Symposium S11  28-29 June 2021

The outer reaches of galaxies: structure, kinematics, and accretion history

Aims and scope

The study of galaxy halos is reaching a golden age where it has become possible to compare observations of their physical properties with predictions from cosmological simulations of structure formation. Thanks to telescopes with large fields of view we can measure surface brightness features as faint as 30 mag arcsec-2, unveiling on-going accretion events. Fine-tuned spectroscopic techniques, using telescopes equipped with integral field, multi-object or custom-built slitless spectrographs, allow 2D kinematic mapping from the centres far into the outer regions of galaxies. Discrete tracers, resolved stars in nearby systems, planetary nebulae and globular clusters further afar, provide velocity fields and angular momentum profiles out to large distances. Modern cosmological simulations resolve the accretion of satellites with a large mass range, enabling detailed predictions of the three-dimensional shapes, kinematics and angular momentum distributions in galaxy halos, and linking these to the merger and accretion history of galaxies. Reaching out to the galaxy outskirts is key to mapping the transition from baryon to dark matter dominated regions, to assessing dark matter?s substructures and to linking galaxies to their cosmological environments.


During this EAS symposium, close interaction between observational astronomers, theorists and simulators will identify those topics that can be tacked jointly as new windows of investigation open up, and that help us learn more about the major physical processes which govern the formation of the outer halos.

  • What are the key measurements from observations and simulations?
  • How do galaxies transition into their environments?
  • What are the 3D shapes, angular momenta, orbital and stellar population properties in the outer halos?
  • How do these relate to the galaxies? merger and accretion histories?
  • How do the halos of early-type and spiral galaxies compare at similar mass?
  • Do spiral galaxies have extended disks of accreted stars, and what do we know about the halos of dwarfs?
  • What are the main merger-accretion channels through which halos form in different galaxies, according to cosmological simulations?

Invited speakers

  • Peter Erwin (MPE)
  • Nicolas Martin (Obs. de Strasbourg)
  • Caroline Foster (Sydney Univ.)
  • Myung Gyoon Lee (Seul National Univ.)
  • Alis Deason (Durham Univ. )
  • Claudia Pulsoni (MPE )

Scientific organisers

    Co-Chairs: Magda Arnaboldi (ESO), Ortwin Gerhard (MPE, Germany), Roger Davies (Univ Oxford, UK)
    SOC members: Francesca Annibali (INAF, Obs. Bologna, Italy), Ralf Bender (MPE, Germany), Vasily Belokurov (IoA, Cambridge, UK), Enrichetta Iodice (INAF-OAC, Italy), Rodrigo Ibata (Univ. Strasbourg, France) , Ewa Lokas (Nicolaus Copernicus Astronomical Center, Poland), Lucio Mayer (Univ Zurich, Switzerland), Annalisa Pillepich (MPIA, Germany), Patricia Sánchez-Blázquez (U. Complutense Madrid, Spain), Daniel Thomas (University of Portsmouth, UK), Ignacio Trujillo (IAC, Spain)


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Updated on Tue Feb 23 12:57:54 CET 2021