  Quantum Chromodynamics predicts phase transition from hadronic matter to
quark matter at high density, which is highly probable in astrophysical systems
like binary neutron star mergers. To explore the critical density where such
phase transition can occur, we performed numerical relativity simulations of
binary neutron star mergers with various masses (equal and unequal binaries).
We aim to understand the effect of the onset of phase transition on the merger
dynamics and gravitational wave spectra. We generated a set of equations of
states by agnostically changing the onset of phase transition, having the
hadronic matter part and quark matter part fixed. This particular arrangement
of the equation of states explores the scenario of mergers where mixed phases
of matter are achieved before or during the merger. Under these circumstances,
if the matter properties with hadronic and quark degrees differ significantly,
it is reflected in the stability of the final merger product for the
intermediate mass binary. We performed a case study on mixed species merger,
where one of the binary companions is hybrid star. If quark matter appears at
low densities, we observe significant change in post-merger gravitational wave
analysis in terms of higher peak frequencies and post-merger frequencies in
power spectral density. We report indications expressed as spikes in phase
difference plots at merger time for mixed mergers. We found that the expression
of phase transition in post-merger gravitational wave signals is more
significant for unequal mass binary than for equal mass binary having the same
total baryonic mass.
