X选BL Lac天体的某些性质

本文给出了包含５６个Ｘ选择的ＢＬ Ｌａｃ天体（ＸＢＬｓ）的完备样品，得到了一些相互关系并讨论了ＸＢＬｓ的一些性质。     

BL Lac Objects and Unified Model

1　ＤｉｆｆｅｒｅｎｃｅａｎｄＵｎｉｔｙｏｆＢＬＬａｃＯｂｊｅｃｔｓ1 1　ＴｈｅＤｉｆｆｅｒｅｎｃｅｓａｎｄＥｘｐｌａｎａｔｉｏｎｂｅｔｗｅｅｎＲＢＬｓａｎｄＸＢＬｓ1 )ＲＢＬｓｄｏｎｏｔｆｉｔｔｈｅＨｕｂｂｌｅｄｉａｇｒａｍｓｏｗｅｌｌａｓｄｏＸＢＬｓ ;2 )ＲＢＬｓｄｏｎｏｔｓｈｏｗａｎｙｍｕｌｔｉｗａｖｅｌｅｎｇｔｈｃｏｒｒｅｌａｔｉｏｎａｓｄｏＸＢＬｓ;3)ＲＢＬｓｈａｖｅｈｉｇｈｅｒｒａｄｉｏａｎｄｏｐｔｉｃａｌｌｕｍｉｎｏｓｉｔｉｅｓｔｈａｎｄｏＸＢＬｓｂｕｔｔｈｅｙｂｏｔｈｈａｖｅａｌｍｏ…     

X选BL Lac天体的某些性质（II）

本文对Ｘ射线选择ＢＬＬａｃ天体（ＸＢＬｓ）的完备样品进行了较细致的研究，讨论了该样品各观测量的分析，最新发现的几例Ｘ射线和ＲＯＳＡＴ选择的ＢＬＬａｃ天体的Ｈｕｂｂｌｅ关系及ＢＬＬａｃ天体的红移起源问题。     

BL Lac天体和FR—I射电星系的统一模型（I）

从射电结构的角度评述了ＢＬＬａｃ天体和ＦＲ－Ｉ射电星系的统一模型的最新进展，内容包括射电结构，延展射电光度（Ｐｅｘｔ），最大角尺度（ＬＡＳ），射电核主导系数（ｆ）的比较以及对相对论聚束的测试。最新的射电观测资料表明ＸＢＬｓ是介于ＦＲ－Ｉ和ＲＢＬｓ之间的过渡型天体，这对ＢＬＬａｃ天体是聚束的ＦＲ－Ｉ射电星系提供了一个很好的证据。     

XRB、SGR和GRB简介

ＸＲＢ、ＳＧＲ和ＧＲＢ简介Ｘ射线爆发（Ｘ－ｒａｙＢｕｒｓｔｅｒｓ，以下简称ＸＲＢ）、软γ射线复现（Ｓｏｆｔ－ｇａｍｍａＲｅｐｅａｔｅｒｓ，以下简称ＳＧＲ）和γ射线爆发（γ－ｒａａＢｕｒｓｔｅｒｓ，以下简称ＧＲＢ）都是天空中暂现、转瞬即逝的高能现象，三...     

VLBI天体物理学的发展（续）

ＶＬＢＩ天体物理学的发展（续）万同山（接上期）下一代的ＶＬＢＩ以ＶＬＢＡ和Ｒａｄｉｏａｓｔｒｏｎ空间ＶＬＢＩ站为代表。美国国立射电天文台的ＶＬＢＡ是世界上第一个ＶＬＢＩ专用设备，在美国领土上从夏威夷到维尔京群岛上放置了１０个２５米口径的射电望远镜，最...     

An Universal Birefringent Filter Developed for Japan

ＯｎＪｕｌｙｏｆ1 998,ＮａｎｊｉｎｇＡｓｔｒｏｎｏｍｉｃａｌＩｎｓｔｒｕｍｅｎｔＲｅｓｅａｒｃｈＣｅｎｔｅｒ (ＮＡＩＲＣ)ｏｆＣｈｉｎｅｓｅＡ ｃａｄｅｍｙｏｆＳｃｉｅｎｃｅｓ,ｈａｓｐｒｏｖｉｄｅｄａＵｎｉｖｅｒｓａｌＢｉｒｅｆｒｉｎｇｅｎｔＦｉｌｔｅｒ (ＵＢＦ)ｔｏＴｏｋｙｏＭｅｉｓｅｉＵｎｉｖｅｒ ｓｉｔｙｔｈｒｏｕｇｈＮｉｋｏｎＣｏｒｐｏｒａｔｉｏｎｏｆＪａｐａｎ .1　Ｏｐｔｉｃａｌｓｃｈｅｍｅ (Ｆｉｇ 1 )ＴｈｅＵＢＦｉｓｃｏｍｐｏｓｅｄｏｆｓｉｘｔｕｎａｂｌｅＬｙｏｔｅｌｅｍｅｎｔｓＬ1 Ｌ6,…     

Re-Discussion on Motion of Shanghai VLBI Station Relative to Eurasian Plate From VLBI

ＩｎｔｒｏｄｕｃｔｉｏｎＡｓｍａｎｙｐａｐｅｒｓｈａｖｅｃｏｎｃｅｒｎｅｄｔｈａｔｔｈｅＳｈａｎｇｈａｉＶＬＢＩｓｔａｔｉｏｎｍａｙｂｅａｆｆｅｃｔｅｄｂｙｔｈｅｅａｓｔ ｗａｒｄｅｘｔｒｕｓｉｏｎｏｆｔｈｅｓｏｕｔｈＡｓｉａｎｂｌｏｃｋａｓｔｈｅｒｅｓｕｌｔｓｏｆｔｈｅｎｏｒｔｈｗａｒｄｃｏｌｌｉｓｉｏｎｏｆｔｈｅｌｎｄｏ Ａｕｓ ｔｒａｌｉａｎＰｌａｔｅｔｏｔｈｅＥｕｒａｓｉａｎＰｌａｔｅ (Ｈｅｋｉ,1 996 ) .Ｗｉｔｈｔｈｉｓｓｉｔｕａｔｉｏｎ ,ｓｐａｃｅｇｅｏｄｅｓｙ ,ｓｕｃｈａｓＶＬＢＩｉ…     

5个新发现的X选BL Lac天体

利用ＲＯＳＡＴ－ＶＬＡ方法筛选，从ＲＯＰＳＡＴ Ｘ射线源中选出了一批新的ＢＬ Ｌａｃ天体和类星体的候选体。１９９６年１２月８日至１７日，利用北京天文台２．１６ｍ望远镜和新从美国引进的ＯＭＲ摄谱仪，对这批新候选体进行了光谱认证。经ＳＵＮ工作站处理，又发现了５个新的Ｘ选ＢＬ Ｌａｃ天体。     

5个新发现的X选BL Lac天体

利用ＲＯＳＡＴＶＬＡ方法筛选，从ＲＯＳＡＴＸ射线源中选出了一批新的ＢＬＬａｃ天体和类星体的候选体．１９９６年１２月８日至１７日，利用北京天文台２．１６ｍ望远镜和新从美国引进的ＯＭＲ摄谱仪，对这批新候选体进行了光谱认证．经ＳＵＮ工作站处理，又发现了５个新的Ｘ选ＢＬＬａｃ天体．此外，还对去年作者在ＯＭＲ引进之前发现的ＢＬＬａｃ天体进行了检验，结果发现，去年发现的７个ＢＬＬａｃ天体中，２３２２＋３４３的ＣａＩＩＨ＆Ｋ“Ｂｒｅａｋｓｔｒｅｎｇｔｈ”为２６．９％，稍大于判据２５％，因此，２３２２＋３４３到底是ＢＬＬａｃ天体还是射电星系还有待于进一步测光及偏振观测的验证．     

X选BL Lac天体的某些性质(Ⅱ)

本文对X射线选择BLLac天体（XBLs）的完备样品进行了较细致的研究，讨论了该样品各观测量的分布、最新发现的几例X射线和ROSAT选择的BLLac天体的Hubble关系及BLLac天体的红移起源问题．     

On the difference between the X-ray selected and the radio selected BL Lac objects in the near infrared

By using results from the 2MASS observation, the differences between the X-ray selected BL Lac objects (XBLs) and the radio selected ones (RBLs) in the near infrared are discussed in this paper. It is found that, statistically, the RBLs have redder near infrared colors and steeper spectral indices in the near infrared than XBLs, whereas the XBLs have more influences from their host galaxies than the RBLs. It is also seen that the RBLs have much brighter luminosity in the near infrared than the XBLs. In addition, the high polarization characteristics are found in common for RBLs, but not for XBLs.     

BL Lac objects and acceleration model

In this paper, the acceleration model is applied to data from RBLs (Radio Selected BL Lac objects). The corrected data from RBLs are found to be nearly the same as those from XBLs (X-Ray Selected BL Lac objects), the expected result, that points ofU - B, B - V of XBLs and RBLs occupy the same region in the (B - V)-(U - B) diagram has been obtained, and the Radio Doppler factors obtained by us are highly consistent with those found by others.     

The unification of RBLs with XBLs

Many astronomers have discussed the property of BL Lacertae objects, including the variation of spectrum, the correlation of multi-wave bands and the property of polarization, which could give good information for studying intrinsic correlation of components and position of BL Lacertae objects. In the paper, we investigated the properties of RBLs and XBLs and RBLs/XBLs (these objects can also be found by radio survey as by X-ray survey). Firstly, we collected the light curve of 28 BL Lacertae objects, and gained their short timescales by Structure Function (SF). Secondly, we analyzed the distribution of the short timescales of some BL Lacertae objects, including 28 objects’ timescales calculated by SF, as well as the distribution of the redshift and the black hole mass and the flux densities of the multi-wavebands (radio, near-infrared, optical and Gamma-ray). Based on statistical analysis, the result of the paper support the unification model of RBLs and XBLs.     

The Relationship between Radio Luminosity and Core-Dominance Parameter for XBLs

In this work, we investigate the correlation between the luminosity and the core-dominance parameter for a sample of X-ray selected BL Lacertae objects (XBLs), and found that the extended luminosity is strongly anti-correlated with the core-dominance parameter while the core (or the total) luminosity is not correlated with the core-dominance parameter. If this is the case, then we can expect that the lower extended luminosity XBLs and their core luminosity is relatively higher. This can be explained by a relativistic beaming model since in this case, the viewing angle is smaller and the emissions dominate the extended emissions. Therefore, the anti-correlation is in fact the result of the relativistic beaming model.     

BL Lac天体中心黑洞周围的物质分布

本文从Ｘ光度与短时标出发讨论了两种选择ＢＬＬａｃ体的统一及它们中心黑洞的周围物质分布     

Anti-correlation between the extended power and the core dominance parameter of BL Lac objects

The XBL and RBL samples presented recently by Kollgaardet al. (1996) are employed to investigate whether the extended power of BL Lac objects is correlated with the core dominance parameter. The results show that the two quantities are statistically anti-corelated at a rather high level of confidence for both XBLs and RBLs. Since the core dominance parameter is generally used as a relative measure of orientation and the extended emission of radio sources is assumed unbeamed and isotropic, the results obviously contradict common inference from unified schemes. By adopting and combining some basic concepts of unified schemes and the different SED scenario, a possible explanation for the results is suggested.     

BL Lac天体和FR-I射电星系的统一模型(Ⅰ)

从射电结构的角度评述了BLLac天体和FR-I射电星系的统一模型的最新进展，内容包括射电结构、延展射电光度（Pext）、最大角尺度（LAS）、射电核主导系数（f）的比较以及对相对论聚束的测试。最新的射电观测资料表明XBLs是介于FR-I和RBLs之间的过渡型天体，这为BLLac天体是聚束的FR-I射电星系提供了一个很好的证据。     

Characteristics of the Radiation from Blazars

We have collected short-timescale variability data of 47 blazars, estimated the masses of their central black holes and the sizes of their radiation regions at different wavebands, and made a statistical analysis on the calculated results. It is found that the central black hole mass of blazars falls in the range 10⁷M to 10¹⁰M, and that the BL Lac objects and the flat-spectrum radio quasars have very different central black hole masses (the latter being generally greater), while they have very similar sizes of radiation regions in the infrared and γ-ray wavebands. Also, using the collected bolometric luminosity data, we have analyzed the relationship between the bolometric luminosity of blazars and their short-timescale variability, and it is concluded that the radiations from the radio-selected BL Lac objects (RBLs) and flat-spectrum radio quasars (FSRQs) are strongly beam-confined, while the effect of relativistic beaming is relatively small for the X-ray-selected BL Lac objects (XBLs).     

Variations in the broad-band spectra of BL Lac objects: millimetre observations of an X-ray-selected sample

Observations at millimetre wavelengths are presented for a representative sample of 22 X-ray-selected BL Lac objects (XBLs). This sample comprises 19 high-energy cut-off BL Lac objects (HBLs), 1 low-energy cut-off BL Lac object (LBL) and 2 'intermediate' sources. Data for LBLs, which are mostly radio-selected BL Lac objects (RBLs), are taken from the literature. It is shown that the radio–millimetre spectral indices of HBLs     are slightly steeper than those of the LBLs     . A correlation exists between α _5–230 and 230 GHz luminosity. While this correlation could be an artefact of comparing two populations of BL Lac objects with intrinsically different radio properties, it is also consistent with the predictions of existing unified schemes that relate BL Lac objects to Fanaroff–Riley class I radio galaxies.
The HBLs have significantly flatter submillimetre–X-ray spectral indices     than the LBLs     although the two intermediate sources also have intermediate values of α _230–X∼−0.9. It is argued that this difference cannot be explained entirely by the viewing-angle hypothesis and requires a difference in physical-source parameters. The α _230–X values for the HBLs are close to the canonical value found for large samples of radio sources and thus suggest that synchrotron radiation is the mechanism that produces the X-ray emission. As suggested by Padovani & Giommi, the inverse-Compton mechanism is likely to dominate in the LBLs requiring the synchrotron spectra of these sources to steepen or cut off at lower frequencies than those of the HBLs.