arXiv 1709.039932017-09-12astro-ph.GA

再电离时期星系的CO线辐射

CO line emission from galaxies in the Epoch of Reionization

L. Vallini, A. Pallottini, A. Ferrara, S. Gallerani, E. Sobacchi, C. Behrens

备注：: 16 pages, 14 figures, accepted for publication in MNRAS
DOI：: 10.1093/mnras/stx2376

摘要：

我们研究了再电离时期星系中CO谱线的光度（$L_{\rm CO}$）、CO谱线能量分布（SLED）的形状以及CO到$L_{\rm CO}$的转换因子。为此，我们建立了一个模型，同时考虑到辐射传输和巨分子云（GMCs）的CO线被激发的cluerous结构。然后，我们使用它的后处理国家的最先进的变焦，高分辨率（$30\, \rm{pc}$），宇宙学模拟的主序星（$M_{*}\approx10^{10}\, \rm{M_{\odot}}$，$SFR\approx 100\,\rm{M_{\odot}\, yr^{-1}}$）星系，“Althæa”，在$z\approx6$。我们发现，CO的发射跟踪到了蜀葵的内分子盘（$r\approx 0.5 \,\rm{kpc}$），CO表面亮度的峰值与[CII] 158 $\rm μm$的发射峰位于同一位置。它的$L_{\rm CO(1-0)}=10^{4.85}\, \rm{L_{\odot}}$与在具有类似恒星质量的本地星系中观测到的相当。在Althæa的高（$Σ_{gas} \approx 220\, \rm M_{\odot}\, pc^{-2}$）气体表面密度，它的大马赫数（\mach $\approx 30$）和GMC的温暖的动力学温度（$T_{k}\approx 45 \, \rm K$）产生了CO SLED在CO（7-6）转变处达到峰值，即在相对高的- $J$，和CO到-$\rm H_2$的转换因子$α_{\rm CO}\approx 1.5 \, \rm M_{\odot} \rm (K\, km\, s^{-1}\, pc^2)^{-1} $低于银河系。ALMA在5 $σ$探测（解析）类似于Althæa星系的CO（7-6）谱线所需的观测时间为$\approx13$ h（$\approx 38$ h）。

英文摘要：

We study the CO line luminosity ($L_{\rm CO}$), the shape of the CO Spectral Line Energy Distribution (SLED), and the value of the CO-to-$\rm H_2$ conversion factor in galaxies in the Epoch of Reionization (EoR). To this aim, we construct a model that simultaneously takes into account the radiative transfer and the clumpy structure of giant molecular clouds (GMCs) where the CO lines are excited. We then use it to post-process state-of-the-art zoomed, high resolution ($30\, \rm{pc}$), cosmological simulation of a main-sequence ($M_{*}\approx10^{10}\, \rm{M_{\odot}}$, $SFR\approx 100\,\rm{M_{\odot}\, yr^{-1}}$) galaxy, "Althæa", at $z\approx6$. We find that the CO emission traces the inner molecular disk ($r\approx 0.5 \,\rm{kpc}$) of Althæa with the peak of the CO surface brightness co-located with that of the [CII] 158$\rm μm$ emission. Its $L_{\rm CO(1-0)}=10^{4.85}\, \rm{L_{\odot}}$ is comparable to that observed in local galaxies with similar stellar mass. The high ($Σ_{gas} \approx 220\, \rm M_{\odot}\, pc^{-2}$) gas surface density in Althæa, its large Mach number (\mach$\approx 30$), and the warm kinetic temperature ($T_{k}\approx 45 \, \rm K$) of GMCs yield a CO SLED peaked at the CO(7-6) transition, i.e. at relatively high-$J$, and a CO-to-$\rm H_2$ conversion factor $α_{\rm CO}\approx 1.5 \, \rm M_{\odot} \rm (K\, km\, s^{-1}\, pc^2)^{-1} $ lower than that of the Milky Way. The ALMA observing time required to detect (resolve) at 5$σ$ the CO(7-6) line from galaxies similar to Althæa is $\approx13$ h ($\approx 38$ h).

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

摘要：

英文摘要：

相关论文