Accounting for Noise and Singularities in Bayesian Calibration Methods for Global 21-cm Cosmology Experiments

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• Christian Kirkham (University of Cambridge)
• Tuesday 18 February 2025, 11:15-12:00
• Coffee area, Battcock Centre.

If you have a question about this talk, please contact Charles Walker.

Due to the large dynamic ranges involved with separating the cosmological 21-cm signal from the Cosmic Dawn from galactic foregrounds, a well-calibrated instrument is essential to avoid biases from instrumental systematics. In this talk I will present three methods for calibrating a global 21-cm cosmology experiment to characterise the low noise amplifier with a careful consideration of how calibrator temperature noise and singularities will bias your fit. Running these methods on a suite of simulated datasets based on the REACH receiver design and a lab dataset, our methods produce a calibrated antenna solution which is equally as or more accurate than the existing conjugate priors method when compared with an analytic estimate of the calibrator’s noise. For lab data I will show that we can calibrate the antenna spectra to within 5\% of the noise floor.

This talk is part of the Hills Coffee Talks series.

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