ALMA-LEGUS. I. The Influence of Galaxy Morphology on Molecular Cloud Properties

Abstract We present a comparative study of the molecular gas in two galaxies from the Legacy ExtraGalactic UV Survey (LEGUS) sample: barred spiral NGC 1313 and flocculent spiral NGC 7793. These two galaxies have similar masses, metallicities, and star formation rates, but NGC 1313 is forming signifi...

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Published in:The Astrophysical journal 2024-03, Vol.964 (1), p.12
Main Authors: Finn, Molly K., Johnson, Kelsey E., Indebetouw, Remy, Costa, Allison H., Adamo, Angela, Aloisi, Alessandra, Bittle, Lauren, Calzetti, Daniela, Dale, Daniel A., Dobbs, Clare L., Donovan Meyer, Jennifer, Elmegreen, Bruce G., Elmegreen, Debra M., Fumagalli, Michele, Gallagher, J. S., Grasha, Kathryn, Grebel, Eva K., Kennicutt, Robert C., Krumholz, Mark R., Lee, Janice C., Messa, Matteo, Nair, Preethi, Sabbi, Elena, Smith, Linda J., Thilker, David A., Whitmore, Bradley C., Wofford, Aida
Format: Article
Language:English
Subjects:
Cloud formation
Cloud properties
Comparative studies
Galaxies
Interstellar medium
Kinetic energy
Massive stars
Molecular clouds
Molecular gases
Radio telescopes
Spiral galaxies
Star & galaxy formation
Star clusters
Star formation
Stars & galaxies
Young star clusters
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Summary:Abstract We present a comparative study of the molecular gas in two galaxies from the Legacy ExtraGalactic UV Survey (LEGUS) sample: barred spiral NGC 1313 and flocculent spiral NGC 7793. These two galaxies have similar masses, metallicities, and star formation rates, but NGC 1313 is forming significantly more massive star clusters than NGC 7793, especially young massive clusters (10 4 M ⊙ ). Using Atacama Large Millimeter/submillimeter Array (ALMA) CO(2–1) observations of the two galaxies with the same sensitivity and resolution (13 pc), we directly compare the molecular gas in these two similar galaxies to determine the physical conditions responsible for their large disparity in cluster formation. By fitting size–line width relations for the clouds in each galaxy, we find that NGC 1313 has a higher intercept than NGC 7793, implying that its clouds have higher kinetic energies at a given size scale. NGC 1313 also has more clouds near virial equilibrium than NGC 7793, which may be connected to its higher rate of massive cluster formation. However, these virially bound clouds do not show a stronger correlation with young clusters than with the general cloud population. We find surprisingly small differences between the distributions of molecular cloud populations in the two galaxies, though the largest of those differences is that NGC 1313 has higher surface densities and lower freefall times.
ISSN:0004-637X
1538-4357
1538-4357
DOI:10.3847/1538-4357/ad1eec