Abstract
Primordial gravitational waves leave a characteristic imprint on the cosmic microwave background (CMB) in the form of B-mode polarization. Photons are also deflected by large scale gravitational waves which intervene between the source screen and our telescopes, resulting in curl-type gravitational lensing. Gravitational waves present at the epoch of reionization contribute to both effects, thereby leading to a nonvanishing cross-correlation between B-mode polarization and curl lensing of the CMB. Observing such a cross-correlation would be very strong evidence that an observation of B-mode polarization was due to the presence of large scale gravitational waves, as opposed to astrophysical foregrounds or experimental systematic effects. We study the cross-correlation across a wide range of source redshifts and show that a post-SKA experiment aimed to map out the 21-cm sky between 15≤z≤30 could rule out non-zero cross-correlation at high significance for r≥0.01.
Original language | English (US) |
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Article number | 063508 |
Journal | Physical Review D |
Volume | 96 |
Issue number | 6 |
DOIs | |
State | Published - Sep 12 2017 |
Externally published | Yes |
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)