发表机构
Indian Institute of Technology Kharagpur（印度理工学院卡拉格普尔分校）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究通过联合建模21厘米信号的两个观测结果，利用HI质量-晕质量关系及贝叶斯推断约束红移z≈1处的HI分布，模拟其分布并预测HI质量函数，发现低质量时HIMF稳定，高质量时下降，且高质量HI星系丰度更大，有助于星系演化和恒星形成研究。
AI 中文摘要
我们通过联合对21厘米信号的两个独立现有观测结果进行建模来约束红移z≈1处的HI分布。这两个观测分别是利用uGMRT通过堆叠蓝色恒星形成星系的21厘米发射测量的HI密度参数Ω_HI，以及利用CHIME测量的21厘米自相关功率谱（PS）。我们在宇宙学模拟中使用具有三个自由参数的HI质量-晕质量（HIHM）关系将HI分配到暗物质晕中，并通过联合贝叶斯推断估计参数值。我们使用推断的HIHM后验来模拟HI分布并预测z≈1处的HI质量函数（HIMF）。结果表明，低HI质量（lesssim 3.6×10^9 M_⊙）时HIMF几乎保持不变，较大质量时迅速下降。约90%的HI气体质量在M_HI∈[2×10^9, 4×10^11] M_⊙范围内。我们的估计预测高质量HI星系的丰度比早期观测和流体动力学模拟预测的要大。这些结果有助于理解星系演化和恒星形成。
英文摘要
We constrain the $z \approx 1$ HI distribution by jointly modeling two independent, existing observations of the 21-cm signal, the HI density parameter $Ω_{\rm HI}$ measured using uGMRT by stacking the 21-cm emission from blue, star-forming galaxies, and the 21-cm autocorrelation power spectrum (PS) measured using CHIME. We assign HI to the dark matter halos in a cosmological simulation using an HI mass-halo mass (HIHM) relation with three free parameters whose values we estimate by performing a joint Bayesian inference comparing the simulated $Ω_{\rm HI}$ and 21-cm PS with the measurements. We use the inferred HIHM posterior to simulate the HI distribution and predict the $z \approx 1$ HI mass function (HIMF). We find that the HIMF remains nearly constant at low HI masses $( \lesssim 3.6 \times 10^9 M_\odot)$, and it declines rapidly for larger HI masses. Around $\sim 90$ percent of the total HI gas is contained in the mass range $M_{\rm HI} \in [2 \times 10^9, \, 4 \times 10^{11}] \, M_\odot$. Our estimates predict a larger abundance of high mass HI galaxies than predicted by earlier observations and hydrodynamical simulations. We expect these results to be useful in understanding galaxy evolution and star formation.
Comments6 pages, 3 figures, published in ApJ Letters
