Zusammenfassung
We revisit the lensing anomaly in the Planck 2018 temperature (TT) data and
examine its robustness to frequency selection and additional sky masking. Our
main findings are: (1) The phenomenological lensing amplitude parameter, $A_L$,
varies with ecliptic latitude, with a $2.9\sigma$ preference for $A_L>1$ near
the ecliptic, and $1.0\sigma$ preference near the ecliptic poles, compared to
$2.5\sigma$ on the original masks. This behavior is largely or solely from 217
GHz and suggestive of some non-random effect given the Planck scan strategy.
(2) The 217 GHz TT data also show a stronger preference for $A_L>1$ than the
lower frequencies. The shifts in $A_L$ from 217 GHz with additional Galactic
dust masking are too large to be explained solely by statistical fluctuations,
indicating some connection with the foreground treatment. Overall, the Planck
$A_L$ anomaly does not have a single simple cause. Removing the 217 GHz TT data
leaves a $1.8\sigma$ preference for $A_L>1$. The low-multipole ($\ell<30$) TT
data contribute to the preference for $A_L>1$ through correlations with
$Łambda$CDM parameters. The 100 and 143 GHz data at $\ell\geq30$ prefer
$A_L>1$ at $1.3\sigma$, and this appears robust to the masking tests we
performed. The lensing anomaly may impact fits to alternative cosmological
models. Marginalizing over $A_L$, optionally applied only to Planck TT spectra,
can check this. Models proposed to address cosmological tensions should be
robust to removal of the Planck 217 GHz TT data.
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