Astronomers predict an unseen class of star-like our bodies referred to as “dark dwarfs” close to our galaxy’s middle. A brand new examine suggests these objects might shine because of annihilating darkish matter, not nuclear fusion. Dark matter makes up a couple of quarter of the universe and interacts by way of gravity. If WIMP-like darkish matter particles accumulate in a brown dwarf, they’d annihilate and warmth it, inflicting a faint glow. Dark dwarfs can be too gentle to fuse hydrogen, however would preserve lithium-7 of their atmospheres, providing a signature. This prediction comes from a JCAP examine. The discovery of 1 might reveal darkish matter’s nature.
Predicted Dark Dwarf Properties
According to the paper, sub-stellar objects slightly below the hydrogen-burning threshold can be powered by darkish matter. The authors discover that the minimal mass for hydrogen fusion shifts above ∼0.075 M⊙ in dense dark-matter environments, so lighter brown dwarfs as a substitute develop into steady dark-matter–powered stars (‘darkish dwarfs’) by way of WIMP annihilation inside them. They predict such objects solely seem in areas with extraordinarily excessive dark-matter density, just like the Galactic middle (ρ_DM ≳ 10^3 GeV/cm^3), as a result of additional out the halo is just too tenuous. Crucially, darkish dwarfs ought to retain lithium-7 in mass ranges the place atypical brown dwarfs burn it away, offering a transparent observational signature.
Observational Prospects and Implications
Sakstein notes that highly effective telescopes just like the James Webb Space Telescope would possibly even already detect extraordinarily chilly objects like darkish dwarfs close to the galactic middle. Alternatively, astronomers might survey brown dwarf populations for a uncommon sub-class with anomalous lithium content material. Notably, even one confirmed darkish dwarf would strongly favor heavy, self-annihilating darkish matter.
Sakstein explains that discovering darkish dwarfs would supply “compelling evidence” for darkish matter that’s large and interacts with itself – basically WIMPs or comparable particles. He notes that lighter candidates (like axions) wouldn’t produce such stars, so a darkish dwarf discovery would disfavor these fashions. While not a proof of WIMPs, a darkish dwarf detection would indicate darkish matter behaves like WIMPs (heavy and weakly interacting). Indeed, future surveys and JWST observations will even check these predictions.
