Bayesian estimation of cross-coupling and reflection systematics in 21cm array visibility data
Abstract
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.
Cite
@article{arxiv.2312.03697,
title = {Bayesian estimation of cross-coupling and reflection systematics in 21cm array visibility data},
author = {Geoff G. Murphy and Philip Bull and Mario G. Santos and Zara Abdurashidova and Tyrone Adams and James E. Aguirre and Paul Alexander and Zaki S. Ali and Rushelle Baartman and Yanga Balfour and Adam P. Beardsley and Gianni Bernardi and Tashalee Billings and Judd D. Bowman and Richard F. Bradley and Jacob Burba and Christopher Cain and Steven Carey and Chris L. Carilli and Carina Cheng and David R. DeBoer and Eloy de Lera Acedo and Matt Dexter and Joshua S. Dillon and Nico Eksteen and John Ely and Aaron Ewall-Wice and Nicolas Fagnoni and Randall Fritz and Steven R. Furlanetto and Kingsley Gale-Sides and Brian Glendenning and Deepthi Gorthi and Bradley Greig and Jasper Grobbelaar and Ziyaad Halday and Bryna J. Hazelton and Jacqueline N. Hewitt and Jack Hickish and Daniel C. Jacobs and Austin Julius and MacCalvin Kariseb and Nicholas S. Kern and Joshua Kerrigan and Piyanat Kittiwisit and Saul A. Kohn and Matthew Kolopanis and Adam Lanman and Paul La Plante and Adrian Liu and Anita Loots and David Harold Edward MacMahon and Lourence Malan and Cresshim Malgas and Keith Malgas and Bradley Marero and Zachary E. Martinot and Andrei Mesinger and Mathakane Molewa and Miguel F. Morales and Tshegofalang Mosiane and Steven G. Murray and Abraham R. Neben and Bojan Nikolic and Hans Nuwegeld and Aaron R. Parsons and Nipanjana Patra and Samantha Pieterse and Nima Razavi-Ghods and James Robnett and Kathryn Rosie and Peter Sims and Jackson Sipple and Craig Smith and Hilton Swarts and Nithyanandan Thyagarajan and Pieter van Wyngaarden and Peter K. G. Williams and Haoxuan Zheng},
journal= {arXiv preprint arXiv:2312.03697},
year = {2025}
}
Comments
22 pages, 15 figures, published in MNRAS