The Chocolate Chip Cookie Model: Dust Geometry of Milky Way–like Disk Galaxies
The Chocolate Chip Cookie Model: Dust Geometry of Milky Way–like Disk Galaxies
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DOI：
10.3847/1538-4357/ac92e9
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发表时间：
2022-09
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通讯作者：
Jiafeng 家风 Lu 卢;S. Shen 沈;Fang-Ting 方婷 Yuan 袁;Zhengyi 正义 Shao 邵;J. Hou 侯;Xianzhong 宪忠 Zheng 郑
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作者：
Jiafeng 家风 Lu 卢;S. Shen 沈;Fang-Ting 方婷 Yuan 袁;Zhengyi 正义 Shao 邵;J. Hou 侯;Xianzhong 宪忠 Zheng 郑
我们提出了一个新的两个组件的尘埃几何模型，巧克力饼干模型，其中cloudibular星云区域嵌入在一个弥漫的恒星/星际介质盘，像巧克力芯片在饼干。通过用连续的高斯分布来近似星云区域的二项分布，并忽略尘埃散射效应，我们的模型通过分析方法解决了发射线和恒星连续体的尘埃衰减过程。我们的巧克力饼干模型成功地适合的倾斜依赖性的有效尘埃红化的恒星组成部分来自恒星的人口合成和的Balmer减量为特征的大样本的银河系（MW样）盘星系的主要星系样本的斯隆数字巡天的星系的发射线。我们的模型表明，对于类MW星系，星云盘比恒星盘薄0.55倍，大1.6倍，而每个星云区在V波段的典型光学厚度为τ cl，V <$0.5。在考虑孔径效应后，我们的模式预测的尘埃衰减的倾斜依赖性也与观测一致。不仅如此，在我们的模型中，星群的尘埃衰减曲线自然地依赖于倾角，其中值情况与经典的卡尔泽蒂定律一致。由于建模约束来自光学波长，因此我们的模型不受光学厚尘埃成分的影响，但这可能会使模型对红外辐射的预测产生偏差。
We present a new two-component dust geometry model, the Chocolate Chip Cookie model, where the clumpy nebular regions are embedded in a diffuse stellar/interstellar medium disk, like chocolate chips in a cookie. By approximating the binomial distribution of the clumpy nebular regions with a continuous Gaussian distribution and omitting the dust scattering effect, our model solves the dust attenuation process for both the emission lines and stellar continua via analytical approaches. Our Chocolate Chip Cookie model successfully fits the inclination dependence of both the effective dust reddening of the stellar components derived from stellar population synthesis and that of the emission lines characterized by the Balmer decrement for a large sample of Milky Way–like (MW-like) disk galaxies selected from the main galaxy sample of the Sloan Digital Sky Survey. Our model shows that the clumpy nebular disk is about 0.55 times thinner and 1.6 times larger than the stellar disk for MW-like galaxies, whereas each clumpy region has a typical optical depth of τ cl,V ∼ 0.5 in the V band. After considering the aperture effect, our model prediction on the inclination dependence of dust attenuation is also consistent with observations. Not only that, in our model, the dust attenuation curve of the stellar population naturally depends on the inclination, and its median case is consistent with the classical Calzetti law. As the modeling constraints are from the optical wavelengths, our model is unaffected by the optically thick dust component, which however could bias the model’s prediction of the infrared emissions.