XMM-Newton Observations of Two Archival X-ray Weak Type 1 Quasars: Obscuration Induced X-ray Weakness and Variability. (arXiv:2307.07554v1 [astro-ph.GA])

XMM-Newton Observations of Two Archival X-ray Weak Type 1 Quasars: Obscuration Induced X-ray Weakness and Variability. (arXiv:2307.07554v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Zhang_Z/0/1/0/all/0/1">Zijian Zhang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Luo_B/0/1/0/all/0/1">Bin Luo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Brandt_W/0/1/0/all/0/1">W.N.Brandt</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Du_P/0/1/0/all/0/1">Pu Du</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hu_C/0/1/0/all/0/1">Chen Hu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Huang_J/0/1/0/all/0/1">Jian Huang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Pu_X/0/1/0/all/0/1">Xingting Pu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wang_J/0/1/0/all/0/1">Jian-Min Wang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Yi_W/0/1/0/all/0/1">Weimin Yi</a>

We report hbox{XMM-Newton} observations of two examples of an unclassified
type of hbox{X-ray} weak quasars from the citet{2020ApJ…900..141P} survey
of hbox{X-ray} weak quasars in the Chandra archive, SDSS J083116.62+321329.6
at $z=1.797$ and SDSS J142339.87+042041.1 at $z=1.702$. They do not belong to
the known populations of hbox{X-ray} weak quasars that show broad absorption
lines, weak ultraviolet (UV) broad emission lines, or red optical/UV continua.
Instead, they display typical quasar UV spectra and spectral energy
distributions. In the hbox{XMM-Newton} observations, both quasars show nominal
levels of hbox{X-ray} emission with typical quasar hbox{X-ray} spectral
shapes (hbox{power-law} photon indices of $1.99^{+0.27}_{-0.23}$ and
$1.86^{+0.15}_{-0.14}$), displaying strong hbox{X-ray} variability compared to
the archival Chandra data (variability factors of $4.0^{+1.6}_{-1.4}$ and
$9.0^{+7.4}_{-3.8}$ in terms of the 2 keV flux density). Simultaneous optical
(rest-frame UV) spectra indicate no strong variability compared to the archival
spectra. Long-term optical/UV and infrared light curves do not show any
substantial variability either. We consider that the hbox{X-ray} weakness
observed in the Chandra data is due to hbox{X-ray} obscuration from a
small-scale dust-free absorber, likely related to accretion-disk winds. Such
hbox{X-ray} weak/absorbed states are probably rare in typical quasars, and
thus both targets recovered to hbox{X-ray} nominal-strength states in the
hbox{XMM-Newton} observations.

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