Letter to the Editor

Unequal-mass galaxy merger remnants: Spiral-like morphology but elliptical-like kinematics

¹ Observatoire de Paris, LERMA, 61 Av. de l'Observatoire, 75014 Paris, France
² École Normale Supérieure, 45 rue d'Ulm, 75005 Paris, France
³ Department of Physics, Indian Institute of Science, Bangalore 560012, India

Corresponding author: F. Bournaud, Frederic.Bournaud@obspm.fr

Received: 14 January 2004
Accepted: 12 March 2004

Abstract

It is generally believed that major galaxy mergers with mass ratios in the range 1:1–3:1 result in remnants that have properties similar to elliptical galaxies, and minor mergers below 10:1 result in disturbed spiral galaxies. The intermediate range of mass ratios 4:1–10:1 has not been studied so far. Using N-body simulations, we show that such mergers can result in very peculiar systems, that have the morphology of a disk galaxy with an exponential profile, but whose kinematics is closer to that of elliptical systems. These objects are similar to those recently observed by Jog & Chitre ([CITE]). We present two cases with mass ratios 4.5:1 and 7:1, and show that the merging causes major heating and results in the appearance of elliptical-type kinematics, while surprisingly the initial spiral-like mass profile is conserved.