GWTC-4.0: Updating the Gravitational-wave Transient Catalog with Observations from the First Part of the Fourth LIGO–Virgo–KAGRA Observing Run

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Armstrong, Steven and Ben Yaala, Marwa and Fazio, Mariana and Gier, Chalisa, The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration (2026) GWTC-4.0: Updating the Gravitational-wave Transient Catalog with Observations from the First Part of the Fourth LIGO–Virgo–KAGRA Observing Run. Astrophysical Journal Letters, 1004 (2). L22. ISSN 2041-8213 (https://doi.org/10.3847/2041-8213/ae2c74)

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Abstract

Version 4.0 of the Gravitational-Wave Transient Catalog (GWTC-4.0) adds new candidates detected by the LIGO, Virgo, and KAGRA observatories through the first part of the fourth observing run (O4a: 2023 May 24 15:00:00 to 2024 January 16 16:00:00 UTC) and a preceding engineering run. In these new data, we find 128 compact binary coalescence candidates that are identified by at least one of our search algorithms with a probability of astrophysical origin pastro ≥ 0.5 and that are not vetoed during event validation. We also provide detailed source property measurements for 86 of these that have a false-alarm rate <1 yr−1. Based on the inferred component masses, these candidates are consistent with signals from binary black holes (BBHs) and neutron star–black hole binaries (GW230518_125908 and GW230529_181500). Median-inferred component masses of BBHs in the catalog now range from 5.79M⊙ (GW230627_015337) to 137 (GW231123_135430), while GW231123_135430 was probably produced by the most massive binary observed in the catalog. For the first time, we have discovered BBH signals with network signal-to-noise ratio exceeding 30, GW230814_230901 and GW231226_101520, enabling high-fidelity studies of the waveforms and astrophysical properties of these systems. Combined with the 90 candidates included in GWTC-3.0, the catalog now contains 218 candidates with pastro ≥ 0.5 and not otherwise vetoed, more than doubling the size of the catalog and further opening our view of the gravitational-wave Universe.

ORCID iDs

Armstrong, Steven, Ben Yaala, Marwa ORCID logoORCID: https://orcid.org/0000-0002-6754-0875, Fazio, Mariana ORCID logoORCID: https://orcid.org/0000-0002-9057-9663 and Gier, Chalisa ORCID logoORCID: https://orcid.org/0000-0003-0897-7943;
CORE (COnnecting REpositories)