利用DINGO-VLA数据叠加测量中性氢的宇宙密度
Measuring Cosmic Density of Neutral Hydrogen via Stacking the DINGO-VLA Data
摘要：
我们利用DINGO-VLA计划的21 cm发射线数据研究了宇宙中原子氢气体H\，{ \textsc i}在红移$z<0.1$处的情况。结果得到使用堆叠分析，结合H\，{ \textsc i}信号从3622个星系中提取的267 VLA点在G 09领域的星系和质量大会调查（GAMA）。而不是使用传统的一维光谱叠加方法，三维立方体叠加方法是用来使反卷积和准确的恢复平均星系通量从这个高分辨率的干涉数据集。通过探测到星系尺度，这个实验还克服了以前的单碟研究中必须包括的混淆校正。在堆叠和去卷积之后，我们从堆叠光谱获得$30σ$ H1，{ \textsc i}质量测量，指示$M_{\rm H\,{\textsc i}}=(1.674\pm 0.183)\times 10^{9}~{\Msun}$的平均H1，{ \textsc i}质量。在红移为$z=0.051$时，中性原子氢的相应宇宙密度为$Ω_{\rm H\,{\textsc i}}=(0.377\pm 0.042)\times 10^{-3}$。这些值与早期的结果吻合得很好，这意味着在较低的红移下$Ω_{\rm H\,{\textsc i}}$没有显著的演化。
英文摘要：
We use the 21 cm emission line data from the DINGO-VLA project to study the atomic hydrogen gas H\,{\textsc i} of the Universe at redshifts $z<0.1$. Results are obtained using a stacking analysis, combining the H\,{\textsc i} signals from 3622 galaxies extracted from 267 VLA pointings in the G09 field of the Galaxy and Mass Assembly Survey (GAMA). Rather than using a traditional one-dimensional spectral stacking method, a three-dimensional cubelet stacking method is used to enable deconvolution and the accurate recovery of average galaxy fluxes from this high-resolution interferometric dataset. By probing down to galactic scales, this experiment also overcomes confusion corrections that have been necessary to include in previous single dish studies. After stacking and deconvolution, we obtain a $30σ$ H\,{\textsc i} mass measurement from the stacked spectrum, indicating an average H\,{\textsc i} mass of $M_{\rm H\,{\textsc i}}=(1.674\pm 0.183)\times 10^{9}~{\Msun}$. The corresponding cosmic density of neutral atomic hydrogen is $Ω_{\rm H\,{\textsc i}}=(0.377\pm 0.042)\times 10^{-3}$ at redshift of $z=0.051$. These values are in good agreement with earlier results, implying there is no significant evolution of $Ω_{\rm H\,{\textsc i}}$ at lower redshifts.
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