Estimates of the Galactic coalescence rate (R) of close binaries with two neutron stars (NS-NS) are known to be uncertain by large factors (about two orders of magnitude) mainly due to the small number of systems detected as binary radio pulsars. We present an analysis method that allows us to estimate the Galactic NS-NS coalescence using the current observed sample and, importantly, to assign
a statistical significance to these estimates and to calculate the allowed ranges of values at various confidence levels. The method involves the simulation of selection effects inherent in all relevant radio pulsar surveys and a Bayesian statistical analysis for the probability distribution of R. The most likely values for the total Galactic coalescence rate (Rtot) lie in the range 2-60 Myr-1 depending on different pulsar population models. For our reference model 1, where the most likely estimates of pulsar population properties are adopted, we obtain Rtot = 8-5+9 Myr-1 at a 68% statistical confidence level. The corresponding range of expected detection rates of NS-NS inspiral are 3-2+4 × 10-3 yr-1 for the initial LIGO and 18-11+21 yr-1 for the advanced LIGO.
The detection of gravitational waves by the first generation of ground-based interferometric detectors, like LIGO, relies on sophisticated data analysis techniques. For the inspiral phase of binary compact objects, the optimal one is the so-called matched-filtering technique. The output of the detector is cross-correlated with a bank of templates. The closer the templates are to the real signal, the higher the S/N of the detection is. In this paper we quantify the loss of S/N that occurs when one tries to detect a precessing binary using non-precessing templates. To do so, we compute the fitting factor which is a measure of the mismatch between the signal and the templates. The precessing signal is obtained using a 1.5 PN analytical approximation of the real solution called simple precession. We found regions of the parameter space for which the detection could be jeopardized if precession is not accounted in the templates. The solution of this problem could be to use more complete templates, that could capture the main features of the precession. Specifically we examine such a family of 'mimic' templates, that requires only three additional parameters, first proposed by Apostolatos. However we find that this family does not recover the main part of the signal. We conclude that a more efficient template family will be needed in the near future.
Using the Star Track population synthesis code we compute the distribution of masses of merging compact object (black hole or neutron star) binaries. The shape of the mass distribution is sensitive to some parameters governing the stellar binary evolution. We discuss the possibility of constraining stellar evolution models using mass measurements abtained from detection of compact object inspiral with upcoming gravitational-wave observatories.