中，我研究了弱棒势和fas的自引力对银河系中心区域气体运动的影响，证明了这些影响对角动量的传递是非常有效的。第一年，我用数值流体力学的方法研究了具有弱棒分量的固定星系势中的自引力气体运动。我得到的数值结果是，气体聚集到内Lindblad共振半径后，由于自引力不稳定形成了气体团块，由于这些团块之间碰撞的能量损失和角动量损失，气体供应到银河系中心。在第二年，我将研究扩展到自引力气体和恒星的双组分模型，因为气体的自引力对于恒星系统来说是不可忽视的。最初，我假设恒星系统具有自洽的弱棒势，并研究气体和恒星运动。我们的数值结果表明，气体通过内部林德布莱德共振积累后，中心质量浓度改变了恒星结构，弱棒结构在气体和恒星相互作用下变得更弱。这些结果表明，当足够的气体集中到星系中心时，就可以探测到棒状结构。我已经将本研究的一部分作为科学论文发表，另外一部分准备提交论文。

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.