Abstract:
An increase in the central density of a neutron star may trigger a phase transition
from hadronic matter to deconfined quark matter in the core, causing it to collapse
to a more compact hybrid-star configuration. We present a study of this, building
on previous work by Lin et al. (2006). We follow them in considering a supersonic
phase transition and using a simplified equation of state, but our calculations are
general relativistic (using 2D simulations in the conformally flat approximation) as
compared with their 3D Newtonian treatment. We also improved the treatment of
the initial phase transformation, avoiding the introduction of artificial convection. As
before, we find that the emitted gravitational-wave spectrum is dominated by the
fundamental quasi-radial and quadrupolar pulsation modes but the strain amplitudes
are much smaller than suggested previously, which is disappointing for the detection
prospects. However, we see significantly smaller damping and observe a nonlinear
mode resonance which substantially enhances the emission in some cases. We explain the damping mechanisms operating, giving a different view from the previous work. Finally, we discuss the detectability of the gravitational waves, showing that the signalto-noise ratio for current or second generation interferometers could be high enough to detect such events in our Galaxy, although third generation detectors would be
needed to observe them out to the Virgo cluster, which would be necessary for having
a reasonable event rate
Submission guide