Analytic gas orbits in an arbitrary rotating galactic potential using the linear epicyclic approximation
Abstract
A code, EPIC5, has been developed which computes, in the twodimensional case, the initially circular orbits of guiding centra in an arbitrary axisymmetric potential with an arbitrary, weak perturbing potential in solid body rotation. This perturbing potential is given by its Fourier expansion. The analytic solution solves the linear epicyclic approximation of the equations of motion. To simulate the motion of interstellar matter and to damp the Lindblad resonances, in these equations we have introduced a friction which is proportional to the deviation from circular velocity. The corotation resonance is also damped by a special parameter. The program produces, in just a few seconds, orbital and density maps, as well as lineofsight velocity maps for a chosen orientation of the galaxy.
We test EPIC5 by comparing its results with previous simulations and observations from the literature, which gives satisfactory agreement. The aim is that this program should be a useful complement to elaborate numerical simulations. Particularly so are its abilities to quickly explore the parameter space, to construct artificial galaxies and to isolate various single agents important for developing the structure of interstellar matter in disc galaxies. The EPIC5 code can be obtained from npi@astro.su.se.
 Publication:

Monthly Notices of the Royal Astronomical Society
 Pub Date:
 April 2012
 DOI:
 10.1111/j.13652966.2011.20367.x
 arXiv:
 arXiv:1112.3658
 Bibcode:
 2012MNRAS.421.1089P
 Keywords:

 galaxies: kinematics and dynamics;
 galaxies: spiral;
 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 16 pages, 16 figures