Photometric characterization of Sb-Sc galaxies

Scientific Results

We have performed a detailed photometric analysis (bulge-disk-bar decomposition and Concentration-Asymmetry-Clumpiness – CAS parametrization) for Sb-Sc morphological types of AMIGA sample, as they are the most representative population among the isolated spiral galaxies.

Fig. 1 Examples of BUDA decomposition

Our analysis yields a large number of important galactic parameters and various correlation plots are used to seek relationships that might shed light on the processes involved in determining those parameters. Assuming that the bulge Sérsic index and/or Bulge/Total luminosity ratios are reasonable diagnostics for pseudo- versus classical bulges, we conclude that the majority of late-type isolated disk galaxies likely host pseudobulges rather than classical bulges.

Fig. 2 Bulge Sérsic index versus Bulge/Total luminosity ratio. A linear regression fit (solid line) and a bisector fit (dashed line) are shown for Sb- type only. The typical 2σ error bars are shown

Our parametrization of galactic bulges and disks suggests that the properties of the pseudobulges are strongly connected to those of the disks. This may indicate that pseudobulges are formed through internal processes within the disks (i.e. secular evolution) and that bars may play an important role in their formation. Although the sample under investigation covers a narrow morphological range, a clear separation between Sb and Sbc-Sc types is observed in various measures, e.g. the former are redder, brighter, have larger disks and larger bars, more luminous bulges, are more concentrated, more symmetric and clumpier than the latter. A comparison with samples of spiral galaxies (within the same morphological range) selected without isolation criteria reveals that the isolated galaxies tend to host larger bars, are more symmetric, less concentrated and less clumpy.

PDF File Durbala et al. 2008