11th INTERNATIONAL CONFERENCE ON ENGINEERING and NATURAL SCIENCES, Muş, Turkey, 18 - 19 September 2021, pp.176
One of the ways of probing the physics of the interstellar medium (ISM) in galaxies is to
study molecular emission lines. In this study, we targeted two galaxies. NGC 5055 is a normal
spiral galaxy, while NGC 3627 is also a spiral galaxy but hosting an active galactic nucleus
(AGN). AGNs are the key to understand the role of the supermassive black hole in the physics
of the central molecular zone and the evolution of galaxies. Using the literature data of four
CO lines available for both galaxies, i.e. 12CO(1-0, 2-1, 3-2) and 13CO(1-0), along with 24hi
and FUV emission properties, we investigated the line ratios across the disk of the galaxies.
Our main results are summarized as follows. 12CO(1-0) is the most extensive and the brightest
gas over the disc of both galaxies compared to the other three CO lines. Integrated CO line
intensity, molecular gas mass (jkl) and CO line ratios [i.e. 12CO(1-0)/13CO(1-0), 12CO(2-
1)/12CO(1-0) and 12CO(3-2)/12CO(1-0)] decrease as a function of distance from the center in
both galaxies, although NGC 3627 shows more fluctuations. Although the line ratios show a
negative correlation with the distance from the center in NGC 5055, there is no such negative
present in NGC 3627. jkl shows a positive correlation with 24hi and FUV flux (mnop), i.e.
both increase with respect to each other, in both galaxies, but the correlation is much weaker
with a higher scatter in NGC 3627. The line ratios and the ratio of 24h/mnop (i.e. the
extinction) also have a positive correlation over the disc of both galaxies but the correlation is
much stronger in NGC 5055 (except the ratio of 12CO(3-2)/12CO(1-0)) compared to NGC
3627. Our results indicate that each galaxy shows some differences in the physical properties
across its disk, possibly because of having different morphology and star formation histories.