Constraining SIDM with halo shapes: Revisited predictions from realistic simulations of early-type galaxies

We study the effect of self-interacting dark matter (SIDM) and baryons on shape early-type galaxies (ETGs) their haloes, comparing them to predictions cold (CDM) scenario. use five hydrodynamical zoom-in simulations haloes hosting ETGs ($M_{\rm vir}\sim 10^{13}M_{\odot}$ $M_{*}\sim10^{11}M_{\odot}$), simulated in CDM a SIDM model with constant cross-section $\sigma_T/m_\chi = 1\ \mathrm{cm}^2 \mathrm{g}^{-1}$. measure three-dimensional projected shapes baryonic content using inertia tensor compare our measurements results three $HST$ samples gravitational lenses $Chandra$ $XMM-Newton$ X-ray observations. find that inclusion greatly reduces differences between SIDM, together ability draw constraints based shapes. Lensing reject dark-matter-only prefer one hydro scenarios. When we consider total sample lenses, observational data The emitting gas are compatible both runs, predicting higher elongations only very centre. Contrary previous claims at scale elliptical galaxies, conclude can still explain observed once include simulations. Our demonstrate this is essential derive realistic new needed confirm extend findings.