4-OGC: Catalog of gravitational waves from compact-binary mergers (2112.06878v2)

Abstract: We present the fourth Open Gravitational-wave Catalog (4-OGC) of binary neutron star (BNS), binary black hole (BBH) and neutron star-black hole (NSBH) mergers. The catalog includes observations from 2015-2020 covering the first through third observing runs (O1, O2, O3a, O3b) of Advanced LIGO and Advanced Virgo. The updated catalog includes 7 BBH mergers which were not previously reported with high significance during O3b for a total of 94 observations: 90 BBHs, 2 NSBHs, and 2 BNSs. The most confident new detection, GW200318_191337, has component masses $49.1^{+16.4}{-12.0}\textrm{M}\odot$ and $31.6^{+12.0}{-11.6}\textrm{M}\odot$; its redshift of $0.84^{+0.4}_{-0.35}$ ($90\%$ credible interval) may make it the most distant merger so far. We estimate the merger rate of BBH sources, assuming a powerlaw mass distribution containing an additive Gaussian peak, to be $16.5_{-6.2}^{+10.4} (25.0_{-8.0}^{+12.6})$ Gpc$^{-3}$ yr$^{-1}$ at a redshift of $z=0$ ($0.2$). For BNS and NSBH sources, we estimate a merger rate of $200^{+309}_{-148}$ Gpc$^{-3}$ yr$^{-1}$ and $19^{+30}_{-14}$ Gpc$^{-3}$ yr$^{-1}$, respectively, assuming the known sources are representative of the total population. We provide reference parameter estimates for each of these sources using an up-to-date model accounting for instrumental calibration uncertainty. The corresponding data release also includes our full set of sub-threshold candidates.

• The paper introduces an updated catalog of 94 gravitational wave merger events from LIGO and Virgo's first three observing runs, including seven newly identified BBH mergers.
• It details merger rate estimates—16.5 to 25.0 Gpc³ yr⁻¹ for BBH, 200 for BNS, and 19 for NSBH—to inform future detector design and population synthesis models.
• The analysis highlights key detections such as GW200318_191337 and advances the understanding of compact binary evolution in extreme gravitational conditions.

Overview of 4-OGC: Catalog of Gravitational Waves from Compact-Binary Mergers

The paper "4-OGC: Catalog of Gravitational Waves from Compact-Binary Mergers" presents a detailed and updated compilation of gravitational wave (GW) detections from the merging of binary neutron stars (BNS), binary black holes (BBH), and neutron star-black hole (NSBH) binaries. Covering observations from 2015 to 2020, this catalog builds upon the results from the previous 3-OGC and includes data from the first through third observing runs of the Advanced LIGO and Advanced Virgo detectors.

Key Results

During the specified period, the catalog identified a total of 94 merger events, detailed as follows:

• 90 BBH mergers: The catalog identifies seven new BBH events from the second half of the third observing run (O3b) which have not been previously reported with significant confidence. These include GW191224_043228, GW200106_134123, GW200129_114245, GW200210_005122, GW200214_223307, GW200305_084739, and GW200318_191337.
• 2 BNS events: This constitutes the observed BNS mergers, consistently corroborated, including the renowned GW170817_124104, which was the first to be associated with electromagnetic counterparts.
• 2 NSBH mergers: The detection of these events adds valuable insights into the population and characteristics of mixed neutron star-black hole systems.

One of the most noteworthy detections is GW200318_191337, potentially marking the most distant merger observed thus far. Its component masses are estimated to be around 49.1 and 31.6 with a high redshift z of approximately 0.84, indicating its considerable distance.

Merger Rate Estimates

The paper presents estimates of the merger rates for various binary types:

• BBH mergers: Using an assumed power-law mass distribution, the merger rate is estimated to be 16.5 to 25.0 Gpc$^3$ yr$^{-1}$ at redshifts of 0 and 0.2, respectively.
• BNS mergers: Assuming GW170817 and GW190425 are typical of a single population, their rate is estimated at approximately 200 Gpc$^3$ yr$^{-1}$ with considerable uncertainty.
• NSBH mergers: The estimated rate is around 19 Gpc$^3$ yr$^{-1}$.

These rates are crucial for informing future GW detector designs and improving population synthesis models, enhancing our understanding of the binary black hole origin, evolution, and the role these systems play in stellar and galactic evolution.

Implications and Future Outlook

The observations from the 4-OGC catalog significantly contribute to our understanding of compact binary populations and gravitational wave astrophysics. By incorporating data from further astrophysical phenomena like gamma-ray bursts and high-energy neutrino correlations, there is potential for new insights into the multi-messenger astronomy landscape. Moreover, the detailed parameter estimation and robust analytical techniques employed in this paper lay the groundwork for deeper exploration of potential deviations from general relativity in extreme gravity conditions, ultimately traversing beyond the existing gravitational model constraints.

Anticipated advancements in observational technology, such as the future involvement of third-generation detectors like Cosmic Explorer and Einstein Telescope, along with ongoing upgrades to current LIGO and Virgo facilities, are expected to significantly enhance the sensitivity and reach of GW detection in the near future. The growth in GW observational capability will likely lead to a larger and more detailed catalog with hundreds, if not thousands, of events to analyze, paving the way for precision gravitational wave astronomy and further expanding the frontier for understanding astrophysical phenomena in the universe.