LIGO
@LIGO@scicomm.xyz
The LIGO Virgo KAGRA study of #GW231123 was posted to the arXiv today, and is free to read
https://arxiv.org/abs/2507.08219
Data are available from the GW Open Science Center
https://gwosc.org/eventapi/html/O4_Discovery_Papers/GW231123_135430/v1/
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arXiv preprint GW231123: a Binary Black Hole Merger with Total Mass 190-265 M⊙ On 2023 November 23 the two LIGO observatories both detected GW231123, a gravitational-wave signal consistent with the merger of two black holes with masses 137+22−17M⊙ and 103+20−52M⊙ (90\% credible intervals), at luminosity distance 0.7-4.1 Gpc and redshift of 0.39+0.27−0.24, and a network signal-to-noise ratio of ∼22.5. Both black holes exhibit high spins, 0.9+0.10−0.19 and 0.80+0.20−0.51 respectively. A massive black hole remnant is supported by an independent ringdown analysis. Some properties of GW231123 are subject to large systematic uncertainties, as indicated by differences in inferred parameters between signal models. The primary black hole lies within or above the theorized mass gap where black holes between 60-130 M⊙ should be rare due to pair instability mechanisms, while the secondary spans the gap. The observation of GW231123 therefore suggests the formation of black holes from channels beyond standard stellar collapse, and that intermediate-mass black holes of mass ∼200 M⊙ form through gravitational-wave driven mergers.
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Figure 7 of the paper showing the inferred masses. The masses are measured to be high, but the exact values depend significantly depending on the waveform model used. These are the most significant systematic uncertainties we have seen so far. New detections are pushing the boundaries of our calculations.
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Figure 8 of the paper showing the inferred spins. Results again vary between waveform models, but they consistently show high spin magnitudes with some support for misalignment relative to the orbit of the binaries.
Boosts are appreciated.
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