An Intensity Mapping Constraint on the CO-galaxy Cross-power Spectrum at Redshift ∼3
An Intensity Mapping Constraint on the CO-galaxy Cross-power Spectrum at Redshift ∼3
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DOI：
10.3847/1538-4357/ac4888
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发表时间：
2021-10
期刊：
影响因子：
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通讯作者：
R. Keenan;G. Keating;D. Marrone
中科院分区：
文献类型：
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作者：
R. Keenan;G. Keating;D. Marrone
丰富的冷分子气体在星系演化模型中起着至关重要的作用。虽然二氧化碳排放线的深度光谱调查一直是测量这种丰度的主要工具，但这些观测的困难激发了研究分子气体含量的替代方法。其中一种技术，即线强度映射，旨在通过 CO 亮度功率谱来限制单个不可探测的星系大样本的平均分子气体特性。在这里，我们提出了 CO 强度图和光学星系目录之间互功率谱的约束。这种交叉测量使我们能够检查 CO 强度绘图数据中的系统问题，并验证用于 CO 功率谱测量的自动功率谱测量的数据分析。我们对 P × < 540 μK h−3 Mpc3 的带均 CO 星系互功率设置了 2σ 上限。我们的测量结果倾向于在 90% 左右的置信度下实现非零 <T CO>，并给出 z ∼ 2.6 处平均分子气体密度的上限为 7.7 × 108 M ⊙ Mpc−3。我们通过将 CO 光度与光晕质量关系的大量文献规定应用于一组模拟光锥来预测预期的交叉功率谱。在最乐观的预测下，只需对此处使用的数据进行适度扩展即可检测到交叉谱，而更保守的模型则可以通过将灵敏度提高 10 倍来检测到。正在进行的 CO 强度绘图实验将针对允许广泛互相关分析的场，并应达到检测互谱信号所需的灵敏度。
The abundance of cold molecular gas plays a crucial role in models of galaxy evolution. While deep spectroscopic surveys of CO emission lines have been a primary tool for measuring this abundance, the difficulty of these observations has motivated alternative approaches to studying molecular gas content. One technique, line intensity mapping, seeks to constrain the average molecular gas properties of large samples of individually undetectable galaxies through the CO brightness power spectrum. Here we present constraints on the cross-power spectrum between CO intensity maps and optical galaxy catalogs. This cross-measurement allows us to check for systematic problems in CO intensity mapping data, and validate the data analysis used for the auto-power spectrum measurement of the CO Power Spectrum Survey. We place a 2σ upper limit on the band-averaged CO-galaxy cross-power of P × < 540 μK h−3 Mpc3. Our measurement favors a nonzero 〈T CO〉 at around 90% confidence and gives an upper limit on the mean molecular gas density at z ∼ 2.6 of 7.7 × 108 M ⊙ Mpc−3. We forecast the expected cross-power spectrum by applying a number of literature prescriptions for the CO luminosity–halo mass relation to a suite of mock light cones. Under the most optimistic forecasts, the cross-spectrum could be detected with only moderate extensions of the data used here, while more conservative models could be detected with a factor of 10 increase in sensitivity. Ongoing CO intensity mapping experiments will target fields allowing for extensive cross-correlation analysis and should reach the sensitivity required to detect the cross-spectrum signal.