Unravelling the stellar Initial Mass Function of early-type galaxies with hierarchical Bayesian modelling

Matthijs Dries

Research output: ThesisThesis fully internal (DIV)

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Stars form with a distribution of masses, called the initial mass function (IMF). In a general sense, one can say that there are much more low-mass than high-mass stars. In recent years, continuing evidence has shown that the ratio between low-mass and high-mass stars in the heaviest galaxies of the universe is not the same as in the Milky Way. If confirmed, this variable mass distribution can help to shed light on theories of star formation and also affect other results that assume a so-called ‘universal IMF’. A careful determination of the stellar mass distribution and possible variations of it is therefore of great importance for astronomy.

In distant galaxies, we cannot observe individual stars. Therefore the stellar mass distribution of these galaxies can only be determined indirectly. In this thesis, we have developed an advanced statistical model for determining the stellar mass distribution of unresolved galaxies with spectroscopy. The results of this thesis confirm that the mass distribution of the heaviest galaxies in the universe is not the same as in the Milky Way. Our results show that the (relative) number of high-mass stars is approximately constant as function of galaxy mass. However, the (relative) number of low-mass stars changes as function of galaxy mass, such that more massive galaxies contain more low-mass stars.
Translated title of the contributionHet ontrafelen van de stellaire initiële massafunctie van elliptische sterrenstelsels met hiërarchisch Bayesiaans modelleren
Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • University of Groningen
  • Trager, Scott, Supervisor
  • Koopmans, Léon, Supervisor
Award date6-Apr-2018
Place of Publication[Groningen]
Print ISBNs978-94-034-0465-3
Electronic ISBNs978-94-034-0464-6
Publication statusPublished - 2018

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