  The gravitational wave and electromagnetic signatures connected to the merger
of two neutron stars allow us to test the nature of matter at supranuclear
densities. Since the Equation of State governing the interior of neutron stars
is only loosely constrained, there is even the possibility that strange quark
matter exists inside the core of neutron stars. We investigate how strange
quark matter cores affect the binary neutron star coalescence by performing
numerical relativity simulations. Interestingly, the strong phase transition
can cause a reduction of the convergence order of the numerical schemes to
first order if the numerical resolution is not high enough. Therefore, an
additional challenge is added in producing high-quality gravitational wave
templates for Equation of States with a strong phase transition. Focusing on
one particular configuration of an equal mass configuration consistent with
GW170817, we compute and discuss the associated gravitational wave signal and
some of the electromagnetic counterparts connected to the merger of the two
stars. We find that existing waveform approximants employed for the analysis of
GW170817 allow describing this kind of systems within the numerical
uncertainties, which, however, are several times larger than for pure hadronic
Equation of States, which means that even higher resolutions have been employed
for an accurate gravitational wave model comparison. We also show that for the
chosen Equation of State, quasi-universal relations describing the
gravitational wave emission after the moment of merger seem to hold and that
the electromagnetic signatures connected to our chosen setup would not be
bright enough to explain the kilonova associated to GW170817.
