Efecto de las colisiones sobre el Plano Fundamental de bulbos de galaxia espirales

SMITH CASTELLI, A. V.; SCANNAPIECO, C.; TISSERA, P. B.

La Plata

Congreso; 46 Reunion Asociacion Argentina de Astronomia; 2003

Facultad de Ciencias Astronómicas y Geofísicas, UNLP

The main aspects of the Fundamental Plane (FP) relation for ellipticals and early type bulges can be explained assuming the virialization of the systems, however, the observed dispersions are larger than instrumentation errors and have been thought to have physical basis. Even more, it is expected that the scatter and the position that different objects ocupy on it, could give clues on the mechanisms of galaxy formation and on the evolutionary path of galaxies. The FP relation has been observed and confirmed in the local Universe and it has been recently estimated for galaxies at intermediate redshifts. However, these estimations are based on a low statitical number and effects such as the evolution of the stellar populations and the presence of dust may introduce additional dispersion. Scannapieco & Tissera (2003) studied the mass distribution of disk systems and the way in which this distribution is modified by mergers. These authors have used numerical simulations which included gravitation, hydrodynamics, cooling and stellar formation in a cosmological frame work. As a consecuence, the collision parameters and the physical features of the simulated objects are the result of the consistent formation of the structure in a hierarchical scenario. The results show that depending on the caracteristics of the potential well, some systems may suffer gas inflows as a result of tidal fields during the orbital decay of the satellite system. This gas inflow originates a star burst previous to the fusion (i.e. secular evolution) which tends to form bulges with exponential profiles. In this work we present preliminary results on the effects of mergers on the FP defined by bulges. We found that the simulated bulges determines a FP in agreement with observations. We have detected that the mergers could significantly affect the FP depending on the internal properties of the galactic systems. And, particularly, secular evolution is found to play a critical role in the determination of a FP with the observed slope (Smith Castelli et al., 2004, in preparation).