Every published IMBH mass estimate for Omega Centauri, plotted chronologically. Each marker is a paper; the y-axis is mass on a log scale.
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Read the description instead →Plots every published IMBH mass measurement for Omega Centauri on a single time-vs-mass chart, so the full evolution of the question is visible at once. Companion to the IMBH Constraint Stacker — that tool answers "what masses are still allowed?"; this one answers "how did we get here?"
Each marker is one published measurement. The x-axis is publication year; the y-axis is mass in solar masses on a log scale. Detections appear as filled circles with vertical error bars. Upper limits are downward-pointing triangles whose horizontal bar marks the limit value (the true mass could be anywhere below). Lower bounds are upward-pointing triangles. "No evidence" results are open diamonds — these are epistemically distinct from upper limits and are not assigned a numeric value.
The story is non-monotonic. Noyola 2008's positive detection at ~4×10⁴ M☉ was challenged by van der Marel & Anderson 2010 with a 3σ upper limit a factor of ~3 lower. Baumgardt 2017 found N-body fits without an IMBH performed as well as those with one. Häberle 2024 reopened the question with a firm proper-motion lower bound at 8,200 M☉. Bañares 2025 then placed an upper limit (6,000 M☉ at 3σ) that lies below Häberle's lower bound — the field is in active tension.
⚠ Observationally debated. The plot itself is just an inventory of published claims; the meta-question of which analyses to trust is unresolved.
All values from tools/data/measurements.js (CC0). Original papers:
From the 2008 Noyola detection to the 2026 TRAPUM upper limit, the OC IMBH question has produced ~15 peer-reviewed studies. The story is non-monotonic: every detection has triggered a contesting upper limit within 2–3 years, and every upper limit has been revisited as new data arrives. The 2024 Häberle proper-motion lower bound was the first detection in over a decade to use a fundamentally different technique (multi-epoch HST astrometry of fast stars), which is why it carries methodological weight even as Bañares 2025 disputes it.
The timeline implicitly tracks the OC observational toolkit: Gemini/GMOS integral-field spectroscopy (2008), HST proper motions (2010, 2024 with extended baseline), N-body modelling on Cray-era supercomputers (2017), MeerKAT pulsar timing (2023+), JWST NIRCam+MIRI photometry (2025). Each new instrument tightens previously-soft constraints and resurfaces old questions: HST's 35-year baseline now permits sub-mas/yr proper motions, MeerKAT detects pulsars 100× fainter than Parkes, and JWST resolves stellar populations a magnitude deeper than HST in the relevant bands.
The Baumgardt 2017 and oMEGACat-VI 2025 markers appear as open diamonds because N-body modelling and bulk-kinematic catalogs don't yield a single numerical limit — they assess whether the data are consistent with an IMBH at any specific mass, which is a different epistemic statement than "M_BH < X at 3σ." Treating "no evidence" as equivalent to a tight upper limit overcounts the constraint; treating it as nothing undercounts it. The Constraint Stacker is the right tool for the synthesis question; this Timeline is the right tool for the chronological-methodology question.
IMBH constraint stacker — same measurements viewed as overlapping constraints on a mass axis rather than chronologically. Cluster comparator — IMBH estimates across multiple globular clusters with the same conventions used here. JWST accretion limit — the parametric curve underlying the 2025 Chen entry. Pulsar timing — what the Bañares 2025 and TRAPUM 2026 entries on the timeline are actually measuring. LISA EMRI/IMRI — the future addition to this timeline if/when LISA catches a dynamical signal from OC. CMD explorer — multi-population context that affects every entry's underlying kinematic centre. Falsification & observational roadmap — what observation would push each entry on this timeline next.