DARK MATTER IN MASSIVE EARLY-TYPE GALAXIES: 100 YEARS OF THE JEANS EQUATIONS

In 1919 James Jeans published the book Problems of Cosmogony and Stellar Dynamics in which he summarized his work on dynamics of stellar systems based on his papers published from 1915 onwards. To mark the centenary of this publication we present here one application of his work relevant for contemporary research of galaxies: we analyze the problem of dark matter in massive early-type galaxies (ellipticals and lenticulars) using various available observational data. After discussing the basics of the Jeans equations we study their application on the integrated stellar spectra of galaxies, planetary nebula data and, especially, globular cluster data. We rely on both Newtonian and MOND frameworks and show their advantages and drawbacks. To infer the contribution of the dark component in early-type galaxies we rely on several stellar population synthesis models. It is shown that dark matter does not dominate in the inner regions of early-type galaxies, but becomes more important beyond three effective radii.