The existence of a new “fifth force” explains the standard model of cosmology, through a model also known as the Lambda cold dark matter (ΛCDM).
The fifth force, mediated by a hypothetical new particle called a symmetron, could guide small “satellite” galaxies into strange orbits around larger galaxies that defy the predictions of the ΛCDM model. In other words, small galaxies captured by the gravitational pull of larger galaxies end up arranged in thin flat planes, or disks, almost like the rings of Saturn, whereas the model suggests they should be distributed in messy orbits all-around their host galaxies. Satellites in these synced-up orbits have been seen around our galaxy, the Milky Way, as well as its closest galactic neighbors, Andromeda and Centaurus A.
Aneesh Naik, a research fellow at the University of Nottingham who led the study, said the novel solution emerged from discussions with his colleagues who study particle physics, including co-author and University of Nottingham physicist Clare Burrage, along with his expertise as an astrophysicist.
Theories suggest that symmetrons have undergone what’s known as symmetry-breaking mechanisms several times throughout the universe’s 13.8-billion-year lifespan.
Naik said that it’s “an open question” whether the hypothetical domain walls would even be stable enough to pass through hulking structures such as the Milky Way or Andromeda galaxies, which is yet another enigma that will have to be addressed in future studies.