http://arxiv.org/abs/1712.08412
Recent detailed simulations have shown that an insufficiently accurate characterization of the contamination of unresolved polarized extragalactic sources can seriously bias measurements of the primordial CMB power spectrum if the tensor-to-scalar ratio $r \sim 0.001$ as predicted by models currently of special interest (e.g., Starobinsky’s $R^2$ and Higgs inflation). This has motivated a re-analysis of the median polarization fraction of extragalactic sources (radio-loud AGNs and dusty galaxies) utilizing data from the Planck polarization maps. Our approach, exploiting the intensity distribution analysis (IDA), mitigates or overcomes the most delicate aspects of earlier analyses based on stacking techniques. The median polarization fraction, ${\Pi}{median}$, of extragalactic radio sources is found to be $\sim 2.75$\%, with no significant dependence on either frequency or flux density, in good agreement with the earlier estimate and with high-sensitivity measurements in the frequency range 5-40 GHz. No polarization signal is detected in the case of dusty galaxies, implying 90\% confidence upper limits of ${\Pi}{dusty} \le 2.2$\% at 353 GHz and of $\le 3.8$\% at 217 GHz. The contamination of CMB polarization maps by unresolved point sources is discussed.
T. Trombetti, C. Burigana, G. Zotti, et. al.
Mon, 25 Dec 17
30/37
Comments: 9 pages, 3 figures, 7 tables
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