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A detection of cosmological 21 cm emission from CHIME in cross-correlation with eBOSS measurements of the Lyα forest

From National Research Council Canada

DOIResolve DOI: https://doi.org/10.3847/1538-4357/ad0f1d
AuthorSearch for: ORCID identifier: https://orcid.org/0000-0001-6523-9029; Search for: ORCID identifier: https://orcid.org/0000-0003-3772-2798; Search for: ORCID identifier: https://orcid.org/0000-0002-7758-9859; Search for: ORCID identifier: https://orcid.org/0000-0001-7166-6422; Search for: ORCID identifier: https://orcid.org/0000-0002-6899-1176; Search for: ORCID identifier: https://orcid.org/0000-0002-0190-2271; Search for: ORCID identifier: https://orcid.org/0000-0002-4903-838X; Search for: ORCID identifier: https://orcid.org/0000-0002-1760-0868; Search for: 1ORCID identifier: https://orcid.org/0000-0001-7301-5666; Search for: ORCID identifier: https://orcid.org/0000-0002-4241-8320; Search for: ORCID identifier: https://orcid.org/0000-0003-4887-8114; Search for: 1ORCID identifier: https://orcid.org/0000-0003-1455-2546; Search for: ORCID identifier: https://orcid.org/0000-0002-0309-9750; Search for: ORCID identifier: https://orcid.org/0000-0001-8064-6116; Search for: ORCID identifier: https://orcid.org/0000-0002-4279-6946; Search for: ORCID identifier: https://orcid.org/0000-0002-0772-9326; Search for: ORCID identifier: https://orcid.org/0000-0001-8292-0051; Search for: ORCID identifier: https://orcid.org/0000-0002-2626-5985; Search for: ORCID identifier: https://orcid.org/0000-0002-7333-5552; Search for: 1ORCID identifier: https://orcid.org/0000-0002-2465-8937; Search for: ORCID identifier: https://orcid.org/0000-0002-8671-2177; Search for: ORCID identifier: https://orcid.org/0000-0003-2155-9578; Search for: ORCID identifier: https://orcid.org/0000-0002-9516-3245; Search for: ORCID identifier: https://orcid.org/0000-0001-6967-7253; Search for: ORCID identifier: https://orcid.org/0000-0002-4543-4588; Search for: ORCID identifier: https://orcid.org/0000-0003-2631-6217; Search for: ORCID identifier: https://orcid.org/0000-0003-4535-9378; Search for: ORCID identifier: https://orcid.org/0000-0002-1491-3738; Search for: ORCID identifier: https://orcid.org/0000-0002-6669-3159; Search for: ORCID identifier: https://orcid.org/0000-0001-7314-9496
Affiliation
  1. National Research Council Canada. Herzberg Astronomy and Astrophysics
FunderSearch for: Canada Foundation for Innovation
FormatText, Article
Subjectcosmology; H I line emission; Lyα forest; power spectra; intergalactic medium; reionizatioon
Abstract
We report the detection of 21 cm emission at an average redshift z ≈ 2.3 in the cross-correlation of data from the Canadian Hydrogen Intensity Mapping Experiment (CHIME) with measurements of the Lyα forest from eBOSS. Data collected by CHIME over 88 days in the 400–500 MHz frequency band (1.8 < z < 2.5) are formed into maps of the sky and high-pass delay filtered to suppress the foreground power, corresponding to removing cosmological scales with k∥ ≲ 0.13 Mpc⁻¹ at the average redshift. Line-of-sight spectra to the eBOSS background quasar locations are extracted from the CHIME maps and combined with the Lyα forest flux transmission spectra to estimate the 21 cm-Lyα cross-correlation function. Fitting a simulation-derived template function to this measurement results in a 9σ detection significance. The coherent accumulation of the signal through cross-correlation is sufficient to enable a detection despite excess variance from foreground residuals ~6–10 times brighter than the expected thermal noise level in the correlation function. These results are the highest-redshift measurement of 21 cm emission to date, and they set the stage for future 21 cm intensity mapping analyses at z > 1.8.
Publication date
PublisherAmerican Astronomical Society
In
  • The Astrophysical Journal 963, no. 1, 23 (23 February 2024): 1–11.
LanguageEnglish
Peer reviewedYes
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Record identifiercb36859d-6202-4461-b85d-8a131ebd47f3
Record created2024-08-12
Record modified2024-08-12
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