Effect of the environment on the fundamental plane of elliptical galaxies

¹ Astronomical Institute of St. Petersburg State University, 198504 St. Petersburg, Russia
² Isaac Netwon Institute of Chile, St. Petersburg Branch, Russia

Corresponding author: E. A. Evstigneeva, katya@gong.astro.spbu.ru

Received: 11 May 2001
Accepted: 17 September 2001

Abstract

We present an analysis of the location of interacting E/S0 galaxies on the Fundamental Plane (FP). Using the NEMO package, we performed simulations of close encounters and mergers of two self-gravitating spherical galaxies. Two models for encounting galaxies – Plummer's and Hernquist's – were used. The number of particles ranged from 20 000 to 50 000 per galaxy. The changes of central density, half-mass radius and central velocity dispersion were analysed. It was found that close encounters between galaxies alter noticeably the above parameters within a very short time interval (10⁷–10⁸ years) just before the final merger. The amplitudes of parameter changes strongly depend on the initial mass concentration of a model. In some experiments we considered an encounter of two spherical galaxies with dark matter components. The effect of parameter changes was less pronounced than for the experiments without a dark halo. The results of the simulations were used to discuss the FP for interacting early-type galaxies.