Dr. Glenn van de Ven
- Dynamical models of galaxies
- globular cluster dynamics
- Integral-field spectroscopy
- Gravitational lensing
Globular clusters (GCs) are the living fossils of the history of their native galaxies and the record keepers of the violent events that made them change their domicile. This project aims to mine GCs as living fossils of galaxy evolution to address fundamental questions in astrophysics:
GCs are dynamically complex stellar systems, with internal rotation and velocity dispersions that depend on both the intrinsic positions and masses of their stars. Yet it is unknown if this complexity is a signature of a central intermediate mass black hole (IMBH), relates to the observed multiple stellar populations in GCs, or arises from external gravitational effects. Following the tidal disruption of satellite galaxies, their GCs, and possibly their nuclei, remain as abundant and easily observed relics of the hierarchical build-up of galaxies. The evolution of galaxies to the present day can thus be unearthed by recovering the orbits of the GCs that are surrounding them.
In the next few years, astrometric data from ESA’s Gaia mission will allow for high-precision measurements of the 6D position-velocity vectors of the GCs in the Milky Way (MW). At the same time, numerous imaging and spectroscopy surveys are providing extensive catalogues of colours, metallicities and radial velocities of hundreds of GCs around nearby galaxies. To make use of this data, we are building tools to ascertain which GCs are accretion survivors and to recover their orbits.
The presence (or absence) of a central intermediate mass black hole (IMBH) or of multiple stellar populations might tell which GCs are accreted, and among these which are former galaxy nuclei. At the same time, detection of IMBHs is important as they are predicted seeds for supermassive black holes in the centres of galaxies; while the multiple stellar populations in GCs are crucial witnesses to the extreme modes of star formation in the early universe. However, for every putative dynamical IMBH detection in a GC so far, the expected kinematic and emission signatures have not been seen; also, the origin of multiple stellar populations within GCs still lacks any uncontrived explanation.
The quantity and quality of chemical and kinematical measurements of individual stars in GCs in the MW is currently dramatically increasing. This includes precision proper motion measurements of tens of thousands of stars in the inner parts of GCs based on Hubble Space Telescope (HST) data. Soon this will be complemented by Gaia proper motions of thousands of giant stars in the outer parts of the GCs. With the novel tools developed in this group, we aim to fully exploit this data to firmly establish the (non)presence of IMBHs and to disentangle the internal dynamics of the multiple stellar populations to decipher their origin.
With the synergy of new population-dynamics tools and exquisite chemo-kinematic data, the ArcheoDyn project aims to unlock the full potential of GCs as living fossils of the past of galaxies.
Current group members and their research interests are listed below. In addition, we function as a subset of the MPIA Dynamics group, with regular meetings between members based at ESO and MPIA.
Description of open positions are listed below: