活动星系核宽吸收线外流定量研究

Outflows in active galactic nuclei (AGNs) are a prevalent and important kind of feedback to the host galaxies. On one hand, as originated from the accretion disk of the central supermassive black hole (SMBH), AGN outflows are intimately linked to the accretion flow; on the other hand, they are generally deemed to impact seriously the evolution of the host galaxy (namely the so-called co-evolution), leading to the final “M_BH-σ_* relation” of the present universe. But it is still not fully understood in a quantitative way as to the physical properties of the outflowing gas, the power and efficiency of the outflow feedback, and the concrete processes of the outflows working onto the host galaxies. In this project we propose to carry out the following studies: (1) by taking advantage of the technique we have developed to detect He I* broad absorption lines (BALs), mainly based on the spectroscopic data sets of the SDSS and the NASA archive, we will compile a largest sample of He I* BAL AGNs covering a rather large redshift range (0<z≤2.2), particularly finding the largest number of low-redshift BAL AGNs (z<0.3). (2) Using He I* BALs as well as other absorption lines, for the first time worldwide for a large sample we will measure the physical properties (including kinematic luminosity and mass loss rate) of the outflows for every sources. (3) Based on our largest BAL AGN sample, we will characterize the redshift evolution of the feedback power of AGN outflows for the first time worldwide. (4) We will conduct spatially resolved observations of low-redshift BAL AGNs, investigating the concrete processes of the outflow feedback to the host galaxies.

外流是活动星系核(AGN)反馈作用中一种普遍而重要的形式。一方面，AGN外流起源于超大质量黑洞的吸积盘，与吸积流密切相连；另一方面，人们普遍认为AGN外流对星系演化有重要影响，是建立当前宇宙中“M_BH-σ_*”关系的关键因素。但目前我们对AGN外流气体的物理性质、反馈效率、及其对星系作用的具体过程仍没有定量的理解。我们计划：(1)利用我们前期发展的HeI*宽吸收线(BAL)探测技术，主要基于SDSS和NASA光谱库编制一个数目最大、较宽红移范围(0<z≤2.2)的HeI* BAL AGN样本；特别地，找出目前数目最多的低红移(z < 0.3) BAL AGN。(2)利用HeI*等多种吸收线，测量样本中每个源外流的物理性质(包括反馈功率和质量外流率)。(3)基于该样本，国际上首次刻画AGN外流反馈能力的红移演化。(4)开展对低红移BAL AGN空间分辨的观测，研究外流对星系作用的具体过程。

外流是活动星系核(AGN)反馈作用中一种普遍而重要的形式。一方面,AGN外流起源于超大质量黑洞的吸积盘,与吸积流密切相连;另一方面,人们普遍认为AGN外流对星系演化有重要影响,是建立当前宇宙中“M_BH-σ_*”关系的关键因素。但目前我们对AGN外流气体的物理性质、反馈效率、及其对星系作用的具体过程仍没有定量的理解。本项目执行期间，我们尝试利用AGN外流气体所产生的HeI*，MgII，AlIII，FeII，NaID等多种吸收线对相当数量的宽吸收线类星体外流的质量外流率和反馈功率给出定量估计，进而对AGN外流进行定量的统计研究。首先，我们扩增了现有的BAL AGN样本。我们系统搜寻了中等红移AlIII BAL AGN的样本。同时，为了有效搜寻更多的低红移BAL AGN，我们在SDSS海量光谱库中证认了目前最大的低红移宽发射线AGN样本，以便后续通过近红外HeI*λ10830吸收线进一步搜寻 低红移BAL AGN。其次，我们针对个别研究数据充分的BAL AGN外流进行了详细的研究。这些工作一方面增加了BAL AGN外流定量研究的数据，另一方面进一步探索了不同离子在吸收线方面的应用，这为之后对BAL AGN外流气体进行高效的、大样本的定量研究做了技术上的准备。本项目执行期间，我们在观测上意外发现了一些中等质量黑洞的大幅宽发射线光变，触发了我们对此类AGN（包括“变脸”AGN）宿主星系的研究。我们发现，相比于相同红移的Seyfert2星系，有明显宽发射线光变的AGN的宿主星系颜色更红，星族更年老，恒星形成率更低。这个工作在观测上将AGN宿主星系的性质和AGN的吸积状态直接联系起来，给我们一个新的视角理解AGN的燃料供给和吸积过程。