Forecasting the Contribution of Polarized Extragalactic Radio Sources in CMB Observations

We combine the latest data sets obtained with different surveys to study the frequency dependence of polarized emission coming from extragalactic radio sources (ERS). We consider data over a very wide frequency range starting from 1.4 GHz up to 217 GHz. This range is particularly interesting since i...

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Bibliographic Details
Published in:The Astrophysical journal 2018-05, Vol.858 (2), p.85
Main Authors: Puglisi, G., Galluzzi, V., Bonavera, L., Gonzalez-Nuevo, J., Lapi, A., Massardi, M., Perrotta, F., Baccigalupi, C., Celotti, A., Danese, L.
Format: Article
Language:English
Subjects:
Astrophysics
cosmic background radiation
Cosmic microwave background
cosmology: observations
Datasets
Depolarization
Emission analysis
Extragalactic radio sources
Flux density
Frequency ranges
Polarization
quasars: general
radio continuum: galaxies
Radio frequency
Spectral sensitivity
Tensors
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Summary:We combine the latest data sets obtained with different surveys to study the frequency dependence of polarized emission coming from extragalactic radio sources (ERS). We consider data over a very wide frequency range starting from 1.4 GHz up to 217 GHz. This range is particularly interesting since it overlaps the frequencies of the current and forthcoming cosmic microwave background (CMB) experiments. Current data suggest that at high radio frequencies ( ≥ 20 GHz) the fractional polarization of ERS does not depend on the total flux density. Conversely, recent data sets indicate a moderate increase of polarization fraction as a function of frequency, physically motivated by the fact that Faraday depolarization is expected to be less relevant at high radio frequencies. We compute ERS number counts using updated models based on recent data, and we forecast the contribution of unresolved ERS in CMB polarization spectra. Given the expected sensitivities and the observational patch sizes of forthcoming CMB experiments, about ∼200 (up to ∼2000) polarized ERS are expected to be detected. Finally, we assess that polarized ERS can contaminate the cosmological B-mode polarization if the tensor-to-scalar ratio is
ISSN:0004-637X
1538-4357
DOI:10.3847/1538-4357/aab3c7