论文标题
Z〜6类星体宿主星系中的分子气
Molecular gas in z~6 quasar host galaxies
论文作者
论文摘要
我们使用IRAM / Northern延伸毫米阵列研究了Z〜6类星体星系的分子气体含量。我们靶向3mm的灰尘连续体，以及CO（6-5），CO（7-6），[CI] 2-1中的线发射，在10个以前已经在其1mm dust Continuum和[CII]线发射中研究过的10个红色红色的类星体。我们在所有靶向来源中以各种显着性的不同程度检测CO（7-6），从而使Z〜6类星体中此类检测的数量增加了一倍。 3mm至1mm的通量密度比与尘埃温度$ t_ {dust} $ 〜47 k的改良黑体光谱一致，并且在[CII]频率下的光学深度$τ_ν$ = 0.2。我们的研究为我们提供了四种独立的方法来估计目标类星体中的分子气体质量$ M_ {H2} $。这使我们能够对分子气体质量估计的各种参数设置约束，例如$α_{co} $和$α_ {[CII]} $的质量质量比例，气体与dust-dust-dust比率$δ__{g/d} $ {g/d} $，以及碳含量$ undance [g/d}。利用在灰尘，co，[CI]或[CII]发射的范围内的质量估计值$ m_ {h2} $〜$〜$ 10^{10} $ to $ 10^{11} $ m $ _ {\ odot} $。我们将观察到的灰尘，[CII]，[CI]和CO（7-6）的亮度与光驱散和X射线主导区域的预测进行了比较。 We find that the former provide better model fits to our data, assuming that the bulk of the emission arises from dense ($n_H>10^4$ cm$^{-3}$) clouds with a column density $N_{H}$~$10^{23}$ cm$^{-2}$, exposed to a radiation field with intensity $G_0$~$10^3$ (in Habing units).我们的分析重申了在$ 〜6 $ 〜6 Quasar宿主星系中存在大量分子气体加油恒星形成和核积聚的水库。它还突出了3mm和1mm观测的功能，用于定量研究宇宙黎明巨大星系中的密集气体含量。
We investigate the molecular gas content of z~6 quasar host galaxies using the IRAM / Northern Extended Millimeter Array. We target the 3mm dust continuum, and the line emission from CO(6-5), CO(7-6), [CI]2-1 in 10 infra-red-luminous quasars that have been previously studied in their 1mm dust continuum and [CII] line emission. We detect CO(7-6) at various degrees of significance in all the targeted sources, thus doubling the number of such detections in z~6 quasars. The 3mm to 1mm flux density ratios are consistent with a modified black body spectrum with a dust temperature $T_{dust}$~47 K and an optical depth $τ_ν$=0.2 at the [CII] frequency. Our study provides us with four independent ways to estimate the molecular gas mass, $M_{H2}$, in the targeted quasars. This allows us to set constraints on various parameters used in the derivation of molecular gas mass estimates, such as the mass per luminosity ratios $α_{CO}$ and $α_{[CII]}$, the gas-to-dust ratio $δ_{g/d}$, and the carbon abundance [C]/H2. Leveraging either on the dust, CO, [CI], or [CII] emission yields mass estimates of the entire sample in the range $M_{H2}$~$10^{10}$ to $10^{11}$ M$_{\odot}$. We compare the observed luminosities of dust, [CII], [CI], and CO(7-6) with predictions from photo-dissociation and X-ray dominated regions. We find that the former provide better model fits to our data, assuming that the bulk of the emission arises from dense ($n_H>10^4$ cm$^{-3}$) clouds with a column density $N_{H}$~$10^{23}$ cm$^{-2}$, exposed to a radiation field with intensity $G_0$~$10^3$ (in Habing units). Our analysis reiterates the presence of massive reservoirs of molecular gas fueling star formation and nuclear accretion in $z$~6 quasar host galaxies. It also highlights the power of combined 3mm and 1mm observations for quantitative studies of the dense gas content in massive galaxies at cosmic dawn.
