The onset of gravothermal core collapse in velocity-dependent self-interacting dark matter subhaloes

ABSTRACT It has been proposed that gravothermal collapse due to dark matter self-interactions (i.e. self-interacting matter, SIDM) can explain the observed diversity of Milky Way (MW) satellites’ central dynamical masses. We investigate process behind this hypothesis using an N-body simulation a MW-analogue halo with velocity-dependent SIDM (vdSIDM) in which low-velocity self-scattering cross-section, $\sigma _{\rm T}/m_{\rm x}$, reaches 100 cm2 g?1; we dub model vd100 model. compare results simulations same employ different models, including cold (CDM) and other, less extreme models. The masses haloes are very similar their CDM counterparts, but values maximum circular velocities, Vmax, significantly higher. determine these high Vmax subhaloes were objects mass range [5 × 106, 1 108] M? at z = undergo core collapse. These collapsed have density profiles described by single power laws down resolution limit simulation, inner slope profile is approximately ?3. Resolving ever decreasing region challenging, tailored will be required runaway instability accurately scales <1 kpc.