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Article Dans Une Revue The Astrophysical Journal Année : 2023

Diverse Molecular Structures across the Whole Star-forming Disk of M83: High-fidelity Imaging at 40 pc Resolution

Jin Koda
Akihiko Hirota
Fumi Egusa
Tsuyoshi Sawada
Mark Heyer
Junichi Baba
Bruce Elmegreen
Nanase Harada
Luis Ho
Masato Kobayashi
Nario Kuno
Amanda Lee
Barry Madore
Fumiya Maeda
Sergio Martín
Kazuyuki Muraoka
Kouichiro Nakanishi
Sachiko Onodera
Jorge Pineda
Nick Scoville
Yoshimasa Watanabe

Résumé

Abstract We present Atacama Large Millimeter/submillimeter Array (ALMA) imaging of molecular gas across the full star-forming disk of the barred spiral galaxy M83 in CO( J = 1–0). We jointly deconvolve the data from ALMA’s 12 m, 7 m, and Total Power arrays using the MIRIAD package. The data have a mass sensitivity and resolution of 10 4 M ⊙ (3 σ ) and 40 pc—sufficient to detect and resolve a typical molecular cloud in the Milky Way with a mass and diameter of 4 × 10 5 M ⊙ and 40 pc, respectively. The full disk coverage shows that the characteristics of molecular gas change radially from the center to outer disk, with the locally measured brightness temperature, velocity dispersion, and integrated intensity (surface density) decreasing outward. The molecular gas distribution shows coherent large-scale structures in the inner part, including the central concentration, offset ridges along the bar, and prominent molecular spiral arms. However, while the arms are still present in the outer disk, they appear less spatially coherent, and even flocculent. Massive filamentary gas concentrations are abundant even in the interarm regions. Building up these structures in the interarm regions would require a very long time (≳100 Myr). Instead, they must have formed within stellar spiral arms and been released into the interarm regions. For such structures to survive through the dynamical processes, the lifetimes of these structures and their constituent molecules and molecular clouds must be long (≳100 Myr). These interarm structures host little or no star formation traced by H α . The new map also shows extended CO emission, which likely represents an ensemble of unresolved molecular clouds.
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hal-04505768 , version 1 (16-03-2024)

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Jin Koda, Akihiko Hirota, Fumi Egusa, Kazushi Sakamoto, Tsuyoshi Sawada, et al.. Diverse Molecular Structures across the Whole Star-forming Disk of M83: High-fidelity Imaging at 40 pc Resolution. The Astrophysical Journal, 2023, 949 (2), pp.108. ⟨10.3847/1538-4357/acc65e⟩. ⟨hal-04505768⟩
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