As part of our study to understand the nature of extragalactic radio sources which are very asymmetric in the surface brightness of the two lobes, often with radio emission on only one side of the nucleus, we have observed a large number of them with high angular resolution and good surface brightness sensitivity at radio frequencies. In this paper we present VLA and MERLIN observations of 15 such sources. We discuss their observed structures and spectra, and possible explanations for their morphologies. We report evidence of a possible correlation between the hot-spot brightness ratio and the degree of core prominence, used as a Statistical measure of source orientation, suggesting that relativistic beaming of the hot-spot emission does play a significant role in the observed brightness asymmetry. To explain the apparently one-sided sources within the relativistic beaming framework, the velocities required are in the range of 0.2 to 0.8c. We discuss the possibility that the lobe which is seen to the south of the jet in 3C273 is the counter-lobe seen in projection. We also draw-attention to a number of one-sided sources with very weak cores, and discuss their possible nature.
Volume 40 | Issue 5
Since January 2016, the Journal of Astrophysics and Astronomy has moved to Continuous Article Publishing (CAP) mode. This means that each accepted article is being published immediately online with DOI and article citation ID with starting page number 1. Articles are also visible in Web of Science immediately. All these have helped shorten the publication time and have improved the visibility of the articles.
Click here for Editorial Note on CAP Mode