Volume 630, October 2019
|Number of page(s)||8|
|Published online||01 October 2019|
Stellar systems following the R1/m luminosity law
IV. The total energy and the central concentration of galaxies
Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281 S9, 9000 Gent, Belgium
2 Dipartimento di Fisica e Astronomia, Università di Bologna, Via Piero Gobetti 93/2, Bologna, Italy
Accepted: 2 September 2019
We expand our previous analytical and numerical studies of the family of Sérsic models, which are routinely used to describe early-type galaxies and the bulges of spiral galaxies. In particular, we focus on the total energy budget, an important dynamical property that has not been discussed in detail in previous works. We use two different methods to calculate the total energy for the Sérsic model family that result in two independent expressions that can be used along the entire sequence of Sérsic models. We use these expressions to investigate whether the Spitzer concentration index is a reliable measure for the intrinsic 3D concentration of galaxies, and we conclude that it is not a very useful measure for the central concentration. The popular Third Galaxy Concentration index, on the other hand, is shown to be a reliable measure for the intrinsic 3D concentration, even though it is based on the surface brightness distribution and not on the intrinsic 3D density.
Key words: galaxies: structure / galaxies: kinematics and dynamics / methods: analytical
© ESO 2019
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