The Atacama Cosmology Telescope: dusty star-forming galaxies and active galactic nuclei in the Southern survey
/ Authors
D. Marsden, M. Gralla, T. Marriage, E. Switzer, B. Partridge, M. Massardi, Gustavo Morales, G. Addison, J. Bond, D. Crichton
and 21 more authors
Sudeep Das, M. Devlin, R. Dunner, A. Hajian, M. Hilton, A. Hincks, J. Hughes, K. Irwin, A. Kosowsky, F. Menanteau, K. Moodley, M. Niemack, L. Page, E. Reese, B. Schmitt, N. Sehgal, J. Sievers, S. Staggs, D. Swetz, R. Thornton, Edward J. Wollack
/ Abstract
We present a catalog of 191 extragalactic sources detected by the Atacama Cosmology Telescope (ACT) at 148 GHz and/or 218 GHz in the 2008 Southern survey. Flux densities span 14 to 1700 mJy, and we use source spectral indices derived using ACT-only data to divide our sources into two subpopulations: 167 radio galaxies powered by central active galactic nuclei (AGN), and 24 dusty star-forming galaxies (DSFGs). We cross-identify 97% of our sources (166 of the AGN and 19 of the DSFGs) with those in currently available catalogs. When combined with flux densities from the Australian Telescope 2 0 GHz survey and follow-up observations with the Australia Telescope Compact Array, the synchrotron-dominated population is seen to exhibit a steepening of the slope of the spec tral energy distribution from 20 to 148 GHz, with the trend continuing to 218 GHz. The ACT dust-dominated source population has a median spectral index, �148 218, of 3.7 +0.62 0.86 , and includes both local galaxies and sources with redshift around 6. Dusty sources with no counterpart in existing catalogs likely belong to a recently discovered subpopulation of DSFGs lensed by foreground galaxies or galaxy groups.
Journal: Monthly Notices of the Royal Astronomical Society
DOI: 10.1093/mnras/stu001