A Comparative Analysis to Deal with Missing Spectral Information Caused by RFI in Cosmological H i 21 cm Observations

Abstract We investigate the effect of radio-frequency interference (RFI) excision in estimating cosmological H i 21 cm power spectrum. Flagging RFI-contaminated channels results a nonuniform sampling instrumental bandpass response. Hence, Fourier transformation visibilities from frequency to delay domain contaminates higher foreground-free modes, and separating spectrally fluctuating signal smooth foregrounds becomes challenging. have done comparative analysis between two algorithms, one-dimensional CLEAN least-squares spectral (LSSA), which been used widely solve this issue literature. test these algorithms using simulated SKA-1 Low observations presence different RFI flagging scenarios. find that, random data, both perform well can mitigate foreground leakage issue. But fails restrict periodic plus broadband gives an extra bias estimated However, LSSA for scenarios unbiased estimate also applied with upgraded GMRT found that give consistent realistic observed data set. This demonstrates effectiveness robustness spectrum sets affected by