English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

The cosmic microwave background (CMB) is gravitationally lensed bylarge-scale structure, which distorts observations of the primordialanisotropies in any given direction. Averaged over the sky, this importanteffect is routinely modelled with the lensed CMB power spectra. This accountsfor the variance of this distortion, where the leading variance effect isquadratic in the lensing deflections. However, we show that if brightextragalactic sources correlated with the large-scale structure are masked in aCMB map, the power spectrum measured over the unmasked area using a standardpseudo-$C_\ell$ estimator has an additional~\emph{linear} lensing effectarising from correlations between the masked area and the lensing. This inducesa scale-dependent average demagnification of the unlensed distance betweenunmasked pairs of observed points and a negative contribution to the CMBcorrelation function peaking at $\sim 10\,\arcmin$. We give simple analyticmodels for point sources and a threshold mask constructed on a correlatedGaussian foreground field. We demonstrate the consistency of their predictionsfor masks removing radio sources and peaks of Sunyaev-Zeldovich and cosmicinfrared background emissions using realistic numerical simulations. We discusssimple diagnostics that can be used to test for the effect in the absence of agood model for the masked sources and show that by constructing specific masksthe effect can be observed on Planck data. For masks employed in the analysisof Planck and other current data sets, the effect is likely to be negligible,but may become an important subpercent correction for future surveys ifsubstantial populations of resolved sources are masked.

Lensed CMB power spectrum biases from masking extragalactic sources