What fraction of black hole energy couples to galactic gas?
In plain words
Simulations assume that a few percent of the energy released by a growing black hole heats or pushes the surrounding gas. Whether real outflows carry this much energy has not been measured reliably.
Precise statement
Measure the coupling efficiency epsilon_f = dE_kin,outflow/dt divided by the AGN bolometric luminosity $L_{\mathrm{bol}}$, summed over ionized, neutral and molecular outflow phases, as a function of $L_{\mathrm{bol}}$ and Eddington ratio, and compare with the values $\sim 0.05-0.15$ used in cosmological simulations. The answer is the measured distribution of $\epsilon_f$ with its dependence on $L_{\mathrm{bol}}$.
What would settle it
Spatially resolved multiphase outflow measurements (JWST integral-field spectroscopy, ALMA, X-ray absorption) for a luminosity-complete AGN sample.
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