Simulation Atlas of Tidal Features in Galaxies Virtual Observatory Resource

Authors
  1. Howard S.
  2. Keel W.C.
  3. Byrd G.G.
  4. Burkey J.
  5. Published by
    CDS
Abstract

The simulation survey of tidally perturbed galaxies provides images of 84 different encounters that vary orbit tilt of companion orbit, perigalacticon distance ratio of primary galaxy mass to companion mass, and the amount of inert matter in the primary galaxy. In total 1764 galaxy images are available in the survey. This data set contains 84 separate simulations, each simulation is run for 1000 time steps, producing image output of the star particles and gas particles separately every 50 time steps. The first 21 images represent the "gas", and the second 21 images represent the "stars". Time steps for matching "gas" and "stars" are the same. There are [256,256] grid points on a Cartesian coordinate system. The renormalized densities are stored as 8-bit floating point numbers. The data have been put into FITS. Each header specifies the parameters for that simulation. Introduction: The simulation atlas provides an image dictionary of simulations that span several encounter parameters with fine morphological resolution and includes the effects of self-gravitation. Observers and theorists can then search the dictionary for the parameters that best match a particular observed morphology. The survey uses a self-gravitating, 180,000 particle, two-component ("stars" and "gas") disk with an inert halo. The companion follows a fully 3D self-gravitating orbit. The disk is constrained to two dimensions. The "star" data and the "gas" data are stored as separate images. The n-body code has a polar-coordinate grid especially well suited to simulate disk galaxies. The grid is exponentially spaced in the radial direction and provides increasing resolution from edge to center. Each bin has a constant angular size as seen from the origin. There are 24 radial and 36 azimutal bins which give an effective resolution that matches a 720x720 Cartesian grid. The code combines the speed of a particle mesh code with tree aspects for fine tuned handling of the companion orbit. The code is stable against intrinsic small perturbations. The initial potential for the disk is a finite Mestel (1963) disk which produces a flat rotation curve. The halo is represented by an inert potential set to match the value of the Mestel potential in the disk. The contribution of this potential is either equal to the potential of one disk mass or ten times the potential of one disk mass. Of the 180,00 particles, 126,000 of the are "stars", each having a velocity dispersion in the disk plane that ensures stability against axisymmetric perturbations. The remaining 54,000 "gas" particles have an initial velocity dispersion of 0.0. The particles are not allowed to collide. The initial velocity of the companion is set to match a zero energy orbit. The initial position is far enough away to assure a clean passage. The companion is treated as a point mass. Each simulation runs for 1000 time steps. With 50 steps per crossing time (one crossing time is the time a particle takes to travel a distance of one disk radius traveling at the initial circular orbital speed), there are 314 time steps for one galactic rotation. Assuming a typical disk radius of 20kpc, and a disk orbital speed of 200 km/s, one time step corresponds to about 1.5 million years.

Keywords
  1. Galaxy classification systems
  2. Galaxies
  3. Astronomical models
Bibliographic source Bibcode
1993ApJ...417..502H
See also HTML
https://cdsarc.cds.unistra.fr/viz-bin/cat/VI/76
IVOA Identifier IVOID
ivo://CDS.VizieR/VI/76

Access

Web browser access HTML
http://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=VI/76
https://vizier.iucaa.in/viz-bin/VizieR-2?-source=VI/76
http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=VI/76
IVOA Table Access TAP
http://tapvizier.cds.unistra.fr/TAPVizieR/tap
Run SQL-like queries with TAP-enabled clients (e.g., TOPCAT).

History

2002-05-03T07:21:28Z
Resource record created
2002-05-03T07:21:28Z
Created
2017-06-19T07:57:48Z
Updated

Contact

Name
CDS support team
Postal Address
CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France
E-Mail
cds-question@unistra.fr