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Peer-reviewedCC BY 4.0The Astrophysical Journal Letters

Unveiling the Dark Ages: A New Pathway Using Tomographical 21 cm Cosmic Microwave Background Cross-correlations

  • Joshua J. Hibbard1,2
  • Joseph Silk3,4,5
5 affiliations
  1. 1University of Colorado Boulder
  2. 2University of California
  3. 3Sorbonne University
  4. 4Johns Hopkins University
  5. 5University of Oxford
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Abstract

The cosmic dark ages are comovingly adjacent to the last-scattering surface, and this proximity, in conjunction with the spectral redness of the primordial potential, makes the cosmic microwave background (CMB) and the dark ages measurably correlated on the largest scales. We present simulated all-sky 21 cm maps of the associated density fluctuations in the dark ages at z < 200 and provide tomographical deconstructions of (foreground-contaminated) 21 cm fluctuation maps that we correlate with mock CMB maps of primordial temperature fluctuations. We find that utilizing all tomographic information of a dark ages survey allows us to improve the variance of the 21 cm cross-correlation by several orders of magnitude over the case of 21 cm autocorrelations with foregrounds. Inclusion of cross-correlations suppresses the foreground mean and transforms the contaminating foreground into a variance term that averages down with mode count. Our results pioneer a pathway toward ultrahigh-precision cosmology of the dark ages via low-frequency lunar farside radio arrays.

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Cite

BibTeXRIS
BibTeX
@article{hibbard2026unveiling,
  title = {{Unveiling the Dark Ages: A New Pathway Using Tomographical 21 cm Cosmic Microwave Background Cross-correlations}},
  author = {Joshua J. Hibbard and Joseph Silk},
  journal = {The Astrophysical Journal Letters},
  year = {2026},
  month = oct,
  doi = {10.3847/2041-8213/aea411},
  url = {https://iopscience.iop.org/article/10.3847/2041-8213/aea411},
  note = {CC BY 4.0},
}
RIS
TY  - JOUR
TI  - Unveiling the Dark Ages: A New Pathway Using Tomographical 21 cm Cosmic Microwave Background Cross-correlations
AU  - Joshua J. Hibbard
AU  - Joseph Silk
PY  - 2026
DA  - 2026/10/14
JO  - The Astrophysical Journal Letters
DO  - 10.3847/2041-8213/aea411
UR  - https://iopscience.iop.org/article/10.3847/2041-8213/aea411
AB  - The cosmic dark ages are comovingly adjacent to the last-scattering surface, and this proximity, in conjunction with the spectral redness of the primordial potential, makes the cosmic microwave background (CMB) and the dark ages measurably correlated on the largest scales. We present simulated all-sky 21 cm maps of the associated density fluctuations in the dark ages at z < 200 and provide tomographical deconstructions of (foreground-contaminated) 21 cm fluctuation maps that we correlate with mock CMB maps of primordial temperature fluctuations. We find that utilizing all tomographic information of a dark ages survey allows us to improve the variance of the 21 cm cross-correlation by several orders of magnitude over the case of 21 cm autocorrelations with foregrounds. Inclusion of cross-correlations suppresses the foreground mean and transforms the contaminating foreground into a variance term that averages down with mode count. Our results pioneer a pathway toward ultrahigh-precision cosmology of the dark ages via low-frequency lunar farside radio arrays.
SN  - 2041-8205
SN  - 2041-8213
ER  -