GRMHD models reveal scale-invariant SANE/MAD states linking stellar-mass X-ray binaries to M87* jets across eight mass decades

The arXiv:2607.06671 analysis integrates GRMHD runs spanning stellar-mass and supermassive regimes, demonstrating that MAD disks launch jets whose power scales linearly with black-hole mass once expressed in Eddington units. Polarization maps from the simulations predict EVPA swings of 30–50° across the jet sheath, independent of absolute mass. This directly extends the Blandford–Znajek mechanism validated at M87* by the EHT to microquasars whose jets remain unresolved today.

Existing SKA precursor observations of Cygnus X-1 already show fractional polarization consistent with the simulated MAD state, yet lack the 10-microarcsecond resolution needed to map toroidal versus poloidal dominance. The preprint correctly identifies this gap but understates the role of time-domain variability; multi-epoch EHT data on Sgr A* reveal flux eruptions on 30-minute timescales that match only MAD runs, supplying an orthogonal test the authors omit.

Next, SKA-VLBI at 5–15 GHz will resolve the jet-launching region in at least three persistent stellar-mass systems within two years, enabling direct comparison of observed rotation-measure gradients against the simulated MAD saturation threshold of φ/φcrit > 50. Non-detection of the predicted EVPA pattern at that sensitivity would falsify scale invariance at >3σ.