活动星系核中相对论电子束的物理效应

本文研究了Ｂｌａｚａｒ天体的辐射性质，提出一种新的喷流模型，即具有幂律分布的极端相对论电子团从中心核注入喷流等离子体中，它在一定的注入速度下，不仅能在喷流等离子体中激发等离子体湍动，产生电磁波的相干辐射，而且能产生强的同步辐射。利用等离子体的弱湍理论，我们研究了极端相对论电子团在喷流等离子体中的辐射过程，并详细研究了它在解释Ｂｌａｚａｒ天体辐射特性中的应用，本文认为，Ｂｌａｚａｒ天体的不稳定辐射与极端相对论电子团的无规注入、喷流等离子体的物理环境瞬息变化有关。Ｂｌａｚａｒ中快速变化的辐射偏振角摆动。产生于相对论电子团在湍动等离子体中的同步辐射过程。另外，Ｘ选和射电选的ＢＬＬａｃ天体之间的区别取决于喷流等离子体的运动状态和物理环境。     

VSOP observations of the BL Lac object 2007+777

A numerical model of magnetic turbulence allows us to compute the diffusion coefficients for different degrees of anisotropy, and in particular for the cases corresponding to the solar wind. We consider here the problem of the propagation of the energetic particles accelerated by corotating interaction regions (CIRs) and observed by Ulysses at high heliographic latitudes. The excursion in latitude of a magnetic field line located at large heliospheric distance is evaluated with a Monte Carlo simulation. In the calculations, the random `force' terms are proportional to the square root of the diffusion coefficient in each direction. By tracing a large number of field lines, we can devise how the particles would be seen by Ulysses. Good agreement with the actual observations is found. This revised version was published online in July 2006 with corrections to the Cover Date.     

Optical and infrared monitoring of BL Lac in 1999–2001

We present the results of our multicolor observations of BL Lac in the period 1999–2001. We show that the spectral energy distribution of the variable component in the range from K to B had remained unchanged for three years. The power-law spectrum is indicative of its synchrotron nature.     

A Millimetre/Submillimetre Polarization Survey of Compact Flat-Spectrum Radio Sources

We present the results of the first survey and monitoring study of the linear polarization properties of compact, flat-spectrum radio sources at mm/submm wavelengths and discuss the implications of the inferred magnetic field structure for the emission models involving shock waves in relativistic jets on subparsec scales. We find significant polarization in most sources but, in general, the magnetic field on subparsec scales is less well ordered than on parsec scales. We observe no difference in polarization properties between the BL Lac objects and compact flat-spectrum quasars at these wavelengths. Although we find the behaviour of some sources, particularly the most highly polarized, to be very consistent with the predictions of transverse shock-in-jet models, the detailed behaviour of most objects is not. Conical shock structures can more readily explain the observed diverse behaviour of the sample, although some degree of bending of the jet may still be necessary in some cases.     

BL Lac天体AO 0235 164在5 GHz上的VLBI观测

应用５ＧＨｚＶＬＢＩ技术在历元１９９７.１２的观测结果,给出ＢＬ　Ｌａｃ天体ＡＯ　０２３５＋１６４在毫角秒尺度上的最新图像．该致密天体的射电结构由一个亮核所支配,另外在东北和西南方向各存在一个相对较弱的子源,其中东北方向的子源要比西南方向的明显得多.模型拟合结果显示,该源的喷流位置角为６６.４°,该数值超过以往的任何一次观测结果．根据流量密度随时间的变化关系,我们发现ＡＯ０２３５＋１６４在波长６ｃｍ上可能存在两种周期性的变化,即１—２年的短周期性变化和３－５年的长周期性变化这两种周期性的变化可能是由于喷流的爆发和旋转两种效应共同作用的结果．     

BL Lac天体的谱性质

研究了等离子体反应堆模型,统一解释活动星系核的辐射性质,特别是ＢＬＬａｃ天体的谱性质．具体的物理过程是:大量相对论电子从中心天体注入周围的等离子体反应堆中,通过同步辐射快速损失能量,同时这些电子同步吸收反应堆中不透明的光子,产生一个稳定、各向同性的幂律分布,其谱指数为γ＝３;然后,这些相对论电子通过等离子体反应堆的爆发或其表面扩散过程逃逸出来,产生低频的同步辐射;来自等离子体反应堆的高频辐射表现出快速的谱变化,即流量减小时谱变陡．另外,还详细分析了具有辐射损失和相对论电子注入的同步辐射源的性质．     

VLBI polarization images of eight compact active galactic nuclei at λ = 1.3 cm

Global VLBI images in intensity and linear polarization at     of the BL Lacertae objects 0235+164, 0300+470, 0735+178, 0954+658, 1803+784, 1823+568, and BL Lac and OVV quasar 3C 279 are presented and analysed. These are the highest resolution polarization images currently available for several of these sources. On the whole, the tendencies observed at longer centimetre wavelengths are also exhibited in these 1.3-cm images. When core polarization is detected, the corresponding polarization angles χ tend to lie either parallel or perpendicular to the direction of the inner jet. The core degrees of polarization are usually comparable to those typical at 6 cm, but somewhat lower in several cases, suggesting that the higher resolution data are better separating the contributions of intrinsically weakly polarized cores and highly polarized emerging knots. The observed χ vectors in the jets of 0735+178, 0954+658, 1823+568, BL Lac and 3C 279 are aligned with the jet, implying the presence of transverse magnetic fields. In 0300+470 and BL Lac, there are regions where the direction of χ seems to be neither parallel nor perpendicular to the jet; it is not clear whether this is due to genuine obliquity of the magnetic field structure or to inadequate knowledge of the local flow direction.     

S5 2007+777的射电性质研究

S5 2007+777是一个典型的低峰值频率的蝎虎天体,该天体具有kpc尺度的X射线喷流,文献中利用模型估算的方法,得出X射线波段的多普勒因子达到13.0,从而喷流尺度可以达到Mpc量级.在此,搜集了有关S5 2007+777的欧洲甚长基线射电干涉网(European VLBI Network, EVN)高分辨率档案数据、美国甚长基线射电干涉网(Very Long Baseline Array, VLBA) 15 GHz观测数据等,研究了喷流的射电结构、亮温度、自行等方面的性质,发现该源的甚长基线干涉测量(Very Long Baseline Interferometry,VLBI)不同波段的喷流方向一致,但与文献中给出的kpc尺度的X射线喷流和甚大阵(Very Large Array, VLA)射电喷流方向存在一定的差异,说明该源的喷流辐射存在多普勒增亮效应.由VLBI观测得到的亮温度,估算了该源的射电多普勒因子的平均值及中值均为5.0,此值小于文献中X射线波段的多普勒因子,但与文献中利用其他方法得到的射电波段多普勒因子是一致的;另外,对多历元观测数据的拟合发现此源相同波段的各个成分在长历元上没有明显的自行,短历元上的自行甚至是视超光速运动.这可能是由低表面亮度成分中心位置的转移造成的.这同时也验证了之前估算的射电多普勒因子不是很大,小于X射线波段多普勒因子的结论.利用所得到的射电多普勒因子,发现该源具有较大尺度的本征射电喷流,可达到0.5 Mpc,由于这里使用的是均值,因此说明该源也有可能具有接近巨射电星系尺度的喷流.