A study of satellite contamination for single dish Hi intensity mapping with MeerKAT
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Date
2025
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University of the Western Cape
Abstract
HI Intensity Mapping is a novel technique that involves detecting the 21 cm emission lines from a large sky area without resolving individual sources, which proves to be a powerful probe for large scale structure cosmology. However, due to the weak nature of the 21 cm line, the majority of the received signal is dominated by astrophysical foregrounds and instrumental systematics that are several orders of magnitude stronger than the HI signal. Therefore, it becomes essential to mitigate these foregrounds and study their properties with respect to parameters such as frequency, scale, and redshift. The data used for this work has been obtained from the MeerKAT pilot survey which was collected from 62 hours of observation using the MeerKAT telescope’s 64 dish array in single dish mode. In this work, we attempt to use the higher L-Band frequency data (1300 - 1500 MHz) and understand the foreground behavior at higher frequencies. We use a foreground removal pipeline used for previous works with the lower L-band frequencies and make additions to it which allow us to identify and remove lowlevel RFI from the data and also compare the noise level estimates with theoretical values. We present the final results in the form of 1D power spectra and residual maps that indicate a decrease in amplitude due to the removal of foregrounds. We also conclude that the noise levels for most of the frequencies are higher than their theoretical estimates, which can be attributed to the presence of low-level contamination still be present in the dataset. Moreover, we conclude that the combined band results show noise levels an order of magnitude higher than individual bands, possibly due to cross-contamination between the foregrounds leading to a more complex structure.
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Keywords
HI Intensity Mapping, novel technique, emission lines, structure cosmology, MeerKAT