Kavli Affiliate: Jacqueline N. Hewitt
| First 5 Authors: Kai-Feng Chen, Michael J. Wilensky, Adrian Liu, Joshua S. Dillon, Jacqueline N. Hewitt
| Summary:
The precise characterization and mitigation of systematic effects is one of
the biggest roadblocks impeding the detection of the fluctuations of
cosmological 21cm signals. Missing data in radio cosmological experiments,
often due to radio frequency interference (RFI), poses a particular challenge
to power spectrum analysis as it could lead to the ringing of bright foreground
modes in Fourier space, heavily contaminating the cosmological signals. Here we
show that the problem of missing data becomes even more arduous in the presence
of systematic effects. Using a realistic numerical simulation, we demonstrate
that partially flagged data combined with systematic effects can introduce
significant foreground ringing. We show that such an effect can be mitigated
through inpainting the missing data. We present a rigorous statistical
framework that incorporates the process of inpainting missing data into a
quadratic estimator of the 21cm power spectrum. Under this framework, the
uncertainties associated with our inpainting method and its impact on power
spectrum statistics can be understood. These results are applied to the latest
Phase II observations taken by the Hydrogen Epoch of Reionization Array,
forming a crucial component in power spectrum analyses as we move toward
detecting 21cm signals in the ever more noisy RFI environment.
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