Calibration requirements for detecting the 21 cm epoch of reionization power spectrum and implications for the SKA

By N. Barry, Bryna J. Hazelton, Ian Sullivan, M. Morales, Jonathan C. Pober. 2016

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21 cm Epoch of Reionization observations promise to transform our understanding of galaxy formation, but these observations are impossible without unprecedented levels of instrument calibration. We present end-to-end simulations of a full EoR power spectrum analysis including all of the major components of a real data processing pipeline: models of astrophysical foregrounds and EoR signal, frequency-dependent instrument effects, sky-based antenna calibration, and the full PS analysis. This study reveals that traditional sky-based per-frequency antenna calibration can only be implemented in EoR measurement analyses if the calibration model is unrealistically accurate. For reasonable levels of catalog completeness, the calibration introduces contamination in otherwise foreground-free power spectrum modes, precluding a PS measurement. We explore the origin of this contamination and potential mitigation techniques. We show that there is a strong joint constraint on the precision of the calibration catalog and the inherent spectral smoothness of antennae, and that this has significant implications for the instrumental design of the SKA and other future EoR observatories.

Subfields: Aerospace Engineering, Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/47243049e0381229013e39cedb07f2ed94d69192

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Citations in the corpus

FIRST SEASON MWA EOR POWER SPECTRUM RESULTS AT REDSHIFT 7 (2016, background): “By reducing the number of free parameters in this step we increase our signal to noise on calibration solutions and avoid absorbing unmodeled confusion source flux density into our gain solutions which has been shown to contaminate the EoR window (Barry et al. 2016).”
Hydrogen Epoch of Reionization Array (HERA) (2016, background): “…challenge, all aspects of the experimental process must be refined and improved, spanning calibration (e.g., Zheng et al. 2014; Jacobs et al. 2016; Barry et al. 2016), handling foreground contamination (e.g., Moore et al. 2013; Thyagarajan et al. 2015b,a; Pober et al. 2016), and the…”
Upper Limits on the 21 cm Epoch of Reionization Power Spectrum from One Night with LOFAR (2017, background): “4) – causing calibration gain errors (e.g. Barry et al. 2016) –, or effects of thermal and ionospheric noise, and leverage (e.g. Patil et al. 2016).”
Improved upper limits on the 21 cm signal power spectrum of neutral hydrogen at z ≈ 9.1 from LOFAR (2020, background): “…source of noise can be mitigated by adequately enforcing spectrally smooth solutions, which has the combined benefit of reducing calibration errors, improving the convergence rate, and smoothing the remaining calibration errors along the frequency direction (Yatawatta 2015; Barry et al. 2016).”