论文标题
使用锥形网格估算器i:前景回避,使用$ z = 2.28 $的21厘米强度映射使用UGMRT
Towards 21-cm Intensity Mapping at $z=2.28$ with uGMRT using the Tapered Gridded Estimator I: Foreground Avoidance
论文作者
论文摘要
解换后$(Z \ le 6)$中性氢(HI)21厘米强度映射信号具有探测大规模结构,研究膨胀历史记录并限制各种宇宙学参数的潜力。在这里,我们将锥形网格估计器(TGE)应用于估计$ p(k _ {\ perp},k _ {\ Parallel})$ $ z = 2.28 $(432.8 \,{\ rm MHz})的功率谱使用$ 21 cm的$ 24.4.4.4.4.4.4.4.44.44.44.44.44.44.44.44.44 fr.摘自UGMRT频段3的欧洲大区域ISO Survey-North 1(Elais-N1)的观察结果。 TGE使我们能够逐渐减少天空响应,从而抑制了望远镜视野外围的来源的前景贡献。我们将TGE应用于测得的可见性数据上,以估算我们从中确定$ p(k _ {\ perp},k _ {\ parallel parallel parallel parally i})$的多频角功率谱(映射)$ c _ {\ ell}(Δν)$,使用最大值使用自然丢失的频段(55)(55)。使用模拟验证了整个方法。对于数据,使用前景回避技术,我们获得了$ 2 \,σ$上限为$δ^2(k)\ le(133.97)^2 \,{\ rm mk}^{2} $ 21 cm亮度温度在$ k = 0.347 \,\ textrm {mpc} $ k = 0.347 \,\ textrm {mpc} $} $ k = 0.347 \,\ rm mk}^{2} $}这对应于$ [ω_ {\ rm hi} b _ {\ rm hi}] \ le 0.23 $,其中$ω_ {\ rm hi} $和$ b _ {\ rm hi} $分别表示cosmic \ hi质量密度和\ hi hi bias bias parameter。以前的工作已经分析了相同数据的$ 8 \,{\ rm MHz} $,$ z = 2.19 $,并报告了$δ^{2} {2}(k)(k)\ le(61.49)^{2} {2} \,{\ rm mk} \ le 0.11 $ at $ k = 1 \,{\ rm mpc}^{ - 1} $。此处介绍的上限仍然比对应于$ω_ {\ rm hi} \ sim 10^{ - 3} $和$ b _ {\ rm hi} \ sim 2 $的预期信号的数量级。
The post-reionization $(z \le 6)$ neutral hydrogen (HI) 21-cm intensity mapping signal holds the potential to probe the large scale structures, study the expansion history and constrain various cosmological parameters. Here we apply the Tapered Gridded Estimator (TGE) to estimate $P(k_{\perp},k_{\parallel})$ the power spectrum of the $z = 2.28$ $(432.8\, {\rm MHz})$ redshifted 21-cm signal using a $24.4\,{\rm MHz}$ sub-band drawn from uGMRT Band 3 observations of European Large-Area ISO Survey-North 1 (ELAIS-N1). The TGE allows us to taper the sky response which suppresses the foreground contribution from sources in the periphery of the telescope's field of view. We apply the TGE on the measured visibility data to estimate the multi-frequency angular power spectrum (MAPS) $C_{\ell}(Δν)$ from which we determine $P(k_{\perp},k_{\parallel})$ using maximum-likelihood which naturally overcomes the issue of missing frequency channels (55 \% here). The entire methodology is validated using simulations. For the data, using the foreground avoidance technique, we obtain a $2\,σ$ upper limit of $Δ^2(k) \le (133.97)^2 \, {\rm mK}^{2}$ for the 21-cm brightness temperature fluctuation at $k = 0.347 \, \textrm{Mpc}^{-1}$. This corresponds to $[Ω_{\rm HI}b_{\rm HI}] \le 0.23$, where $Ω_{\rm HI}$ and $b_{\rm HI}$ respectively denote the cosmic \HI mass density and the \HI bias parameter. A previous work has analyzed $8 \, {\rm MHz}$ of the same data at $z=2.19$, and reported $Δ^{2}(k) \le (61.49)^{2} \, {\rm mK}^{2}$ and $[Ω_{\rm HI} b_{\rm HI}] \le 0.11$ at $k=1 \, {\rm Mpc}^{-1}$. The upper limits presented here are still orders of magnitude larger than the expected signal corresponding to $Ω_{\rm HI} \sim 10^{-3}$ and $b_{\rm HI} \sim 2 $.