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The Atacama Cosmology Telescope: two-season ACTPol extragalactic point sources and their polarization properties

Author(s): Datta, Rahul; Aiola, Simone; Choi, Steve K; Devlin, Mark; Dunkley, Joanna; et al

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Abstract: We report on measurements of the polarization of extragalactic sources at 148 GHz made during the first two seasons of the Atacama Cosmology Telescope Polarization (ACTPol) survey. The survey covered 680 deg2 of the sky on the celestial equator. Polarization measurements of 169 intensity-selected sources brighter than 30 mJy, that are predominantly active galactic nuclei, are presented. Above a total flux of 215 mJy where the noise bias removal in the polarization measurement is reliable, we detect 26 sources, 14 of which have a detection of linear polarization at greater than 3σ significance. The distribution of the fractional polarization as a function of total source intensity is analysed. Our result is consistent with the scenario that the fractional polarization of our measured radio source population is independent of total intensity down to the limits of our measurements and well described by a Gaussian distribution with a mean fractional polarization pm = 0.028 ± 0.005 and standard deviation σpm = 0.054, truncated at p = 0. Extrapolating this model for the distribution of source polarization below the ACTPol detection threshold, we predict that one could get a clean measure of the E- mode polarization power spectrum of the microwave background out to ≈ 6000 with 1 μK-arcminute maps over 10% of the sky from a future survey. We also study the spectral energy distribution of the total and polarized source flux densities by cross-matching with low radio frequency catalogues. We do not find any correlation between the spectral indices for total flux and polarized flux.
Publication Date: 1-Nov-2018
Electronic Publication Date: 1-Nov-2018
Citation: Datta, Rahul, Aiola, Simone, Choi, Steve K, Devlin, Mark, Dunkley, Joanna, Dünner, Rolando, Gallardo, Patricio A, Gralla, Megan, Halpern, Mark, Hasselfield, Matthew, Hilton, Matt, Hincks, Adam D, Ho, Shuay-Pwu P, Hubmayr, Johannes, Huffenberger, Kevin M, Hughes, John P, Kosowsky, Arthur, López-Caraballo, Carlos H, Louis, Thibaut, Lungu, Marius, Marriage, Tobias, Maurin, Loïc, McMahon, Jeff, Moodley, Kavilan, Naess, Sigurd K, Nati, Federico, Niemack, Michael D, Page, Lyman A, Partridge, Bruce, Prince, Heather, Staggs, Suzanne T, Switzer, Eric R, Wollack, Edward J, Farren, Gerrit. (2019). The Atacama Cosmology Telescope: two-season ACTPol extragalactic point sources and their polarization properties. Monthly Notices of the Royal Astronomical Society, 486 (4), 5239 - 5262. doi:10.1093/mnras/sty2934
DOI: doi:10.1093/mnras/sty2934
ISSN: 0035-8711
EISSN: 1365-2966
Keywords: polarization – techniques: polarimetric – catalogues – surveys – galaxies: active – cosmology: observations.
Pages: 5239 - 5262
Language: en
Type of Material: Journal Article
Journal/Proceeding Title: Monthly Notices of the Royal Astronomical Society
Version: Final published version. Article is made available in OAR by the publisher's permission or policy.

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