Delay-Weighted Calibration: Precision Calibration for 21 cm Cosmology with Resilience to Sky Model Error

TL;DR

Delay-Weighted Calibration (DWCal) improves 21 cm cosmology calibration accuracy by focusing on error-free modes, significantly reducing calibration errors caused by sky model inaccuracies and enhancing power spectrum sensitivity.

Contribution

The paper introduces DWCal, a novel calibration method that mitigates sky model error effects, enabling more precise calibration in 21 cm cosmology experiments.

Findings

DWCal reduces calibration error in simulated data with sky model errors.

DWCal improves 21 cm power spectrum sensitivity by about 100 times.

The method selectively fits calibration solutions from error-free modes.

Abstract

One of the principal challenges of 21 cm cosmology experiments is overcoming calibration error. Established calibration approaches in the field require an exquisitely accurate sky model, and low-level sky model errors introduce calibration errors that corrupt the cosmological signal. We present a novel calibration approach called Delay-Weighted Calibration, or DWCal, that enables precise calibration even in the presence of sky model error. Sky model error does not affect all power spectrum modes equally, and DWCal fits calibration solutions preferentially from error-free modes. We apply this technique to simulated data, showing that it substantially reduces calibration error in the presence of realistic levels of sky model error and can improve 21 cm power spectrum sensitivity by approximately 2 orders of magnitude.