Herschel-ATLAS/GAMA: SDSS cross-correlation induced by weak lensing
Danese, L.; González-Nuevo, J.; Scott, D.; Cooray, A.; Ibar, E.; Negrello, M.; Lapi, A.; De Zotti, G.; Bussmann, R. S.; Baes, M.; Dunne, L.; Dye, S.; Eales, S.; Maddox, S.; Michałowski, M. J.; Valiante, E.; Smith, M. W. L.; Brough, S.; Bourne, N.; Loveday, J.; Robotham, A. S. G.; Ivison, R.; Bland-Hawthorn, J.; Cai, Z. -Y.; Driver, S. P.; Amber, S.; Xia, J. -Q.; Liske, J.
Spain, Italy, United Kingdom, Belgium, Australia, United States, New Zealand, Chile, Germany, Canada, China
Abstract
We report a highly significant (>10σ) spatial correlation between galaxies with S350 μm ≥ 30 mJy detected in the equatorial fields of the Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS) with estimated redshifts ≳ 1.5, and Sloan Digital Sky Survey (SDSS) or Galaxy And Mass Assembly (GAMA) galaxies at 0.2 ≤ z ≤ 0.6. The significance of the cross-correlation is much higher than those reported so far for samples with non-overlapping redshift distributions selected in other wavebands. Extensive, realistic simulations of clustered sub-mm galaxies amplified by foreground structures confirm that the cross-correlation can be explained by weak gravitational lensing (μ < 2). The simulations also show that the measured amplitude and range of angular scales of the signal are larger than can be accounted for by galaxy-galaxy weak lensing. However, for scales ≲ 2 arcmin, the signal can be reproduced if SDSS/GAMA galaxies act as signposts of galaxy groups/clusters with halo masses in the range 1013.2-1014.5 M⊙. The signal detected on larger scales appears to reflect the clustering of such haloes.