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arXiv 2101.09288astro-ph.COastro-ph.GA
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从21厘米强度图的Minkowski泛函研究红移$z \sim 1$处的HI晕质量关系

The HI-halo mass relation at redshift $z \sim 1$ from the Minkowski functionals of 21 cm intensity maps

Benedetta Spina, Cristiano Porciani, Carlo Schimd

摘要:

作为晕质量函数的暗物质晕的HI含量的平均值和分散度是有用的统计数据,可以用来检验结构和星系形成的模型。我们调查的可能性,约束这个HI晕质量关系(HIHMR)的强度图的红移21厘米线。特别是,我们使用的几何形状和拓扑结构的亮度温度等值线在一个单一的频率通道量化的闵可夫斯基泛函。首先,我们从考虑热噪声和前景去除的影响的大型N体模拟中生成模拟地图。然后,我们使用Fisher信息形式主义预测HIHMR的参数模型的约束。我们考虑一个20,000度的$^2$调查(最初提出的暗能量科学)进行的平方公里阵列阶段1(SKA-1)MID天文台在单碟模式下运行。对于2 MHz的信道带宽,我们表明,几个$\,\times\,10^4$ s每指向的积分时间是足够的图像的平滑HI分布在红移$z \simeq 1$和测量HIHMR在一个接近最佳的方式从闵可夫斯基泛函。对一些参数的更严格的约束也可以通过使用平均HI密度的独立测量来获得。组合来自不同频率通道的结果提供了对HIHMR的演进的精细约束,特别是在数据立方体的中心频率范围中。

英文摘要:

The mean and the scatter of the HI content of a dark-matter halo as a function of the halo mass are useful statistics that can be used to test models of structure and galaxy formation. We investigate the possibility of constraining this HI-halo mass relation (HIHMR) from intensity maps of the redshifted 21 cm line. In particular, we use the geometry and topology of the brightness-temperature isocontours in a single frequency channel as quantified by the Minkowski functionals. First, we generate mock maps from a large N-body simulation considering the impact of thermal noise and foreground removal. We then use the Fisher information formalism to forecast constraints on a parametric model for the HIHMR. We consider a 20,000 deg$^2$ survey (originally proposed for dark-energy science) conducted with the Square Kilometre Array Phase 1 (SKA-1) MID observatory operating in single-dish mode. For a channel bandwidth of 2 MHz, we show that an integration time of a few$\,\times\,10^4$ s per pointing is sufficient to image the smoothed HI distribution at redshift $z \simeq 1$ and to measure the HIHMR in a nearly optimal way from the Minkowski functionals. Tighter constraints on some of the parameters can be obtained by using also an independent measurement of the mean HI density. Combining the results from different frequency channels provides exquisite constraints on the evolution of the HIHMR, especially in the central frequency range of the data cube.

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