arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1206.1353astro-ph.CO
收藏

NGC 3227宽线区的尺寸、结构和电离

The Size, Structure and Ionization of the Broad Line Region in NGC 3227

Nick Devereux

备注：
Accepted for publication in the Astrophysical Journal, 17 October, 2012. v2 revised to include a photoionization model and referee comments
阅读 PDF
arXiv 页面 ↗HTML 原文 ↗

摘要：

哈勃太空望远镜（HST）对塞弗特1.5星系（NGC 3227）的光谱分析证实了先前的报告，即宽H-α发射线通量是随时间变化的，在1999年至2000年之间减少了11%，对应的是基础连续谱减少了37%。模拟的气体分布负责广泛的H-α，H-β和H-γ发射线有利于一个球对称的流入，而不是薄盘。根据先前的混响映射，采用中心黑洞质量为7.6 x 10^{6} Msun，可以得出发射宽H-α线的区域尺寸如下：外半径约为90 l.d，内半径约为3 l. d。因此，先前确定的宽线区域（BLR）的混响大小始终与更大体积的电离气体的内径一致。然而，感知到的BLR的大小是一种错觉，这是由于发射区域在外半径处被电离束缚并且在内半径处被多普勒展宽减小的事实的结果。流入的实际尺寸仍有待确定。尽管如此，稳态质量流入速率估计为~ 10^{-2} Msun/yr，这足以解释活动星系核的X射线光度是辐射无效吸积的结果。总的来说，这些结果挑战了许多关于活动星系核中BLR性质的先入为主的观念。

英文摘要：

Hubble Space Telescope (HST) spectroscopy of the Seyfert 1.5 galaxy, NGC 3227, confirms previous reports that the broad H-alpha emission line flux is time variable, decreasing by a modest ~ 11% between 1999 and 2000 in response to a corresponding ~ 37% decrease in the underlying continuum. Modeling the gas distribution responsible for the broad H-alpha, H-beta and H-gamma emission lines favors a spherically symmetric inflow as opposed to a thin disk. Adopting a central black hole mass of 7.6 x 10^{6} Msun, determined from prior reverberation mapping, leads to the following dimensions for the size of the region emitting the broad H-alpha line; an outer radius ~ 90 l.d and an inner radius ~ 3 l.d. Thus, the previously determined reverberation size for the broad line region (BLR) consistently coincides with the inner radius of a much larger volume of ionized gas. However, the perceived size of the BLR is an illusion, a consequence of the fact that the emitting region is ionization bounded at the outer radius and diminished by Doppler broadening at the inner radius. The actual dimensions of the inflow remain to be determined. Nevertheless, the steady state mass inflow rate is estimated to be ~ 10^{-2} Msun/yr which is sufficient to explain the X-ray luminosity of the AGN in terms of radiatively inefficient accretion. Collectively, the results challenge many preconceived notions concerning the nature of BLRs in active galactic nuclei.

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。

↑