Science and Technology Facilities Council
Printable version

Interactive dark matter could explain Milky Way’s missing satellite galaxies

Scientists believe they have found a way to explain why there are not as many galaxies orbiting the Milky Way as expected. 

Computer simulations of the formation of our galaxy suggest that there should be many more, smaller galaxies around the Milky Way than are observed through telescopes.

This has thrown doubt on the generally accepted theory of cold dark matter, a substance that scientists predict should allow for more galaxy formation around the Milky Way than is seen.

The research, supported by STFC and led by scientists from Durham University, alongside researchers from LAPTh College & University in France, suggests a potential solution to the problem. The results have been published in the journal Monthly Notices of the Royal Astronomical Society (MNRAS).

The paper proposes that dark matter particles, as well as feeling the force of gravity, could have interacted with photons and neutrinos in the young Universe, causing the dark matter to scatter. This scattering wipes out the structures that can trap gas, stopping more galaxies from forming around the Milky Way and reducing the number that should exist.

Lead author Dr Celine Boehm, in the Institute for Particle Physics Phenomenology, at, Durham University, said: “We don’t know how strong these interactions should be, so this is where our simulations come in. By tuning the strength of the scattering of particles, we change the number of small galaxies, which lets us learn more about the physics of dark matter and how it might interact with other particles in the Universe.

The computer simulations and calculations were carried out using the COSMA supercomputer at Durham University, which is part of the UK-wide DiRAC (link to DiRAC website) super-computing framework, and was also part-funded by STFC.

The researchers say their current findings could provide a new technique to study interactions between other particles and cold dark matter.

Read the full Durham University press release.

ENDS

Subscribers can view the paper at the Oxford Journals.

A pdf copy of this paper and images are available from Durham University Media Relations Team on +44 (0)191 334 6075; email Media Relations.

Images available:

Simulated_DM_haloes.jpg: The simulated distribution of DM in a Milky Way-like galaxies for standard, non-interacting dark matter (top left), warm dark matter (top right) and the new dark matter model that interacts with the photon background (bottom). Smaller structures are erased up to the point where, in the most extreme model (bottom right), the galaxy is completely sterilized (credit Durham University).

Simulated_DM_haloes_2_nolables.jpg: Two models of the dark matter distribution in the halo of a galaxy like the Milky Way, separated by the white line. The colours represent the density of dark matter, with red indicating high-density and blue indicating low-density. Left: Non-interacting cold dark matter produces an abundance of smaller satellite galaxies. Right: Interactions of dark matter with other particles reduces the number of satellite galaxies we expect to observe around the Milky Way (credit Durham University)

Channel website: http://www.stfc.ac.uk/

Share this article

Latest News from
Science and Technology Facilities Council

Facing the Future...find out more