Volume 462, Number 2, February I 2007
|Page(s)||507 - 523|
|Published online||13 November 2006|
The AMIGA sample of isolated galaxies
III. IRAS data and infrared diagnostics
Departamento de Física Teórica y del Cosmos, Facultad de Ciencias, Universidad de Granada, Spain e-mail: email@example.com
2 Instituto de Astrofísica de Andalucía (IAA/CSIC), Apdo. 3004, 18080 Granada, Spain
3 Department of Astronomy, University of Alabama, Tuscaloosa, USA
4 Instituto de Radioastronomía Milimétrica (IRAM), Avda. Divina Pastora 7, local 20, 18012 Granada, Spain
5 GEPI/CAI, Observatoire de Paris, 77 avenue Denfert-Rochereau, 75014 Paris, France
6 LERMA - Observatoire de Paris, 61 avenue de l'Observatoire, 75014 Paris, France
7 INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
Accepted: 26 September 2006
Aims.We describe the mid- (MIR) and far- (FIR) infrared properties of a large (~1000) sample of the most isolated galaxies in the local Universe. This sample is intended as a “nurture-free” zero point against which more environmentally influenced samples can be compared.
Methods.We reprocess IRAS MIR/FIR survey data using the ADDSCAN/SCANPI utility for 1030 out of 1050 galaxies from the Catalogue of Isolated Galaxies (CIG) as part of the AMIGA project. We focus on diagnostics (FIR luminosity LFIR, , and IRAS colours) thought to be sensitive to effects of environment or interaction.
Results.The distribution of sharply peaks from 9.0–10.5, with very few (<2%) galaxies above 10.5. Review of available optical images of the most FIR luminous galaxies finds the majority likely to be interacting systems missed in our earlier morphological reevaluation. The optically normalised luminosity diagnostic shows a sharply peaked distribution between 0.0 and -1.0. These results were compared to the magnitude limited sample of the Center for Astrophysics that was selected without environmental discrimination. This modestly (e.g., compared to cluster, binary galaxy, and compact group samples) environmentally affected sample shows a significantly higher mean , and R, whereas the mean is the same. Our sample shows a strong LFIR vs. LB correlation, with a slope steeper than one (). Interacting galaxies were found above this correlation, showing an enhancement in LFIR. With respect to the IRAS colours, we found higher values for ellipticals and late-type galaxies than for spirals, indicating a higher dust temperature. The mean value of was found to be lower than for interacting samples from the literature.
Conclusions.The results indicate that the FIR emission is a variable enhanced by interaction, and that our sample probably shows the lowest possible mean value. This attests to the utility of our sample for defining a nurture-free zero point.
Key words: galaxies: evolution / galaxies: interactions / galaxies: luminosity function, mass function / surveys / infrared: galaxies
© ESO, 2007
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