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arXiv · 2302.07969

Search for the Epoch of Reionisation with HERA: Upper Limits on the Closure Phase Delay Power Spectrum

Pascal M. Keller·Bojan Nikolic·Nithyanandan Thyagarajan·Chris L. Carilli·Gianni Bernardi·Ntsikelelo Charles·Landman Bester·Oleg M. Smirnov·Nicholas S. Kern·Joshua S. Dillon·Bryna J. Hazelton·Miguel F. Morales·Daniel C. Jacobs·Aaron R. Parsons·Zara Abdurashidova·Tyrone Adams·James E. Aguirre·Paul Alexander·Zaki S. Ali·Rushelle Baartman·Yanga Balfour·Adam P. Beardsley·Tashalee S. Billings·Judd D. Bowman·Richard F. Bradley·Philip Bull·Jacob Burba·Steven Carey·Carina Cheng·David R. DeBoer·Eloy de Lera Acedo·Matt Dexter·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·Jacqueline N. Hewitt·Jack Hickish·Austin Julius·MacCalvin Kariseb·Joshua Kerrigan·Piyanat Kittiwisit·Saul A. Kohn·Matthew Kolopanis·Adam Lanman·Paul La Plante·Adrian Liu·Anita Loots·Yin-Zhe Ma·David Harold Edward MacMahon·Lourence Malan·Cresshim Malgas·Keith Malgas·Bradley Marero·Zachary E. Martinot·Andrei Mesinger·Mathakane Molewa·Tshegofalang Mosiane·Steven G. Murray·Abraham R. Neben·Hans Nuwegeld·Robert Pascua·Nipanjana Patra·Samantha Pieterse·Jonathan C. Pober·Nima Razavi-Ghods·James Robnett·Kathryn Rosie·Mario G. Santos·Peter Sims·Craig Smith·Hilton Swarts·Pieter Van Wyngaarden·Peter K. G. Williams·Haoxuan Zheng
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Abstract

Radio interferometers aiming to measure the power spectrum of the redshifted 21 cm line during the Epoch of Reionisation (EoR) need to achieve an unprecedented dynamic range to separate the weak signal from overwhelming foreground emissions. Calibration inaccuracies can compromise the sensitivity of these measurements to the effect that a detection of the EoR is precluded. An alternative to standard analysis techniques makes use of the closure phase, which allows one to bypass antenna-based direction-independent calibration. Similarly to standard approaches, we use a delay spectrum technique to search for the EoR signal. Using 94 nights of data observed with Phase I of the Hydrogen Epoch of Reionization Array (HERA), we place approximate constraints on the 21 cm power spectrum at $z=7.7$. We find at 95% confidence that the 21 cm EoR brightness temperature is $\le$(372)$^2$ "pseudo" mK$^2$ at 1.14 "pseudo" $h$ Mpc$^{-1}$, where the "pseudo" emphasises that these limits are to be interpreted as approximations to the actual distance scales and brightness temperatures. Using a fiducial EoR model, we demonstrate the feasibility of detecting the EoR with the full array. Compared to standard methods, the closure phase processing is relatively simple, thereby providing an important independent check on results derived using visibility intensities, or related.

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Pascal M. Keller, Bojan Nikolic, Nithyanandan Thyagarajan, Chris L. Carilli, Gianni Bernardi, Ntsikelelo Charles, Landman Bester, Oleg M. Smirnov, Nicholas S. Kern, Joshua S. Dillon, Bryna J. Hazelton, Miguel F. Morales, Daniel C. Jacobs, Aaron R. Parsons, Zara Abdurashidova, Tyrone Adams, James E. Aguirre, Paul Alexander, Zaki S. Ali, Rushelle Baartman, Yanga Balfour, Adam P. Beardsley, Tashalee S. Billings, Judd D. Bowman, Richard F. Bradley, Philip Bull, Jacob Burba, Steven Carey, Carina Cheng, David R. DeBoer, Eloy de Lera Acedo, Matt Dexter, 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, Jacqueline N. Hewitt, Jack Hickish, Austin Julius, MacCalvin Kariseb, Joshua Kerrigan, Piyanat Kittiwisit, Saul A. Kohn, Matthew Kolopanis, Adam Lanman, Paul La Plante, Adrian Liu, Anita Loots, Yin-Zhe Ma, David Harold Edward MacMahon, Lourence Malan, Cresshim Malgas, Keith Malgas, Bradley Marero, Zachary E. Martinot, Andrei Mesinger, Mathakane Molewa, Tshegofalang Mosiane, Steven G. Murray, Abraham R. Neben, Hans Nuwegeld, Robert Pascua, Nipanjana Patra, Samantha Pieterse, Jonathan C. Pober, Nima Razavi-Ghods, James Robnett, Kathryn Rosie, Mario G. Santos, Peter Sims, Craig Smith, Hilton Swarts, Pieter Van Wyngaarden, Peter K. G. Williams, Haoxuan Zheng. 2023-02-15. Search for the Epoch of Reionisation with HERA: Upper Limits on the Closure Phase Delay Power Spectrum. https://doi.org/10.1093/mnras%2Fstad371

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