arXiv 2008.123612020-08astro-ph.GA

中心分子带的AzTEC巡天：随密度增加的尘埃光谱指数

AzTEC Survey of the Central Molecular Zone: Increasing Spectral Index of Dust with Density

Yuping Tang, Q. Daniel Wang, Grant W. Wilson

备注：: Accepted for publication by MNRAS
DOI：: 10.1093/mnras/staa3230

摘要：

我们银河系的中央分子区（CMZ）拥有一个极端的环境，类似于遥远宇宙中典型的星暴星系。为了了解像我们的CMZ的环境中的灰尘属性，我们提出了我们的AzTEC/大型毫米望远镜调查的联合SED分析的结果，连同现有的\textit{Herschel}远红外数据的CMZ，从$160$ $μm$到$1.1$ $mm$的波长范围。我们包括全球前景和背景的贡献，在一个新的贝叶斯模型，采用了点扩散函数（PSF）的不同的地图，这使得我们的高分辨率（$10.5''$）地图在1.1 $mm$的充分利用，并揭示了前所未有的详细信息的尘埃气体的空间分布在整个CMZ。有一个显着的趋势增加灰尘光谱指数$β$，从$2.0-2.4$，在CMZ密集的峰值，表明缺乏大颗粒或根本改变尘埃光学性质。$β$的这种环境依赖性可能对其他研究中粉尘温度的测定产生重大影响。根据尘埃的光学特性如何偏离传统模型，$10-50\%$在特别密集的区域可能会低估尘埃温度。

英文摘要：

The Central Molecular Zone (CMZ) of our Galaxy hosts an extreme environment analogous to that found in typical starburst galaxies in the distant universe. In order to understand dust properties in environments like our CMZ, we present results from a joint SED analysis of our AzTEC/Large Millimeter Telescope survey, together with existing \textit{Herschel} far-IR data on the CMZ, from a wavelength range of $160$ $μm$ to $1.1$ $mm$. We include global foreground and background contributions in a novel Bayesian modeling that incorporates the Point Spread Functions (PSFs) of the different maps, which enables the full utilization of our high resolution ($10.5''$) map at 1.1 $mm$ and reveals unprecedentedly detailed information on the spatial distribution of dusty gas across the CMZ. There is a remarkable trend of increasing dust spectral index $β$, from $2.0-2.4$, toward dense peaks in the CMZ, indicating a deficiency of large grains or a fundamental change in dust optical properties. This environmental dependence of $β$ could have a significant impact on the determination of dust temperature in other studies. Depending on how the optical properties of dust deviate from the conventional model, dust temperatures could be underestimated by $10-50\%$ in particularly dense regions.

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