Multitracer CMB delensing maps from Planck and WISE data
  Delensing, the removal of the limiting lensing B-mode background, is crucial
for the success of future cosmic microwave background (CMB) surveys in
constraining inflationary gravitational waves (IGWs). In recent work, delensing
with large-scale structure tracers has emerged as a promising method both for
improving constraints on IGWs and for testing delensing methods for future use.
However, the delensing fractions (i.e., the fraction of the lensing-B mode
power removed) achieved by recent efforts have been only $20-30\%$. In this
work, we provide a detailed characterization of a full-sky, dust-cleaned cosmic
infrared background (CIB) map for delensing and construct a further-improved
delensing template by adding additional tracers to increase delensing
performance. In particular, we build a multitracer delensing template by
combining the dust-cleaned Planck CIB map with a reconstructed CMB lensing map
from Planck and a galaxy number density map from the Wide-field Infrared Survey
Explorer (WISE) satellite. For this combination, we calculate the relevant
weightings by fitting smooth templates to measurements of all the cross- and
auto-spectra of these maps. On a large fraction of the sky
($f_\mathrm{sky}=0.43$), we demonstrate that our maps are capable of providing
a delensing factor of $43 \pm 1\%$; using a more restrictive mask
($f_\mathrm{sky}=0.11$), the delensing factor reaches $48 \pm 1\%$. For
low-noise surveys, our delensing maps, which cover much of the sky, can thus
improve constraints on the tensor-to-scalar ratio ($r$) by nearly a factor of
2. The delensing tracer maps are made publicly available, and we encourage
their use in ongoing and upcoming B-mode surveys.
