The Bullet Cluster, the result of a recent collision of two galaxy clusters, provides a challenge for modified gravity theories because its apparent center of mass is far displaced from the baryonic center of mass.
For lack of a better name, scientists call this mysterious force dark energy.
Additional data from other observing projects or direct-detection experiments would be required to validate the interpretation. In particular, it could be capable of interacting with neutrinos, the former front-runner for the HDM scenario.
This means it does not absorb, reflect or emit light, making it extremely hard to spot. Maybe there is something wrong with Einstein's theory of gravity and a new theory could include some kind of field that creates this cosmic acceleration.
Instead, they found the stars in both locations traveled at the same velocity, indicating the galaxies contained more mass than could be seen. These simulations considered how galaxy formation would be affected by the presence of both warm and Dark Matter from about 1 billion after the Big Bang to 14 billion years roughly the present.
Currently, the most widely accepted models of Dark Matter presume that it does not interact with any other kinds of matter or radiation including itself beyond the influence of gravity — i. What is significant here is that they obtained a result that deviated from the naive assumptions of simple gravity and visible matter only.
Baryonic matter could still make up the dark matter if it were all tied up in brown dwarfs or in small, dense chunks of heavy elements.