论文标题
在$ z \ sim4 $的巨大的星爆银河GN20中的看似冷尘
Deceptively cold dust in the massive starburst galaxy GN20 at $z\sim4$
论文作者
论文摘要
我们提出了与Iram Noema进行的新观察结果，该观察结果是在492 GHz处的原子中性碳过渡[CI]（1-0）和809 GHz GN20的[CI]（2-1），这是一个精心研究的星星，$ Z = 4.05美元。高亮度线比[CI]（2-1）/[CI]（1-0）意味着$ 48^{+14} _ { - 9} $ K的激发温度明显高于$ t _ {\ rm d} = 33 \ pm2 $ k（$ k = 1.9 $ by frardive）的明显灰尘温度明显高于$ t _ {\ rm d}与$ t _ {\ rm d} = 52 \ pm5 $ k的通用不透明度模型完全一致，其中光学深度（$τ$）以$λ_0= 170 \ pm23 $ $ $ m $ m的波长达到统一。此外，一般不透明度解决方案返回$ \ sim 2 \ tims $降低尘埃质量的元素，因此，固定气体与尘埃比的分子气体质量低于光学薄的灰尘模型。因此，GN20的派生特性为令人困惑的发现的衍生特性提供了一种吸引人的解决方案，而除了较低的尘埃质量比率较低的尘埃质量比以外的$ z> 2.5 $的主序列星系看起来还要冷，该星系的物理价值较低，而尘埃质量比的物理价值较低。
We present new observations, carried out with IRAM NOEMA, of the atomic neutral carbon transitions [CI](1-0) at 492 GHz and [CI](2-1) at 809 GHz of GN20, a well-studied star-bursting galaxy at $z=4.05$. The high luminosity line ratio [CI](2-1)/[CI](1-0) implies an excitation temperature of $48^{+14}_{-9}$ K, which is significantly higher than the apparent dust temperature of $T_{\rm d}=33\pm2$ K ($β=1.9$) derived under the common assumption of an optically thin far-infrared dust emission, but fully consistent with $T_{\rm d}=52\pm5$ K of a general opacity model where the optical depth ($τ$) reaches unity at a wavelength of $λ_0=170\pm23$ $μ$m. Moreover, the general opacity solution returns a factor of $\sim 2\times$ lower dust mass and, hence, a lower molecular gas mass for a fixed gas-to-dust ratio, than with the optically thin dust model. The derived properties of GN20 thus provide an appealing solution to the puzzling discovery of starbursts appearing colder than main-sequence galaxies above $z>2.5$, in addition to a lower dust-to-stellar mass ratio that approaches the physical value predicted for starburst galaxies.
