Impact of instrument and data characteristics in the interferometric reconstruction of the 21 cm power spectrum
Year: 2023
Type: article
Abstract: ABSTRACT Combining the visibilities measured by an interferometer to form a cosmological power spectrum is a complicated process. In a delay-based analysis, the mapping between instrumental and cosmological space is not a one-to-one relation. Instead, neighbouring modes contribute to the power measured at one point, with their respective contributions encoded in the window functions. To better understand the power measured by an interferometer, we assess the impact of instrument characteristics and analysis choices on these window functions. Focusing on the Hydrogen Epoch of Reionization Array (HERA) as a case study, we find that long-baseline observations correspond to enhanced low-k tails of the window functions, which facilitate foreground leakage, whilst an informed choice of bandwidth and frequency taper can reduce said tails. With simple test cases and realistic simulations, we show that, apart from tracing mode mixing, the window functions help accurately reconstruct the power spectrum estimator of simulated visibilities. The window functions depend strongly on the beam chromaticity and less on its spatial structure – a Gaussian approximation, ignoring side lobes, is sufficient. Finally, we investigate the potential of asymmetric window functions, down-weighting the contribution of low-k power to avoid foreground leakage. The window functions presented here correspond to the latest HERA upper limits for the full Phase I data. They allow an accurate reconstruction of the power spectrum measured by the instrument and will be used in future analyses to confront theoretical models and data directly in cylindrical space.
Authors: Adélie Gorce, Samskruthi Ganjam, Adrian Liu, Steven G Murray, Zara Abdurashidova, Tyrone Adams, James E Aguirre, Paul Alexander, Zaki S Ali, Rushelle Baartman, Yanga Balfour, Adam P Beardsley, Gianni Bernardi, Tashalee S Billings, Judd D Bowman, Richard F Bradley, Philip Bull, Jacob Burba, Steven Carey, Chris L Carilli, Carina Cheng, David R DeBoer, Eloy de Lera Acedo, Matt Dexter, Joshua S Dillon, Nico Eksteen, John Ely, Aaron Ewall-Wice, Nicolas Fagnoni, Randall Fritz, Steven R Furlanetto, Kingsley Gale-Sides, Brian Glendenning, Deepthi Gorthi, Bradley Greig, Jasper Grobbelaar, Ziyaad Halday, Bryna J Hazelton, Jacqueline N Hewitt, Jack Hickish, Daniel C Jacobs, Austin Julius, MacCalvin Kariseb, Nicholas S Kern, Joshua Kerrigan, Piyanat Kittiwisit, Saul A Kohn, Matthew Kolopanis, Adam Lanman, Paul La Plante, Anita Loots, David Harold Edward MacMahon, Lourence Malan, Cresshim Malgas, Keith Malgas, Bradley Marero, Zachary E Martinot, Andrei Mesinger, Mathakane Molewa, Miguel F Morales, Tshegofalang Mosiane, Abraham R Neben, Bojan Nikolic, Hans Nuwegeld, Aaron R Parsons, Nipanjana Patra, Samantha Pieterse, Jonathan C Pober, Nima Razavi-Ghods, James Robnett, Kathryn Rosie, Peter Sims, Hilton Swarts, Nithyanandan Thyagarajan, Pieter van Wyngaarden, Peter K G Williams, Haoxuan Zheng
Institutions: Trottier Space Institute at McGill, McGill University, Arizona State University, University of California, Berkeley, South African Radio Astronomy Observatory, University of Pennsylvania, University of Cambridge, Winona State University, Rhodes University, Istituto di Radioastronomia di Bologna, National Institute for Astrophysics, National Radio Astronomy Observatory, University of Manchester, University of the Western Cape, Brown University, University of California, Los Angeles, The University of Melbourne, University of Washington, Massachusetts Institute of Technology, University of Nevada, Las Vegas, Scuola Normale Superiore, Commonwealth Scientific and Industrial Research Organisation, American Astronomical Society, Center for Astrophysics Harvard & Smithsonian
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funders: National Science Foundation, Gordon and Betty Moore Foundation, Massachusetts Institute of Technology, Canadian Institute for Advanced Research, McGill University, European Commission, National Research Foundation, Natural Sciences and Engineering Research Council of Canada, Science and Technology Facilities Council
Awards: HERA: Unveiling the Cosmic Dawn, G1568714346, Astronomy Research at Queen Mary 2020 - 2023, G3049033505, Astrophysics and Cosmology Research at the JBCA 2020-2023, G434337789, Astronomy Research at Queen Mary, Illuminating our Early Universe with HERA, the Hydrogen Epoch of Reionization Array
OpenAlex ID: W4315784029