Dynamics of Stellar Systems

The research in our group focuses on understanding the dynamical structure and evolution of stellar systems. In nearby galaxies and stellar clusters, we look for the 'fossil records' of their formation by constructing realistic dynamical models that fit their photometric and spectroscopic observations in detail. The latter include integral-field spectroscopy, observed motions and properties of individual stars, as well as (strong) gravitational lensing observations. Our individual research interests are listed below - for information, see group members' websites or look at some of our recent papers.

Group Members

Current group members and their research interests are listed below. We have some overlap with the MPIA Dynamics group, with regular meetings between members based at UniVie, ESO and MPIA.

Group Leader

Postdocs

Dr. Ryan Leaman
  • Dwarf galaxy evolution
  • Globular clusters as probes of accretion events
  • Semi-analytic models for galaxy assembly
Dr. Sabine Thater
  • Supermassive black holes in nearby galaxies
  • Galaxy kinematics from different tracers
  • Dynamical models of galaxies
  • Integral-field Spectroscopy

PhD students

MSc Students

Laura Posch
  • Effect of binary stars in globular clusters on chemical and kinematical properties

Open Positions

No open positions at the moment.

Publications

A complete listing of all publications by members of our group can be found at ADS. Below we list a few key papers that highlight the work done by our group.

The stellar orbit distribution in present-day galaxies inferred from the CALIFA survey
2018, NatAs, 2, 233
Zhu, Ling; van de Ven, Glenn; van den Bosch, Remco; Rix, Hans-Walter; Lyubenova, Mariya; Falcón-Barroso, Jesús; Martig, Marie; Mao, Shude; Xu, Dandan; Jin, Yunpeng; Obreja, Aura; Grand, Robert J. J.; Dutton, Aaron A.; Macciò, Andrea V.; Gómez, Facundo A.; Walcher, Jakob C.; García-Benito, Rubén; Zibetti, Stefano; Sánchez, Sebastian F.
Characterization of the internal dynamical strucuture of a large sample of galaxies.
A Discrete Chemo-Dynamical Model of the Dwarf Spheroidal Galaxy Sculptor: Mass Profile, Velocity Anisotropy and Internal Rotation
2016, MNRAS, 463, 1117
L. Zhu; G. van de Ven; L.L. Watkins; L. Posti
Development of discrete chemo-dynamics.
A novel look at energy equipartition in globular clusters
2016, MNRAS, 458, 3644
Bianchini, P.; van de Ven, G.; Norris, M. A.; Schinnerer, E.; Varri, A. L.
Velocity dispersion - stellar mass relation in globular cluster using MCMC simulations.
An over-massive black hole in the compact lenticular galaxy NGC 1277
2012, Natur, 491, 729
van den Bosch, Remco C. E.; Gebhardt, Karl; Gültekin, Kayhan; van de Ven, Glenn; van der Wel, Arjen; Walsh, Jonelle L.
Observational evidence for very high black hole-to-bulge ratio of 59% in a compact lenticular galaxy.
The Einstein Cross: Constraint on Dark Matter from Stellar Dynamics and Gravitational Lensing
2010, ApJ, 719, 1481
van de Ven, Glenn; Falcón-Barroso, Jesús; McDermid, Richard M.; Cappellari, Michele; Miller, Bryan W.; de Zeeuw, P. Tim
Constraining enclosed mass and mass-to-light ratio from stellar kinematics and gravitational lensing.
Triaxial orbit based galaxy models with an application to the (apparent) decoupled core galaxy NGC 4365
2008, MNRAS, 385, 647
van den Bosch, R. C. E.; van de Ven, G.; Verolme, E. K.; Cappellari, M.; de Zeeuw, P. T.
Introduction of the Triaxial Schwarzschild model and application to an elliptical galaxy.
The Dynamical Distance and Intrinsic Structure of the Globular Cluster omega Centauri
2006, A&A, 445, 513
G. van de Ven; R.C.E. van den Bosch; E.K. Verolme; P.T. de Zeeuw
An application of the Triaxial Schwarzschild code.

Activities

Meeting Organisation

Members of our group have organised conferences and workshops on a variety of topics.

Survival of Dense Star Clusters in the Milky Way System
Haus der Astronomie, Heidelberg - 19-21 November 2018
The Exciting Lives of Galactic Nuclei
Ringberg Castle - 26 February - 3 March 2017
MPIA Summer Conference 2015
Haus der Astronomie & MPIA, Heidelberg - 6-10 July 2015
3rd DAGAL Annual Meeting
MPIA Heidelberg - 23-27 March 2015
Gaia Challenge II
Haus der Astronomie / MPIA, Heidelberg - 27-31 October 2014
3rd CALIFA Busy Week
Haus der Astronomie, Heidelberg - 11-15 June 2012
Dynamics Meets Kinematic Tracers
Ringberg Castle - 10-14 April 2012

Workshops

Several times a year, we run workshops for researchers interested in running dynamical models. Find out more information here.

ArcheoDyn

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.