Shape and kinematics of elliptical galaxies: evolution due to merging at z 1.5

Departamento de Física Teórica, Universidad Autónoma de Madrid, 28049 Madrid, Spain e-mail: c.gonzalezgarcia@uam.es

Received: 1 December 2008
Accepted: 14 January 2009

Abstract

Aims. We investigate the evolution in the shape and kinematics of elliptical galaxies in a cosmological framework.

Methods. We identified relaxed, elliptical-like objects (ELOs) at redshifts , , and within a set of hydrodynamic, self-consistent simulations completed for a concordance cosmological model.

Results. The population of elliptical systems that we analysed evolve systematically with time becoming rounder in general by and also more velocity dispersion supported. We found that this is due primarily to major dry mergers where only a modest amount of angular momentum is involved in the merger event. Despite the general trend, in a significant number of cases the merger event involves a relatively high amount of specific angular momentum, which causes the system in general to acquire higher rotational support and/or a more oblate shape. These evolutionary patterns persist when we study our systems in projection, in simulating true observations, and thus should be evident in future observations.