Ellipticals at $z=0$ from Self-Consistent Hydrodynamical Simulations: Comparison with SDSS Structural and Kinematical Data

摘要

We present results of an analysis of the structural and kinematicalproperties of a sample of elliptical-like objects (ELOs) identified in fourhydrodynamical, self-consistent simulations run with the DEVA code (Serna etal. 2003). Star formation has been implemented in the code through a simplephenomenological parameterization, that takes into account stellar physicsprocesses only implicitly through the values of a threshold gas density,$\rho_{\rm g,thres}$, and an efficiency parameter, $c_*$. The four simulationsoperate in the context of a $\Lambda$CDM cosmological model consistent withobservations, resolve ELO mass assembly at scales up to $\simeq$ 2 kpc, anddiffer in the values of their star formation parameters. Stellar masses,projected half-mass radii and central l.o.s. velocity dispersions, $\sigma_{\rmlos, 0}$, have been measured on the ELO sample and their values compared withdata from the Sloan digital sky survey. For the first time in self-consistentsimulations, a good degree of agreement has been shown, including theFaber-Jackson and the $D_n - \sigma_{\rm los, 0}$ relations, among others, butonly when particular values of the $\rho_{\rm g,thres}$ and $c_*$ parametersare used. This demostrates the effect that the star formation parameterizationhas on the ELO mass distribution. Additionally, our results suggest that it isnot strictly necessary, at the scales resolved in this work, to appeal toenergy sources other than gravitational (as for example supernovae feedbackeffects) to account for the structure and kinematics of large ellipticals.