Predictions for the Rates of Compact Binary Coalescences Observable by Ground-based Gravitational-wave Detectors (1003.2480v2)

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 per Myr per Milky Way Equivalent Galaxy (MWEG), although the rate could plausibly range from 1 per Myr per MWEG to 1000 per Myr per MWEG. 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 0.0002 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.

• The paper provides predictions for compact binary coalescence rates by integrating pulsar observations and detector sensitivity models.
• It estimates binary neutron star rates spanning 1 to 1000 Myr⁻¹ MWEG⁻¹ with initial LIGO/Virgo detection rates around 0.02 events per year.
• The study highlights the need for refined astrophysical modeling to enhance advanced detector performance, forecasting up to 40 annual detections.

Overview of Compact Binary Coalescence Rates for Ground-based GW Detectors

The paper presents a detailed evaluation of the anticipated rates of compact binary coalescence (CBC) events detectable by ground-based gravitational-wave (GW) detectors like LIGO and Virgo. This research constitutes an essential endeavor for astrophysics, given the critical role of accurate event rate predictions in guiding both detector configuration and data analysis strategies. The paper synthesizes various methodologies and presents rate estimates for different types of binary systems, including binary neutron stars (BNS), binary black holes (BBH), and neutron star-black hole (NS-BH) systems.

Methodology and Estimates

The authors survey a range of models and assumptions employed in predicting the coalescence rates. One key source of data is observations of binary pulsars within the Milky Way, which have been extrapolated to place the rate of binary neutron star coalescences at around 100 events per million years per Milky Way Equivalent Galaxy (MWEG). This estimate, however, features a substantial degree of uncertainty, with plausible rates spanning from 1 to 1000 Myr$^{-1}$ MWEG$^{-1}$.

To transform these coalescences into detectable events, the paper calculates detection rates based on the sensitivity outcomes from LIGO's S5 and Virgo's VSR2 science runs. The paper reports a likely detection rate of 0.02 per year using the initial LIGO-Virgo detectors, with a wide range extending from 2×10$^{-4}$ to 0.2 per year due to inherent uncertainties in the models. This rate dramatically increases for the advanced detector network, projecting 40 potential detections annually, ranging from 0.4 to 400 events.

Implications and Future Directions

This work underscores the necessity of rigorous astrophysical modeling in informing the ongoing development of GW observatories. As the sensitivity of detectors like Advanced LIGO improves, resulting in greater detection volumes, these rate estimates become pivotal in validating or refuting extant theoretical models. Moreover, they can illuminate aspects of stellar evolution such as natal kick velocities, supernova mechanisms, and mass-transfer dynamics in binary systems.

Practically, these detection probabilities will guide the optimization of detector configurations, tuning their sensitivity to prioritize more probable frequency ranges or binary types. The forthcoming observations can refine the parameters of CBC models, providing a feedback loop to recalibrate astrophysical theories based on empirical data.

In the context of future advancements, the paper hints at the potentiality for discoveries extending beyond conventional stellar-mass black holes and neutron stars, gesturing towards intermediate-mass black hole investigations. Such inquiries promise to expand our understanding of black hole formation and evolution processes significantly.

Conclusions

This work furnishes a critical assessment of current knowledge and predictive efforts concerning gravitational wave astronomy. By aggregating various estimates and offering a coherent conversion to detection rates, the paper serves both as a scientific reference point and a roadmap for future explorations in gravitational-wave physics. This foundational paper in GW detection rates underscores the interdisciplinary cooperation between observational insights and theoretical modeling as a haLLMark of contemporary astrophysical research.