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The Lx–Luv–Lradio relation and corona–disc–jet connection in optically selected radio-loud quasars
报告题目:The Lx–Luv–Lradio relation and corona–disc–jet connection in optically selected radio-loud quasars
报 告  人:Shifu Zhu (PSU)
报告时间:2020-11-02 08:30:00
报告地点:https://zoom.com.cn/j/5576839595

Abstract: Radio-loud quasars (RLQs) are more X-ray luminous than predicted by the
Lx-Luv relation for radio-quiet quasars (RQQs). The excess X-ray
emission depends on the radio-loudness parameter (R) and radio spectral
slope (alpha_r). We construct a uniform sample of 729 optically selected
RLQs with high fractions of X-ray detections and alpha_r measurements.
We find that steep-spectrum radio quasars (SSRQs) follow a
quantitatively similar Lx-Luv relation as that for RQQs, suggesting a
common coronal origin for the X-ray emission of both SSRQs and RQQs.
However, the corresponding intercept of SSRQs is larger than that for
RQQs and increases with R, suggesting a connection between the radio
jets and the configuration of the accretion flow. Flat-spectrum radio
quasars (FSRQs) are generally more X-ray luminous than SSRQs at given
Luv and R, likely involving more physical processes. The emergent
picture is different from that commonly assumed where the excess X-ray
emission of RLQs is attributed to the jets. We thus perform model
selection to compare critically these different interpretations, which
prefers the coronal scenario with a corona-jet connection. A distinct
jet component is likely important for only a small portion of FSRQs. We
suggest that RLQs and RQQs are in different accretion states, similar to
those of microquasars when their ballistic jets are either active or
quenched. The corona-jet, disk-corona, and disk-jet connections of RLQs
are likely driven by independent physical processes. Furthermore, the
corona-jet connection implies that small-scale processes in the vicinity
of SMBHs, probably associated with the magnetic flux/topology instead of
black-hole spin, are controlling the radio-loudness of quasars.