Gravitational waves, neutrino emissions and effects of hyperons in binary neutron star mergers

Numerical simulations for the merger of binary neutron stars are performed in full general relativity incorporating both nucleonic and hyperonic finite-temperature equations of state (EOS) and neutrino cooling. It is found that for the nucleonic and hyperonic EOS, a hyper-massive neutron star (HMNS) with a long lifetime (t(life) greater than or similar to 10 ms) is the outcome for the total mass approximate to 2.7 M-circle dot. For the total mass approximate to 3 M-circle dot, a long-lived (short-lived with t(life) approximate to 3 ms) HMNS is the outcome for the nucleonic (hyperonic) EOS. It is shown that the typical total neutrino luminosity of the HMNS is similar to 3-6 x 10(53) erg s(-1) and the effective amplitude of gravitational waves from the HMNS is 1-4 x 10(-22) at f approximate to 2-3.2 kHz for a source of distance of 100 Mpc. During the HMNS phase, characteristic frequencies of gravitational waves shift to a higher frequency for the hyperonic EOS in contrast to the nucleonic EOS in which they remain constant approximately. Our finding suggests that the effects of hyperons are well imprinted in gravitational waves and their detection will give us a potential opportunity to explore the composition of the neutron star matter. We present the neutrino luminosity curve when a black hole is formed as well.