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arXiv · 2610.39692

Feeding or Fleeing: The Impact of Enhanced Early Black Hole Growth on Circumgalactic Clumps at $z > 6$

Floor van Donkelaar·Lucas Tortora·Debora Sijacki
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Abstract

The circumgalactic medium (CGM) of massive high-redshift galaxies contains inflowing filamentary gas, recycled material, and feedback-driven outflows. We investigate the formation and evolution of dense CGM clumps in two cosmological zoom-in simulations of the same massive halo at $z > 6$: the fiducial Fable model and the modified Fable-SE model, which includes enhanced early black hole growth through mild super-Eddington accretion. We identify dense gas clumps in the CGM and follow their gas properties, stellar content, and radial evolution across cosmic time. At the resolution probed here, the two simulations show broadly similar distributions of clump gas mass, gas size and associated stellar mass. Instead, the clump populations differ mainly in their abundance, metallicity, and radial evolution. Fable-SE produces substantially more metal-enriched clumps, including an outward-moving population during the strong AGN-driven blow-out phase at $z \lesssim 7$. These systems are associated with disturbed HI-rich gas and relatively high gas densities, linking the increased prevalence of dense, metal-enriched CGM structures in Fable-SE to its stronger AGN-driven blow-out phase. Although inward migration dominates overall, Fable-SE also contains an outward-moving clump population during the blow-out phase, with some clumps moving beyond the virial radius. Our results therefore indicate that the distribution of dense CGM clumps around massive high-redshift galaxies reflects both filamentary accretion and feedback-driven CGM evolution, with strong early AGN activity associated with the outward migration of dense, metal-enriched gas structures containing relatively cool gas.

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Floor van Donkelaar, Lucas Tortora, Debora Sijacki. 2026-10-29. Feeding or Fleeing: The Impact of Enhanced Early Black Hole Growth on Circumgalactic Clumps at $z > 6$. https://arxiv.org/abs/2610.39692

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