We report on extragalactic sources detected in a 455 deg(2) map of the southern sky made with data at a frequency of 148 GHz from the Atacama Cosmology Telescope (ACT) 2008 observing season. We provide a catalog of 157 sources with flux densities spanning two orders of magnitude: from 15 mJy 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 millimeter-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(5-20) = -0.07 +/- 0.06, alpha(20-148) = -0.39 +/- 0.04, and alpha(5-148) = -0.20 +/- 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-Sync = (2.8 +/- 0.3) x 10(-6) mu K-2.
THE ATACAMA COSMOLOGY TELESCOPE: EXTRAGALACTIC SOURCES AT 148 GHz IN THE 2008 SURVEY / Tobias A., M., Jean Baptiste, J., Yen Ting, L., Danica, M., Michael R., N., Partridge, B., Peter A. r., A., Paula, A., Mandana, A., John William, A., L., F.B., Battistelli, E.S., John R., B., Brown, B., Burger, B., Chervenak, J., Sudeep, D., J., D.M., R., D.S., W., B.D., et al.. - In: THE ASTROPHYSICAL JOURNAL. - ISSN 0004-637X. - 731:2(2011), p. 100. [10.1088/0004-637x/731/2/100]
THE ATACAMA COSMOLOGY TELESCOPE: EXTRAGALACTIC SOURCES AT 148 GHz IN THE 2008 SURVEY
BATTISTELLI, Elia Stefano;
2011
Abstract
We report on extragalactic sources detected in a 455 deg(2) map of the southern sky made with data at a frequency of 148 GHz from the Atacama Cosmology Telescope (ACT) 2008 observing season. We provide a catalog of 157 sources with flux densities spanning two orders of magnitude: from 15 mJy 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 millimeter-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(5-20) = -0.07 +/- 0.06, alpha(20-148) = -0.39 +/- 0.04, and alpha(5-148) = -0.20 +/- 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-Sync = (2.8 +/- 0.3) x 10(-6) mu K-2.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
