Neutron star and strange quark star binaries in the late inspiral phase

Mateusz Wiśniewicz and Dorota Gondek-Rosińska

Coalescing neutron star binaries are considered among the strongest and most likely sources of gravitational waves to be seen by Advanced Virgo and LIGO interferometers (Abadie et al., 2010; Kim et al., 2004). The evolution of a binary system of compact objects is entirely driven by gravitational radiation and can be roughly divided into three phases: point-like inspiral, hydrodynamical inspiral and merger. Gravitational wave signal of the late inspiral or merger phase of such binaries could yield important information about the equation of state (EOS) of neutron stars (Read et al., 2009). It is worth mentioning that strange quark stars are currently considered as a possible alternative to neutron stars as compact objects. In 1971, Bodmer (Bodmer, 1971) remarked that matter consisting of deconfined up, down and strange quarks could be the absolute ground state of matter at zero pressure and temperature. If this is true objects made of such matter, the so-called strange stars could exist (Witten, 1984; Haensel et al., 1986; Alcock et al., 1986). Most of calculations were performed for equal-mass neutron star and strange quark star binaries (Taniguchi & Gourgoulhon, 2003; Oechslin et al., 2004; Bejger et al., 2005; Limousin et al., 2005; Gondek-Rosińska & Limousin, 2008; Taniguchi & Shibata, 2010). However the radio observations of neutron star binaries and population synthesis show that binaries with non-equal masses should be considered as well (Gondek-Rosińska et al., 2007; Os lowski et al., 2011). Numerical calculations have shown that the mass-ratio q = M1=M2, where M1 < M2 are component masses, has important impact on the evolution scenario. In particular, the mass and the radius of the disk created after the merger depends strongly on q (Rezzolla et al., 2010).
We present first results on non-equal strange star binaries as well the results for equal-mass binaries described by different EOSs.

Proceedings of the Polish Astronomical Society, vol. 1, 136-139 (2014)

Download full article as PDF file: