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

DOI：

10.3847/1538-4357/acc65e

发表时间：

2023-03

期刊：

The Astrophysical Journal

影响因子：

通讯作者：

中科院分区：

其他

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作者：

J. Koda;A. Hirota;F. Egusa;K. Sakamoto;T. Sawada;M. Heyer;J. Baba;S. Boissier;D. Calzetti;J. Donovan Meyer;B. Elmegreen;A. Gil de Paz;N. Harada;L. Ho;Masato I. N. Kobayashi;N. Kuno;A. Lee;B. Madore;F. Maeda;Sergio Martín;K. Muraoka;K. Nakanishi;S. Onodera;J. Pineda;N. Scoville;Yoshimasa Watanabe

我们提出了阿塔卡马大型毫米/亚毫米阵列（阿尔马）成像的分子气体在整个恒星形成盘的棒旋星系M83在CO（J = 1-0）。我们联合反卷积的数据从阿尔马的12米，7米，总功率阵列使用MIRIAD包。这些数据的质量灵敏度和分辨率分别为104 M <$3 σ和40 pc，足以探测和分辨银河系中质量和直径分别为4 × 105 M <$4和40 pc的典型分子云。全盘覆盖显示分子气体的特征从中心向外盘径向变化，与当地测量的亮度温度，速度色散，和积分强度（面密度）向外递减。分子气体的分布在内部显示出连贯的大尺度结构，包括中心浓度，沿杆沿着偏移的脊，和突出的分子螺旋臂。然而，虽然臂仍然存在于外盘中，但它们在空间上不那么连贯，甚至呈絮状。即使在臂间区域，也有大量的天然气富集。在臂间区域建立这些结构将需要很长的时间（约1亿年）。相反，它们一定是在恒星的旋臂内形成的，然后被释放到旋臂间的区域。为了使这些结构在动力学过程中存活下来，这些结构及其组成分子和分子云的寿命必须很长（约1亿年）。这些臂间结构中几乎没有Hα追踪到的星星形成。新的地图还显示了扩展的CO排放，这可能代表了未解析分子云的集合。

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 104 M ⊙ (3σ) and 40 pc—sufficient to detect and resolve a typical molecular cloud in the Milky Way with a mass and diameter of 4 × 105 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 Hα. The new map also shows extended CO emission, which likely represents an ensemble of unresolved molecular clouds.

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

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