Issue |
A&A
Volume 449, Number 3, April III 2006
|
|
---|---|---|
Page(s) | 937 - 949 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361:20054020 | |
Published online | 24 March 2006 |
The AMIGA sample of isolated galaxies
II. Morphological refinement
1
Department of Astronomy, University of Alabama, Tuscaloosa, USA
2
Instituto de Astrofísica de Andalucía, CSIC, Apdo. 3004, 18080 Granada, Spain e-mail: lourdes@iaa.es
3
GEPI, Observatoire de Paris-Meudon, 61 avenue de l'Observatoire, 75014 Paris, France
4
Departamento de Física Teórica y del Cosmos, Facultad de Ciencias, Universidad de Granada, Spain
5
LERMA, Observatoire de Paris, 61 avenue de l'Observatoire, 75014 Paris, France
Received:
8
August
2005
Accepted:
16
November
2005
We present a refinement of the optical morphologies for
galaxies in the Catalog of Isolated Galaxies that forms the basis of
the AMIGA (Analysis of the interstellar Medium of Isolated GAlaxies) project.
Uniform reclassification using the digitized POSS II data
benefited from the high resolution and dynamic range of that sky survey.
Comparison with independent classifications made for an SDSS
overlap sample of more than 200 galaxies confirms the reliability of the
early vs. late-type discrimination and the accuracy of spiral subtypes
within 1–2. CCD images
taken at the Observatorio de Sierra Nevada were also used to solve
ambiguities in early versus late-type classifications.
A considerable number of galaxies in the catalog
(
193) are flagged for the presence of nearby companions or signs of
distortion likely due to interaction.
This most isolated sample of galaxies in the local Universe is dominated by
two populations: 1) 82% are spirals (Sa–Sd) with the bulk being luminous
systems with small bulges (63% between types Sb–Sc) and 2) a significant
population of early-type E–S0 galaxies (14%). Most of the types later than Sd are low luminosity galaxies concentrated in the local supercluster where
isolation is difficult to evaluate. The late-type spiral majority of the
sample spans a luminosity range
18 to -22 mag.
Few of the E/S0 population are more luminous than -21.0 marking the absence of the
often-sought super L* merger (e.g. fossil elliptical) population. The
rarity of high luminosity systems results in a fainter derived M* for this
population compared to the spiral optical luminosity function (OLF).
The E–S0 population is from 0.2 to 0.6 mag fainter depending on
how the sample is defined. This marks the AMIGA sample as
unique among samples that compare early and late-type OLFs separately.
In other samples, which always involve galaxies in higher density
environments,
is almost always 0.3–0.5 mag brighter than
, presumably reflecting a stronger correlation between M* and
environmental density for early-type galaxies.
Key words: galaxies: evolution / galaxies: interactions / galaxies: luminosity function, mass function / surveys
© ESO, 2006
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