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Published January 1, 2012 | Published
Journal Article Open

Correlations in the (Sub)millimeter Background from ACT × BLAST


We present measurements of the auto- and cross-frequency correlation power spectra of the cosmic (sub)millimeter background at 250, 350, and 500 μm (1200, 860, and 600 GHz) from observations made with the Balloon-borne Large Aperture Submillimeter Telescope (BLAST); and at 1380 and 2030 μm (218 and 148 GHz) from observations made with the Atacama Cosmology Telescope (ACT). The overlapping observations cover 8.6 deg^2 in an area relatively free of Galactic dust near the south ecliptic pole. The ACT bands are sensitive to radiation from the cosmic microwave background, to the Sunyaev-Zel'dovich effect from galaxy clusters, and to emission by radio and dusty star-forming galaxies (DSFGs), while the dominant contribution to the BLAST bands is from DSFGs. We confirm and extend the BLAST analysis of clustering with an independent pipeline and also detect correlations between the ACT and BLAST maps at over 25σ significance, which we interpret as a detection of the DSFGs in the ACT maps. In addition to a Poisson component in the cross-frequency power spectra, we detect a clustered signal at 4σ, and using a model for the DSFG evolution and number counts, we successfully fit all of our spectra with a linear clustering model and a bias that depends only on redshift and not on scale. Finally, the data are compared to, and generally agree with, phenomenological models for the DSFG population. This study demonstrates the constraining power of the cross-frequency correlation technique to constrain models for the DSFGs. Similar analyses with more data will impose tight constraints on future models.

Additional Information

© 2012 The American Astronomical Society. Received 2011 January 11; accepted 2011 September 9; published 2011 December 13. BLAST was made possible through the support of NASA through grant Nos. NAG5-12785, NAG5-13301, and NNGO- 6GI11G, the NSF Office of Polar Programs, the Canadian Space Agency, the Natural Sciences and Engineering Research Council (NSERC) of Canada, and the UK Science and Technology Facilities Council (STFC). C.B.N. acknowledges support from the Canadian Institute for Advanced Research. ACT was supported by the U.S. National Science Foundation through awards AST-0408698 for the ACT project, and PHY-0355328, AST- 0707731, and PIRE-0507768. Funding was also provided by Princeton University and the University of Pennsylvania. Computations were performed on the GPC supercomputer at the SciNet HPC Consortium. SciNet is funded by the Canada Foundation for Innovation under the auspices of Compute Canada; the Government of Ontario; Ontario Research Fund–Research Excellence; and the University of Toronto. J.D. acknowledges support from an RCUK Fellowship. S.D., A.H., and T.M. were supported through NASA grant NNX08AH30G. A.K. was partially supported through NSF AST-0546035 and AST-0606975 for work on ACT. E.S. acknowledges support by NSF Physics Frontier Center grant PHY-0114422 to the Kavli Institute of Cosmological Physics. S.D. acknowledges support from the Berkeley Center for Cosmological Physics. We thank CONICYT for overseeing the Chajnantor Science Preserve, enabling instruments like ACT to operate in Chile; and we thank AstroNorte for operating our scientific base station. Some of the results in this paper have been derived using the HEALPix (Gόrski et al. 2005) package. The authors thank Matthieu Béthermin and Guilaine Lagache for their help.

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