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Impact of instrument and data characteristics in the interferometric reconstruction of the 21 cm power spectrum

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

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.<br />Comment: 18 pages, 19 figures, accepted for publication in MNRAS

Details

Database :
arXiv
Publication Type :
Report
Accession number :
edsarx.2210.03721
Document Type :
Working Paper
Full Text :
https://doi.org/10.1093/mnras/stad090