The nature of science is learning and revision. Our understanding of existence involves fine-tuning, sometimes completely restructuring our knowledge to comprise new discoveries. Physics, medicine, chemistry, all improve on themselves by revising older ideas, such as it is with dark matter and its place in the Universe.
Dark matter can’t be seen by the human eye, but for 40 years it has been established as the essential matter responsible for certain gravitational relationships in space, such as the movement of stars in galaxies.
New research in astrophysics shows how it might be possible for galaxies to exist without dark matter.
How could galaxies exist without dark matter?
A new study from the University of California Irvine has demonstrated that it is possible for galaxies to exist with significantly less dark matter. The notion first came about when a pair of astrophysicists from Princeton University and Yale University discovered in 2018 two galaxies that appeared to exist largely without dark matter.
The astrophysicists, Shany Danieli and Pieter van Dokkum, then joined up with a research team, including Jorge Moreno, professor of astronomy at Pomona College to test the newfound discovery and published their findings in Nature.
The team ran computer simulations of the evolution of a portion of the universe after the Big Bang and found that galaxies can exist with very little dark matter in certain circumstances. This happens when galaxies collide with each other, the much more massive galaxies shearing the smaller ones of most of their material, including dark matter.
Improving on dark matter framework
“You don’t have to get rid of the standard dark matter paradigm,” Moreno says.
This work doesn’t show that the theory around black matter is false. It simply shows that galaxies can exist with very little, having been stripped of their dark matter by much larger galaxies, something that Moreno and the team will start looking for in real space. They hope that their findings and simulations will encourage other astrophysicists to do the same and better our understanding of the Universe.