# GW231123

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Gravitational-wave event detected in 2023

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GW231123 Event type Gravitational wave Discovered Detected 23 November 2023, 13:54:30 UTC Duration 0.1 seconds Instrument LIGO Distance 2.2+1.9 −1.5 Gpc Redshift 0.39+0.27 −0.24 Progenitor type Binary black hole [edit on Wikidata]

**GW231123** was a [gravitational wave](/source/Gravitational_wave) detected by the two [LIGO](/source/LIGO) detectors on 23 November 2023. As of 2025, it is the largest [binary black hole merger](/source/Black_hole_merger) yet detected, at 225+26 −43 [solar masses](/source/Solar_mass) (M☉) for the final object. One or both of the objects involved in the merger may have been in the upper [black hole mass gap](/source/Stellar_black_hole#Upper_mass_gap).[1][2]

## Characteristics

GW231123 was the result of the merger of a 137+22 −17 M☉ black hole and a 103+20 −52 M☉ black hole creating a new [intermediate-mass black hole](/source/Intermediate-mass_black_hole). It occurred at an estimated distance of 2.2+1.9 −1.5 Gpc. The parent black holes have unusually large spins, with a magnitude of 0.9+0.10 −0.19 and 0.8+0.20 −0.51 for the two.[3]

## Science results

The high mass of both components of the binary black hole raises questions on its formation, as some very massive stars are thought to undergo [pair-instability supernova](/source/Pair-instability_supernova), which do not leave a remnant; this is thought to result in a gap in the black hole mass distribution between 60 and 130 M☉ (although there is some uncertainty on the limits). This suggests that the system has undergone a more complex process, e.g. with the black holes possibly resulting from earlier mergers, which is known as a "hierarchical" merger (this hypothesis is in particular supported by the high spins of the black holes).[3]

As the signal is extremely short, it is also possible that the signal originates from another type of system, such as [cosmic strings](/source/Cosmic_string), although it is considered unlikely.[3]

## References

1. **[^](#cite_ref-1)** Conover, Emily (July 13, 2025). ["The biggest black hole smashup ever detected challenges physics theories"](https://www.sciencenews.org/article/biggest-black-hole-gravitational-waves). *[Science News](/source/Science_News)*. Gravitational waves reveal the birth of a black hole with about 225 times the mass of the sun

1. **[^](#cite_ref-2)** Sample, Ian (2025-07-13). ["Scientists detect biggest ever merger of two massive black holes"](https://www.theguardian.com/science/2025/jul/14/scientists-detect-biggest-ever-merger-of-two-massive-black-holes). *[The Guardian](/source/The_Guardian)*. [ISSN](/source/ISSN_(identifier)) [0261-3077](https://search.worldcat.org/issn/0261-3077). Retrieved 2025-07-14.

1. ^ [***a***](#cite_ref-2507.08219_3-0) [***b***](#cite_ref-2507.08219_3-1) [***c***](#cite_ref-2507.08219_3-2) The LIGO Scientific Collaboration; the Virgo Collaboration; the KAGRA Collaboration (2025). ["GW231123: A Binary Black Hole Merger with Total Mass 190–265 *M* ⊙"](https://doi.org/10.3847%2F2041-8213%2Fae0c9c). *[The Astrophysical Journal Letters](/source/The_Astrophysical_Journal_Letters)*. **993**: L25. [arXiv](/source/ArXiv_(identifier)):[2507.08219](https://arxiv.org/abs/2507.08219). [doi](/source/Doi_(identifier)):[10.3847/2041-8213/ae0c9c](https://doi.org/10.3847%2F2041-8213%2Fae0c9c).

v t e 2023 in space « 2022 2024 » Space probe launches Jupiter Icy Moons Explorer (April 2023) Chandrayaan-3 (July 2023) Luna 25 (August 2023) XRISM (September 2023) SLIM (September 2023) Psyche (October 2023) Impact events 2023 CX1 Selected NEOs Asteroid close approaches 2023 AV 2023 BU (367789) 2011 AG5 2023 DW 2023 DZ2 2023 GQ2 (164121) 2003 YT1 (341843) 2008 EV5 2023 FW13 Discoveries F200DB-045 Rings of Quaoar WISE J0336−0143 CEERS 1019 black hole UHZ1 quasar Volcanism on Venus confirmation 3 moons of Jupiter (S/2022 J 1, S/2022 J 2, S/2022 J 3) 63 moons of Saturn SN 2023ixf supernova in Pinwheel Galaxy (M101) SN H0pe supernova in Constellation Ursa Major Phosphates on Enceladus Gravitational wave background detection Neutrino Milky Way map GRB 230307A Second-brightest gamma-ray burst 152830 Dinkinesh is a binary Ursa Major III GW231123 C/2023 A3 (Tsuchinshan–ATLAS) Exoplanets HD 110067 b c d e f g LHS 475 b TOI-672 b TOI-700 e TOI-1853 b TOI-3235 b WASP-193b Silicates in VHS J1256–1257 b No atmosphere in TRAPPIST-1b No atmosphere in TRAPPIST-1c K2-18b of methane and carbon dioxide Comets C/2022 E3 (ZTF) 96P/Machholz C/2022 A2 (PanSTARRS) C/2023 E1 (ATLAS) C/2021 T4 (Lemmon) C/2023 P1 (Nishimura) 103P/Hartley 2P/Encke C/2023 H2 (Lemmon) 62P/Tsuchinshan 12P/Pons–Brooks brightening multiple times Space exploration Lucy (Dinkinesh flyby; November 2023) OSIRIS-REx (sample return from asteroid Bennu; September 2023) First space-based solar power demonstration Euclid space telescope (launch; 1 July 2023) Outer space portal Category:2022 in outer space — Category:2023 in outer space — Category:2024 in outer space

v t e Black holes Outline Types BTZ black hole Schwarzschild Rotating Charged Virtual Kugelblitz Supermassive Primordial Direct collapse Rogue Malament–Hogarth spacetime Size Micro Extremal Electron Stellar Microquasar Intermediate-mass Supermassive Active galactic nucleus Quasar LQG Blazar BL Lac FSRQ Formation Stellar evolution Gravitational collapse Neutron star Related links Tolman–Oppenheimer–Volkoff limit Oppenheimer–Snyder model White dwarf Related links Supernova Micronova Hypernova Related links Gamma-ray burst Binary black hole Quark star Supermassive star Quasi-star Supermassive dark star X-ray binary Properties Astrophysical jet Gravitational singularity Ring singularity BKL singularity Shock singularity Theorems Event horizon Photon sphere Innermost stable circular orbit Ergosphere Penrose process Blandford–Znajek process Accretion disk Hawking radiation Gravitational lens Microlens Cauchy horizon Mass inflation Bondi accretion M–sigma relation Quasi-periodic oscillation Thermodynamics Bekenstein bound Bousso's holographic bound Immirzi parameter Schwarzschild radius Spaghettification Issues Information paradox Complementarity Soft hair Cosmic censorship ER = EPR Final parsec problem Firewall (physics) Holographic principle No-hair theorem Metrics Schwarzschild (Derivation) Kerr Reissner–Nordström Kerr–Newman Hayward Alternatives Nonsingular black hole models Black star Dark star Dark-energy star Gravastar Magnetospheric eternally collapsing object Planck star Q star Fuzzball Geon Analogs Optical black hole Sonic black hole Lists Black holes Most massive Nearest Quasars Microquasars Related Outline of black holes Black Hole Initiative Black hole starship Black holes in fiction Big Bang Big Bounce Compact star Exotic star Quark star Preon star Gravitational waves Gamma-ray burst progenitors Gravity well Hypercompact stellar system Membrane paradigm Naked singularity Population III star Supermassive star Quasi-star Supermassive dark star Rossi X-ray Timing Explorer Superluminal motion Timeline of black hole physics White hole Wormhole Tidal disruption event Notable 1ES 1927+654 3C 273 A0620-00 AT2018hyz Centaurus A Cygnus X-1 Gaia BH1 Hercules A Markarian 501 MS 0735.6+7421 NeVe 1 OJ 287 Phoenix Cluster PKS 1302-102 PSO J030947.49+271757.31 Q0906+6930 Sagittarius A* SDSS J0849+1114 Swift J1644+57 TON 618 ULAS J1342+0928 XTE J1118+480 XTE J1650-500 Category Commons

v t e Gravitational-wave astronomy Gravitational wave Gravitational-wave observatory Detectors Resonant mass antennas Active NAUTILUS (IGEC) AURIGA (IGEC) MiniGRAIL Mario Schenberg Past EXPLORER (IGEC) ALLEGRO (IGEC) NIOBE (IGEC) Stanford gravitational wave detector ALTAIR GEOGRAV AGATA Weber bar Proposed TOBA Past proposals GRAIL (downsized to MiniGRAIL) TIGA SFERA Graviton (downsized to Mario Schenberg) Ground-based interferometers Active AIGO (ACIGA) CLIO Fermilab Holometer GEO600 Advanced LIGO (LIGO Scientific Collaboration) KAGRA Advanced Virgo (European Gravitational Observatory) Past TAMA 300 TAMA 20, later known as LISM TENKO-100 Caltech 40m interferometer Planned INDIGO (LIGO-India) Proposed Cosmic Explorer Einstein Telescope Past proposals LIGO-Australia Space-based interferometers Planned LISA Proposed Big Bang Observer DECIGO TianQin Taiji Pulsar timing arrays EPTA IPTA NANOGrav PPTA Data analysis Einstein@Home PyCBC Zooniverse: Gravity Spy Observations Events List of observations First observation (GW150914) GW151226 GW170104 GW170608 GW170814 GW170817 (first neutron star merger) GW190412 GW190521 (first-ever possible light from bh–bh merger) GW190814 (first-ever "mass gap" collision) GW200105 (first black hole – neutron star merger) Methods Direct detection Laser interferometers Resonant mass detectors Proposed: Atom interferometers Indirect detection B-modes of CMB Pulsar timing array Binary pulsar Theory General relativity Tests of general relativity Metric theories Graviton Effects/properties Polarization Spin-flip Redshift Travel with speed of light h strain Chirp signal (chirp mass) Carried energy Gravitational wave background Types/sources Stochastic Cosmic inflation–quantum fluctuation Phase transition Binary inspiral Supermassive black holes Stellar black holes Neutron stars EMRI Continuous Rotating neutron star Burst Supernova or from unknown sources Hypothesis Colliding cosmic string and other unknown sources

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