An ultra-deep ISOCAM observation through a cluster-lens
B. Altieri, L. Metcalfe, J. P. Kneib, B. McBreen, H. Aussel, A. Biviano, M. Delaney, D. Elbaz, K. Leech, L. Lémonon, K. Okumura, R. Pell\'o, B. Schulz;
AaA, 1999, 343, L65
ABSTRACT:We present results of ultra-deep ISOCAM observations through a cluster-lens at 7mu m and 15mu m with the Infrared Space Observatory (ISO)
satellite.
These observations reveal a large number of luminous Mid-Infrared (MIR)
sources.
Cross-identification in the optical and Near-Infrared (NIR) wavebands shows that about half
of the 7 mu m sources are cluster galaxies.
The other 7 mu m and almost all 15
mu m sources are identified as lensed distant galaxies.
Thanks to the
gravitational amplification they constitute the faintest sources detected in the
MIR, allowing us to extend the number counts in both the 7 and 15 mum bands.
In
particular, we find that the 15 mum counts have a steep slope alpha_ {15mum } = -1.5 +/-
0.3 and are large, with N_{15mum }(> 30muJy ) = 13 +/- 5 arcmin(-2) .
These
numbers rule out non-evolutionary models and favour very strong
evolution.
Down to our counts limit, we found that the resolved 7 mum and 15 mum
background radiation intensities are respectively (1.7+/-0.5)x10(-9) and
(3.3+/-1.3)x10(-9) W m(-2) sr(-1) .
Based on observations with ISO, an ESA project with
instruments funded by ESA Member States (especially the PI countries: France,
Germany, the Netherlands and the United Kingdom) with the participation of ISAS
and NASA
KEYWORDS: galaxies: abundances, galaxies: clusters: general, galaxies: evolution, cosmology: gravitational lensing, infrared: galaxies
CODE: altieri99