Deep near-ir observations of the chandra deep field and of the hdf-south - color and number counts
Apr, 2001Citations per year
Abstract: (arXiv)
We present near-IR (J and Ks) number counts and colors of galaxies detected in deep VLT-ISAAC images centered on the Chandra Deep Field and Hubble Deep Field-South for a total area of 13.6 arcmin. The limiting surface brightness obtained is Ks22.8 mag/arcsec and J24.5 (1) on both fields. A dN/dm relation with a slope of in J and in Ks is found in both fields with no evidence of decline near the magnitude limit. The median J-Ks color of galaxies becomes bluer at magnitudes fainter than Ks, in agreement with the different number counts slope observed in the two bands. We find a fraction ( of the total sample) of sources with color redder than J-Ks=2.3 at magnitudes Ks. Most of them appear as isolated sources, possibly elliptical or dusty starburst galaxies at redshift . The comparison of the observed number counts with models shows that our J-band and Ks-band counts are consistent with the prediction of a model based on a small amount of merging in a cosmology. On the other hand, we fail to reproduce the observed counts if we do not consider merging independently of the parameters defining the universe.References(48)
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