Speaker
Description
Recent studies have reported an unexpected negative Cosmic Microwave Background (CMB) temperature signal around nearby galaxies, extending to angular scales well beyond their visible sizes. We investigate this signal using the Planck PR3 SMICA temperature map and nearby late-type spiral galaxies from the 2MASS Redshift Survey (2MRS), selected at . We compare the conventional raw pixel-weighted stacking approach with a unique-pixel estimator designed to account for repeated CMB-pixel contributions caused by galaxy clustering. Both estimators recover a broad negative temperature profile. Using simulations, we further characterize the signal through complementary profile-depth, cumulative-area, and covariance-aware tests. The results indicate that the inferred anomaly depends on galaxy size, angular scale, and statistical estimator, with the strongest deviations found for large galaxies in targeted decrement statistics, while the full covariance-weighted profile remains statistically consistent with the simulated CMB ensemble. These findings motivate further investigation of the signal's dependence on local galaxy density and large-scale environment.