The X-ray spectral and variability properties of typical radio-loud quasars. (arXiv:2105.06478v2 [astro-ph.HE] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Zhu_S/0/1/0/all/0/1">Shifu Zhu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Timlin_J/0/1/0/all/0/1">John Timlin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Brandt_W/0/1/0/all/0/1">W. N. Brandt</a>
We present X-ray spectral and long-term variability analyses of an unbiased
sample of 361 optically selected radio-loud quasars (RLQs) utilizing sensitive
serendipitous X-ray data from the Chandra and XMM-Newton archives. The spectral
and temporal properties of RLQs are compared with those of radio-quiet quasars
(RQQs) matched in $L_mathrm{2500A}$ and $z$. The median power-law photon index
($Gamma$) of RLQs is $1.84^{+0.01}_{-0.01}$, which is close to that of matched
RQQs ($1.90^{+0.02}_{-0.01}$). No significant correlations between $Gamma$ and
radio-loudness, $L_mathrm{x}/L_mathrm{x,rqq}$ (the X-ray luminosity over that
expected from the $L_mathrm{x}$-$L_mathrm{uv}$ relation for RQQs), redshift,
or Eddington ratio are found for our RLQs. The stacked X-ray spectra of our
RLQs show strong iron-line emission and a possible Compton-reflection hump. The
intrinsic X-ray variability amplitude is $approx40$% for RLQs on timescales of
months-to-years in the rest frame, which is somewhat smaller than for the
matched RQQs ($approx60$%) on similar timescales, perhaps due to the larger
black-hole masses and lower Eddington ratios in our RLQ sample. The X-ray
spectral and variability results for our RLQs generally support the idea that
the X-ray emission of typical RLQs is dominated by the disk/corona, as is also
indicated by a recent luminosity correlation study.
We present X-ray spectral and long-term variability analyses of an unbiased
sample of 361 optically selected radio-loud quasars (RLQs) utilizing sensitive
serendipitous X-ray data from the Chandra and XMM-Newton archives. The spectral
and temporal properties of RLQs are compared with those of radio-quiet quasars
(RQQs) matched in $L_mathrm{2500A}$ and $z$. The median power-law photon index
($Gamma$) of RLQs is $1.84^{+0.01}_{-0.01}$, which is close to that of matched
RQQs ($1.90^{+0.02}_{-0.01}$). No significant correlations between $Gamma$ and
radio-loudness, $L_mathrm{x}/L_mathrm{x,rqq}$ (the X-ray luminosity over that
expected from the $L_mathrm{x}$-$L_mathrm{uv}$ relation for RQQs), redshift,
or Eddington ratio are found for our RLQs. The stacked X-ray spectra of our
RLQs show strong iron-line emission and a possible Compton-reflection hump. The
intrinsic X-ray variability amplitude is $approx40$% for RLQs on timescales of
months-to-years in the rest frame, which is somewhat smaller than for the
matched RQQs ($approx60$%) on similar timescales, perhaps due to the larger
black-hole masses and lower Eddington ratios in our RLQ sample. The X-ray
spectral and variability results for our RLQs generally support the idea that
the X-ray emission of typical RLQs is dominated by the disk/corona, as is also
indicated by a recent luminosity correlation study.
http://arxiv.org/icons/sfx.gif
