2004MNRAS.349..933R

ESO 566-24 is an extraordinary barred galaxy that has four regularly spaced spiral arms in blue light images. This type of spiral structure, which is rare among the spiral population, is also clearly seen in near-infrared (NIR) images, and thus is present in the old stellar population. We have constructed dynamical models of ESO 566-24. The gravitational potential is determined using NIR photometry, and the gas dynamics is modelled as inelastically colliding particles. The resulting morphology and kinematics with different assumed pattern speeds, disc vertical thicknesses and dark halo contributions are compared with observations. Our models reproduce the main morphological features of this galaxy: the four-armed spiral, and the inner and nuclear rings. The pattern speed of the bar is such that the corotation resonance is well outside the bar radius, r_CR/r_b= 1.6±0.3. The four-armed spiral resides in the region between inner and outer 4/1 resonances. In addition, the main kinematical features, including bar-induced deviations from circular rotation, are explained by our models. The best fit is obtained when the dark halo contribution is just enough to make the modelled rotation curve match the observed one. Thus, luminous matter dominates the rotation curve within the disc region.