两颗致密射电源的327MHz VLBI观测

1989年6月，对两颗射电源（3C345和3C454.3）作了327MHz VLBI观测。本文给出两颗源的模型拟合参数，并就结构作了分析和讨论。VLBI数据的相关处理和分析是在上海天文台VLBI系统上完成的。     

ROSAT选射电源的性质：Ⅰ.样本

ＲＯＳＡＴ卫星的全天巡天观测到了一大批射电星系和各种活动星核,为我们研究这些活动性剧烈的河外天体的辐射机制、多波段辐射相关性以及各类星系核之间的演化联系提供了重要数据。通过将ＲＯＳＡＴ全天巡天观测与ＰＭＮ射电（５ＧＨｚ）巡天观测进行交叉证认,我们得到了６４２颗天射电源。对这些对应体随后进行的光学证认构建了一个星系和活动星系核的大样本。其中３１１个对应体（占５２％）被过去的光学观测证实为河外天体（包     

FR—Ⅰ和FR—Ⅱ型射电源的关系—谱特征

本文比较了两类射电源ＦＲ－Ⅰ和ＦＲ－Ⅱ型的射电－光学－Ｘ－ｒａｙ的谱特征。ＦＲ－Ⅰ射电源的射电－光学谱比ＦＲ－Ⅱ射电源平得多；但对于光学－Ｘ－ｒａｙ和射电－Ｘ－ｒａｙ谱，ＦＲ－Ⅰ却比ＦＲ－Ⅱ陡得多。初步结果表明：ＦＲ－Ⅱ（Ｇ）可能是ＦＲ－Ⅱ（Ｑ）向ＦＲ－Ⅰ过渡的中间状态。     

VLBI天体测量观测的南天射电源工作表

本文给出了上海、Kashima和Tidbinbilla三个台站组成的VLBI同多进行天体测量观测的南天射电源工作表，共有167颗，赤纬范围为0°＞δ＞－42°17′，相关流量密度大于0.25Jy，观测高度大于10°。还计算了三条基线或三个台站同时观测每颗射电源的时间图，利用它们可以编制观测纲要。     

高频射电源中的类星体

研究表明，高频射电源与低频射电源相比，前者中的类星体比例更大。３ＣＲ低频射电源（Ｓ１７８ＭＨｚ＞９Ｊｙ）中有１７．８％是类星体，而在２．７ＧＨｚ亮射电源样本中（Ｓ２．７ＧＨｚ≥２．０Ｊｙ），有３５．６％是类星体。更有趣的是，５１８个５ＧＨｚ亮射电源中（Ｓ５ＧＨｚ≥１．０Ｊｙ），至少有２９１个（≥５６％）是类星体。因此，我们认为高频亮射电源的证认是发现类星体的有效手段。     

射电选BLLac（RBLs）天体的观测性质

本文给出了射电选ＱＬＬａｃ天体的完备样品及它们的观测数据并讨论了它们的各种性质。     

活动星系的非相对论性外流

活动星系核有两类常见外流，相对论性的射电喷流和非相对论性的物质外流，前者主要在射电强的适动星系核中，以非热辐射为特征，非相对论性外流主要通过紫外吸收线观测到，总结了类星体非对论性外流的一些性质及其X射线观测给出了的问题，指出现有的观测表明非相对论性外流引起的质量损失很重要。     

射电选和X射线选BL Lacertae天体的射电性质

收集了射电选和X射线选BL Lac天体的射电数据(包括核和延展光度), 并计算了它们的核主导系数R.研究显示: 射电选BL Lac(RBLs)天体的总射电光度是X射线选BL Lac(XBLs)天体的2个量级.详细分析得到这种差别主要是来自于核光度的差别因为延展光度差别只有1个量级.研究RBLs和XBLs的核(延展元)光度与核主导系数之间的关系, 发现延展元光度与核主导系数负相关, 而核(总)光度几乎与核主导系数没有相关.     

河外射电源的核谱指数和延展谱指数(英文)

我们采用 6cm和 2 0cm核流量密度和总流量密度的观测资料 ,分别计算出星系和类星体的核谱指数和延展谱指数 .此外 ,我们得到 :(1 )核谱指数和核主导系数相关 ;(2 )核主导系数同红移线性相关。     

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.     

Faraday rotation in the VLBI core of BL Lacertae

External Faraday rotation has been detected in both the core and the parsec-scale jet of BL Lac in a four-frequency very long baseline interferometry (VLBI) experiment. This unexpected result indicates the presence of significant amounts of thermal gas close to the nucleus of this object. The rotation measure (RM) in the jet components is constant, and differs from the currently accepted Galactic RM, indicating that this value (−205 rad m⁻²) is not applicable to the components in the parsec-scale jet. The similarity of the RM in these jet components leads us to suspect that the jet RM is caused by a foreground screen in our Galaxy, although we cannot rule out a combination of Galactic RM and RM local to the jet. If the jet RM is due solely to the Galaxy, this would mean that the currently accepted value of the foreground RM (−205 rad m⁻² ) is not correct, either because the value changed between 1982 and 1997, or because the assumption of no intrinsic source rotation was incorrect, as it was at our later epoch of observation. Our observations suggest a value of     .
After correcting for the foreground RM, the core value is −427 rad m⁻², which is unexpected since, owing to the weakness of their line emission, BL Lac objects are often assumed to be depleted in gas. The core RM appears to be variable, probably because of the presence of at least two polarized components close to the core the relative contributions of which vary with time.     

Blazar 的X射线谱性质

从Donato文献中选择了一个含有69个Blazar的样本，样本中每个源有多个X射线辐射流量数据，用该样本研究了流量密度和谱指数之间的关系，以及研究了三类源（HBL，LBL，FSRQ）的红移和谱指数的分布。结果表明：对于HBLs，谱指数和流量密度之间有一个较好的反相关关系存在，而对于LBLs和FSRQs却没有相关。因此认为HBL的X射线是同步辐射所致，而LBL和FSRQ的X射线辐射较为复杂可能是同步自康普顿过程导致。HBL显示软X射线谱，而FSRQ显示硬X射线谱，LBL居中。在谱图中HBL位于近端，rSRQ位于远端，LBL居中。     

Spectral Indices of Core and Extended Components of Extragalactic Radio Sources

We use observed peak and total flux densities at 6cm and 20cm to determine the spectral indices separately for the core and extended components of QSOs and galaxies, as well as their core-dominance parameters. Our results indicate that 1) Nine QSOs show both greater than 1.0 core-dominance parameters (those objects should be blazars) and greater than 0.5 spectral indices. The average core spectral index is αCore = 0.85±0.21 for the nine blazars, which implies that it is not reliable to use αradio = 0.0 for blazars. For the different subclasses, the core and extended spectral indices are as follows: for the blazars, αCore = 0.22±0.06 and αExt =0.77±0.12; the galaxies,αCore = 1.01±0.13 and αExt =0.83±0.21, and for the QSOs, αCore = 0.28±0.10 and αExt =0.68±0.08. 2) The core spectral index and core dominance parameter (R) show an anti-correlation, αC = (-1.28±0.26) log R+ (0.65 ± 0.11); 3) R is approximately linearly correlated with redshift (z).     

Optical multiband observations of BL Lacertae during the outburst of 2005

The aim of our observations is to investigate the intranight variability properties and the spectral variability of BL Lacertae. 799 optical multiband observations were intensively made with the Beijing–Arizona–Taiwan–Connecticut (BATC) 60/90 cm Schmidt telescope during the outburst composed of two subsequent flares in 2005. The second flare, whose rising phase lasted at least 44 d, was observed with amplitudes of more than 1.1 mag in three BATC optical bands. In general, on intranight time-scale the amplitude of variability and the variation rate are larger at the shorter wavelength, and the variation rate is comparable in the rising and decaying phases within each band. A possible time-lag between the light curves in bands e and m , around 11.6 min, was obtained. Based on the analysis of the colour index variation with the source brightness, the variability of BL Lacertae can be interpreted as having two components: a 'strongly chromatic' intranight component and a 'mildly chromatic' internight component, which may be the results of both intrinsic physical mechanism and geometric effects.