To make their discovery, researchers combined different tracers of the centripetal acceleration found in different types of galaxies, from which they made 1-to-1 comparisons.

If you want to really understand why circular motion is a type of acceleration, you need to start with the definition of acceleration. Here the Δ means "change in".

The type of acceleration profiles generated in the study were analogous to those found in flow over airfoils and in converging /diverging nozzles.