SIMBAD references

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. We present the ¹²CO(1-0) data for 273 AMIGA galaxies, most of them (n=186) from our own observations with the IRAM 30m and the FCRAO 14m telescopes and the rest from the literature. We constructed a redshift-limited sample containing galaxies with 1500km/s<v<5000km/s 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, M_H2, in the range of ∼10⁸-10¹⁰M_☉. 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 M_H2 and other galactic properties (L_B, D₂₅², L_K, L_FIR, and M_HI). We find correlations between M_H2 and L_B, D₂₅², L_K, and L_FIR. The tightest correlation of M_H2 holds with L_FIR and, for T=3-5, with L_K, and the poorest with D₂₅². The correlations with L_FIR and L_K are very close to linearity. The correlation with L_B is nonlinear so that M_H2/L_B increases with L_B. The molecular and the atomic gas masses of our sample show no strong correlation. We find a low mean value, log(M_H2/M_HI) = -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 M_H2 with L_B and L_K 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.