论文标题
在低红移宇宙中采用最佳的前景缓解策略
Towards Optimal Foreground Mitigation Strategies for Interferometric HI Intensity Mapping in the Low-Redshift Universe
论文作者
论文摘要
我们进行了第一个案例研究，以开发最佳的前景缓解策略，以使用低红移的无线电干涉仪进行中性氢（HI）强度映射。建立了用于模拟，前景缓解和功率谱估计的管道，该管道可用于使用Meerkat和Square Kilmore阵列天文台（SKAO）进行持续和将来的调查。它模拟了逼真的天空信号，以生成给定工具和观察规范的可见性数据，随后将其用于进行前景缓解和功率谱估计。开发了二次估计量形式，以估计可见性空间中的温度功率谱。使用Meerkat望远镜规范进行红移范围的观测值z〜0.25-0.30，与Meerkat International GHz分层分层外探索（Mightee）调查相对应，我们提出了一个案例研究，我们比较了前景缓解的不同方法。我们发现，可见性空间中的组件分离提供了与前景回避相比的HI聚类的更准确估计，而不确定性较小30％。与可见性的估计相比，发现来自图像的功率谱估计的较大偏差和更多信息丢失的较小效果。我们得出的结论是，对于Z〜0.25-0.30，Mightee调查将能够以高准确的速度从K〜0.5 Mpc $^{ - 1} $到K〜10 MPC $^{ - 1} $测量HI功率谱。我们是第一个表明，在低红移时，可见性空间中的组件分离抑制了大范围内的前景污染，从而可以测量接近前景楔形的HI功率谱，这对于对未来检测的数据分析至关重要。
We conduct the first case study towards developing optimal foreground mitigation strategies for neutral hydrogen (HI) intensity mapping using radio interferometers at low redshifts. A pipeline for simulation, foreground mitigation and power spectrum estimation is built, which can be used for ongoing and future surveys using MeerKAT and Square Kilometre Array Observatory (SKAO). It simulates realistic sky signals to generate visibility data given instrument and observation specifications, which is subsequently used to perform foreground mitigation and power spectrum estimation. A quadratic estimator formalism is developed to estimate the temperature power spectrum in visibility space. Using MeerKAT telescope specifications for observations in the redshift range z~0.25-0.30 corresponding to the MeerKAT International GHz Tiered Extragalactic Exploration (MIGHTEE) survey, we present a case study where we compare different approaches of foreground mitigation. We find that component separation in visibility space provides a more accurate estimation of HI clustering comparing to foreground avoidance, with the uncertainties being 30 per cent smaller. Power spectrum estimation from image is found to be less robust with larger bias and more information loss when compared to estimation in visibility. We conclude that for z~0.25-0.30, the MIGHTEE survey will be capable of measuring the HI power spectrum from k~0.5 Mpc$^{-1}$ to k~10 Mpc$^{-1}$ with high accuracy. We are the first to show that, at low redshift, component separation in visibility space suppresses foreground contamination at large line-of-sight scales, allowing measurement of HI power spectrum closer to the foreground wedge, crucial for data analysis towards future detections.
