Gravitational wave signature from phase transition of a combusting neutron star to quark star. (arXiv:2003.00693v2 [astro-ph.HE] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Mallick_R/0/1/0/all/0/1">Ritam Mallick</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Singh_S/0/1/0/all/0/1">Shailendra Singh</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Prasad_R/0/1/0/all/0/1">R Prasad</a>
Fluctuation at the neutron star center gives rise to a small deconfined quark
core very close to the star center. The density discontinuity at the
quark-hadron boundary initiates a shock wave, which propagates outwards of the
star. The shock has enough energy to combust nuclear matter to 2-flavor quark
matter in the star. The 2-flavor quark matter is not stable and settles to a
stable 3-flavor matter in the weakly interacting timescale. In this paper, we
study the conversion of 2-flavor matter to 3-flavor matter. We set up a
differential equation to convert the excess of down quarks to strange quarks
involving weak reaction and diffusion of quarks. Calculating the reaction rate,
we solve the differential equation to find the velocity of the conversion
front. As the conversion front moves out, the density profile changes, bringing
about a change in the star’s quadrupole moment and thereby emitting
gravitational waves. We find that the GW signal depends strongly on the star
temperature and mass. The GW amplitude of a colder star is well within present
detector capability, but the frequency is slightly on the higher side.
Relatively hotter stars are on the boundary of present detectors and easily
detectable with future detectors, and their frequency is also within the
present detectability range. In comparison, PT from galactic pulsars is easily
detectable with present detectors.
Fluctuation at the neutron star center gives rise to a small deconfined quark
core very close to the star center. The density discontinuity at the
quark-hadron boundary initiates a shock wave, which propagates outwards of the
star. The shock has enough energy to combust nuclear matter to 2-flavor quark
matter in the star. The 2-flavor quark matter is not stable and settles to a
stable 3-flavor matter in the weakly interacting timescale. In this paper, we
study the conversion of 2-flavor matter to 3-flavor matter. We set up a
differential equation to convert the excess of down quarks to strange quarks
involving weak reaction and diffusion of quarks. Calculating the reaction rate,
we solve the differential equation to find the velocity of the conversion
front. As the conversion front moves out, the density profile changes, bringing
about a change in the star’s quadrupole moment and thereby emitting
gravitational waves. We find that the GW signal depends strongly on the star
temperature and mass. The GW amplitude of a colder star is well within present
detector capability, but the frequency is slightly on the higher side.
Relatively hotter stars are on the boundary of present detectors and easily
detectable with future detectors, and their frequency is also within the
present detectability range. In comparison, PT from galactic pulsars is easily
detectable with present detectors.
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