Cosmic microwave background (CMB) experiments that constrain the tensor-to-scalar ratio r are now approaching the sensitivity at which delensing---removing the B modes induced by the gravitational lensing of large-scale structure---is necessary. We consider the improvement in delensing that maps of large-scale structure from tomographic line intensity mapping (IM) experiments targeting 2<z<10 could provide. Compared to a nominal baseline of cosmic infrared background and internal delensing at CMB-S4 sensitivity, we find that the addition of high-redshift IM data could improve delensing performance by ~11%. Achieving the requisite sensitivity in the IM data is feasible with next-generation experiments that are now being planned. However, these results are contingent on the ability to measure low-k modes along the line of sight. Without these modes, IM datasets are unable to to correlate with the lensing kernel and do not aid in delensing.
@article{arxiv.1908.08128,
title = {Delensing Degree-Scale $B$-Mode Polarization with High-Redshift Line Intensity Mapping},
author = {Kirit S. Karkare},
journal= {arXiv preprint arXiv:1908.08128},
year = {2019}
}
Comments
9 pages, 4 figures, 1 table. Matches version published in Phys. Rev. D