Delensing CMB polarization with external datasets

By Kendrick M. Smith, D. Hanson, M. Loverde, C. Hirata, Oliver Zahn. 2010

150 citations recorded by the source corpus.

One of the primary scientific targets of current and future CMB polarization experiments is the search for a stochastic background of gravity waves in the early universe. As instrumental sensitivity improves, the limiting factor will eventually be B-mode power generated by gravitational lensing, which can be removed through use of so-called "delensing" algorithms. We forecast prospects for delensing using lensing maps which are obtained externally to CMB polarization: either from large-scale structure observations, or from high-resolution maps of CMB temperature. We conclude that the forecasts in either case are not encouraging, and that significantly delensing large-scale CMB polarization requires high-resolution polarization maps with sufficient sensitivity to measure the lensing B-mode. We also present a simple formalism for including delensing in CMB forecasts which is computationally fast and agrees well with Monte Carlos.

Subfields: Artificial Intelligence, Astronomy and Astrophysics, Oceanography

View Paper: https://www.semanticscholar.org/paper/d4ca324d5d4006aa18dcab1530b5c8d3c5234e71

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Citations in the corpus

The Quest for B Modes from Inflationary Gravitational Waves (2015, background): “The precise level of delensing depends on a variety of experimental parameters, as discussed, for example, in Smith et al. (2012) and Simard, Hanson & Holder (2015).”
Phases of new physics in the CMB (2015, methodology): “For CMB-S4, the lensing reconstruction noise was computed using the iterated delensing method described in [54] (based on [55–57]).”
PICO: Probe of Inflation and Cosmic Origins (2019, background): “bination peak (‘ = 80). For lower levels of r, the lensing B-mode dominates, but the B-mode maps can be ‘delensed’ if the polarization maps are measured with few-arcmin resolution and sufﬁcient depth [39, 40]. Forecasts for PICO show that at least 73% of the lensing B-mode power can be removed for t”
Robust forecasts on fundamental physics from the foreground-obscured, gravitationally-lensed CMB polarization (2015, methodology): “[31] properties no delensing iterative delensing delensing using delensing with performed using CMB correlation between perfect LSS polarization only CMB and CIB measurements to zmax Table 2.”
CMB-S4 Science Case, Reference Design, and Project Plan (2019, methodology): “The TT , TE, EE, and φφ spectra were included, with the lensing reconstruction noise calculated using the minimum variance combination of quadratic estimators [543, 544], including the improvement from iterative EB reconstruction [575, 562].”
CMB-S4: Forecasting Constraints on Primordial Gravitational Waves (2020, methodology): “PGWs leave imprints on the polarization of the CMB (Seljak & Zaldarriaga 1997; Kamionkowski et al. 1997; Hu & White 1997).”