We use high resolution Hydro + N-Body cosmological simulations to compare the assembly and evolution of a small field dwarf ( stellar mass \sim 10 ^ { 6 - 7 } M _ { \sun } , total mass 10 ^ { 10 } M _ { \sun } ) in \Lambda dominated CDM and 2keV WDM cosmologies .
We find that star formation ( SF ) in the WDM model is reduced and delayed by 1-2 Gyr relative to the CDM model , independently of the details of SF and feedback .
Independent of the DM model , but proportionally to the SF efficiency , gas outflows lower the central mass density through ‘ dynamical heating ’ , such that all realizations have circular velocities < 20 km s ^ { -1 } at 500 pc , in agreement with local kinematic constraints .
As a result of dynamical heating , older stars are less centrally concentrated than younger stars , similar to stellar population gradients observed in nearby dwarf galaxies .
Introducing an important diagnostic of SF and feedback models , we translate our simulations into artificial color-magnitude diagrams and star formation histories in order to directly compare to available observations .
The simulated galaxies formed most of their stars in many \sim 10 Myr long bursts .
The CDM galaxy has a global SFH , HI abundance and Fe/H and alpha-elements distribution well matched to current observations of dwarf galaxies .
These results highlight the importance of directly including ‘ baryon physics ’ in simulations when 1 ) comparing predictions of galaxy formation models with the kinematics and number density of local dwarf galaxies and 2 ) differentiating between CDM and non-standard models with different DM or power spectra .