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Stellar and Gas Dynamics of Merging Galaxies

Published online by Cambridge University Press:  03 August 2017

Joshua E. Barnes*
Affiliation:
Canadian Institute for Theoretical Astrophysics 60 Saint George St., Toronto, Ontario, M5S 1A1 CANADA

Abstract

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Numerical models permit a detailed study of the dynamics of merging disk galaxies. To first order, a typical galactic encounter is a well-posed problem in collisionless stellar-dynamics, since ≳ 90% of the mass is in the form of stars or dark matter. Mergers between disk/halo galaxies produce objects resembling elliptical galaxies in structure and kinematics. The three major orbit families expected in triaxial ellipsoids are all present in these merger remnants, and the distribution of stars between orbit families reflects the initial orientations of the colliding disks.

Models including gas dynamics, developed in collaboration with L. Hernquist, show how mergers, and perhaps other violent interactions, may fuel nuclear starbursts. In these experiments a large fraction (~ 60%) of the gas distributed throughout the galactic disks winds up in a central cloud with dimensions of a few hundred parsecs, a result of gravitational torques which transfer angular momentum from the gas to stellar bar. Nuclear gas clouds and starbursts observed in merging galaxies such as NGC 520 and Arp 220 may well be generated by this mechanism.

Type
XI- Galaxy Evolution
Copyright
Copyright © Kluwer 1991 

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