Relationships between the Stellar, Gaseous, and Star Formation Disks in LITTLE THINGS Dwarf Irregular Galaxies: Indirect Evidence for Substantial Fractions of Dark Molecular Gas
Relationships between the Stellar, Gaseous, and Star Formation Disks in LITTLE THINGS Dwarf Irregular Galaxies: Indirect Evidence for Substantial Fractions of Dark Molecular Gas
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DOI：
10.3847/1538-3881/abd089
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发表时间：
2020-11
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影响因子：
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通讯作者：
D. Hunter;B. Elmegreen;Esther Goldberger;Hannah Taylor;A. Ermakov;K. Herrmann;Se-Heon Oh;B. Malko;B. Barandi;Ryan Jundt
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文献类型：
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作者：
D. Hunter;B. Elmegreen;Esther Goldberger;Hannah Taylor;A. Ermakov;K. Herrmann;Se-Heon Oh;B. Malko;B. Barandi;Ryan Jundt
对附近矮不规则星系的LITTLE THINGS样本中的恒星盘、气体盘和年轻恒星盘进行了函数拟合，以寻找参数之间的相关性。我们发现，H i的径向配置文件通常是平坦的中心和下降速度比V-波段配置文件的外部区域，而年轻的恒星更集中的中心，特别是如果H i是更中心平坦。这种模式表明，氢在中心变成分子，分子云正在形成恒星和FUV。一个假设分子表面密度与总气体表面密度成1.5或2次方的比例的模型，类似于Kennicutt-Schmidt关系，再现了可见光与H i标度长度之比与H i Sérsic指数之间的关系。分子分数估计为每个星系的半径的函数，通过使用传统的校准转换的FUV的分子表面密度。3RD内的平均分子分数为23% ± 17%。然而，恒星表面亮度剖面的突变并没有与星星形成相关的统一示踪物。
The stellar, gaseous and young stellar disks in the LITTLE THINGS sample of nearby dwarf irregular galaxies are fitted with functions to search for correlations between the parameters. We find that the H i radial profiles are generally flatter in the center and fall faster in the outer regions than the V-band profiles, while young stars are more centrally concentrated, especially if the H i is more centrally flat. This pattern suggests that the H i is turning into molecules in the center, and the molecular clouds are forming stars and FUV. A model that assumes the molecular surface density is proportional to the total gas surface density to a power of 1.5 or 2, in analogy with the Kennicutt–Schmidt relation, reproduces the relationship between the ratio of the visible to the H i scale length and the H i Sérsic index. The molecular fraction is estimated as a function of radius for each galaxy by converting the FUV to a molecular surface density using conventional calibrations. The average molecular fraction inside 3R D is 23% ± 17%. However, the break in the stellar surface brightness profile has no unified tracer related to star formation.