We present a suite of FIRE -2 cosmological zoom-in simulations of isolated field dwarf galaxies , all with masses of M _ { halo } \approx 10 ^ { 10 } { M } _ { \odot } at z = 0 , across a range of dark matter models .
For the first time , we compare how both self-interacting dark matter ( SIDM ) and/or warm dark matter ( WDM ) models affect the assembly histories as well as the central density structure in fully hydrodynamical simulations of dwarfs .
Dwarfs with smaller stellar half-mass radii ( \mathrm { r _ { 1 / 2 } } < 500 pc ) have lower \sigma _ { \star } / V _ { max } ratios , reinforcing the idea that smaller dwarfs may reside in halos that are more massive than is naively expected .
The majority of dwarfs simulated with self-interactions actually experience contraction of their inner density profiles with the addition of baryons relative to the cores produced in dark-matter-only runs , though the simulated dwarfs are always less centrally dense than in \Lambda CDM .
The \mathrm { V _ { 1 / 2 } } - \mathrm { r _ { 1 / 2 } } relation across all simulations is generally consistent with observations of Local Field dwarfs , though compact objects such as Tucana provide a unique challenge .
Overall , the inclusion of baryons substantially reduces any distinct signatures of dark matter physics in the observable properties of dwarf galaxies .
Spatially-resolved rotation curves in the central regions ( < 400 pc ) of small dwarfs could provide a way to distinguish between CDM , WDM , and SIDM , however : at the masses probed in this simulation suite , cored density profiles in dwarfs with small \mathrm { r _ { 1 / 2 } } values can only originate from dark matter self-interactions .