The Q-FFF Theory says: Dark matter nuclei (all black holes) have no mass (only Axion vacuum pressure gravity from outside.) in contrast with baryonic matter.
Even the Big Bang Black Hole singularity seems to have no mass, only decreasing Vacuum gravity pressure before exploding of the Axion string knot called singularity black hole.
The Dark Matter Tidal disruption of Galaxies and Dark Matter concentration between merger galaxies.The evidence to support the mechanism of tidal disruption as the explanation for the galaxy’s missing dark matter has not only supported to solve an astronomical conundrum. Scientists should still revise their standard model on dark matter and gravity. by introducing the Axion vacuum pressure gravity. (below)
This result is a good indicator that, while the dark matter of the galaxy was evaporated from the system, the stars are only now starting to suffer the disruption mechanism,” explained team member Ignacio Trujillo of the Instituto de Astrofysica de Canarias in Spain. “In time, NGC1052-DF4 will be cannibalised by the large system around NGC1035, with at least some of their stars floating free in deep space.”
see:
https://esahubble.org/news/heic2019/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+hubble_news+%28Hubble+News%29
Other examples are Galaxy cluster mergers. like: the bullet cluster 1E 0657-56.
Axion vacuum gravity: