On the baryonic, stellar, and luminous scaling relations of disk galaxies

Abstract

We explore how the slopes and scatters of the scaling relations of disk galaxies (V m-L[-M], R-L[-M], and V m-R) change when moving from B- to K-bands and to stellar and baryonic quantities. For our compiled sample of 76 normal, non-interacting, high and low-surface brightness (SB) disk-galaxies, we find important changes, which evidence evolution effects, mainly related to the gas infall and star-formation (SF) processes. We also explore correlations among the (B - K) color, stellar mass fraction, f s, mass, M, luminosity, L, and surface density (or SB), as well as correlations among the residuals of the scaling relations, and among these residuals and those of the other relations studied here. Some of our findings are the following: (i) the scale length R bar is a third parameter in the baryonic Tully-Fisher relation (TFR) and the residuals of this relation follow a trend (slope -0.15) with the residuals of the R bar-M bar relation; for the stellar and K-band cases, the scale length is no longer a third parameter and the mentioned trend disappears; (ii) among the TFRs, the B-band TFR is the most scattered; in this case, the color is a third parameter, in agreement with previous works; (iii) the low-SB (LSB) galaxies break some observed trends in diagrams that include SD, color, and f s, suggesting then a threshold in the gas SD, Σg, below which the SF efficiency becomes independent of Σg and of the gas infall rate. Our results are interpreted and discussed in the light of Λ Cold Dark Matter (ΛCDM)-based models of disk-galaxy formation and evolution. These models are able to explain not only the baryonic scaling correlations, but also most of the processes responsible for the observed changes in the slopes, scatters, and correlations among the residuals when changing to stellar and luminous quantities. The galaxy baryon fraction, f gal, is required to be smaller than 0.05 on average. We detect some potential difficulties for the models: the observed color-M and SD-M correlations are steeper, and the intrinsic scatter in the baryonic TFR is smaller than those predicted. © 2008. The American Astronomical Society. All rights reserved.