论文标题
从漂移扫描观测的功率谱的跟踪锥形网格估计器（TTGE）
The Tracking Tapered Gridded Estimator (TTGE) for the power spectrum from drift scan observations
论文作者
论文摘要
红移21厘米线的强度映射是宇宙学的新兴工具。漂移扫描观察结果，即天线固定在地面上，望远镜的指向中心（PC）由于地球旋转而在天空上不断变化，提供了宽阔的天空覆盖范围和21厘米强度映射所需的持续仪器稳定性。在这里，我们介绍跟踪锥形格栅估计量（TTGE），以量化直接从漂移扫描无线电干涉观测值中测得的可见性估计的天空信号的功率谱。 TTGE使用来自不同PC的数据来估计位于固定跟踪中心（TC）周围的小角区域的信号的功率谱。该角区域的大小由适当选择的锥形窗口函数决定，该功能可减少来自TC的大角度的明亮源的前景污染。可以使用多个TC覆盖漂移扫描观察的角度足迹，并将估计的功率谱相结合以增加信号与噪声比。在这里，我们使用$ 154 \，{\ rm MHz} $ MWA漂移扫描观测值的模拟验证了TTGE。我们表明，TTGE可以在$ 20 \％$ $ \ ell $ rangage $ 40 <\ ell <700 $的$ 20 \％$中恢复输入模型Angular Power Spectrum $ c _ {\ ell} $。
Intensity mapping with the redshifted 21-cm line is an emerging tool in cosmology. Drift scan observations, where the antennas are fixed to the ground and the telescope's pointing center (PC) changes continuously on the sky due to earth's rotation, provide broad sky coverage and sustained instrumental stability needed for 21-cm intensity mapping. Here we present the Tracking Tapered Grided Estimator (TTGE) to quantify the power spectrum of the sky signal estimated directly from the visibilities measured in drift scan radio interferometric observations. The TTGE uses the data from the different PC to estimate the power spectrum of the signal from a small angular region located around a fixed tracking center (TC). The size of this angular region is decided by a suitably chosen tapering window function which serves to reduce the foreground contamination from bright sources located at large angles from the TC. It is possible to cover the angular footprint of the drift scan observations using multiple TC, and combine the estimated power spectra to increase the signal to noise ratio. Here we have validated the TTGE using simulations of $154 \, {\rm MHz}$ MWA drift scan observations. We show that the TTGE can recover the input model angular power spectrum $C_{\ell}$ within $20 \%$ accuracy over the $\ell$ range $40 < \ell < 700$.
