Determination of resonance locations in barred spiral galaxies using multiband photometry

Abstract

In this paper, we apply a method identified by Puerari&Dottori to find the corotation radii (CR) in spiral galaxies. We apply our method to 57 galaxies, 17 of which have already have their CR locations determined using other methods. The method we adopted entails taking Fourier transforms along radial cuts in the u, g, r, i, and z wavebands and comparing the phase angles as a function of radius between them. The radius at which the phase angles cross indicates the location of the corotation radius. We then calculated the relative bar pattern speed, R, and classified the bar as 'fast', where R < 1.4, slow, where R ≥ 1.4, or intermediate, where the errors on R are consistent with the bar being 'slow' or 'fast'. For the 17 galaxies that had their CR locations previously measured, we found that our results were consistent with the values of R obtained by the computer simulations of Rautiainen, Salo & Laurikainen. For the larger sample, our results indicate that 34 out of 57 galaxies (≃60 per cent) have fast bars. We discuss these results in the context of its implications for dark matter concentrations in disc galaxies. We also discuss these results in the context of different models for spiral structure in disc galaxies.