  A strong correlation has been known to exist between the far-infrared (FIR)
and radio emission of the star-forming galaxies. Observations have shown that
although scatter is present, this correlation holds over a range of redshifts
and does not evolve. However, there has been a number of more recent
observations, especially in higher redshift surveys, indicating the opposite.
The question that then presents itself is - what is driving this evolution? In
this work we explore the possibility that the answer might be hiding in
galactic interactions and revealed by morphology. We present a number of models
based on the evolving number of galaxies of different morphological types, some
of which could potentially explain observed trends and scatter in general.
Furthermore, we analyze a small sample of 34 submillimeter galaxies whose
observations have been published and morphology classified. In this sample we
look at the FIR-radio correlation separately in galaxies of different
morphological types. We find that, while for both disk and irregular
star-forming galaxies there are hints of evolution of this correlation with
redshift, where this evolution appears to be stronger in irregular galaxies,
due to low number statistics, both samples are also consistent with no
evolution, making it at this point, difficult to discriminate between models.
However, when analysis was performed on the combined sample, evolving and
decreasing trend was indeed found, indicating, that evolution should be
expected in at least one of the morphological types.

Astrophysics of Galaxies