High-Resolution VLA Observations of FR II Radio Galaxies and Quasars at 3.6 cm

We report the results of high-resolution VLA observations at 8.4 GHz of 23 FR II radio sources: 11 radio galaxies (RGs) and 12 quasars (QSRs). The main objective of this work is to analyze the radio properties of these objects in terms of the radio hot spots (HSs). We emphasize on the location, size, and morphological structures of the HSs in the two types of objects. These HSs can be edged, i.e. located at the extreme edges of the lobe, or recessed, i.e. located near the inner edges of the lobe. The location of these HSs has been quantified by a ratio (i.e., ) which is the ratio of the distance between the hot spot peak and the radio core of the source to the full extent of the lobe measured from the core along the core-hot spot axis. The mean E (edged) ratios for the RGs and QSRs are quite similar, 0.94  0.01. For the E distributions, the RGs and the QSRs distributions are similar at the 34% significance level using a Kolmogorov-Smirnov two-sample test. Furthermore, we ran Student’s T-test to compare the distributions’ means for the location of the edged hot spots. We find that there is a 73 % probability that the means were drawn from the same parent population. The mean R (recessed) ratios for the RGs and QSRs are 0.78  0.05 and 0.78  0.03, respectively. The R distributions for the RGs and the QSRs look also similar and a Kolmogorov-Smirnov two-sample test shows that the two distributions are similar at the 99 % significance level. Furthermore, we ran Student’s T-test. There is a 94 % probability that the means were drawn from the same parent population. To further quantify the asymmetry between the two lobes in the amount of hot spot recession, we have also computed a parameter  defined as the ratio of the smaller to the larger value of the  parameter. The RGs and the QSRs distributions differ with mean values of  equal to 0.91+/-  0.04 and 0.88+/-  0.04, respectively. The QSRs have a sligthly smaller asymmetry parameter than the RGs. A K-S test shows that the two distributions are similar at the 80 % significance level. A Student’s T-test gives a 59 % probability that the means were drawn fro the same parent population. We would like to analyze these statistics to check if the HS location (edged or recessed) can be used as an orientation indicator to differentiate between the RGs and the QSRs if we take into account the unification model of Barthel. The overall picture is that our objects have more edged hot spots than recessed hot spots with the jetted sources (mostly QSRs) having more recessed hot spots than the un-jetted sources.