Dark matter in early-type galaxies: Dynamical modelling of IC 1459, IC 3370, NGC 3379 and NGC 4105

Abstract

We analyse long-slit spectra of four early-type galaxies which extend from ∼1 to 3 effective radii: IC 1459; IC 3370; NGC 3379 and NGC 4105. We have extracted the full line-of-sight velocity distribution (in the case of NGC 3379 we also used data from the literature), which we model using the two-integral approach. Using two-integral modelling, we find no strong evidence for dark haloes, but the fits suggest that three-integral modelling is necessary. We also find that the inferred constant mass-to-light ratio in all the four cases is typical for early-type galaxies. Finally, we also discuss the constraints on the mass-to-light ratio, which can be obtained using X-ray haloes in the case of IC 1459, NGC 3379 and NGC 4105, and compare the estimated values with the predictions from the dynamical modelling. © 2005 RAS.