Encounters-between-spherical-galaxies-II：systems-with-dark-halo.pdfVIP

A Mon. Not. R. Astron. Soc. 000, 000–000 (0000) Printed 23 May 2006 (MN LT X style file v2.2) E Encounters between spherical galaxies II: systems with dark halo ´ ´ 1,2 1 A.C. Gonzalez-Garcıa and T.S. van Albada 1 Kapteyn Astronomical Institute,P.O. BOX 800, 9700 AV Groningen, The Netherlands 2 Instituto de Astrof´ısica de Canarias, V´ıa L´actea s/n, La Laguna, 38200, Spain 23 May 2006 ABSTRACT We performe N-body simulations of encounters between spherical systems surrounded by a spherical halo. Following a preceding paper with a similar aim, the initial systems include a spherical Jaffe model for the luminous matter and a Hernquist model for the halo. The merger remnants from this sample are mainly slowly rotating, prolate spheroids with a radially anisotropic velocity distribution. The results are compared with real-life ellipticals and with the models without halo in paper I. We argue that elliptical galaxies with evidence of dark matter could be formed in the field via a merger of spheroids surrounded by a dark matter halo, while ellipticals with no evidence of dark matter might be formed via a merger of two spheroids in a cluster. Key words: galaxies:interactions– kinematics and dynamics– structure– ellip