First LABOCA/APEX observation of a proto-cluster at z =2.4
Alexandre BEELEN
IAS, Orsay
Résumé :
Narrow-band surveys are a very powerful technique for detecting Lyman
alpha emission from various structures at high redshift. In addition to
numerous Ly-alpha galaxies, they have revealed the existence of very
extended Ly-alpha nebulae, called Ly-alpha blobs, generally part of
larger structures of Ly-alpha emitters of various sizes.
I will present observations aimed at exploring both the nature of
Ly-alpha blobs at z=2.38 and the way they trace large scale structure,
by exploring their proximity to ``maximum starbursts'' through
sub-millimeter emission.
We used the newly commissioned Large APEX Bolometer Camera on the
Atacama Pathfinder EXperiment telescope to carry out a deep 10'x10' map
at 870 micron. Our map, the first published deep image, allowed the
detection of twenty-two sources with 870 micron flux densities in the
range 3-21 mJy and far-IR luminosities probably in the range ~5-20 x
10(12) Lsolar. Only one of the four 50 kpc-extended Ly-alpha blobs has a
secure 870 micron counterpart. The 870 micron source counts in the whole
area are marginally higher than in the SHADES SCUBA survey, with a
possible over-density around this blob. The majority of the 3.6-24
micron SEDs of the sub-millimeter sources indicate they are starburst
dominated, with redshifts mostly greater than 2.
