What is meant by the "mini disk" of a blackhole? Is it the same as accretion disk? If not, whats the difference?
Eg: In the abstract of this paper https://arxiv.org/abs/1806.05697 it is mentioned "When the accretion rate is relatively high, the circumbinary disk, accretion streams, and mini-disks combine to emit light in the UV/EUV bands"
This paper, Quasi-Periodic Behavior of Mini-Disks in Binary Black Holes Approaching Merger, which shares authors with the paper linked in the question, sheds some light on the terminology.
We present the first magnetohydrodynamic simulation in which a circumbinary disk around a relativistic binary black hole feeds mass to individual accretion disks ("mini-disks") around each black hole.
They are talking about active binary black hole systems. The system as a whole has an accretion disk, the circumbinary disk, and each black hole has its own accretion disk, which they call the mini-disk.
