Radio-loud quasars (RLQs) are known to produce excess X-ray emission, compared to radio-quiet quasars (RQQs) of the same luminosity, commonly attributed to jet-related emission. Recently, we found that the HeII EW and αox in RQQs are strongly correlated, which suggests that their extreme-ultraviolet (EUV) and X-ray emission mechanisms are tightly related. Using 48 RLQs, we show that steep-spectrum radio quasars (SSRQs) and low radio-luminosity (LR) flat-spectrum radio quasars (FSRQs) follow the αox--HeII EW relation of RQQs. This suggests that the X-ray and EUV emission mechanisms in these types of RLQs is the same as in RQQs, and is not jet related. High-LR FSRQs show excess X-ray emission given their HeII EW by a factor of ≈ 3.5, which suggests that only in this type of RLQ is the X-ray production likely jet related.
@article{arxiv.2104.14407,
title = {The aox--HeII EW Connection in Radio-Loud Quasars},
author = {John D. Timlin and Shifu Zhu and W. Niel Brandt and Ari Laor},
journal= {arXiv preprint arXiv:2104.14407},
year = {2021}
}