{"about":{"site":"https://codewithpapers.app","non_affiliation":"Code with Papers and Syntology are not affiliated with, endorsed by, or sponsored by Papers with Code, Meta, or the pwc-archive mirror.","licence":"CC BY-SA 4.0","licence_url":"https://creativecommons.org/licenses/by-sa/4.0/legalcode","attribution":"https://codewithpapers.app/attribution","modified":"archive material modified by Syntology; see the attribution page"},"url":"/paper/paper-64-constraints-on-reionization-the-21cm","title":"PAPER-64 Constraints on Reionization: The 21cm Power Spectrum at z=8.4","arxiv_id":"1502.06016","date":"2015-02-20","proceeding":null,"authors":["Zaki S. Ali","Aaron R. Parsons","Haoxuan Zheng","Jonathan C. Pober","Adrian Liu","James E. Aguirre","Richard F. Bradley","Gianni Bernardi","Chris L. Carilli","Carina Cheng","David R. DeBoer","Matthew R. Dexter","Jasper Grobbelaar","Jasper Horrell","Daniel C. Jacobs","Pat Klima","David H. E. MacMahon","Matthys Maree","David F. Moore","Nima Razavi","Irina I. Stefan","William P. Walbrugh","Andre Walker"],"abstract":"In this paper, we report new limits on 21cm emission from cosmic reionization based on a 135-day observing campaign with a 64-element deployment of the Donald C. Backer Precision Array for Probing the Epoch of Reionization (PAPER) in South Africa. This work extends the work presented in Parsons et al. (2014) with more collecting area, a longer observing period, improved redundancy-based calibration, optimal fringe-rate filtering, and improved power-spectral analysis using optimal quadratic estimators. The result is a new $2\\sigma$ upper limit on $\\Delta^{2}(k)$ of (22.4 mK)$^2$ in the range $0.15 < k < 0.5h\\ {\\rm Mpc}^{-1}$ at $z = 8.4$. This represents a three-fold improvement over the previous best upper limit. As we discuss in more depth in a forthcoming paper (Pober et al. 2015, in prep), this upper limit supports and extends previous evidence against extremely cold reionization scenarios. We conclude with a discussion of implications for future 21cm reionization experiments, including the newly funded Hydrogen Epoch of Reionization Array (HERA). $\\textbf{The limits presented in this paper have been retracted: The erratum can be found in Appendix A.}$","url_abs":"http://arxiv.org/abs/1502.06016v3","url_pdf":"http://arxiv.org/pdf/1502.06016v3.pdf","source":{"archive":"pwc-archive (Hugging Face), CC BY-SA 4.0","snapshot":"2025-07-28","licence_url":"https://creativecommons.org/licenses/by-sa/4.0/legalcode","row_kind":"links_only","authors_date_abstract":"arXiv metadata, CC0 1.0 (https://info.arxiv.org/help/license), from the Kaggle arXiv metadata snapshot of 2026-09-12"},"code_links":[{"paper_slug":"paper-64-constraints-on-reionization-the-21cm","repo_url":"https://github.com/HERA-Team/omnical","is_official":0,"mentioned_in_paper":0,"mentioned_in_github":1,"framework":"none","reach":null}],"tasks":[],"methods":[],"datasets_introduced":[],"methods_introduced":[],"results":[],"syntology":{"syntology_url":null,"atlas_url":null,"mcp":null,"developers":"https://syntology.ai/developers"},"arxiv_metadata":null,"syntology_extracted_results":null}