The Unusual Weak-Line Quasar PG1407+265 and its Foreground z~0.7 X-ray
  Cluster
  We present new observations of the odd $z=0.96$ weak-line quasar PG1407+265,
and report the discovery of CXOU J140927.9+261813, a $z=0.68$ X-ray cluster.
Archival X-ray photometry spanning nearly four decades reveals that PG1407+265
is variable at the 1 dex level on a timescale of years. V-band variability is
present with an amplitude less than 0.1 mag. The emission-line properties of
PG1407+265 also reveal clear evidence for a powerful inflow or outflow due to
near- or super-Eddington accretion, having a mechanical luminosity of order
$10^{48}$ erg s$^{-1}$. Our follow-up {\sl Chandra} exposure centered on this
object reveal a foreground $z=0.68$ cluster roughly 1' x 1'.5 in extent, offset
to the east of PG1407+265, roughly coincident with the $z=0.68$ radio galaxy
FIRST J140927.8+261818. This non-cool-core cluster contributes about 10\% of
the X-ray flux of PG1407+265, has a mass of $(0.6- 5.5)\times10^{14} M_\odot$,
and an X-ray gas temperature of ($2.2-4.3$) keV. Because the projected position
of the quasar lies at about twice that of the cluster's inferred Einstein
radius, lensing by the cluster is unlikely to explain the quasar's unusual
properties. We also discuss the evidence for a second cluster centered on and
at the redshift of the quasar.
