Motion induced second order temperature and y-type anisotropies after the subtraction of linear dipole in the CMB maps

TL;DR

This paper discusses second-order temperature and y-type anisotropies in CMB maps caused by incomplete subtraction of the motion-induced dipole, proposing their detection and potential use for calibration in CMB experiments.

Contribution

It introduces a method to identify and subtract artificial anisotropies caused by the motion-induced dipole in y-type CMB maps, improving the accuracy of cosmological measurements.

Findings

Artificial hot spots can result from incomplete dipole subtraction.

These anisotropies are detectable by Planck HFI and Pixie.

The distortions can be precisely calculated and removed from y-maps.

Abstract

y-type spectral distortions of the cosmic microwave background allow us to detect clusters and groups of galaxies, filaments of hot gas and the non-uniformities in the warm hot intergalactic medium. Several CMB experiments (on small areas of sky) and theoretical groups (for full sky) have recently published y-type distortion maps. We propose to search for two artificial hot spots in such y-type maps resulting from the incomplete subtraction of the effect of the motion induced dipole on the cosmic microwave background sky. This dipole introduces, at second order, additional temperature and y-distortion anisotropy on the sky of amplitude few \mu K which could potentially be measured by Planck HFI and Pixie experiments and can be used as a source of cross channel calibration by CMB experiments. This y-type distortion is present in every pixel and is not the result of averaging the whole sky. This distortion, calculated exactly from the known linear dipole, can be subtracted from the final y-type maps, if desired.