Dust masses, PAH abundances, and starlight intensities in the SINGS galaxy sample
Dust masses, PAH abundances, and starlight intensities in the SINGS galaxy sample
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DOI：
10.1086/518306
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发表时间：
2007-07-10
影响因子：
4.9
通讯作者：
Teplitz, H. I.
中科院分区：
文献类型：
--
作者：
Draine, B. T.;Dale, D. A.;Teplitz, H. I.
物理尘埃模型的65个星系的SINGS强烈检测到的四个IRAC波段和三个MIPS波段。对于每个星系，我们估计（1）尘埃总质量，（2）多环芳烃占尘埃质量的比例，以及（3）加热尘埃颗粒的星光强度。我们发现螺旋星系的尘埃性质类似于银河系局部区域的尘埃，具有相似的尘埃-气体比和相似的PAH丰度。所观察到的SED，包括SCUBA测光的星系，可以通过不需要“冷”（T小于或类似于10 K）尘埃的尘埃模型来复制。尘埃与气体的比例被观察到取决于金属丰度。在A（O）等于12 + log（10）（O/ H）> 8：1的星系的星际介质中，颗粒含有相当大比例的星际Mg、Si和Fe。AO < 8的镀锌层：在某些情况下，扩展的H I包层似乎具有相对于其测得的氧丰度而言较低的全球尘埃与气体的比率，但是在检测到红外发射的区域中的尘埃与气体的比率通常似乎与尘埃中所含的星际Mg、Si和Fe的大部分相一致。多环芳烃指数qPAH，即尘埃质量中多环芳烃的比例，与金属含量相关。在我们的样本中，AO < 8：1的9个星系的qPAH中位数为1：0%，而AO > 8：1的星系的qPAH中位数为3：55%。由此得到的尘埃质量的XCO值近似为4.1020 cm（-2）（K km s（-1））（-1）。除了一些恒星爆发系统（Mrk 33，Tol 89，NGC 3049），弥漫的ISM中的尘埃主导了IR功率。
Physical dust models are presented for 65 galaxies in SINGS that are strongly detected in the four IRAC bands and three MIPS bands. For each galaxy we estimate ( 1) the total dust mass, ( 2) the fraction of the dust mass contributed by PAHs, and ( 3) the intensity of the starlight heating the dust grains. We find that spiral galaxies have dust properties resembling the dust in the local region of the MilkyWay, with similar dust- to- gas ratio and similar PAH abundance. The observed SEDs, including galaxies with SCUBA photometry, can be reproduced by dust models that do not require `` cold'' ( T less than or similar to 10 K) dust. The dust- to- gas ratio is observed to be dependent on metallicity. In the interstellar media of galaxies with A(O) equivalent to 12 + log(10)( O/ H) > 8: 1, grains contain a substantial fraction of interstellar Mg, Si, and Fe. Galaxies with AO < 8: 1 and extended H I envelopes in some cases appear to have global dust- to- gas ratios that are low for their measured oxygen abundance, but the dust- to- gas ratio in the regions where infrared emission is detected generally appears to be consistent with a substantial fraction of interstellar Mg, Si, and Fe being contained in dust. The PAH index qPAH, the fraction of the dust mass in the form of PAHs, correlates with metallicity. The nine galaxies in our sample with AO < 8: 1 have a median qPAH 1: 0%, whereas galaxies with AO > 8: 1 have a median qPAH 3: 55%. The derived dust masses favor a value XCO approximate to 4.1020 cm(-2) ( K km s(-1))(-1) for the CO- to- H-2 conversion factor. Except for some starbursting systems ( Mrk 33, Tol 89, NGC 3049), dust in the diffuse ISMdominates the IR power.