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arXiv · 1908.08128

Delensing Degree-Scale $B$-Mode Polarization with High-Redshift Line Intensity Mapping

Kirit S. Karkare
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Abstract

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.

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Kirit S. Karkare. 2019-08-21. Delensing Degree-Scale $B$-Mode Polarization with High-Redshift Line Intensity Mapping. https://doi.org/10.1103/physrevd.100.043529

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