Analysis of star formation in galaxy-like objects

Using cosmological hydrodynamical simulations, we investigate the effects of hierarchical aggregation on the triggering of star formation in galactic-like objects. We include a simple star formation model to transform the cold gas in dense regions into stars. Simulations with different parameters have been performed in order to quantify the dependence of the results on the parameters. We then resort to stellar population synthesis models to trace the color evolution of each object with redshift and in relation to their merger histories. We find that, in a hierarchical clustering scenario, the process of assembling of the structure is one natural mechanism that may trigger star formation. The resulting star formation rate history for each individual galactic object is composed of a continuous one (less than or equal to 3 M-circle dot yr(-1)) and a series of starbursts. We find that even the accretion of a small satellite can be correlated with a stellar burst. Massive mergers are found to be more efficient at transforming gas into stars.