摘要: 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
$\alpha_{\rm{ox}}$ 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 ($L_{\rm R}$) flat-spectrum radio quasars (FSRQs) follow the
$\alpha_{\rm ox}$--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-$L_{\rm R}$ FSRQs show excess X-ray emission given their
HeII EW by a factor of $\approx$ 3.5, which suggests that only in this type of
RLQ is the X-ray production likely jet related.