  In a recent paper [arXiv:2305.08922], it has been proposed that the endpoint
of the Kerr-AdS superradiant instability is a Grey Galaxy. The conjectured
solutions are supposed to be made up of a black hole with critical angular
velocity in the centre of AdS, surrounded by a large flat disk of thermal bulk
gas that revolves around the black hole. In the analysis of the proposed
solutions so far, gravitational effects due to the black hole on the thermal
gas have been neglected. A way to estimate these effects is via computing tidal
forces. With this motivation, we study tidal forces on objects moving in the
Kerr-AdS spacetime. To do so, we construct a parallel-transported orthonormal
frame along an arbitrary timelike or null geodesic. We then specialise to the
class of fast rotating geodesics lying in the equatorial plane, and estimate
tidal forces on the gas in the Grey Galaxies, modelling it as a collection of
particles moving on timelike geodesics. We show that the tidal forces are small
(and remain small even in the large mass limit), thereby providing additional
support to the idea that the gas is weakly interacting with the black hole.
