Fermionic Halos at Finite Temperature in AdS/CFT

TL;DR

This paper investigates the structure and stability of fermionic matter configurations at finite temperature in AdS space, revealing a core-halo density profile and analyzing conditions leading to gravitational collapse, with implications for dual CFTs.

Contribution

It introduces a novel 'dense core-diluted halo' structure for fermionic matter in AdS and studies the critical conditions for black hole formation, connecting bulk configurations to boundary CFT effects.

Findings

Discovery of a core-halo density profile in AdS fermionic matter.

Identification of critical temperatures for gravitational collapse.

Construction of holographic correlators to probe boundary CFT effects.

Abstract

We explore the gravitational backreaction of a system consisting in a very large number of elementary fermions at finite temperature, in asymptotically AdS space. We work in the hydrodynamic approximation, and solve the Tolman-Oppenheimer-Volkoff equations with a perfect fluid whose equation of state takes into account both the relativistic effects of the fermionic constituents, as well as its finite temperature effects. We find a novel 'dense core-diluted halo' structure for the density profiles in the AdS bulk, similarly as recently reported in flat space, for the case of astrophysical dark matter halos in galaxies. We further study the critical equilibrium configurations above which the core undergoes gravitational collapse towards a massive black hole, and calculate the corresponding critical central temperatures, for two qualitatively different central regimes of the fermions: the diluted-Fermi case, and the degenerate case. As a probe for the dual CFT, we construct the holographic two-point correlator of a scalar operator with large conformal dimension in the worldline limit, and briefly discuss on the boundary CFT effects at the critical points.