Whole-disk Sampling of Molecular Clouds in M83

• Published in: The Astrophysical journal 2024-12, Vol.976 (2), p.198
• Main Authors: Hirota, Akihiko, Koda, Jin, Egusa, Fumi, Sawada, Tsuyoshi, Sakamoto, Kazushi, Heyer, Mark, Lee, Amanda M, Maeda, Fumiya, Boissier, Samuel, Calzetti, Daniela, Elmegreen, Bruce G., Harada, Nanase, Ho, Luis C., Kobayashi, Masato I. N., Kuno, Nario, Madore, Barry F., Martín, Sergio, Donovan Meyer, Jennifer, Muraoka, Kazuyuki, Watanabe, Yoshimasa
• Format: Article
• Language: English
• Subjects: Brightness temperature; Cloud properties; CO line emission; Dilution; Giant molecular clouds; Interstellar medium; Luminosity; Milky Way; Millimeter astronomy; Molecular clouds; Radio telescopes; Sciences of the Universe; Sensitivity; Spatial data; Spatial resolution; Spiral galaxies
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/ad8228

We present a catalog of clouds identified from the 12 CO (1–0) data of M83, which was observed using the Atacama Large Millimeter/submillimeter Array with a spatial resolution of ∼46 pc and a mass sensitivity of ∼10 4 M ⊙ (3 σ ). The almost full-disk coverage and high sensitivity of the data allowed us to sample 5724 molecular clouds with a median mass of ∼1.9 × 10 5 M ⊙ , which is comparable to the most frequently sampled mass of giant molecular clouds by surveys in the Milky Way (MW). About 60% of the total CO luminosity in M83's disk arises from clouds more massive than 10 6 M ⊙ . Such massive clouds comprise 16% of the total clouds in number and tend to concentrate toward the arm, bar, and center, while smaller clouds are more prevalent in interarm regions. Most >10 6 M ⊙ clouds have peak brightness temperatures T peak above 2 K with the current resolution. Comparing the observed cloud properties with the scaling relations determined by P. M. Solomon et al. (1987, hereafter S87), T peak > 2 K clouds follow the relations, but T peak < 2 K clouds, which are dominant in number, deviate significantly. Without considering the effect of beam dilution, the deviations would suggest modestly high virial parameters (median α vir ∼ 2.7) and low surface mass densities (median Σ ∼ 22 M ⊙ pc −2 ) for the entire cloud samples, which are similar to values found for the MW clouds by T. S. Rice et al. (2016) and M.-A Miville-Deschênes et al. (2017). However, once beam dilution is taken into account, the observed α vir and Σ for a majority of the clouds (mostly T peak