XMM-Newton, Swift and ROSAT observations of LBQS 0102-2713
  We have analyzed the first XMM-Newton, Swift and archival ROSAT PSPC
observations of the quasar LBQS 0102-2713.The object was selected from the
ROSAT archive as being notable due to the steep soft X-ray photon index and due
to the UV brightness based on HST and optical spectroscopic observations. The
first XMM-Newton observations carried out in December 2009 and the first Swift
observations from 2010 have confirmed the steepness of the soft X-ray photon
index, which ranges between 3.35 and 4.41 for the different XMM-Newton and
ROSAT detectors, the UV brightness of the source and the absence of significant
absorption by neutral hydrogen. The new data allow a combined spectral fitting
to the Swift UVOT and the XMM-Newton/ROSAT data which results in a huge
luminosity of (6.2+-0.2)x10^47 erg s^(-1) and alpha_ox values ranging between
(-1.87+-0.11) and (-2.11+-0.12). The nature of the soft X-ray emission can be
explained as local Comptonized emission of the UV disc photons in the
pseudo-Newtonian potential. The black hole mass is estimated from the Mg II
line and translates into an Eddington ratio of L/L_edd = 18(+33)(-12). For the
dimensionless electron temperature of the plasma cloud theta = kT_e/ (m_e c^2)
we derive an upper limit of about 10 keV.
