射电强窄线赛弗特1型星系辐射性质

Narrow line Seyfert 1 galaxies (NLS1s) are often thought to be young active galactic nuclei (AGNs) with relatively small black hole masses and high accretion rates. About 7% NLS1s are radio-loud, however, radio-loud NLS1s (RLNLS1s) are inhomogeneous in their radio properties, with some associated with compact steep-spectrum (CSS) radio sources, and others resemble to blazars. Relativistic jets were shown to exist in a few RLNLS1s based on VLBI observations and confirmed by the gamma-ray flaring of some of them. These properties are unexpected, in light of the low black hole masses, high accretion rates, which however provide observational evidence of jet formation under such conditions. Up to now, little has been known on the jet properties of RLNLS1s. In this project, by combining VLBI radio observations with the investigations on gamma-ray emission, SED model fit, and variability monitoring, we will investigate: (1) the compact radio structure and properties, and the physical conditions of jet formation for a large sample of RLNLS1s; (2) the properties and mechanism of gamma-ray emission; (3) the relationship between RLNLS1s and CSSs, and blazars, and also the place of RLNLS1s in overall AGNs populations. The results will be great helpful for us to study deeply the jet formation in AGNs.

窄线赛弗特1型星系黑洞质量较小，吸积率较高，可能是年轻活动星系核，其中大约7%为射电强源，但其射电性质并不统一，有些源与致密陡谱源相似，另一些源与耀变体相似。VLBI观测，和探测到的伽马射线辐射证明相对论性喷流的存在，但目前对它们的喷流性质还知之甚少。射电强窄线赛弗特1型星系由于黑洞质量较小，吸积率较高，因此与典型射电强活动星系核有很大差别，为喷流形成机制的研究提供了新的观测依据。本项目将结合射电高分辨率观测，伽马射线辐射研究，多波段数据模型拟合，光变监测，研究：（1）大样本射电强窄线赛弗特1型星系致密射电结构和性质，喷流形成物理条件；（2）伽马射线辐射性质，产生机制；（3）射电强窄线赛弗特1型星系与致密陡谱源、耀变体之间关系，它们在活动星系核整体框架下的位置。研究结果将有助于深入探索活动星系核喷流形成机制。

射电强窄线赛弗特1型星系由于黑洞质量较小，吸积率较高，与典型射电强活动星系核有很大差别，为喷流形成机制的研究提供了新的观测依据。项目对窄线赛弗特1型星系的VLBI射电结构观测，伽马射线辐射探测，多波段光变特征，中性氢观测等方面进行了研究。建立了最大的VLBI观测样本，发现射电结构致密，射电核亮温度较高，射电辐射来自于喷流。喷流的多普勒增亮效应不强，很可能喷流速度较低。较低的喷流速度可能是由于喷流是由吸积盘上的冕通过磁场和辐射压加速的，或者喷流是由BZ机制产生，但由于黑洞自转较小而喷流速度较小。通过多历元VLBI观测研究了喷流成分的自行。发现两个具有致密陡谱源性质的窄线赛弗特1型星系中的高置信度伽马射线辐射，利用VLBA多波段观测对其中一个源的多波段射电结构进行了研究，确认了射电核，对核移进行了分析研究。通过GMRT和Arecibo的观测，研究了中性氢气体性质。发现窄线赛弗特1型星系MCG-06-30-15的X射线波段约为一个小时的准周期振荡。对其他活动星系核多波段辐射和光变性质进行了研究。发表SCI文章25篇。