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arXiv 1404.0908astro-ph.GA
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中央黑洞如何通过AGN反馈塑造其宿主星系

How the central black hole may shape its host galaxy through AGN feedback

W. Ishibashi, A. C. Fabian

摘要:

活动星系核(AGN)的反馈提供了中央黑洞和它的宿主星系之间的联系。我们假设活动星系核反馈驱动的辐射压力的灰尘,扫了周围的尘埃气体到一个外流壳,并考虑反馈触发的恒星形成的流出。星系特征尺寸的上限可以用临界半径来定义,超过这个半径,尘埃上的辐射压力就不再能够驱动壳层。相应的封闭质量可以与宿主星系的核球质量相比较。我们表明,由此产生的特征半径和质量之间的关系,$R \propto \sqrt M$的形式,对应于观察到的早期类型的星系的质量-半径关系。我们认为,这种简单的物理标度可以解释一些观察到的星系标度关系。在这幅图中,星系的大小和结构演化都可以解释为活动星系核反馈驱动的恒星形成的结果,主要与球状分量有关。吸积的黑洞负责触发宿主星系中的恒星形成,同时最终将尘埃气体清除出宿主,从而也有助于星系的化学演化。我们讨论了尘埃辐射压在确定星系大尺度性质中的重要性,并考虑了中心黑洞通过活动星系核反馈直接塑造其宿主星系的可能性。

英文摘要:

Active galactic nucleus (AGN) feedback provides the link between the central black hole and its host galaxy. We assume AGN feedback driven by radiation pressure on dust, which sweeps up the ambient dusty gas into an outflowing shell, and consider feedback-triggered star formation in the outflow. An upper limit to the characteristic size of galaxies may be defined by the critical radius beyond which radiation pressure on dust is no longer able to drive the shell. The corresponding enclosed mass may be compared with the host galaxy bulge mass. We show that the resulting relation between characteristic radius and mass, of the form $R \propto \sqrt M$, corresponds to the observed mass-radius relation of early-type galaxies. We suggest that such simple physical scalings may account for a number of observed galaxy scaling relations. In this picture, both the size and structural evolution of galaxies can be interpreted as a consequence of AGN feedback-driven star formation, mainly associated with the spheroidal component. The accreting black hole is responsible for triggering star formation in the host galaxy, while ultimately clearing the dusty gas out of the host, thus also contributing to the chemical evolution of galaxies. We discuss the importance of radiation pressure on dust in determining the galaxies large-scale properties, and consider the possibility of the central black hole directly shaping its host galaxy through AGN feedback.

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