Near-IR Galaxy Counts and Evolution from the Wide-Field ALHAMBRA survey
Abstract
The ALHAMBRA survey aims to cover 4 square degrees using a system of 20 contiguous, equal width, medium-band filters spanning the range 3500 A to 9700 A plus the standard JHKs filters. Here we analyze deep near-IR number counts of one of our fields (ALH08) for which we have a relatively large area (0.5 square degrees) and faint photometry (J=22.4, H=21.3 and K=20.0 at the 50% of recovery efficiency for point-like sources). We find that the logarithmic gradient of the galaxy counts undergoes a distinct change to a flatter slope in each band: from 0.44 at [17.0, 18.5] to 0.34 at [19.5, 22.0] for the J band; for the H band 0.46 at [15.5, 18.0] to 0.36 at [19.0, 21.0], and in Ks the change is from 0.53 in the range [15.0, 17.0] to 0.33 in the interval [18.0, 20.0]. These observations together with faint optical counts are used to constrain models that include density and luminosity evolution of the local type-dependent luminosity functions. Our models imply a decline in the space density of evolved early-type galaxies with increasing redshift, such that only 30% - 50% of the bulk of the present day red-ellipticals was already in place at z~1.
Cite
@article{arxiv.0902.2403,
title = {Near-IR Galaxy Counts and Evolution from the Wide-Field ALHAMBRA survey},
author = {D. Cristobal-Hornillos and J. A. L. Aguerri and M. Moles and J. Perea and F. J. Castander and T. Broadhurst and E. J. Alfaro and N. Benitez and J. Cabrera and J. Cepa and M. Cervino and A. Fernandez-Soto and R. M. Gonzalez-Delgado and C. Husillos and L. Infante and I. Marquez and V. J. Martinez and J. Masegosa and A. del Olmo and F. Prada and J. M. Quintana and S. F. Sanchez},
journal= {arXiv preprint arXiv:0902.2403},
year = {2011}
}
Comments
Accepted for publication in The Astrophysical Journal