Thesis Topic: Fundamental planes of dynamically hot stellar systems in the local universe
Thesis Supervisor: Michael Hilker
In recent years the fundamental plane of dynamically hot stellar systems (i.e. old star clusters and early-type galaxies) got filled with new types of objects, like ultra-compact dwarf galaxies (UCDs), compact ellipticals (cEs), ultra-faint dwarf spheroidals (UFDs) and extended star clusters (ECs). The scaling relations of those systems can now be studied in great detail over ten orders of magnitude in mass.
So far, scaling relations like the mass-radius and surface density-mass relations have been presented for object samples that were assembled from very different environments, reaching from the Local Group to massive galaxy clusters (see figure on the right, Misgeld & Hilker 2011, MNRAS 414, 3699).
The idea of this PhD topic is twofold:
First, a study of the environmental dependence of the fundamental plane of dynamically hot stellar systems shall be performed. I.e. how does it look like for the Local Group, how for galaxy groups of the Local Volume and how for the most nearby galaxy clusters (Virgo, Fornax, Hydra, Centaurus and Coma)? What is the relative number ratio of star cluster to galaxies, of dwarf to giant galaxies, and the frequency of cEs and UCDs? How do these number ratios change with environment? What are the observational biases of different samples? How many objects are not detected yet in the local universe?
The goal of this first part is to develop completeness corrected fundamental planes for different environments (with data mainly collected from the literature, but also initiatives of applying for observing time to obtain complementary data sets are appreciated).
In a second step, the idea is to 'fill' the fundamental planes of the local galaxy and star cluster samples with evolutionary paths. How does star cluster evolution move globular clusters in the mass-size plane? How do major or minor mergers move galaxies around in this plane? In which direction work disruption processes (in particular for dwarf galaxies)? Can all the features in the fundamental plane be explained by those processes? Many of the evolutionary models can be found in the literature, but new ideas and calculations are welcome.
A concrete goal for this second part could be to develop a time series of fundamental planes for the Fornax or Virgo cluster, two environments with rich data sets.
In summary, the overall goal of the PhD thesis is to make a further step in understanding galaxy and their associated star cluster system evolution.
Depending on the preferences of the PhD candidate, this PhD thesis is flexible in setting the focus on either more theoretical aspects (galaxy evolution models and related simulations), or on gathering and analysing more data related to this project (including ESO telescopes).