Can galaxies stop dark matter from collapsing into itself?

Dark matter with self-interactions can undergo "gravothermal collapse"—a runaway densification at the halo center. Using simulations, the authors tested whether galaxy feedback (supernovae, black hole jets) can stop this process. For dense halos, collapse merely pauses during feedback but resumes afterward; less dense ones show more variation. This robustness supports recent claims that ultra-compact features seen in gravitational lensing are genuine collapsed dark matter structures.