THE HYDROGEN EPOCH of REIONIZATION ARRAY DISH. II. CHARACTERIZATION of SPECTRAL STRUCTURE with ELECTROMAGNETIC SIMULATIONS and ITS SCIENCE IMPLICATIONS

Aaron Ewall-Wice, Richard Bradley, David DeBoer, Jacqueline Hewitt, Aaron Parsons, James Aguirre, Zaki S. Ali, Judd Bowman, Carina Cheng, Abraham R. Neben, Nipanjana Patra, Nithyanandan Thyagarajan, Mariet Venter, Eloy De Lera Acedo, Joshua S. Dillon, Roger Dickenson, Phillip Doolittle, Dennis Egan, Mike Hedrick, Patricia KlimaSaul Kohn, Patrick Schaffner, John Shelton, Benjamin Saliwanchik, H. A. Taylor, Rusty Taylor, Max Tegmark, Butch Wirt

Research output: Contribution to journalArticlepeer-review

28 Scopus citations

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.

Original languageEnglish (US)
Article number196
JournalAstrophysical Journal
Volume831
Issue number2
DOIs
StatePublished - Nov 10 2016

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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