Gravitational Wave Searches for Aligned-Spin Binary Neutron Stars Using Nonspinning Templates

We study gravitational wave searches for merging binary neutron stars (NSs). We use nonspinning template waveforms towards the signals emitted from aligned-spin NS-NS binaries, in which the spins of the NSs are aligned with the orbital angular momentum. We use the TaylorF2 waveform model, which can generate inspiral waveforms emitted from aligned-spin compact binaries. We employ the single effective spin parameter $\chi_{\rm eff}$ to represent the effect of two component spins ($\chi_1, \chi_2$) on the wave function. For a target system, we choose a binary consisting of the same component masses of $1.4 M_{\odot}$ and consider the spins up to $\chi_i= 0.4$, We investigate fitting factors of the nonspinning templates to evaluate their efficiency in gravitational wave searches for the aligned-spin NS-NS binaries. We find that the templates can achieve the fitting factors exceeding $0.97$ only for the signals in the range of $-0.2 \lesssim \chi_{\rm eff} \lesssim 0$. Therefore, we demonstrate the necessity of using aligned-spin templates not to lose the signals outside that range. We also show how much the recovered total mass can be biased from the true value depending on the spin of the signal.