论文标题
21cm强度映射功率谱的多极扩展：SKA天文台的预测宇宙学参数估计
Multipole expansion for 21cm Intensity Mapping power spectrum: forecasted cosmological parameters estimation for the SKA Observatory
论文作者
论文摘要
通过氢21cm线发射通过射线望远镜获得的后期宇宙中中性氢的大规模分布的测量，有可能在接下来的几年中成为关键的宇宙学探测器。我们探索了描述$λ$ CDM模型的完整宇宙学参数集对21厘米强度映射观测值的约束功率。我们假设对SKA天文台进行单次调查，并在$ z = 0.25-3 $的范围内模拟21cm线性功率谱单极和四极杆。预测约束是通过马尔可夫链蒙特卡洛技术来数字计算的。我们通过实现21cm功率谱多物的可能性函数来扩展Sampler \ texttt {Cosmomc}。我们仅评估模拟数据集的限制能力，并与Planck 2018 CMB观察结果结合使用。我们包括有关在分析中将测量结果扩展到非线性量表的影响的讨论。我们发现，仅21cm多尔观测值就足以获得与其他探针相当的宇宙学参数的约束。将21cm数据集与CMB观测值结合起来会导致所有宇宙学参数的误差大大减少。最强大的效果是对$ω_CH^2 $和$ H_0 $，为此，错误几乎减少了一个因子四。 The percentage errors we estimate are $σ_{Ω_ch^2} = 0.25\%$ and $σ_{H_0} = 0.16\%$, to be compared with the Planck only results $σ_{Ω_ch^2} = 0.99\%$ and $σ_{H_0} = 0.79\%$.我们得出的结论是，21cm SKAO观察将提供竞争性的宇宙学探针，互补与CMB相辅相成，因此，对于在宇宙参数约束上获得统计显着性的关键性，从而为当前的宇宙学模型提供了压力测试。
The measurement of the large scale distribution of neutral hydrogen in the late Universe, obtained with radio telescopes through the hydrogen 21cm line emission, has the potential to become a key cosmological probe in the upcoming years. We explore the constraining power of 21cm intensity mapping observations on the full set of cosmological parameters that describe the $Λ$CDM model. We assume a single-dish survey for the SKA Observatory and simulate the 21cm linear power spectrum monopole and quadrupole within six redshift bins in the range $z=0.25-3$. Forecasted constraints are computed numerically through Markov Chain Monte Carlo techniques. We extend the sampler \texttt{CosmoMC} by implementing the likelihood function for the 21cm power spectrum multipoles. We assess the constraining power of the mock data set alone and combined with Planck 2018 CMB observations. We include a discussion on the impact of extending measurements to non-linear scales in our analysis. We find that 21cm multipoles observations alone are enough to obtain constraints on the cosmological parameters comparable with other probes. Combining the 21cm data set with CMB observations results in significantly reduced errors on all the cosmological parameters. The strongest effect is on $Ω_ch^2$ and $H_0$, for which the error is reduced by almost a factor four. The percentage errors we estimate are $σ_{Ω_ch^2} = 0.25\%$ and $σ_{H_0} = 0.16\%$, to be compared with the Planck only results $σ_{Ω_ch^2} = 0.99\%$ and $σ_{H_0} = 0.79\%$. We conclude that 21cm SKAO observations will provide a competitive cosmological probe, complementary to CMB and, thus, pivotal for gaining statistical significance on the cosmological parameters constraints, allowing a stress test for the current cosmological model.
