||Plausible Boosting of Millimeter-Galaxies in the COSMOS Field by
Intervening Large-Scale Structure
||446, Galaxy Evolution: Infrared to Millimeter Wavelength Perspective
||Aretxaga, I.; Wilson, G. W.; Aguilar, E.; Alberts, S.; Scott, K. S.; Scoville, N.; Yun, M. S.; Austermann, J.; Downes, T. D.; Ezawa, H.; Hatsukade, B.; Hughes, D. H.; Kawabe, R.; Kohno, K.; Oshima, T.; Perera, T. A.; Tamura, Y.; Zeballos, M.
||The 0.72 sq. deg. contiguous 1.1mm survey in the central area
of the COSMOS field, carried out to a 1σ≈1.26 mJy
beam-1 depth with the AzTEC camera mounted on the 10m Atacama
Submillimeter Telescope Experiment (ASTE), shows
number counts with a
significant excess of sources when compared to the number counts derived
from the ∼0.5 sq. deg. area sampled at similar depths in the
Scuba HAlf Degree Extragalactic Survey (SHADES, Austermann et al. 2010).
They are, however, consistent with those derived from fields that were
considered too small to characterize the overall blank-field population.
We identify differences to
be more significant in the S1.1mm
∼> 5 mJy regime, and demonstrate that these excesses in number counts are
related to the areas where galaxies at redshifts ∼< 1.1 are more
densely clustered. The positions of optical-IR galaxies in the redshift
interval 0.6 ∼< z ∼< 0.75 are the ones that show the strongest
with the positions of the 1.1mm
bright population (S1.mm ∼>5 mJy), a result which
does not depend
exclusively on the presence of rich clusters within the survey sampled area.
The most likely
explanation for the observed excess in number counts at 1.1mm is
galaxy-galaxy and galaxy-group lensing at moderate amplification levels,
in amplitude as one samples larger and larger flux densities.