Dark Matter: A Hidden Threat to Neutron Stars express
A neutron star is the compressed remnant of a sun: a mountain of matter the size of a thimble. If dark matter, the invisible substance that holds galaxies together, accumulates inside, under certain conditions it spells doom. In ordinary space, an incredible mass is needed, but hidden dimensions change the rules.
Gravity is curved spacetime, like a stretched trampoline. Dark matter particles, like tiny ball bearings, slightly dent it. Extra dimensions roll them into a leaden marble that tears the fabric — a black hole forms. Zwicky predicted neutron stars, Rubin proved the reality of dark matter; now their ideas converge in a terrifying scenario.
A twist: the miniature hole doesn't evaporate instantly — extra dimensions slow down the radiation. It devours the star whole, imposing strict limits on the properties of dark matter: particles heavier than tens of TeV are ruled out if the dimensions are real. In flat three-dimensional space, the threshold would be orders of magnitude higher — by millions.
Original abstract
as written by the authors arXiv:2512.14837
We investigate hydrostatic configurations of asymmetric dark matter (DM) spheres in scenarios where fermionic DM can propagate into extra spatial dimensions, while Standard Model fields remain confined to ordinary three dimensions. As the number of extra dimensions increases, the effective equation of state for non-relativistic matter softens, making even modest DM accumulation inside neutron stars susceptible to gravitational collapse into extra-dimensional black holes. These black holes are longer lived than their $$3$$ dimensional counterparts and can accrete enough material to consume an entire neutron star, ultimately producing solar-mass black holes. For geometric cross sections, DM with masses above $$\mathcal{O}(10\,{\rm TeV})$$ may already be excluded for more than two extra dimensions of size $${\mathcal{O}(\rm fm})$$ -- sharply contrasting with the standard $$3$$ dimensional case, where comparable limits only appear for masses $$\gtrsim 10^{5}$$ TeV at typical halo densities of $$0.3\, \rm{GeV/cm^3}$$.
Extra dimensions could be no larger than an atomic nucleus — about a femtometer, which is a billion times thinner than a hair.
Like in 'Interstellar,' where five-dimensional space helped survive a black hole — only here, hidden dimensions create that hole in the first place.