Near-Infrared Galaxy Counts and Evolution from the Wide-Field ALHAMBRA Survey
Cristóbal-Hornillos, D.; Aguerri, J. A. L.;Moles, M.; Perea, J.; Castander, F. J.;Broadhurst, T.; Alfaro, E. J.; Benítez, N.;Cabrera-Caño, J.; Cepa, J.; Cerviño, M.;Fernández-Soto, A.; Delgado, R. M. González;Husillos, C.; Infante, L.; Márquez, I.;Martínez, V. J.; Masegosa, J.; del Olmo, A.;Prada, F.; Quintana, J. M.; Sánchez, S. F.. Near-Infrared Galaxy Counts and Evolution from the Wide-Field ALHAMBRA Survey. The Astrophysical Journal. 2009, Vol. Volume 696, Issue 2, pp. 1554-1575 (2009)., p. -2009.
The ALHAMBRA survey aims to cover 4 deg<SUP>2</SUP> using a system of 20
contiguous, equal width, medium-band filters spanning the range 3500
Å-9700 Å 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 deg<SUP>2</SUP>) 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.
Based on observations collected at the German-Spanish Astronomical
Center, Calar Alto, jointly operated by the Max-Planck-Institut für
Astronomie Heidelberg and the Instituto de Astrofísica de
Andalucía (CSIC).
The ALHAMBRA survey aims to cover 4 deg<SUP>2</SUP> using a system of 20
contiguous, equal width, medium-band filters spanning the range 3500
Å-9700 Å 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 deg<SUP>2</SUP>) 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.
Based on observations collected at the German-Spanish Astronomical
Center, Calar Alto, jointly operated by the Max-Planck-Institut für
Astronomie Heidelberg and the Instituto de Astrofísica de
Andalucía (CSIC).