期刊
ASTROPHYSICAL JOURNAL
卷 854, 期 2, 页码 -出版社
IOP PUBLISHING LTD
DOI: 10.3847/1538-4357/aaa76d
关键词
galaxies: individual (M83 or NGC 5236); galaxies: structure; ISM: molecules
资金
- Japan Society for the Promotion of Science (JSPS) [JP17K14259, JP26800099, JP17K14251]
We have obtained (CO)-C-12(1-0) data of the nearby barred spiral galaxy M83 from Atacama Large Millimeter/submillimeter Array and Nobeyama 45 m observations. By combining these two data sets, the total CO flux has been recovered, and a high angular resolution (2 '' corresponding to similar to 40 pc at the distance of M83) has been achieved. The field of view is 3' corresponding to similar to 3.4 kpc and covers the galactic center, bar, and spiral arm regions. In order to investigate how these galactic structures affect gas properties, we have created a probability distribution function (PDF) of the CO integrated intensity (I-CO), peak temperature, and velocity dispersion for a region with each structure. We find that the I-CO PDF for the bar shows a bright-end tail while that for the arm does not. As the star formation efficiency is lower in the bar, this difference in PDF shape is contrary to the trend in Milky Way studies where the bright-end tail is found for star-forming molecular clouds. While the peak temperature PDFs are similar for the bar and arm regions, velocity dispersion in the bar is systematically larger than in the arm. This large velocity dispersion is likely a major cause of the bright-end tail and of suppressed star formation. We also investigate an effect of stellar feedback to PDF profiles and find that the different I-CO PDFs between bar and arm regions cannot be explained by the feedback effect, at least at the current spatial scale.
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