Machine Learning Confirms GW231123 is a “Lite” Intermediate Mass Black Hole Merger

Abstract The LIGO–Virgo–KAGRA Collaboration recently reported GW231123, a black hole merger with total mass of around 190–265 M ⊙ . This event adds to the growing evidence of “lite” intermediate mass black hole (IMBH) discoveries of postmerger black holes ≳100 M ⊙ . GW231123 posed several data analysis challenges owing to waveform-model systematics and the presence of noise artifacts called glitches. We present the first comprehensive machine learning analysis to further validate this event, strengthen its astrophysical inference, and characterize instrumental noise in its vicinity. Our approach uses a combination of tools tailored for specific analyses: GW-W hisper , an adaptation of OpenAI’s audio transformer; A rch GEM, a Gaussian mixture model–based soft clustering and density approximation software; and AWaRe , a convolutional autoencoder. We identify the data segment containing the merger with >70% confidence in both detectors and verify its astrophysical origin. We then characterize the scattered light glitch around the event, providing the first physically interpretable parameters for the glitch. We also reconstruct the real waveforms from the data with slightly better agreement to model-agnostic reconstructions than to quasi-circular models, hinting at possible astrophysics beyond current waveform families (such as noncircular orbits or environmental imprints). Finally, by demonstrating high-fidelity waveform reconstructions for simulated mergers with total masses between 100 and 1000 M ⊙ , we show that our method can confidently probe the IMBH regime. Our integrated framework offers a powerful complementary tool to traditional pipelines for rapid, robust analysis of massive, glitch-contaminated events.