The fifth image uncovers the nature of dark matter.

"A mysterious fifth image inside a rare Einstein Cross exposed a massive halo of dark matter, giving astronomers a rare chance to study both the distant galaxy and the invisible structures shaping the cosmos. (Artist’s concept.) Credit: SciTechDaily.com" (ScitechDaily, Astronomers Spot “Impossible” Fifth Image Unlocking Dark Matter Secrets)

Einstein’s cross is the gravitational effect where gravity bends light; its image is multiplied to appear as if it were four galaxies. The fifth image in Einstein’s cross was caused by an invisible massive object. That massive object could be a massive dark matter cloud. This effect tells us about the nature of dark matter. We know that only confirmed interaction between dark and visible matter is gravitational. Dark matter can also form things like black holes. The black hole that dark matter’s mutual gravity effect forms could exist in intergalactic space. This kind of black hole could get its energy from dark matter. 

And the gravitational microlensing can uncover this kind of black hole. The black hole pulls so small an amount of visible matter that this black hole cannot form a bright halo that could be seen from Earth. Dark matter can form a wave movement, where the wavelength is the same as the diameter of a hypothetical weakly interacting massive particle, WIMPs. That means that those WIMPs could be a source of dark energy when a black hole pulls those particles. That thing makes those particles impact and press energy into them. Black holes pull energy inside them. 

"A rare cosmic configuration: An Einstein Cross with five points of light, instead of the usual four, has been discovered by scientists. Credit: P. Cox et al. – ALMA (ESO/NAOJ/NRAO)" (ScitechDaily, Astronomers Spot “Impossible” Fifth Image Unlocking Dark Matter Secrets)

And this means. Black holes can also pull dark energy into them. If dark energy interacts with dark matter particles near black holes, that energy causes them to glow. And maybe, that glow is at least one part of the dark energy. We know that dark matter is not homogeneously spread across the universe. Gravitational centers pull dark matter around them. And that means galaxies, and especially black holes and neutron stars, are pulling dark matter halos around them. Those effects are micro-level phenomena. If we compare them with galaxy-size effects. 

Almost all galaxies are surrounded by dark matter halos, but there are exceptions. And that means dark matter can form similar structures with visible material. In galaxies, dark matter has a gravitational effect. Allows galaxies to rotate faster than they would without dark matter’s effect. Without dark matter, the centripetal force breaks the galactic structures. So, a galaxy that has no dark matter should spin more slowly. The dark matter halo outside the galaxy pulls material out, and the supermassive black hole with the object’s mutual gravity keeps galaxies in their form. 

https://scitechdaily.com/astronomers-spot-impossible-fifth-image-unlocking-dark-matter-secrets/