paper

Dark-Matter-Deficient Galaxies from Collisions: A New Probe of Bursty Feedback and Dark Matter Physics

arXiv:2509.24270 · doi:10.3847/2041-8213/ae375a

Abstract

High-velocity collisions between gas-rich ultra-diffuse galaxies present a promising formation channel for dark-matter-deficient galaxies (DMDGs). Using hydrodynamical simulations, we show that the progenitors' baryonic binding energy, , critically controls the outcome. Repeated potential fluctuations, e.g., from bursty feedback, inject energy and reduce by , yielding fewer but substantially more massive DMDGs. By contrast, elastic self-interacting dark matter (SIDM) produces comparable cores without lowering , perturbing DMDG masses without clear enhancement. This differs from what happens in host halos, where SIDM-induced cores enhance dark matter tidal stripping while keeping baryons compact and resilient to tidal effects. The contrasting roles of SIDM may provide a means to distinguish feedback-formed halo cores from those created by SIDM. Among 15 paired simulation runs, 13 show higher DMDG masses in the weakened-binding case, and about two thirds exhibit mass enhancements. The simulations also predict systematically lower gas fractions due to sustained post-collision star formation, yielding a clean observational signature. Upcoming wide-field imaging (CSST, LSST), HI surveys (FAST), and kinematic follow-up will be crucial to test this scenario.

arXiv comment16 pages, 11 figures. Extended for distinguishing cores from SIDM vs. stellar feedback. Matches the accepted version by ApJL

References in corpus (54)