Impact of instrument and data characteristics in the interferometric reconstruction of the 21 cm power spectrum
Creators: name: Gorce, Adélie
name: Ganjam, Samskruthi
name: Liu, Adrian
name: Murray, Steven G.
name: Abdurashidova, Zara
name: Adams, Tyrone
name: Aguirre, James E.
name: Alexander, Paul
name: Ali, Zaki S.
name: Baartman, Rushelle
name: Balfour, Yanga
name: Beardsley, Adam P.
name: Bernardi, Gianni
name: Billings, Tashalee S.
name: Bowman, Judd D.
name: Bradley, Richard F.
name: Bull, Philip
name: Burba, Jacob
name: Carey, Steven
name: Carilli, Chris L.
name: Cheng, Carina
name: DeBoer, David R.
name: Acedo, Eloy de Lera
name: Dexter, Matt
name: Dillon, Joshua S.
name: Eksteen, Nico
name: Ely, John
name: Ewall-Wice, Aaron
name: Fagnoni, Nicolas
name: Fritz, Randall
name: Furlanetto, Steven R.
name: Gale-Sides, Kingsley
name: Glendenning, Brian
name: Gorthi, Deepthi
name: Greig, Bradley
name: Grobbelaar, Jasper
name: Halday, Ziyaad
name: Hazelton, Bryna J.
name: Hewitt, Jacqueline N.
name: Hickish, Jack
name: Jacobs, Daniel C.
name: Julius, Austin
name: Kariseb, MacCalvin
name: Kern, Nicholas S.
name: Kerrigan, Joshua
name: Kittiwisit, Piyanat
name: Kohn, Saul A.
name: Kolopanis, Matthew
name: Lanman, Adam
name: La Plante, Paul
name: Loots, Anita
name: MacMahon, David Harold Edward
name: Malan, Lourence
name: Malgas, Cresshim
name: Malgas, Keith
name: Marero, Bradley
name: Martinot, Zachary E.
name: Mesinger, Andrei
name: Molewa, Mathakane
name: Morales, Miguel F.
name: Mosiane, Tshegofalang
name: Neben, Abraham R.
name: Nikolic, Bojan
name: Nuwegeld, Hans
name: Parsons, Aaron R.
name: Patra, Nipanjana
name: Pieterse, Samantha
name: Pober, Jonathan C.
name: Razavi-Ghods, Nima
name: Robnett, James
name: Rosie, Kathryn
name: Sims, Peter
name: Smith, Craig
name: Swarts, Hilton
name: Thyagarajan, Nithyanandan
name: van Wyngaarden, Pieter
name: Williams, Peter K. G.
name: Zheng, Haoxuan
Publisher: name: arXiv
Year: 2022
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: 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.
description: 18 pages, 19 figures, accepted for publication in MNRAS