A CONSTANT MOLECULAR GAS DEPLETION TIME IN NEARBY DISK GALAXIES
A CONSTANT MOLECULAR GAS DEPLETION TIME IN NEARBY DISK GALAXIES
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DOI：
10.1088/2041-8205/730/2/l13
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发表时间：
2011-02
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影响因子：
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通讯作者：
F. Bigiel;A. Leroy;F. Walter;E. Brinks;W. D. Blok;C. Kramer;H. Rix;A. Schruba;K. Schuster;A. Usero;H. Wiesemeyer
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文献类型：
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作者：
F. Bigiel;A. Leroy;F. Walter;E. Brinks;W. D. Blok;C. Kramer;H. Rix;A. Schruba;K. Schuster;A. Usero;H. Wiesemeyer
我们将 HERACLES 巡天的新敏感宽视场 CO 数据与 GALEX 和 Spitzer 的紫外和红外数据相结合，比较了 30 个附近盘状星系中数千个位置的 H2、ΣH2 表面密度和近期恒星形成率 ΣSFR。与之前的工作相比，我们将星系样本的大小增加了四倍以上，并包含具有广泛星系特性的目标。尽管本研究中的盘状星系具有广泛的特性，但我们发现在 1 kpc 的共同分辨率下，ΣSFR 和 ΣH2 之间存在很强的近似线性相关性。这意味着我们的样品中 H2 消耗时间中值 τH2Dep = ΣH2/ΣSFR 大致恒定，约为 2.35 Gyr（包括重元素）。在 1 kpc 分辨率下，ΣH2 和 τH2Dep 在 ΣH2 ≈ 5–100 M☉ pc−2 范围内仅存在微弱相关性，这是我们的数据探测到的。我们汇编了一系列广泛的文献测量结果，这些测量结果是使用各种恒星形成示踪剂、采样方案和物理尺度获得的，并表明总体而言，这些数据产生几乎完全相同的结果，尽管更加分散。我们将这些结果解释为强有力的、尽管是间接的证据，表明恒星形成在螺旋星系盘中的巨型分子云中以统一的方式进行。
We combine new sensitive, wide-field CO data from the HERACLES survey with ultraviolet and infrared data from GALEX and Spitzer to compare the surface densities of H2, ΣH2, and the recent star formation rate, ΣSFR, over many thousands of positions in 30 nearby disk galaxies. We more than quadruple the size of the galaxy sample compared to previous work and include targets with a wide range of galaxy properties. Even though the disk galaxies in this study span a wide range of properties, we find a strong, and approximately linear correlation between ΣSFR and ΣH2 at our common resolution of 1 kpc. This implies a roughly constant median H2 consumption time, τH2Dep = ΣH2/ΣSFR, of ∼2.35 Gyr (including heavy elements) across our sample. At 1 kpc resolution, there is only a weak correlation between ΣH2 and τH2Dep over the range ΣH2 ≈ 5–100 M☉ pc−2, which is probed by our data. We compile a broad set of literature measurements that have been obtained using a variety of star formation tracers, sampling schemes, and physical scales and show that overall, these data yield almost exactly the same results, although with more scatter. We interpret these results as strong, albeit indirect evidence that star formation proceeds in a uniform way in giant molecular clouds in the disks of spiral galaxies.