The Vcirc-σc relation in high and low surface brightness galaxies

We investigate the relation between the asymptotic circular velocity, V_circ, and the central stellar velocity dispersion, σ_c, in galaxies. We consider a new sample of high surface brightness spiral galaxies (HSB), low surface brightness spiral galaxies (LSB), and elliptical galaxies with HI-based V_circ measurements. We find that: 1) elliptical galaxies with HI measurements fit well within the relation; 2) a linear law can reproduce the data as well as a power law (used in previous works) even for galaxies with σ_c < 70 km/s; 3) LSB galaxies, considered for the first time with this respect, seem to behave differently, showing either larger V_circ values or smaller σ_c values.