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New 'Dark Dwarfs' Theory Proposes Substellar Objects Fueled by Dark Matter

Astrophysicists propose brown dwarfs in dark matter–rich regions may capture WIMPs to power them via annihilation, with lithium-7 retention serving as a unique observational signature.

image: ©Nick_Pandevonium | iStock
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This artist's conception illustrates the brown dwarf named 2MASSJ22282889-431026. NASA's Hubble and Spitzer space telescopes observed the object to learn more about its turbulent atmosphere. Brown dwarfs are more massive and hotter than planets but lack the mass required to become sizzling stars. Their atmospheres can be similar to the giant planet Jupiter's. Spitzer and Hubble simultaneously observed the object as it rotated every 1.4 hours. The results suggest wind-driven, planet-size clouds. Image credit:
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Overview

  • The peer-reviewed paper in the Journal of Cosmology and Astroparticle Physics formalizes dark dwarfs as low-mass bodies heated by self-annihilation of captured dark matter.
  • Dark dwarfs are predicted to have roughly 8% of the Sun’s mass—insufficient for hydrogen fusion but sustained by energy from WIMP annihilation.
  • Only massive, self-interacting candidates like WIMPs can supply the necessary heating, ruling out lighter particles such as axions and sterile neutrinos.
  • Lithium-7 retention in dark dwarfs offers a distinguishing spectral marker since ordinary stars deplete this isotope through fusion.
  • Researchers recommend leveraging JWST’s sensitivity to cold objects and conducting statistical surveys of substellar populations toward the galactic center to search for these signatures.