2011/12/02 by Laura G. Book, Laura Book, Marc Kamionkowski +1 · 1 citation
Physics and Astronomy · #Astrophysics #Astrophysics and Cosmic Phenomena #Galaxy #Gravitational lens #Gravitational wave #Physics #Primordial black hole #Pulsars and Gravitational Waves Research #Quantum electrodynamics #Radio Astronomy Observations and Technology #Redshift #Weak gravitational lensing #astro-ph.CO #gr-qc #hep-ph
paper · pdf · doi:10.1103/physrevlett.108.211301
4 pages, 1 figure; comments welcome
arxiv created 2011/12/02 · openalex publication_date 2012/05/22 · arxiv updated 2013/05/29 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Weak-gravitational-lensing distortions to the intensity pattern of 21-cm radiation from the dark ages can be decomposed geometrically into curl and curl-free components. Lensing by primordial gravitational waves induces a curl component, while the contribution from lensing by density fluctuations is strongly suppressed. Angular fluctuations in the 21-cm background extend to very small angular scales, and measurements at different frequencies probe different shells in redshift space. There is thus a huge trove of information with which to reconstruct the curl component of the lensing field, allowing tensor-to-scalar ratios conceivably as small as r~10(-9)-far smaller than those currently accessible-to be probed.