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Validation of the HERA Phase i Epoch of Reionization 21 cm Power Spectrum Software Pipeline

Published version
Peer-reviewed

Change log

Authors

Pascua, R 
Martinot, ZE 
Burba, J 

Abstract

We describe the validation of the HERA Phase I software pipeline by a series of modular tests, building up to an end-to-end simulation. The philosophy of this approach is to validate the software and algorithms used in the Phase I upper limit analysis on wholly synthetic data satisfying the assumptions of that analysis, not addressing whether the actual data meet these assumptions. We discuss the organization of this validation approach, the specific modular tests performed, and the construction of the end-to-end simulations. We explicitly discuss the limitations in scope of the current simulation effort. With mock visibility data generated from a known analytic power spectrum and a wide range of realistic instrumental effects and foregrounds, we demonstrate that the current pipeline produces power spectrum estimates that are consistent with known analytic inputs to within thermal noise levels (at the 2 sigma level) for k > 0.2 h/Mpc for both bands and fields considered. Our input spectrum is intentionally amplified to enable a strong `detection' at k ~0.2 h/Mpc -- at the level of ~25 sigma -- with foregrounds dominating on larger scales, and thermal noise dominating at smaller scales. Our pipeline is able to detect this amplified input signal after suppressing foregrounds with a dynamic range (foreground to noise ratio) of > 10^7. Our validation test suite uncovered several sources of scale-independent signal loss throughout the pipeline, whose amplitude is well-characterized and accounted for in the final estimates. We conclude with a discussion of the steps required for the next round of data analysis.

Description

Keywords

astro-ph.IM, astro-ph.IM

Journal Title

Astrophysical Journal

Conference Name

Journal ISSN

0004-637X
1538-4357

Volume Title

924

Publisher

American Astronomical Society
Sponsorship
National Science Foundation (NSF) (1636646)
National Science Foundation (NSF) (1836019)
Gordon and Betty Moore Foundation (GBMF) (N/A)
Australian Research Council Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D) (CE170100013)
INAF PRIN-SKA 2017 (1.05.01.88.04)
Ministero degli Affari Esteri della Cooperazione Internazionale—Direzione Generale per la Promozione del Sistema Paese Progetto di Grande Rilevanza (ZA18GR02)
National Research Foundation of South Africa (113121)
Royal Society and the Newton Fund (NA150184)
National Research Foundation of South Africa (103424)
European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (948764)
NSF AAPF (1701536)
MIT Pappalardo fellowship (N/A)
New Frontiers in Research Fund Exploration grant program, the Canadian Institute for Advanced Research (CIFAR) Azrieli Global Scholars program, a Natural Sciences and Engineering Research Council of C (N/A)
STFC Grant (ST/T000341/1)
New Frontiers in Research Fund Exploration (N/A)
Canadian Institute for Advanced Research (CIFAR) Azrieli Global Scholars (N/A)
Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery Grant and a Discovery Launch Supplement (N/A)
Sloan Fellowship (N/A)
William Dawson Scholarship (N/A)
South African Square Kilometre Array Project and National Research Foundation (84156)
NSF CAREER (1455151)