This article has an erratum: [erratum]
Volume 534, October 2011
|Number of page(s)||25|
|Published online||14 October 2011|
The AMIGA sample of isolated galaxies
Departamento de Física Teórica y del Cosmos, Universidad de Granada, 18071 Granada, Spain
2 Instituto Carlos I de Física Teórica y Computacional, Universidad de Granada, Spain
3 Instituto de Astrofísica de Andalucía (CSIC) Apdo. 3004, 18080 Granada, Spain
4 National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, 181-8588 Tokyo, Japan
5 Nobeyama Radio Observatory, Minamimaki, Minamisaku, 384-1805 Nagano, Japan
6 Joint Alma Observatory/ESO, Las Condes, Santiago, Chile
7 Institute for Astronomy, University of Edinburgh, EH9 3 HJ Edinburgh, UK
8 Student Center for Independent Research in the Science, Wakayama University, 930 Sakaedani, 640-8510 Wakayama, Japan
9 Department of Astronomy, University of Massachusetts, MA 01003 Amherst, USA
Received: 8 April 2011
Accepted: 25 July 2011
Aims. We characterize the molecular gas content (ISM cold phase) using CO emission of a redshift-limited subsample of isolated galaxies from the AMIGA (Analysis of the interstellar Medium of Isolated GAlaxies) project in order to provide a comparison sample for studies of galaxies in different environments.
Methods. We present the 12CO(1–0) data for 273 AMIGA galaxies, most of them (n = 186) from our own observations with the IRAM 30 m and the FCRAO 14 m telescopes and the rest from the literature. We constructed a redshift-limited sample containing galaxies with 1500 km s-1 < v < 5000 km s-1 and excluded objects with morphological evidence of possible interaction. This sample (n = 173) is the basis for our statistical analysis. It contains galaxies with molecular gas masses, MH2, in the range of ~108 − 1010 M⊙. It is dominated, both in absolute number and in detection rate, by spiral galaxies of type T = 3–5 (Sb-Sc). Most galaxies were observed with a single pointing towards their centers. Therefore, we performed an extrapolation to the total molecular gas mass expected in the entire disk based on the assumption of an exponential distribution. We then studied the relationships between MH2 and other galactic properties (LB, , LK, LFIR, and MHI).
Results. We find correlations between MH2 and LB, , LK, and LFIR. The tightest correlation of MH2 holds with LFIR and, for T = 3–5, with LK, and the poorest with . The correlations with LFIR and LK are very close to linearity. The correlation with LB is nonlinear so that MH2/LB increases with LB. The molecular and the atomic gas masses of our sample show no strong correlation. We find a low mean value, log(MH2/MHI) = −0.7 (for T = 3–5), and a strong decrease in this ratio with morphological type. The molecular gas column density and the surface density of the star formation rate (the Kennicutt-Schmidt law) show a tight correlation with a rough unity slope. We compare the relations of MH2 with LB and LK found for AMIGA galaxies to samples of interacting galaxies from the literature and find an indication for an enhancement of the molecular gas in interacting galaxies of up to 0.2–0.3 dex.
Key words: galaxies: evolution / galaxies: interactions / galaxies: ISM / radio lines: ISM / radio lines: galaxies / surveys
Full Tables 1, 4 and 5 are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (22.214.171.124) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/534/A102
Appendix is available in electronic form at http://www.aanda.org
© ESO, 2011
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