Work

Bayesian power spectrum estimation with modelling of systematic effects in delay-fringe rate space

Year: 2026

Type: article

Abstract: ABSTRACT Observing the Epoch of Reionization using 21 cm radio interferometry has proven to be a challenging task. Extraction of the extremely faint redshifted signal is complicated by the presence of bright foregrounds, radiofrequency interference, and systematic artefacts. We discuss the challenge of accounting for systematic effects, particularly cable reflections, that appear in the visibility data obtained from 21 cm interferometers. Cable reflections cause attenuated copies of the foreground signal to appear outside the ‘foreground wedge’ region in which foreground contamination is supposed to be localized. We build on the hydra-pspec Gibbs sampler to implement a model of the systematics as a multiplicative effect in delay-fringe rate space. We include this model in the inference of the joint posterior distribution, in addition to the 21 cm signal, its power spectrum, and foregrounds. This allows the systematics contribution to be marginalized, rather than filtering it out and causing additional signal loss. We demonstrate the method on simulated visibility data for a single baseline, showing that the 21 cm delay power spectrum can be recovered well regardless of the location of the systematics in delay-fringe rate space. Our implementation is suitable for modelling other multiplicative factors on the visibilities, e.g. residual gain errors.

Source: RAS Techniques and Instruments

DOI: 10.1093/rasti/rzag074

Authors: Sohini Dutta, Philip Bull, Jacob Burba, Michael J Wilensky, Zheng Zhang, Ainulnabilah Nasirudin

Institutions: University of Manchester, University of the Western Cape, Trottier Space Institute at McGill, McGill University

Language: English

Topic: Radio Astronomy Observations and Technology

Subfield: Astronomy and Astrophysics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $1,732

Funder: European Commission