A Detection of Cosmological 21 cm Emission from CHIME in Cross-correlation with eBOSS Measurements of the Lyα Forest

Mandana Amiri; Kevin Bandura; Arnab Chakraborty; Matt Dobbs; Mateus Fandino; Simon Foreman; Hyoyin Gan; Mark Halpern; Alex S. Hill; Gary Hinshaw; Carolin Höfer; T. L. Landecker; Zack Li; Joshua MacEachern; Kiyoshi Masui; Juan Mena-Parra; Nikola Milutinovic; Arash Mirhosseini; Laura Newburgh; Anna Ordog; Sourabh Paul; Ue Li Pen; Tristan Pinsonneault-Marotte; Alex Reda; J. R. Shaw; Seth R. Siegel; Keith Vanderlinde; Haochen Wang; D. V. Wiebe; Dallas Wulf

doi:10.3847/1538-4357/ad0f1d

A Detection of Cosmological 21 cm Emission from CHIME in Cross-correlation with eBOSS Measurements of the Lyα Forest

Mandana Amiri, Kevin Bandura, Arnab Chakraborty, Matt Dobbs, Mateus Fandino, Simon Foreman, Hyoyin Gan, Mark Halpern, Alex S. Hill, Gary Hinshaw, Carolin Höfer, T. L. Landecker, Zack Li, Joshua MacEachern, Kiyoshi Masui, Juan Mena-Parra, Nikola Milutinovic, Arash Mirhosseini, Laura Newburgh, Anna OrdogSourabh Paul, Ue Li Pen, Tristan Pinsonneault-Marotte, Alex Reda, J. R. Shaw, Seth R. Siegel, Keith Vanderlinde, Haochen Wang, D. V. Wiebe, Dallas Wulf

Physics

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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.

Original language	English (US)
Article number	23
Journal	Astrophysical Journal
Volume	963
Issue number	1
DOIs	https://doi.org/10.3847/1538-4357/ad0f1d
State	Published - Mar 1 2024

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

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10.3847/1538-4357/ad0f1d

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Amiri, M., Bandura, K., Chakraborty, A., Dobbs, M., Fandino, M., Foreman, S., Gan, H., Halpern, M., Hill, A. S., Hinshaw, G., Höfer, C., Landecker, T. L., Li, Z., MacEachern, J., Masui, K., Mena-Parra, J., Milutinovic, N., Mirhosseini, A., Newburgh, L., ... Wulf, D. (2024). A Detection of Cosmological 21 cm Emission from CHIME in Cross-correlation with eBOSS Measurements of the Lyα Forest. Astrophysical Journal, 963(1), Article 23. https://doi.org/10.3847/1538-4357/ad0f1d

Amiri, M, Bandura, K, Chakraborty, A, Dobbs, M, Fandino, M, Foreman, S, Gan, H, Halpern, M, Hill, AS, Hinshaw, G, Höfer, C, Landecker, TL, Li, Z, MacEachern, J, Masui, K, Mena-Parra, J, Milutinovic, N, Mirhosseini, A, Newburgh, L, Ordog, A, Paul, S, Pen, UL, Pinsonneault-Marotte, T, Reda, A, Shaw, JR, Siegel, SR, Vanderlinde, K, Wang, H, Wiebe, DV & Wulf, D 2024, 'A Detection of Cosmological 21 cm Emission from CHIME in Cross-correlation with eBOSS Measurements of the Lyα Forest', Astrophysical Journal, vol. 963, no. 1, 23. https://doi.org/10.3847/1538-4357/ad0f1d

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title = "A Detection of Cosmological 21 cm Emission from CHIME in Cross-correlation with eBOSS Measurements of the Lyα Forest",

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.",

author = "Mandana Amiri and Kevin Bandura and Arnab Chakraborty and Matt Dobbs and Mateus Fandino and Simon Foreman and Hyoyin Gan and Mark Halpern and Hill, {Alex S.} and Gary Hinshaw and Carolin H{\"o}fer and Landecker, {T. L.} and Zack Li and Joshua MacEachern and Kiyoshi Masui and Juan Mena-Parra and Nikola Milutinovic and Arash Mirhosseini and Laura Newburgh and Anna Ordog and Sourabh Paul and Pen, {Ue Li} and Tristan Pinsonneault-Marotte and Alex Reda and Shaw, {J. R.} and Siegel, {Seth R.} and Keith Vanderlinde and Haochen Wang and Wiebe, {D. V.} and Dallas Wulf",

note = "Publisher Copyright: {\textcopyright} 2024. The Author(s). Published by the American Astronomical Society.",

year = "2024",

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doi = "10.3847/1538-4357/ad0f1d",

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T1 - A Detection of Cosmological 21 cm Emission from CHIME in Cross-correlation with eBOSS Measurements of the Lyα Forest

AU - Amiri, Mandana

AU - Bandura, Kevin

AU - Chakraborty, Arnab

AU - Dobbs, Matt

AU - Fandino, Mateus

AU - Foreman, Simon

AU - Gan, Hyoyin

AU - Halpern, Mark

AU - Hill, Alex S.

AU - Hinshaw, Gary

AU - Höfer, Carolin

AU - Landecker, T. L.

AU - Li, Zack

AU - MacEachern, Joshua

AU - Masui, Kiyoshi

AU - Mena-Parra, Juan

AU - Milutinovic, Nikola

AU - Mirhosseini, Arash

AU - Newburgh, Laura

AU - Ordog, Anna

AU - Paul, Sourabh

AU - Pen, Ue Li

AU - Pinsonneault-Marotte, Tristan

AU - Reda, Alex

AU - Shaw, J. R.

AU - Siegel, Seth R.

AU - Vanderlinde, Keith

AU - Wang, Haochen

AU - Wiebe, D. V.

AU - Wulf, Dallas

PY - 2024/3/1

Y1 - 2024/3/1

N2 - 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.

AB - 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.

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SN - 0004-637X

VL - 963

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 1

M1 - 23

ER -

A Detection of Cosmological 21 cm Emission from CHIME in Cross-correlation with eBOSS Measurements of the Lyα Forest

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