We investigate the question of the nature of compact stars, considering they
may be neutron stars or hybrid stars containing a quark core, within the
present constraints given by gravitational waves, radio-astronomy, X-ray
emissions from millisecond pulsars and nuclear physics. A Bayesian framework is
used to combine together all these constraints and to predict tidal
deformabilities and radii for a 1.4~M⊙ compact star. We find that
present gravitation wave and radio-astronomy data favors asy-stiff EoS
compatible with nuclear physics and that GW170817 waveform is best described
for binary hybrid stars. In addition, this data favors stiff quark matter,
independently of the nuclear EoS. Combining this result with constraints from
X-ray observation supports the existence of canonical 1.4~M⊙ mass
hybrid star, with a radius predicted to be R1.4=12.02(8)~km.Comment: 5 pages, 3 figure