Kavli Affiliate: Jacqueline N. Hewitt
| First 5 Authors: Geoff G. Murphy, Philip Bull, Mario G. Santos, Zara Abdurashidova, Tyrone Adams
| Summary:
Observations with radio arrays that target the 21-cm signal originating from
the early Universe suffer from a variety of systematic effects. An important
class of these are reflections and spurious couplings between antennas. We
apply a Hamiltonian Monte Carlo sampler to the modelling and mitigation of
these systematics in simulated Hydrogen Epoch of Reionisation Array (HERA)
data. This method allows us to form statistical uncertainty estimates for both
our models and the recovered visibilities, which is an important ingredient in
establishing robust upper limits on the Epoch of Reionisation (EoR) power
spectrum. In cases where the noise is large compared to the EoR signal, this
approach can constrain the systematics well enough to mitigate them down to the
noise level for both systematics studied. Incoherently averaging the recovered
power spectra can further reduce the noise and improve recovery. Where the
noise level is lower than the EoR, our modelling can mitigate the majority of
the reflections and coupling with there being only a minor level of residual
systematics. Our approach performs similarly to existing filtering/fitting
techniques used in the HERA pipeline, but with the added benefit of rigorously
propagating uncertainties. In all cases it does not significantly attenuate the
underlying signal.
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