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Abstract:
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The study of galaxies through high redshifts are key to understanding the
evolution of galaxies through cosmic times. As such objects are very difficult to
observe directly, they are mainly examined using empirically derived tools such as
the numerous correlations between their different parametric characteristics, one
of them being the linear relationship between far-infrared and radio emission in
star-forming galaxies, named the Far Infrared-Radio (FIR) Correlation.Although
the correlation was considered to be stable in terms of linearity, recent works,
which include galaxies at high redshifts (0 < z < 6), showed a large deviation
from the correlation in these systems. The goal of this doctoral dissertation is
an examination of the physical processes that lead to this kind of behavior. As
a possible cause of this evolution, we will assume for the first time, and examine
interactions between galaxies (collisions and close approaches). Interactions be-
tween galaxies lead to the formation of shock waves on large scales that can lead
to changes in the relationship between infrared and radio emissions. Our hypoth-
esis was tested in several stadiums and the main results are as follows: 1. We
developed models of the evolution of the FIR correlation with redshift as functions
of the galaxy interaction rate. We tested the models on a sample of galaxies with
an already determined morphology separately for disc galaxies and for galaxies
that have recently been or are currently interacting - irregular galaxies.
2. In a small sample of 34 galaxies that we took from paper Miettinen et al. (2017),
it was shown that there is an indication that the interaction between galaxies can
be responsible for the evolution of the correlation with the redshift.
3. The next analysis was performed on a much larger sample of star-forming
galaxies taken from COSMOS field, where we did not find any evolution of corre-
lation with the redshift. Also, it was shown that the mean value of the correlation
parameter is lower in irregular galaxies than in disk galaxies.
Although recent observations indicated an evolution of the FIR correlation
with redshift, the results of this research failed to reproduce that evolution and
showed that the FIR correlation is stable with redshift. However, it was also
shown that due to the interaction of galaxies, the evolution of the FIR correlation
is possible if the representation of interacting systems in the sample is higher. |