Special Session SS17  25 June 2025

The Galactic Center: Multiscale and Multiphysics Evolution through Multiwavelength Observations

Aims and scope

This special session aims to bring together observers, theorists, and simulators to advance our understanding of the Central Molecular Zone (CMZ) — the most extreme star-forming region in the Milky Way. Located at the Galactic Center, the CMZ contains approximately 10 million solar masses within only a radius of about 200 parsecs and is shaped by extreme environmental conditions (including high pressures, strong magnetic fields, and intense turbulence, and elevated cosmic ray ionization rates, all orders of magnitude higher than in the solar neighborhood) . It serves as a key laboratory for studying star formation in conditions akin to those in starburst and high-redshift galaxies. By bringing together experts working across multiple wavelengths, theoretical frameworks, and computational models, this session will address key open questions, including:

  • How does star formation operate under extreme conditions?
  • What role does stellar feedback play in regulating this process?
  • How do gas flows shape the CMZ's 3D structure and fuel mass accretion onto the central black hole, Sgr A?
  • What are the physical conditions that govern the formation and evolution of young star clusters in the CMZ?
Over the past decade, major observational efforts using facilities such as ALMA (ACES), VLA, MeerKAT, VLT (GalacticNucleus), HST, JWST, and Chandra have provided unprecedented insights into the CMZ. The coming years promise even more breakthroughs, with upcoming facilities such as the Extremely Large Telescope (ELT), next-generation Very Large Array (ngVLA), and ALMA upgrades set to revolutionize our understanding. Alongside these observational advances, theoretical and numerical simulations are playing a crucial role in testing the impact of various physical processes across scales—from the Galactic bar to individual molecular clouds. By integrating observations and models, this session aims to bridge knowledge gaps and refine our understanding of the CMZ's role in Galactic evolution.

Programme

Our special session will cover the following fundamental questions about the CMZ and its role in Galactic evolution:

  • Star formation and stellar feedback
    • The CMZ presents an extreme star-forming environment with intense turbulence, high gas densities, and strong magnetic fields. Understanding how stars form under these conditions and the efficiency of the star formation process remains an open question. Additionally, stellar feedback through radiation, winds, and supernovae plays a crucial role in regulating star formation. This session will explore how feedback operates in such an environment and its impact on the surrounding gas.
  • 3D structure and mass accretion/flows
    • Gas flows in the CMZ are shaped by the Galactic bar and interact with the nuclear stellar disc, fuelling mass inflows toward the central black hole, Sgr A*. However, the exact structure of the CMZ remains unclear, with competing models proposing ring-like or spiral-arm morphologies. Additionally, the mechanisms governing mass accretion across different scales, from the Galactic bar to the central parsecs, remain an area of active research. This session will discuss recent observational and theoretical efforts to resolve these questions.
  • Cluster formation and evolution
    • The CMZ hosts some of the most massive and young star clusters in the Galaxy. However, how these clusters form, evolve, and survive in such an extreme environment is not yet well understood. High gas densities and strong tidal forces could disrupt clusters before they fully form, or they may instead act as incubators for the formation of massive star clusters seen in nearby galaxies. This session will explore the lifecycle of star clusters in the CMZ and their role in shaping the Galactic Centre.

Invited speakers

  • Laura Colzi (Center for Astrobiology (CAB), Spain)
  • Rebecca Houghton (Liverpool John Moores University, Great Britain)
  • Álvaro Martínez Arranz (Instituto de Astrofísica de Andalucía, Spain)
  • Robin Tress (École Polytechnique Fédérale de Lausanne, Switzerland)
  • Daniel Walker (UK ALMA Regional Centre, Great Britain)

Scientific organisers

Katharina Immer (ESO, chair), Ashley Barnes (ESO, co-chair), Francisco Nogueras Lara (ESO) Maya Petkova (Chalmers University of Technology, Sweden)

Contact

Katharina Immer: kimmer at eso.org; Ashley Barnes: Ashley.Barnes at eso.org

Updated on Mon Feb 24 16:47:48 CET 2025
European Astronomical Society