In our attempt to investigate how significant the spiral structure is when doing radiative transfer modeling of spiral galaxies seen edge-on, we constructed a model galaxy with very prominent spiral arms in the disk. This quite realistic image of the galaxy is now treated as observation and the widely adopted exponential model for the galactic disk is now fitted to the data.
This analysis shows that the plain exponential disk model is a very accurate description for galactic disks seen edge-on with only small deviations of its parameters from the real ones (typically a few percent). Furthermore, the variation from the real parameters would be averaged out if we could see the same galaxy from several point of views. This is of course impossible for an individual galaxy, but suggests that if the exponential model is used for a statistical study of many edge-on galaxies no systematic error is introduced. Thus, we conclude that the exponential model is a very good approximation of the galactic disks.
© European Southern Observatory (ESO) 2000
Online publication: December 8, 1999