Issue |
A&A
Volume 422, Number 3, August II 2004
|
|
---|---|---|
Page(s) | 841 - 863 | |
Section | Cosmology (including clusters of galaxies) | |
DOI | https://doi.org/10.1051/0004-6361:20047140 | |
Published online | 16 July 2004 |
The ESO-Sculptor Survey: Evolution of late-type galaxies at redshifts 0.1–0.5*
1
Institut d'Astrophysique de Paris, CNRS, Univ. Pierre et Marie Curie, 98 bis boulevard Arago, 75014 Paris, France e-mail: lapparen@iap.fr
2
Laboratoire d'Astrophysique de Marseille, BP8, Traverse du Siphon, 13376 Marseille Cedex 12, France e-mail: stephane.arnouts@oamp.fr
3
Depto. de Astronomía et Astrofísica, Pontificia Universidad Católica de Chile, Casilla 306, Santiago 22, Chile e-mail: ggalaz@astro.puc.cl
4
INAF-Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna, Italy e-mail: bardelli@excalibur.bo.astro.it
Received:
26
January
2004
Accepted:
1
April
2004
Using the Gaussian+Schechter composite luminosity functions measured
from the ESO-Sculptor Survey ([CITE], A&A, 404, 831) and assuming that
these functions do not evolve with redshift out to , we obtain
evidence for evolution in the late spectral class containing late-type
Spiral (Sc+Sd) and dwarf Irregular (dI) galaxies. There are
indications that the Sc+Sd galaxies are the evolving population, but
we cannot exclude that the dI galaxies also undergo some evolution.
This evolution is detected as an increase of the Sc+Sd+dI galaxy
density which can be modeled as either
or
using the currently favored cosmological
parameters
and
; the uncertainty in
the linear and power-law evolution rates is of the order of unity. For
and
, the linear and power-law
evolution rates are ~
and ~
respectively. Both
models yield a good match to the ESS
redshift
distributions to
mag and to the number-counts to
mag, which probe the galaxy distribution to redshifts
and
respectively.
The present analysis shows the usefulness of the joint use of the
magnitude and redshift distributions for studying galaxy evolution. It
also illustrates how Gaussian+Schechter composite luminosity functions
provide more robust constraints on the evolution rate than pure
Schechter luminosity functions, thus emphasizing the importance of
performing realistic parameterizations of the luminosity functions for
studying galaxy evolution.
The detected density evolution indicates that mergers could play
a significant role in the evolution of late-type Spiral and dwarf
Irregular galaxies. However, the ESO-Sculptor density increase with
redshift could also be caused by a ~1mag brightening of the
Sc+Sd+dI galaxies at
and
mag brightening at
, which is compatible with the expected passive brightening of
Sc galaxies at these redshifts. Distinguishing between luminosity and
density evolution is a major difficulty as these produce the same
effect on the redshift and magnitude distributions. The detected
evolution rate of the ESO-Sculptor Sc+Sd+dI galaxies is nevertheless within the
range of measured values from the other existing analyses, whether
they provide evidence for density or luminosity evolution.
Key words: galaxies: luminosity function, mass function / galaxies: evolution / galaxies: distances and redshifts / galaxies: spiral / galaxies: irregular / galaxies: dwarf
© ESO, 2004
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