ArcheoDyn

Globular clusters as living fossils of the past of galaxies

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:

  • Do satellite galaxies merge as predicted by the hierarchical build-up of galaxies? ⟷ Can we recover disrupted satellite galaxies from the GCs they left in their host?
  • What are the seeds of supermassive black holes in the centres of galaxies? ⟷ Do GCs harbour the intermediate mass black holes?
  • How did star formation originate in the earliest phases of galaxy formation? ⟷ Can the origin of multiple stellar populations in GCs be uncovered from distinct dynamical fossil signatures?
To answer these questions we will use population-dependent dynamical models to take full advantage of the emerging wealth of chemical and kinematical data on GCs.

ArcheoDyn is funded through a Consolidator Grant from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (under grant agreement No 724857).

Background

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.

Group Members

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.

Group Leader

Dr. Glenn van de Ven
  • Dynamical models of galaxies
  • globular cluster dynamics
  • Integral-field spectroscopy
  • Gravitational lensing
  • glenn.vandeven@eso.org

Postdocs

Dr. Prashin Jethwa
  • Dark matter distribution of galaxies
  • Hierarchical growth of galaxies
  • MW halo substructures
  • Large surveys
  • pjethwa@eso.org

Ph.D students

Francisco Aros (currently at MPIA)
  • Dynamical signatures of IMBHs in globular clusters
  • Dark matter in dwarf spheroidal galaxies
  • aros@mpia.de

Undergraduate and visiting students

Open positions

Description of open positions are listed below:

Postdocs

We are looking to fill one (possibly two) postdoc position(s) within the ArcheoDyn project. Applicants should have a PhD in astronomy/physics with affinity for programming, or in computer science/applied mathematics with affinity for astronomy. The full job advertisement can be found here.

MSc and BSc students

Various aspects of the ArcheoDyn project are well-suited for a bachelor or master project in astronomy, physics or computer science. Please contact any of the group members above for further information.