X-Ray Cavities Mismatch

Galaxy clusters with active radio-mode AGN feedback frequently display X-ray cavities — bubbles of radio-emitting plasma inflated by AGN jets that displace the hot ICM and appear as depressions in the X-ray surface brightness map. The mechanical power of the AGN feedback can be estimated from the cavity enthalpy (PV work done on the ICM per cavity) and compared to the ICM cooling luminosity to assess whether AGN feedback can balance radiative cooling in cool core clusters. While the average enthalpy often approximately balances the cooling luminosity, the detailed spatial and temporal matching between cavity positions, ICM cooling rates, and feedback duty cycles is often poor: some clusters show cavities with enthalpies that greatly exceed the cooling luminosity while others have cooling luminosities that vastly exceed cavity enthalpies, and the cavity sizes and positions do not always align with the ICM cooling region geometry.

Successive Collision Theory explains the mismatches between X-ray cavity enthalpies and ICM cooling luminosities through the angular momentum inheritance mechanism applied to AGN jet directions and ICM flow patterns. In SCT, the jet axis of the central AGN is set by the SMBH spin, which itself is inherited from the collision debris angular momentum. The ICM flow patterns within the cluster are organized by the same angular momentum field, creating preferred circulation directions for hot gas. When the jet axis is aligned with the ICM circulation — as it frequently is in SCT because both trace the same inherited angular momentum — the jet-inflated cavities are efficiently swept into the ICM circulation pattern and their enthalpy is distributed over a larger volume of gas than the immediate cooling region. This spatial mismatch between where energy is deposited (along the jet axis) and where cooling occurs (in the core) produces the observed discrepancy between cavity enthalpies and local cooling luminosities.

The tensor mesh dissipation mechanism introduces a secular evolution of the ICM thermodynamic state that is not captured in standard steady-state feedback models. As the frame hierarchy dissipates over Gyr timescales, the effective gravitational depth of the cluster slowly decreases, reducing the confinement pressure on the central cool core. This secular reduction in confinement means that cool cores that were stable in earlier epochs gradually become marginally unstable at late times, with cooling slightly exceeding the feedback compensation in some phases and slightly undercompensating in others. The resulting quasi-periodic mismatch between cooling luminosity and cavity enthalpy — driven by the slow evolution of the frame hierarchy — produces the observed diversity in cooling-to-feedback ratios across cluster samples without requiring fine-tuned AGN feedback prescriptions for each individual cluster.