Dark matter can't co-exist with ordinary matter. If it did, Earth would have 6-times the mass that we have estimated. Same goes with the Sun, whose mass is known. Also the Sun represents 99 percent of the mass of the solar system, so there is no dark matter in our solar system. So it must exist outside of solar systems where it is cold, or not exist at all.

That is, unless dark matter does co-exist with ordinary matter. That would mean gravity has 6-times less force per particle as we think. Perhaps in these galaxies in which dark matter has been ripped apart from normal matter, matter there exists a state of hypogravity, like having same gravity as the surface of the moon, but on a planet with the mass of Earth. That would be wierd. Imagine the consequences!