"Using dust to constrain dark matter models" - Ussing et al. (2024)

The nature of dark matter is an oustanding mystery - but broadly can be described as an enormous accumulation of particles that have little internal motion (so-called cold dark matter) or one with movement that can be relativistic (so-called hot dark matter) or somewhere in between known as warm dark matter. A sterile neutrino could be candidate warm dark matter particle for example, but more generally without knowing the particle itself can we measure that ‘temperature’ of the dark matter?

Well my student Adam Ussing did just that - by simulating the same galaxy with cold dark matter and then again with warm dark matter (which typically makes it hard for galaxies to collapse and form stars) but at the same time playing with the recipe of the ways star form to make a realistic, and similar, amount of stars. The really clever bit is that he then explored the simulated galaxies to see if there were observable consequences elsewhere - and found that the dust produced by the galaxies differed dramatically. Finding that a galaxy with the same amount of stars in a warm dark matter universe will be dustier than the cold dark matter case. There remains a lot of work to be undertaken (including just how statistically robust that signal is) but this is a unique and promosing probe into the nature of dark matter through the dust in our telescopes’ eyes..!