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Fractional polarization of extragalactic sources in the 500 deg2 SPTpol survey

Gupta, N., Reichardt, C.L., Ade, P. A. R. ORCID:, Anderson, A.J., Archipley, M., Austermann, J.E., Avva, J.S., Beall, J.A., Bender, A.N., Benson, B.A., Bianchini, F., Bleem, L.E., Carlstrom, J.E., Chang, C.L., Chiang, H.C., Citron, R., Corbett Moran, C., Crawford, T.M., Crites, A.T., de Haan, T., Dobbs, M.A., Everett, W., Feng, C., Gallicchio, J., George, E.M., Gilbert, A., Halverson, N.W., Harrington, N., Henning, J.W., Hilton, G.C., Holder, G.P., Holzapfel, W.L., Hou, Z., Huang, N., Hrubes, J.D., Hubmayr, J., Irwin, K.D., Knox, L., Lee, A.T., Li, D., Lowitz, A., Luong-Van, D., Marrone, D.P., McMahon, J.J, Meyer, S.S., Mocanuohr, L.M., Montgomery, J., Nadolski, A., Natoli, T., Nibarger, J.P., Noble, G.I., Novosad, V., Padin, S., Patil, S., Pryke, C., Ruhl, J.E., Saliwanchik, B.R., Sayre, J.T., Schaffer, K.K., Shirokoff, E., Sievers, C., Smecher, G., Z Staniszewski, Z., Stark, A.A., Story, K.T., Switzer, E.R., Tucker, Carole ORCID:, Vanderlinde, K., Veach, T., Vieira, J.D., Wang, G., Whitehorn, N., Williamson, R., Wu, W.L.K., Yefremenko, V. and Zhang, L. 2019. Fractional polarization of extragalactic sources in the 500 deg2 SPTpol survey. Monthly Notices of the Royal Astronomical Society 490 (4) 10.1093/mnras/stz2905

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We study the polarization properties of extragalactic sources at 95 and 150 GHz in the SPTpol 500 deg<sup>2</sup> survey. We estimate the polarized power by stacking maps at known source positions, and correct for noise bias by subtracting the mean polarized power at random positions in the maps. We show that the method is unbiased using a set of simulated maps with similar noise properties to the real SPTpol maps. We find a flux-weighted mean-squared polarization fraction <p><sup>2</sup>> = [8.9 ± 1.1] × 10<sup>-4</sup> at 95 GHz and [6.9 ± 1.1] × 10<sup>-4</sup> at 150 GHz for the full sample. This is consistent with the values obtained for a subsample of active galactic nuclei. For dusty sources, we find 95 per cent upper limits of </p><p><sup>2</sup>><sub>95</sub> < 16.9 × 10<sup>-3</sup> and </p><p><sup>2</sup>><sub>150</sub> < 2.6 × 10<sup>-3</sup>. We find no evidence that the polarization fraction depends on the source flux or observing frequency. The 1σ upper limit on measured mean-squared polarization fraction at 150 GHz implies that extragalactic foregrounds will be subdominant to the CMB E and B mode polarization power spectra out to at least ℓ ≲ 5700 (ℓ ≲ 4700) and ℓ ≲ 5300 (ℓ ≲ 3600), respectively, at 95 (150) GHz....</p>

Item Type: Article
Date Type: Published Online
Status: Published
Schools: Physics and Astronomy
Date of First Compliant Deposit: 28 February 2023
Date of Acceptance: 7 October 2019
Last Modified: 03 May 2023 09:01

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