An ultra-deep ISOCAM observation through a cluster-lens
Abstract
We present results of ultra-deep ISOCAM observations through a cluster-lens at 7 and 15 micron 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 micron sources are cluster galaxies. The other 7 micron and almost all 15 micron sources are identified as lensed distant galaxies. Thanks to the gravitational amplification they constitute the faintest MIR detected sources, allowing us to extend the number counts in both the 7 and 15 micron bands. In particular, we find that the 15 micron counts have a steep slope alpha_15 = -1.5 +/- 0.3 and are large, with N_15 (>30 microJy}) = 13 +/- 5 per square arcmin. These numbers rule out non-evolutionary models and favour very strong evolution. Down to our counts limit, we found that the resolved 7 and 15 microns background radiation intensity is respectively (2 +/-0.5) 10^(-9) and (5 +/-1) 10^(-9) W m^(-2) sr^(-1).
Keywords
Cite
@article{arxiv.astro-ph/9810480,
title = {An ultra-deep ISOCAM observation through a cluster-lens},
author = {B. Altieri and L. Metcalfe and J. P. Kneib and B. McBreen and H. Aussel and A. Biviano and M. Delaney and D. Elbaz and K. Leech and L. Lémonon and K. Okumura and R. Pelló and B. Schulz},
journal= {arXiv preprint arXiv:astro-ph/9810480},
year = {2007}
}
Comments
5 pages, 4 figures, submitted to A&A as a letter