Structure of Merger Remnants. IV. Isophotal Shapes
Abstract
This paper examines the shapes of isophotes of galaxy merger remnants. More specifically, we perform a series of numerical experiments to study galaxy mergers. The simulations explore a variety of encounter geometries, types of progenitor galaxies, and particle numbers. We "observe" each of the remnants from 64 viewpoints to estimate how the isophotal shapes vary with the orientation of the remnant. Also, by comparing the results from the various simulations, we learn how encounter geometry and the structure of the progenitors can affect the shape of the remnants The encounter geometry, the structure of the progenitors, and the orientation of the remnant play deciding roles in the shape of the "observed" isophotes, so much so that these simulated merger remnants have both "boxy" and "disky" isophotes and ellipticities ranging from E0 to E7. Thus, the shapes seen in our merger simulation remnants span a similar range to observed isophotal shapes of real galaxies. Furthermore, to estimate the errors in this analysis, we introduce the statistical bootstrap. Bootstrapping is used rather widely in observational astronomy when dealing with small samples; however, its use is practically unheard of for tackling theoretical problems. We believe that bootstrapping can be extremely useful for dealing with the small samples found in numerical simulations; therefore, we present the rudiments and basis of the technique with emphasis on its use in Nbody calculations. Also, by comparing the errors for the smaller simulations with those of the larger ones, we speculate on the number of particles required to accurately explore isophotal shapes in simulations.
 Publication:

The Astrophysical Journal
 Pub Date:
 May 1994
 DOI:
 10.1086/174130
 Bibcode:
 1994ApJ...427..165H
 Keywords:

 Electron Distribution;
 Elliptical Galaxies;
 Galactic Structure;
 Geometry;
 Interacting Galaxies;
 Isophotes;
 Mathematical Models;
 Statistical Analysis;
 Algorithms;
 Charge Coupled Devices;
 Ellipticity;
 Many Body Problem;
 Star Formation;
 Velocity Distribution;
 Astrophysics;
 GALAXIES: INTERACTIONS;
 GALAXIES: STRUCTURE;
 METHODS: NUMERICAL