The Atacama Cosmology Telescope: Extragalactic Sources at 148 GHz in the 2008 Survey

• Published in: arXiv.org 2011-06
• Main Authors: Marriage, T A, Juin, J B, Y -T Lin, Marsden, D, Nolta, M R, Partridge, B, Ade, P A R, Aguirre, P, Amiri, M, Appel, J W, Barrientos, L F, Battistelli, E S, Bond, J R, Brown, B, Burger, B, Chervenak, J, Das, S, Devlin, M J, Dicker, S R, Doriese, W B, Dunkley, J, Dunner, R, Essinger-Hileman, T, Fisher, R P, Fowler, J W, Hajian, A, Halpern, M, Hasselfield, M, Hernandez-Monteagudo, C, Hilton, G C, Hilton, M, Hincks, A D, Hlozek, R, Huffenberger, K M, Hughes, D H, Hughes, J P, Infante, L, Irwin, K D, Kaul, M, Klein, J, Kosowsky, A, Lau, J M, Limon, M, Lupton, R H, Martocci, K, Mauskopf, P, Menanteau, F, Moodley, K, Moseley, H, Netterfield, C B, Niemack, M D, Page, L A, Parker, L, Quintana, H, Reid, B, Sehgal, N, Sherwin, B D, Sievers, J, Spergel, D N, Staggs, S T, Swetz, D S, Switzer, E R, Thornton, R, Trac, H, Tucker, C, Warne, R, Wilson, G, Wollack, E, Zhao, Y
• Format: Article
• Language: English
• Subjects: Cosmology; Emission; Flux density; Galactic clusters; Galaxies; Millimeter waves; Radio astronomy; Radio frequency; Radio sources (astronomy); Red shift; Southern sky; Spectra; Telescopes
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1007.5256

We report on extragalactic sources detected in a 455 square-degree map of the southern sky made with data at a frequency of 148 GHz from the Atacama Cosmology Telescope 2008 observing season. We provide a catalog of 157 sources with flux densities spanning two orders of magnitude: from 15 to 1500 mJy. Comparison to other catalogs shows that 98% of the ACT detections correspond to sources detected at lower radio frequencies. Three of the sources appear to be associated with the brightest cluster galaxies of low redshift X-ray selected galaxy clusters. Estimates of the radio to mm-wave spectral indices and differential counts of the sources further bolster the hypothesis that they are nearly all radio sources, and that their emission is not dominated by re-emission from warm dust. In a bright (>50 mJy) 148 GHz-selected sample with complete cross-identifications from the Australia Telescope 20 GHz survey, we observe an average steepening of the spectra between 5, 20, and 148 GHz with median spectral indices of \(\alpha_{\rm 5-20} = -0.07 \pm 0.06\), \(\alpha_{\rm 20-148} = -0.39 \pm0.04\), and \(\alpha_{\rm 5-148} = -0.20 \pm 0.03\). When the measured spectral indices are taken into account, the 148 GHz differential source counts are consistent with previous measurements at 30 GHz in the context of a source count model dominated by radio sources. Extrapolating with an appropriately rescaled model for the radio source counts, the Poisson contribution to the spatial power spectrum from synchrotron-dominated sources with flux density less than 20 mJy is \(C^{\rm Sync} = (2.8 \pm 0.3) \times 10^{-6} \micro\kelvin^2\).