Astronomers predict an unseen class of star-like our bodies known as “darkish dwarfs” close to our galaxy’s heart. A brand new examine suggests these objects may shine because of annihilating darkish matter, not nuclear fusion. Darkish matter makes up a few quarter of the universe and interacts by way of gravity. If WIMP-like darkish matter particles gather in a brown dwarf, they’d annihilate and warmth it, inflicting a faint glow. Darkish 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 invention of 1 may reveal darkish matter’s nature.

Predicted Darkish Dwarf Properties

According to the paper, sub-stellar objects slightly below the hydrogen-burning threshold can be powered by dark 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 an alternative develop into secure 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 heart (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 strange 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 may even already detect extraordinarily chilly objects like darkish dwarfs close to the galactic heart. Alternatively, astronomers may 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 proof” for darkish matter that’s huge and interacts with itself – basically WIMPs or related particles. He notes that lighter candidates (like axions) wouldn’t produce such stars, so a darkish dwarf discovery would disfavor these fashions. Whereas not a proof of WIMPs, a darkish dwarf detection would suggest darkish matter behaves like WIMPs (heavy and weakly interacting). Certainly, future surveys and JWST observations may also check these predictions.