Exploring the consequences of chromatic data excision in 21-cm Epoch of Reionization power spectrum observations

Abstract

We explore how chromatic RFI flags affect 21-cm power spectrum measurements. We particularly study flags that are coarser than the analysis resolution. We find that such RFI flags produce excess power in the EoR window in much the same way as residual RFI. We use Fast Holographic Deconvolution (FHD) simulations to explain this as a result of chromatic disruptions in the interferometric sampling function of the array. We also use these simulations in conjunction with Error Propagated Power Spectrum with InterLeaved Observed Noise ($\epsilon$ppsilon) to show that without modifying current flagging strategies or implementing extremely accurate and complete foreground subtraction, 21-cm EoR experiments will fail to make a significant detection. As a mitigation strategy, we find that circumventing the chromatic structure altogether by flagging the entire analysis band when RFI is detected is simple to implement and highly successful. This demands a detection strategy with a low false positive rate in order to prevent excessive data loss.

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• Why and When to Expect Gaussian Error Distributions in Epoch of Reionization 21-cm Power Spectrum Measurements
• Sensitivity of Bayesian 21 cm power spectrum estimation to foreground model errors
• Deep learning approach for identification of HII regions during reionization in 21-cm observations -- III. image recovery
• 21 cm Intensity Mapping with the DSA-2000
• Detecting Cosmic 21 cm Global Signal Using an Improved Polynomial Fitting Algorithm
• Power spectrum multipoles and clustering wedges during the Epoch of Reionization