Substructures in multiscale host haloes: from Galaxies to Clusters

3-7 February 2025

Recent high-resolution observations from exquisite ground and space-based facilities (Euclid, LSST, Keck, JWST and future instruments like SKA and ELT) are giving us a very detailed view of the multiscale substructure systems hosted in galaxies and clusters of galaxies. Gravitational lensing presents the utmost technique to reconstruct the projected matter density distribution by modelling the distortion of background galaxy images, in the weak and strong lensing regime. In particular, both in cluster systems and galaxy-scale haloes, strong lensing by satellite galaxies and subhaloes predicts more compact mass distribution than what is measured in standard hydrodynamical CDM simulations. This has generated a renewed interest in alternative models at this scale and the production of new hydrodynamical simulations in CDM and alternative models – especially self-interacting dark matter (SIDM).

In this Focus Week, we will bring together experts in lensing observations and mass modelling on different scales and researchers working on numerical hydrodynamical simulations, aspiring to bridge the gap between multiscale satellite properties and the predictions from theory. In particular, we will discuss how to best exploit the new “AIDA” simulations, which will include CDM, WDM and SIDM together with the TNG galaxy formation model. This meeting will give us the possibility to strengthen our national and international collaborations and join our efforts to model dark matter content in galaxies and clusters, and thus constrain the nature of dark matter


  • Carlo Giocoli (INAF, Bologna)
  • Giulia Despali (University of Bologna)
  • Simona Vegetti (MPA, Garching)


  • TBA