  The direct detection of new extrasolar planets from high-precision photometry
data is commonly based on the observation of the transit signal of the planet
as it passes in front of its star. Close-in planets, however, leave additional
imprints in the light curve even if they do not transit. These are the
so-called phase curve variations that include ellipsoidal, reflection and
beaming effects. In Millholland & Laughlin (2017), the authors scrutinized the
Kepler database looking for these phase variations from non-transiting planets.
They found 60 candidates whose signals were compatible with planetary
companions. In this paper, we perform a ground-based follow-up of a sub-sample
of these systems with the aim of confirming and characterizing these planets
and thus validating the detection technique. We used the CAFE and HERMES
instruments to monitor the radial velocity of ten non-transiting planet
candidates along their orbits. We additionally used AstraLux to obtain
high-resolution images of some of these candidates to discard blended binaries
that contaminate the Kepler light curves by mimicking planetary signals. Among
the ten systems, we confirm three new hot-Jupiters (KIC8121913 b, KIC10068024
b, and KIC5479689 b) with masses in the range 0.5-2 M$_{\rm Jup}$ and set mass
constraints within the planetary regime for the other three candidates
(KIC8026887b, KIC5878307 b, and KIC11362225 b), thus strongly suggestive of
their planetary nature. For the first time, we validate the technique of
detecting non-transiting planets via their phase curve variations. We present
the new planetary systems and their properties. We find good agreement between
the RV-derived masses and the photometric masses in all cases except KIC8121913
b, which shows a significantly lower mass derived from the ellipsoidal
modulations than from beaming and radial velocity data.
