Predictions for the rates of compact binary coalescences observable by ground-based gravitational-wave detectors

Abstract

We present an up-to-date, comprehensive summary of the rates for all types of compact binary coalescence sources detectable by the initial and advanced versions of the ground-based gravitational-wave detectors LIGO and Virgo. Astrophysical estimates for compact-binary coalescence rates depend on a number of assumptions and unknown model parameters and are still uncertain. The most confident among these estimates are the rate predictions for coalescing binary neutron stars which are based on extrapolations from observed binary pulsars in our galaxy. These yield a likely coalescence rate of 100 Myr−1 per Milky Way Equivalent Galaxy (MWEG), although the rate could plausibly range from 1 Myr−1 MWEG−1 to 1000 Myr−1 MWEG−1 (Kalogera et al 2004 Astrophys. J. 601 L179; Kalogera et al 2004 Astrophys. J. 614 L137 (erratum)). We convert coalescence rates into detection rates based on data from the LIGO S5 and Virgo VSR2 science runs and projected sensitivities for our advanced detectors. Using the detector sensitivities derived from these data, we find a likely detection rate of 0.02 per year for Initial LIGO–Virgo interferometers, with a plausible range between 2 × 10−4 and 0.2 per year. The likely binary neutron–star detection rate for the Advanced LIGO–Virgo network increases to 40 events per year, with a range between 0.4 and 400 per year.

Search for gravitational waves from intermediate mass binary black holes

“…Since globular clusters are the most likely hosts of IMBHs, we convert our overall search upper limit into an astrophysical density of 3×10 3 GC −1 Gyr −1 . This rate is still few orders of magnitude above the predictions for IMBH-IMBH rates in [41]. It should be noted, however, that the predicted astrophysical rates are very uncertain due to the lack of knowledge of the distribution and formation of IMBH sources.…”

“…Concerning the rate of IMBH-IMBH coalescence, the upper limit has been estimated at 0.07 GC −1 Gyr −1 [41].…”

R-process enrichment from a single event in an ancient dwarf galaxy

“…The low-metallicity environment may also affect the binary fraction and merging delay time. We note that the expected rate of neutron star mergers is uncertain to 1-2 orders of magnitude even in the local universe 50 . A neutron star binary may experience large velocity kicks during its formation, which can eject the binary from its host galaxy and further reduce the expected rate of these mergers 51 .…”

Extracting Information on the Equation of State from Binary Neutron Stars

“…They are the most promising sources of GWs in a series of advanced detectors such as LIGO [1], Virgo [2] and KAGRA [3], which will be operated within next five years. Especially binary neutron star mergers (BNSs) may be the most common source with realistic detection rate of ∼40 yr −1 [4].…”