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Abstract

We investigate how the quasi-universal relations connecting tidal
deformability with gravitational waveform characteristics and/or properties of
individual neutron stars that were proposed in the literature within general
relativity would be influenced in the massive Damour-Esposito-Farese-type
scalar-tensor gravity. For this purpose, we systematically perform numerical
relativity simulations of ~120 binary neutron star mergers with varying scalar
coupling constants. Although only three neutron-star equations of state are
adopted, a clear breach of universality can be observed in the data sets. In
addition to presenting difficulties in constructing quasi-universal relations
in alternative gravity theories, we also briefly compare the impacts of
non-general-relativity physics on the waveform features and those due to the
first order or cross-over quantum chromodynamical phase transition.