Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The most luminous blue quasars at 3.0<z<3.3. II. CIV/X-ray emission and
  accretion disc physics   We analyse the properties of the CIV broad emission line in connection with
the X-ray emission of 30 bright SDSS quasars at z~3.0-3.3 with pointed
XMM-Newton observations, which were selected to test the suitability of AGN as
cosmological tools. In our previous work, we found that a large fraction (~25%)
of the quasars in this sample are X-ray underluminous by factors of >3-10. As
absorbing columns of >10$^{23}$ cm$^{-2}$ can be safely ruled out, their
weakness is most likely intrinsic. Here we explore possible correlations
between the UV and X-ray features of these sources to investigate the origin of
X-ray weakness. We fit their UV SDSS spectra and analyse their CIV properties
(e.g., equivalent width, EW; line peak velocity, $\upsilon_{\rm peak}$) as a
function of the X-ray photon index and 2-10 keV flux. We confirm the trends of
CIV $\upsilon_{\rm peak}$ and EW with UV luminosity at 2500 angstrom for both
X-ray weak and X-ray normal quasars, as well as the correlation between X-ray
weakness and CIV EW. In contrast to some recent work, we do not observe any
clear relation between the 2-10 keV luminosity and $\upsilon_{\rm peak}$. We
find a correlation between the hard X-ray flux and the integrated CIV flux for
X-ray normal quasars, whilst X-ray weak quasars deviate from the main trend by
more than 0.5 dex. We argue that X-ray weakness might be interpreted in a
starved X-ray corona picture associated with an ongoing disc-wind phase. If the
wind is ejected in the vicinity of the black hole, the extreme-UV radiation
that reaches the corona will be depleted, depriving the corona of seeds photons
and generating an X-ray weak quasar. Yet, at the largest UV luminosities
(>10$^{47}$ erg s$^{-1}$), there will still be an ample reservoir of ionising
photons that can explain the excess CIV emission observed in the X-ray weak
quasars with respect to normal sources of similar X-ray luminosities.

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The categories of this paper are: math
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The categories of this paper are: funct-an
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The categories of this paper are: stat
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The categories of this paper are: bayes-an
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The categories of this paper are: hep-ph
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The categories of this paper are: solv-int
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The categories of this paper are: eess
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The categories of this paper are: cond-mat
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The categories of this paper are: gr-qc