Cross-correlation between the CMB Lensing Potential Measured by Planck and High-z Submillimeter Galaxies Detected by the Herschel-Atlas Survey

We present the first measurement of the correlation between the map of the cosmic microwave background (CMB) lensing potential derived from the Planck nominal mission data and z≳ 1.5 galaxies detected by the Herschel-ATLAS (H-ATLAS) survey covering about 600 {{deg }2}, i.e., about 1.4% of the sky. We reject the hypothesis that there is no correlation between CMB lensing and galaxy detection at a 20sigma significance, checking the result by performing a number of null tests. The significance of the detection of the theoretically expected cross-correlation signal is found to be 10sigma . The galaxy bias parameter, b, derived from a joint analysis of the cross-power spectrum and of the autopower spectrum of the galaxy density contrast is found to be b=2.80-0.11+0.12, consistent with earlier estimates for H-ATLAS galaxies at similar redshifts. On the other hand, the amplitude of the cross-correlation is found to be a factor 1.62 ± 0.16 higher than expected from the standard model and also found by cross-correlation analyses with other tracers of the large-scale structure. The enhancement due to lensing magnification can account for only a fraction of the excess cross-correlation signal. We suggest that part of it may be due to an incomplete removal of the contamination of the cosmic infrared background, which includes the H-ATLAS sources we are cross-correlating with. In any case, the highly significant detection reported here using a catalog covering only 1.4% of the sky demonstrates the potential of CMB lensing correlations with submillimeter surveys. © 2015. The American Astronomical Society. All rights reserved.