本地卷的芳香性目录
An Aromatic Inventory of the Local Volume
摘要：
使用红外测光从斯皮策太空望远镜，我们执行的芳香族特征发射（AFE，但通常也被称为PAH排放）的统计完整的样本恒星形成星系的本地体积的第一个库存。所涉及的光度测量方法进行校准，并证明恢复芳香馏分的IRAC 8微米通量的标准偏差为6%的训练集的40个SINGS星系（范围从恒星尘埃为主）与合适的中红外斯皮策IRS光谱和等效测光。利用合适的5.5和10微米光度法，例如JWST将来可能提供的光度法，可以实现两个改进的潜在因素。由此产生的技术，然后应用到中红外测光的258个星系的本地体积遗产（LVL）调查，一个大的样本占主导地位的低光度矮星系的数量，获得可比的中红外光谱是不可行的。我们发现，由于在8微米的复杂的五个强芳香族功能的总LVL光度为2.47E10太阳光度与8.8E6太阳光度每立方兆秒差距的平均体积密度。24个LVL星系，对应于B带中M = -18.22的光度切割，占芳香族光度的90%。使用氧丰度从258 LVL星系的129个文献中编译，我们发现金属丰度和芳香族总红外发射比之间的相关性，但不是芳香族总8微米尘埃发射比。一个可能的解释是，相对于总尘埃含量，金属含量在芳香分子的丰度中起着作用，但其他因素，如恒星形成和/或局部辐射场影响这些分子的激发。
英文摘要：
Using infrared photometry from the Spitzer Space Telescope, we perform the first inventory of aromatic feature emission (AFE, but also commonly referred to as PAH emission) for a statistically complete sample of star-forming galaxies in the local volume. The photometric methodology involved is calibrated and demonstrated to recover the aromatic fraction of the IRAC 8 micron flux with a standard deviation of 6% for a training set of 40 SINGS galaxies (ranging from stellar to dust dominated) with both suitable mid-infrared Spitzer IRS spectra and equivalent photometry. A potential factor of two improvement could be realized with suitable 5.5 and 10 micron photometry, such as what may be provided in the future by JWST. The resulting technique is then applied to mid-infrared photometry for the 258 galaxies from the Local Volume Legacy (LVL) survey, a large sample dominated in number by low-luminosity dwarf galaxies for which obtaining comparable mid-infrared spectroscopy is not feasible. We find the total LVL luminosity due to five strong aromatic features in the 8 micron complex to be 2.47E10 solar luminosities with a mean volume density of 8.8E6 solar luminosities per cubic Megaparsec. Twenty-four of the LVL galaxies, corresponding to a luminosity cut at M = -18.22 in the B band, account for 90% of the aromatic luminosity. Using oxygen abundances compiled from the literature for 129 of the 258 LVL galaxies, we find a correlation between metallicity and the aromatic to total infrared emission ratio but not the aromatic to total 8 micron dust emission ratio. A possible explanation is that metallicity plays a role in the abundance of aromatic molecules relative to the total dust content, but other factors such as star formation and/or the local radiation field affect the excitation of those molecules.
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