First Results from HERA Phase I: Upper Limits on the Epoch of Reionization 21 cm Power Spectrum
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Published:2022-02-01
Issue:2
Volume:925
Page:221
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ISSN:0004-637X
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Container-title:The Astrophysical Journal
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language:
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Short-container-title:ApJ
Author:
Abdurashidova Zara, Aguirre James E.ORCID, Alexander Paul, Ali Zaki S., Balfour Yanga, Beardsley Adam P.ORCID, Bernardi GianniORCID, Billings Tashalee S., Bowman Judd D.ORCID, Bradley Richard F., Bull PhilipORCID, Burba Jacob, Carey Steve, Carilli Chris L.ORCID, Cheng Carina, DeBoer David R.ORCID, Dexter Matt, de Lera Acedo Eloy, Dibblee-Barkman Taylor, Dillon Joshua S.ORCID, Ely John, Ewall-Wice AaronORCID, Fagnoni Nicolas, Fritz Randall, Furlanetto Steven R.ORCID, Gale-Sides Kingsley, Glendenning Brian, Gorthi DeepthiORCID, Greig BradleyORCID, Grobbelaar Jasper, Halday Ziyaad, Hazelton Bryna J.ORCID, Hewitt Jacqueline N., Hickish Jack, Jacobs Daniel C.ORCID, Julius Austin, Kern Nicholas S.ORCID, Kerrigan JoshuaORCID, Kittiwisit PiyanatORCID, Kohn Saul A.ORCID, Kolopanis MatthewORCID, Lanman Adam, La Plante Paul, Lekalake Telalo, Lewis David, Liu AdrianORCID, MacMahon David, Malan Lourence, Malgas Cresshim, Maree Matthys, Martinot Zachary E., Matsetela Eunice, Mesinger AndreiORCID, Molewa Mathakane, Morales Miguel F.ORCID, Mosiane Tshegofalang, Murray Steven G.ORCID, Neben Abraham R.ORCID, Nikolic Bojan, Nunhokee Chuneeta D.ORCID, Parsons Aaron R., Patra NipanjanaORCID, Pascua Robert, Pieterse Samantha, Pober Jonathan C.ORCID, Razavi-Ghods Nima, Ringuette Jon, Robnett James, Rosie Kathryn, Sims PeterORCID, Singh SaurabhORCID, Smith Craig, Syce Angelo, Thyagarajan NithyanandanORCID, Williams Peter K. G.ORCID, Zheng Haoxuan
Abstract
Abstract
We report upper limits on the Epoch of Reionization 21 cm power spectrum at redshifts 7.9 and 10.4 with 18 nights of data (∼36 hr of integration) from Phase I of the Hydrogen Epoch of Reionization Array (HERA). The Phase I data show evidence for systematics that can be largely suppressed with systematic models down to a dynamic range of ∼109 with respect to the peak foreground power. This yields a 95% confidence upper limit on the 21 cm power spectrum of
Δ
21
2
≤
(
30.76
)
2
mK
2
at k = 0.192 h Mpc−1 at z = 7.9, and also
Δ
21
2
≤
(
95.74
)
2
mK
2
at k = 0.256 h Mpc−1 at z = 10.4. At z = 7.9, these limits are the most sensitive to date by over an order of magnitude. While we find evidence for residual systematics at low line-of-sight Fourier k
∥ modes, at high k
∥ modes we find our data to be largely consistent with thermal noise, an indicator that the system could benefit from deeper integrations. The observed systematics could be due to radio frequency interference, cable subreflections, or residual instrumental cross-coupling, and warrant further study. This analysis emphasizes algorithms that have minimal inherent signal loss, although we do perform a careful accounting in a companion paper of the small forms of loss or bias associated with the pipeline. Overall, these results are a promising first step in the development of a tuned, instrument-specific analysis pipeline for HERA, particularly as Phase II construction is completed en route to reaching the full sensitivity of the experiment.
Publisher
American Astronomical Society
Subject
Space and Planetary Science,Astronomy and Astrophysics
Cited by
75 articles.
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