Dark matter on the move
https://phys.org/news/2019-01-dark.html
Dark matter is thought to make up most of the mass of the universe. However since it doesn't interact with light in the same way as normal matter, it can only be observed through its gravitational effects. The key to studying it may however lie in how stars are formed in these galaxies.
When stars form, strong winds can push gas and dust away from the heart of the galaxy. As a result, the galaxy's centre has less mass, which affects how much gravity is felt by the remaining dark matter. With less gravitational attraction, the dark matter gains energy and migrates away from the centre, an effect called 'dark matter heating'.
Peak your interest for answers to this dark matter conundrum by reviewing an alternative theory of the universe from a more 4th dimensional perspective. This concept was previously approached in the book, 'The Evolutioning of Creation: Volume 2', copyrighted in 2011. As the predominant condition of the universe is a combination of dark energy and dark matter (i.e., massless matter or negative mass density), then the existence of our universe [or positive mass density] is more of an intrusion upon this norm. Such is it that positive density mass (i.e., baryonic mass) provides for a displacement effect, which is expressed as if the positive mass has intruded upon the inertial condition of the space-time continuum.
You can peak your interest for answers to this mystery from the perspective of the science fiction novel, 'Shadow-Forge Revelations'. As science fiction imitates science theory, this novel discusses how dark energy and dark matter interplays with the concept of the expanding universe from the inception of its creation.