Bibliographic Information: Pascua, R., Martinot, Z.E., Liu, A., Aguirre, J.E., Kern, N.S., Dillon, J.S., Wilensky, M.J., Fagnoni, N., Acedo, E.D.L., & DeBoer, D.R. (2024). A Generalized Method for Characterizing 21-cm Power Spectrum Signal Loss from Temporal Filtering of Drift-scanning Visibilities. [Preprint submitted to arXiv]. arXiv:2410.01872v1 [astro-ph.CO].
Research Objective: This paper aims to develop a generalized analytical framework for characterizing the signal loss incurred when applying linear time-based filters to 21-cm intensity mapping data from drift-scanning telescopes. The authors focus on applying this framework to fringe-rate filtering, a technique used to mitigate systematic effects in interferometric data.
Methodology: The authors utilize the m-mode formalism to analytically characterize the time-time covariance of interferometric visibilities. They derive an expression for the signal loss associated with a given linear filter based on the m-mode power spectrum. The authors validate their analytical predictions against a suite of Monte Carlo simulations designed to mimic realistic observing conditions for the Hydrogen Epoch of Reionization Array (HERA).
Key Findings: The authors demonstrate that their analytical formalism accurately predicts the signal loss due to fringe-rate filtering, showing excellent agreement with the Monte Carlo simulations. They find that the commonly used "instantaneous fringe-rate" model, which assumes that the time variability in the data is dominated by sources drifting through the interferometric fringe pattern, is insufficient for characterizing the signal loss for baselines with lengths comparable to the dish diameter.
Main Conclusions: The authors conclude that their m-mode-based signal loss formalism provides a more accurate and computationally efficient alternative to traditional Monte Carlo signal loss analyses for drift-scanning telescopes. They recommend that HERA, and other similar experiments, adopt this formalism when applying linear time-based filters to their data.
Significance: This research provides a crucial tool for analyzing data from current and future 21-cm intensity mapping experiments. By accurately characterizing and correcting for signal loss, astronomers can obtain more reliable power spectrum measurements, enabling more robust constraints on the physics of the Epoch of Reionization and Cosmic Dawn.
Limitations and Future Research: The paper primarily focuses on signal loss from statistically isotropic signals like the cosmological 21-cm signal. Future work could extend the formalism to account for signal loss from anisotropic foreground contamination. Additionally, exploring the application of this formalism to other time-based filtering techniques, such as optimal Wiener filtering, could be beneficial.
To Another Language
from source content
arxiv.org
Key Insights Distilled From
by Robert Pascu... at arxiv.org 10-04-2024
https://arxiv.org/pdf/2410.01872.pdfDeeper Inquiries