N-body Simulation of "The Antennae"

in collaboration with John Hibbard (NRAO) and Josh Barnes (IfA)


Very few detailed models of interacting systems exist in the literature, and most that do fail to use the line-of-sight velocity information to constrain the encounter parameters. This is especially true of the closest and most recognized merging system, NGC 4038/9 "The Antennae". For this system many "look-alike" models have been published, none of which reproduce the observed kinematics. To remedy this situation, John has recently obtained high-quality HI spectral line observations of this system. For further information, see http://www.cv.nrao.edu/~jhibbard/n4038.

During the initial stages of this project, I evaluated several visualisation packages that would allow an interactive 3D approach to analysis of our data. Geomview was chosen as the most appropriate approach to take. Software was written that would convert the data files produced by the simulations into the oogl format. A Tk/Tcl based user interface was also created that allows users to carry out the conversion and then view the results in Geomview. Collectively the software and user interface greatly facilitate the visualisation of the data. (See Sim2Oogl)

I am currently working with an N-body simulation package available from Josh Barnes to model the observed HI distribution and kinematics of "The Antennae", as well as helping to further develop software written by John Hibbard which will allow the inter-comparison of observational and simulation data. Ideally, I would like to establish a method of model matching that will lead to the process being automated.

HST Image of the Antennae (F.Schweizer)

NGC4038/9 in 3D

The images below illustrate how Geomview has been used to display our data. In this instance, we are looking at the results of HI observations of NGC4038/9, otherwise known as "The Antennae".

Position Velocity Position with Line of
 Sight Velocity Position with
Velocity Vectors
Position: x-y-z Velocity: Vx-Vy-Vz Position with Velocity in Z direction: x-y-Vz Position with Velocity Vectors: x-y-z-Vx-Vy-Vz

Useful Tools

Animations and Movies

Catalogues and Surveys of Peculiar, Interacting Galaxies


Papers relevant to NGC4038/9



For John.....

Last updated on 14th September, 1999.

Chris Power, cpower@nospamplease.nrao.edu

Research: http://www.dunsink.dias.ie/~cpower/astro
Personal: http://www.dunsink.dias.ie/~cpower
National Radio Astronomy Observatory, 520 Edgemont Road,
22903-2475 VA