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Title: Is jet power set by black hole spin via Blandford-Znajek?
Plain: Theory predicts that magnetic fields threading a spinning black hole extract its rotational energy into jets, so faster-spinning holes should have stronger jets.
Precise: Test the Blandford-Znajek scaling $P_{\mathrm{jet}} = (\kappa/(4 \pi c)) \Phi_{\mathrm{BH}}^2 \Omega_H^2$ (Gaussian units; $\Phi_{\mathrm{BH}}$ the magnetic flux through the horizon, $\Omega_H$ the horizon angular frequency, $\kappa \sim 0.05$) against measured spins and jet powers in X-ray binaries and AGN. Answer: a demonstrated correlation, or its absence, of jet power with spin at fixed flux and accretion rate, using spins from independent methods.
Settled by: A sample of black holes with spins measured by two independent methods and jet powers from calorimetry, showing or excluding the predicted $\Omega_{\mathrm{H}}^2$ dependence.
Kind: well-posed
Answer type: yes-no
References: (empty)
Literature status: contested
Status note: Proposed spin-jet power correlations in X-ray binaries (2012) were disputed; Event Horizon Telescope polarimetric images of M87* (2021) favor magnetically arrested accretion consistent with spin-powered jets but do not measure spin.
Posed since: 1977