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arXiv 1104.0827astro-ph.CO
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探测亚毫米波镓尘特性II。矮星系中尘埃-气体质量比随金属丰度和超毫米数的变化趋势

Probing the Dust Properties of Galaxies at Submillimetre Wavelengths II. Dust-to-gas mass ratio trends with metallicity and the submm excess in dwarf galaxies

Maud Galametz, Suzanne C. Madden, Frederic Galliano, Sacha Hony, George J. Bendo, Marc Sauvage

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19 pages, 10 figures, 1 table, accepted for publication in A&A
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摘要：

我们正在研究亚毫米观测对尘埃总质量的影响，从而研究尘埃与气体质量比测量的影响。我们收集了广泛的样本，已观察到在submm波长的星系模型的光谱能量分布使用submm观测，然后没有submm观测的限制，以量化的误差时，submm数据不可用的尘埃质量。我们的模型没有对尘埃温度分布进行强有力的假设，以精确避免研究中的submm偏差。我们的样本包括52个星系在submm波长观察。在这些星系中，有9个星系在我们的基准模型中没有考虑到，它们中的大多数是低金属量的矮星。我们选择添加一个独立的非常冷的尘埃成分（T= 10 K）来解释这种过量。我们发现，富含金属的星系与submm数据建模往往显示较低的尘埃质量比没有submm数据建模时。事实上，这些星系通常具有在较长波长处达到峰值的尘埃SED，并且需要160 μ m以上的约束来正确定位峰值并对其SED的亚毫米斜率进行采样，从而正确覆盖尘埃温度分布。另一方面，一些贫金属矮星系与submm数据建模时显示更高的尘埃质量比没有submm数据建模。使用submm约束的尘埃质量估计，我们发现一个紧密的相关性的尘埃气体质量比与星系的金属丰度。我们还经常发现，当存在亚毫米过量时，它优先发生在低金属丰度星系中。我们分析了这种过剩存在的条件，并找到了160/850微米的比例和submm过剩之间的关系。

英文摘要：

We are studying the effects of submm observations on the total dust mass and thus dust-to-gas mass ratio measurements. We gather a wide sample of galaxies that have been observed at submm wavelengths to model their Spectral Energy Distributions using submm observations and then without submm observational constraints in order to quantify the error on the dust mass when submm data are not available. Our model does not make strong assumptions on the dust temperature distribution to precisely avoid submm biaises in the study. Our sample includes 52 galaxies observed at submm wavelengths. Out of these, 9 galaxies show an excess in submm which is not accounted for in our fiducial model, most of these galaxies being low- metallicity dwarfs. We chose to add an independant very cold dust component (T=10K) to account for this excess. We find that metal-rich galaxies modelled with submm data often show lower dust masses than when modelled without submm data. Indeed, these galaxies usually have dust SEDs that peaks at longer wavelengths and require constraints above 160 um to correctly position the peak and sample the submillimeter slope of their SEDs and thus correctly cover the dust temperature distribution. On the other hand, some metal-poor dwarf galaxies modelled with submm data show higher dust masses than when modelled without submm data. Using submm constraints for the dust mass estimates, we find a tightened correlation of the dust-to-gas mass ratio with the metallicity of the galaxies. We also often find that when there is a submm excess present, it occurs preferentially in low-metallicity galaxies. We analyse the conditions for the presence of this excess and find a relation between the 160/850 um ratio and the submm excess.

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