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

Abstract

y-type spectral distortions of the cosmic microwave background allow usto detect clusters and groups of galaxies, filaments of hot gas and thenon-uniformities in the warm hot intergalactic medium. Several CMBexperiments (on small areas of sky) and theoretical groups (for full sky)have recently published y-type distortion maps. We propose to search fortwo artificial hot spots in such y-type maps resulting from theincomplete subtraction of the effect of the motion induced dipole on the cosmic microwavebackground sky. This dipole introduces, at second order, additionaltemperature and y-distortion anisotropy on the sky of amplitude few μK which couldpotentially be measured by Planck HFI and Pixie experiments and can be used as a source of crosschannel calibration by CMB experiments. This y-type distortion is present inevery pixel and is not the result of averaging the whole sky. Thisdistortion, calculated exactly from the known linear dipole, can besubtracted from the final y-type maps, if desired.