Reporting a deficit of intrinsic N  <scp>v</scp> absorbers in core-dominated radio-loud quasars

ABSTRACT We searched the Hubble Space Telescope Cosmic Origins Spectrograph archive for ultraviolet spectra of 428 active galactic nuclei (AGNs) to identify intrinsic N v absorption systems. We filtered out Type 2 AGNs, blazars, and spectra that do not cover at least part of the velocity window from 5000 km s$^{-1}$ blueward to 5000 km s$^{-1}$ redward (hereafter, the ‘associated’ region) of the N v emission line. This yielded 175 Type 1 quasars, 34 radio-loud, 133 radio-quiet, and eight unconstrained. Our survey uncovered 77 associated N v systems in the spectra of 48 of these low-redshift quasars. We consider the incidence of intrinsic absorbers as a function of quasar properties $\left(\rm {optical,~radio~and~X-ray}\right)$. We find a statistically significant dearth of intrinsic N v systems in the spectra of the 34 radio-loud quasars (6 per cent), compared to 29 per cent of the 133 radio-quiet quasars containing at least one intrinsic system. Assuming intrinsic systems are equally likely to occur in radio-loud and radio-quiet quasars and the orientations of the two subsamples are comparable, there is a $0.1{{\ \rm per\ cent}}$ probability of such a deficit occurring by chance in the radio-loud population. We propose that this deficit of systems is caused by orientation effects. Faint Images of the Sky at 20-cm survey radio images are available for 14 of the 33 radio-loud quasars. These show that only three of the 14 radio-loud quasars have lobe-dominated morphologies, whereas 11 of the 14 radio-loud quasars have compact radio morphologies, implying that these quasars are face on, and suggesting that clouds that produce N v absorption are rarely found along the polar axis.