Mitigating calibration errors from mutual coupling with time-domain filtering of 21 cm cosmological radio observations
Abstract
The 21 cm transition from neutral Hydrogen promises to be the best observational probe of the Epoch of Reionisation (EoR). This has led to the construction of low-frequency radio interferometric arrays, such as the Hydrogen Epoch of Reionization Array (HERA), aimed at systematically mapping this emission for the first time. Precision calibration, however, is a requirement in 21 cm radio observations. Due to the spatial compactness of HERA, the array is prone to the effects of mutual coupling, which inevitably lead to non-smooth calibration errors that contaminate the data. When unsmooth gains are used in calibration, intrinsically spectrally-smooth foreground emission begins to contaminate the data in a way that can prohibit a clean detection of the cosmological EoR signal. In this paper, we show that the effects of mutual coupling on calibration quality can be reduced by applying custom time-domain filters to the data prior to calibration. We find that more robust calibration solutions are derived when filtering in this way, which reduces the observed foreground power leakage. Specifically, we find a reduction of foreground power leakage by 2 orders of magnitude at k=0.5.
Cite
@article{arxiv.2407.20923,
title = {Mitigating calibration errors from mutual coupling with time-domain filtering of 21 cm cosmological radio observations},
author = {N. Charles and N. S. Kern and R. Pascua and G. Bernardi and L. Bester and O. Smirnov and E. d. L. Acedo and Z. Abdurashidova and T. Adams and J. E. Aguirre and R. Baartman and A. P. Beardsley and L. M. Berkhout and T. S. Billings and J. D. Bowman and P. Bull and J. Burba and R. Byrne and S. Carey and K. Chen and S. Choudhuri and T. Cox and D. R. DeBoer and M. Dexter and J. S. Dillon and S. Dynes and N. Eksteen and J. Ely and A. Ewall-Wice and R. Fritz and S. R. Furlanetto and K. Gale-Sides and H. Garsden and B. K. Gehlot and A. Ghosh and A. Gorce and D. Gorthi and Z. Halday and B. J. Hazelton and J. N. Hewitt and J. Hickish and T. Huang and D. C. Jacobs and A. Josaitis and J. Kerrigan and P. Kittiwisit and M. Kolopanis and A. Lanman and A. Liu and Y. -Z. Ma and D. H. E. MacMahon and L. Malan and K. Malgas and C. Malgas and B. Marero and Z. E. Martinot and L. McBride and A. Mesinger and N. Mohamed-Hinds and M. Molewa and M. F. Morales and S. Murray and B. Nikolic and H. Nuwegeld and A. R. Parsons and N. Patra and P. L. Plante and Y. Qin and E. Rath and N. Razavi-Ghods and D. Riley and J. Robnett and K. Rosie and M. G. Santos and P. Sims and S. Singh and D. Storer and H. Swarts and J. Tan and M. J. Wilensky and P. K. G. Williams and P. v. Wyngaarden and H. Zheng},
journal= {arXiv preprint arXiv:2407.20923},
year = {2024}
}