Tong-shan Wan

Superluminal source candidates 0208-512 and 2243-123

This paper describes the superluminal source candidates 0208-512 and 2243-123 found in the second cycle observation of the Southern Sky 5 GHz VLBI Survey. Further observations should be made to confirm the findings.

A VLBI Study of Blazars in the Southern Hemisphere

Abstract In this paper, we describe the second session of the Southern Hemisphere VLBI Survey, which was conducted in May 1993. Twenty five radio sources were observed and 24 sources detected, of which 23 high-resolution VLBI images for a sample of blazars in the southern hemisphere were obtained. Of these VLBI-imaging has been conducted for 15 sources for the first time and seven are high-energy (>100 MeV) γ-ray sources. Twelve sources appear to be having core-jet structures and eleven sources having single compact cores. No compact double sources were found. In particular, apparent superluminal phenomenon was noticed in two sources.

A statistical study of the Southern 5 GHz VLBI Survey

Abstract We present a statistical summary of the results obtained in the already completed two cycles of observations in our Southern 5 GHz VLBI Survey and a statistical comparison with the results of the Pearson-Redhead general survey, the Wehrle et al. survey of variable sources and the γ-ray sources detected by egret

Superluminal motion in the radio sources 0420-014, 1334-127 and 2345-167☆

Abstract This paper presents some preliminary results on three superluminal sources 0421-014, 1334-127 and 2345-167, found in a VLBI survey in the southern hemisphere at 5 GHz. Further VLBI observations are needed for confirmation of the results

Observations of the superluminal source 0106+013

Abstract In the course of a Southern Sky, 5 GHz VLBI Survey using the Shanghai+SHEVE network, we made further studies on the superluminal motion of the compact radio source 0106+013. The results show 1) that Component 1 is most likely to be the core, 2) that the original superluminal jet is continuing to move outward at a proper motion of 0.2 mas/yr, 3) the explosion of a new component which is again superluminal at a proper motion of 0.18 mas/yr and 4) that the jet shows clear bending at about 5 mas and then tends to the direction of the VLA jet.

A VLBI study of 20 southern extragalactic radio sources

Abstract This paper describes a 5 GHz VLBI survey in the southern hemisphere. The first observation of 23 extragalactic radio sources was conducted in November 1992. Twenty VLBI images were obtained, of which 15 sources show core-jet structure, one has a two-sided jet, and three sources are unresolved. No compact double source was found. Eleven of the 16 sources with core-jet (including a two-aided jet) show evidence of jet bending. In addition, four sources appear to be superluminal, of which three sources are new.

Second epoch VLBI observations of four extragalactic radio sources at 327 MHz

Abstract We present the results of a second epoch VLBI observation of 3C 84, 3C 345, 3C 380 and 3C 454.3 at 327 MHz made with the Shanghai radio telescope and EVN in March 1991. Data correlation was made both in Shanghai and Caltech/JPL. Hybrid maps are shown. No significant changes in flux since the first epoch are shown in 3C 345 and 3C 380, while there is an obvious change in the structure of 3C 345. 3C 84 and 3C 345 appear to have jets. An increase of 25% in the flux density of 3C 454.3 in less than two years suggests a new outburst, if the increase is intrinsic.

A statistical test of the unified model of active galactic nuclei

A statistical test is carried out on the AGN unified model using a sample of superluminal sources. For different classes of source the distribution of R, the luminosity ration between the core and extended region, and the mean angle φ between the jet and the line of sight were evaluated. Correlations among R, the Lorentz factor γ, the projected size of the jet d and the linear size of the source l were examined. It was found that there is anticorrelation between R and d, and correlation between γ and l. These results are favorable to the orientation interpretation of the unified model of the AGN.