Dr Maarten Baes (Ghent University)

Dark matter and dust attenuation in elliptical galaxies - Dr Maarten Baes Colloquium

ATNF Marsfield Lecture Theatre

Abstract

It is generally assumed that elliptical galaxies are, like disk galaxies,
embedded in a massive dark matter halo. Recent stellar kinematical results
suggest that ellipticals start to be dark matter dominated at a few effective
radii.

The current stellar dynamical modelling techniques, however, don't
incorporate dust attenuation. Nevertheless, even modest amounts of dust can affect all
optical observables, including the observed kinematics. We have constructed
a set of dynamical models for elliptical galaxies in which dust attenuation is
included through a Monte Carlo technique. We find that a dust component with
an optical depth of order unity (as suggested by the observations) affects the
observed kinematics significantly, in the way that it mimics the presence of
a dark matter halo. Taking dust into account in dynamical modelling procedures
will hence reduce or may even eliminate the need for a dark matter halo at a
few effective radii.