The hydrogen epoch of reionization array dish. II. Characterization of spectral structure with electromagnetic simulations and its science implications
Name
Ewall-Wice-2016-The Hydrogen Epoch of Reioniza.pdf
Size
2.08 MB
Format
Adobe PDF
Checksum (MD5)
ae84d955f6b3f8929bc3301f1d2eda33
Author(s)
Bradley, Richard
Deboer, David
Parsons, Aaron
Aguirre, James
Ali, Zaki S.
Bowman, Judd
Cheng, Carina
Patra, Nipanjana
Thyagarajan, Nithyanandan
Venter, Mariet
Date Issued
November 2016
Journal
Astrophysical Journal
Publisher
IOP Publishing
Citation
Ewall-Wice, Aaron, Richard Bradley, David Deboer, Jacqueline Hewitt, Aaron Parsons, James Aguirre, Zaki S. Ali, et al. “THE HYDROGEN EPOCH OF REIONIZATION ARRAY DISH. II. CHARACTERIZATION OF SPECTRAL STRUCTURE WITH ELECTROMAGNETIC SIMULATIONS AND ITS SCIENCE IMPLICATIONS.” The Astrophysical Journal 831, no. 2 (November 9, 2016): 196. © 2016 The American Astronomical Society
Version
Final published version
Abstract
We use time-domain electromagnetic simulations to determine the spectral characteristics of the Hydrogen Epoch of Reionization Arrays (HERA) antenna. These simulations are part of a multi-faceted campaign to determine the effectiveness of the dish's design for obtaining a detection of redshifted 21 cm emission from the epoch of reionization. Our simulations show the existence of reflections between HERA's suspended feed and its parabolic dish reflector that fall below −40 dB at 150 ns and, for reasonable impedance matches, have a negligible impact on HERA's ability to constrain EoR parameters. It follows that despite the reflections they introduce, dishes are effective for increasing the sensitivity of EoR experiments at a relatively low cost. We find that electromagnetic resonances in the HERA feed's cylindrical skirt, which is intended to reduce cross coupling and beam ellipticity, introduces significant power at large delays (−40 dB at 200 ns), which can lead to some loss of measurable Fourier modes and a modest reduction in sensitivity. Even in the presence of this structure, we find that the spectral response of the antenna is sufficiently smooth for delay filtering to contain foreground emission at line-of-sight wave numbers below k ∥ ≲ 0.2 h Mpc⁻¹, in the region where the current PAPER experiment operates. Incorporating these results into a Fisher Matrix analysis, we find that the spectral structure observed in our simulations has only a small effect on the tight constraints HERA can achieve on parameters associated with the astrophysics of reionization.
MIT Department
Massachusetts Institute of Technology. Department of Physics
Terms of Use
Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
Persistent DSpace Link
DOI of Published Version
https://doi.org/10.3847/0004-637X/831/2/196
