18-Month Decision Tree

Before following any branch, orient yourself. The Falsification & Observational Roadmap tabulates every active observation that can confirm or rule out the IMBH, MTH, and Fermi claims made by this site. The IMBH section lists each experiment, its predicted outcome under each hypothesis, and its current observational status. The four tools that follow correspond to four rows in that table. Astrometric microlensing (step 2) and LISA (step 5) are the only ones flagged as sensitive to the compactness of the central mass — not merely its enclosed value. That distinction is what makes lensing the primary branch point.

A point-mass lens of mass M produces a centroid shift Θ_c ≈ √M that peaks at the Einstein radius. For an 8,200 M⊙ point lens at 5.43 kpc, Θ_c reaches hundreds of μas — well above Gaia DR4’s ≈ 30 μas precision floor for bright bulge sources. For a 10 M⊙ stellar remnant in a Bañares dark cluster, Θ_c ≈ 0.4 μas — far below any threshold this decade. This is the decisive difference between a point mass and a distributed cluster: gravitational lensing is sensitive to compactness, not just enclosed mass. Gaia DR4 (scheduled late 2026) and the Roman Space Telescope (2027, ≈ 10 μas) both probe this signal.

Bondi-Hoyle accretion onto an 8,200 M⊙ IMBH in ω Cen’s low-density core gives a bolometric luminosity L = ε × ˙m × c² that depends on the local gas density and the radiative efficiency. For ADAF-mode accretion (ε = 10⁻³) and ambient density ρ ≈ 10⁻²¹ kg m⁻³, the predicted near-infrared flux at 5.43 kpc falls inside JWST NIRCam’s detection envelope. A null result does not rule out an IMBH — it only constrains the product ε × ρ to below the Bondi floor, consistent with a quiescent IMBH in a gas-poor environment. A positive detection would be the first independent, non-kinematic signature of the IMBH.

Every pulsar timed in ω Cen provides a line-of-sight gravitational acceleration a_z from its spin-down rate. The enclosed-mass sensitivity is M_min ≈ r² × a_z / G: a pulsar at smaller projected separation r gives a tighter bound. At 10″ offset with 1 μs timing precision on a 10-year baseline, MeerKAT reaches ≈ 10³ M⊙ sensitivity — probing the full range of IMBH candidates. A fourth pulsar detected inside 5″ by TRAPUM would immediately halve the projected separation and double the constraint. Each new TRAPUM pulsar is a decision-relevant observation in its own right. Timing is not binary, but it is cumulative: the bound sharpens as √t.

If an IMBH exists and a stellar-mass compact object is spiralling inward, LISA will detect the characteristic-strain chirp as the orbital frequency sweeps through LISA’s mHz band over a 4-year observation. For M_BH = 8,200 M⊙ at 5.43 kpc, the integrated SNR exceeds 50; the IMBH mass and companion mass are recovered to a few percent. No other planned experiment can measure the IMBH mass directly and dynamically — LISA turns a “likely IMBH” into a measured, characterised IMBH. For the Bañares scenario, this step probes the 6,000 M⊙ upper-limit case: if any point mass at the Bañares boundary persists, LISA reaches it. For the threshold scenario, M_BH = 4,000 M⊙ yields SNR ≈ 0.70 × the Häberle value — a comfortable detection. Only a fully null Gaia DR4 + null LISA result would jointly close the IMBH window to below ≈ 100 M⊙.