Characterization of extragalactic point-sources on E- and B-mode maps of the CMB polarization

arXiv:2009.10441v2: Prepared for submission to JCAP.Although interesting in themselves, extragalactic sources emitting in the microwave range (mainly radio-loud active galactic nuclei and dusty galaxies) are also considered a contaminant from the point of view of Cosmic Microwave Background (CMB) experiments. These sources appear as unresolved point-like objects in CMB measurements because of the limited resolution of CMB experiments. Amongst other issues, point-like sources are known to obstruct the reconstruction of the lensing potential, and can hinder the detection of the Primordial Gravitational Wave Background for low values of r. Therefore, extragalactic point-source detection and subtraction is a fundamental part of the component separation process necessary to achieve some of the science goals set for the next generation of CMB experiments. As a previous step to their removal, in this work we present a new filter based on steerable wavelets that allows the characterization of the emission of these extragalactic sources. Instead of the usual approach of working in polarization maps of the Stokes' Q and U parameters, the proposed filter operates on E- and B-mode polarization maps. In this way, it benefits from the lower intensity that, both, the CMB, and the galactic foreground emission, present in B-modes to improve its performance. To demonstrate its potential, we have applied the filter to simulations of the future PICO satellite, and we predict that, for the regions of fainter galactic foreground emission in the 30 GHz and 155 GHz bands of PICO, our filter will be able to characterize sources down to a minimum polarization intensity of, respectively, 125 pK and 14 pK. Adopting a Π=0.02 polarization degree, these values correspond to 169 mJy and 288 mJy intensities.PDP acknowledge partial financial support from the Formación del Profesorado Universitario (FPU) programme of the Spanish Ministerio de Ciencia, Innovación y Universidades. DH acknowledges partial financial support from the Spanish Ministerio de Ciencia, Innovación y Universidades project PGC2018-101814-B-I00. The authors would like to thank the Spanish Agencia Estatal de Investigación (AEI, MICIU) for the financial support provided under the projects with references ESP2017-83921-C2-1-R and AYA2017-90675-REDC, co-funded with EU FEDER funds, and also acknowledge the funding from Unidad de Excelencia María de Maeztu (MDM-2017-0765).Peer reviewe