Detecting the integrated Sachs-Wolfe effect with high-redshift 21-cm surveys

Alvise Raccanelli, Ely Kovetz, Liang Dai, Marc Kamionkowski

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


We investigate the possibility of detecting the integrated Sachs-Wolfe (ISW) effect by cross-correlating 21-cm surveys at high redshifts with galaxies in a way similar to the usual CMB-galaxy cross-correlation. The high-redshift 21-cm signal is dominated by CMB photons that travel freely without interacting with the intervening matter, and hence its late-time ISW signature should correlate extremely well with that of the CMB at its peak frequencies. Using the 21-cm temperature brightness instead of the CMB would thus be a further check of the detection of the ISW effect, measured by different instruments at different frequencies and suffering from different systematics. We also study the ISW effect on the photons that are scattered by HI clouds. We show that a detection of the unscattered photons is achievable with planned radio arrays, while one using scattered photons will require advanced radio interferometers, either an extended version of the planned Square Kilometre Array or futuristic experiments such as a lunar radio array.

Original languageEnglish
Article number083512
JournalPhysical Review D
Issue number8
StatePublished - 14 Apr 2016
Externally publishedYes

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)


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