Dark matter in early-type galaxies: dynamical modelling of IC1459, IC3370, NGC3379 and NGC4105

Abstract

We analyse long-slit spectra of four early-type galaxies which extend from ~1 to ~3 effective radii: IC1459, IC3370, NGC3379 and NGC4105. We have extracted the full line-of-sight velocity distribution (in the case of NGC3379 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 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 IC1459, NGC3379 and NGC4105 and compare the estimated values with the predictions from the dynamical modelling.