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arXiv 0806.1020astro-ph
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解释星系紫外、可见光和红外辐射的一个简单模型

A simple model to interpret the ultraviolet, optical and infrared emission from galaxies

Elisabete da Cunha, Stephane Charlot, David Elbaz

摘要:

我们提出了一个简单的,主要是经验,但物理动机的模型来解释中,远红外光谱能量分布的星系一致的紫外线,光学和近红外波长的发射。我们的模型依赖于现有的角度平均处方计算恒星诞生云和星系中的ISM环境中的尘埃对星光的吸收。我们计算的光谱能量分布的功率再辐射的尘埃在恒星诞生云作为三个组成部分的总和:一个组成部分的多环芳烃;一个中红外连续表征从热颗粒的发射;和一个组成部分的温暖的谷物在热平衡与可调温度。在环境ISM中,为了简单起见,我们固定这三个组成部分的相对比例,以再现银河系中弥漫卷云发射的光谱形状,我们包括一个组成部分的冷颗粒在热平衡与可调温度。我们的模型可以用来推导统计约束的恒星形成历史和尘埃含量的大样本的星系使用紫外线,光学和红外观测。我们说明了这一点,推导出中位数似然估计的恒星形成率,恒星质量,有效的尘埃光学深度,尘埃质量,和相对强度不同的尘埃成分的66个良好的研究附近的恒星形成星系的斯皮策红外近星系巡天(SINGS)。从这个分析中,我们得出结论,星系的中红外和远红外颜色与特定的恒星形成率密切相关,以及与此参数相关的其他星系范围的数量。我们的模型可以直接应用于解释任何星系样本的紫外,光学和红外光谱能量分布。[删节]

英文摘要:

We present a simple, largely empirical but physically motivated model to interpret the mid- and far-infrared spectral energy distributions of galaxies consistently with the emission at ultraviolet, optical and near-infrared wavelengths. Our model relies on an existing angle-averaged prescription to compute the absorption of starlight by dust in stellar birth clouds and in the ambient ISM in galaxies. We compute the spectral energy distribution of the power reradiated by dust in stellar birth clouds as the sum of three components: a component of PAHs; a mid-IR continuum characterising the emission from hot grains; and a component of warm grains in thermal equilibrium with adjustable temperature. In the ambient ISM, we fix for simplicity the relative proportions of these three components to reproduce the spectral shape of diffuse cirrus emission in the Milky Way, and we include a component of cold grains in thermal equilibrium with adjustable temperature. Our model can be used to derive statistical constraints on the star formation histories and dust contents of large samples of galaxies using UV, optical and IR observations. We illustrate this by deriving median-likelihood estimates of the star formation rates, stellar masses, effective dust optical depths, dust masses, and relative strengths of different dust components of 66 well-studied nearby star- forming galaxies from the Spitzer Infrared Nearby Galaxy Survey (SINGS). From this analysis, we conclude that the mid- and far-IR colours of galaxies correlate strongly with the specific star formation rate, as well as with other galaxy-wide quantities connected to this parameter. Our model can be straightforwardly applied to interpret UV, optical and IR spectral energy distributions from any galaxy sample. [abridged]

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