Spectroscopic Surveys with the ELT:

A Gigantic Step into the Deep Universe

17 – 20 October 2017

Scientific Rationale


The European Extremely Large Telescope (E-ELT) will be the world’s largest optical/IR facility for at least a generation. It will have an immense collecting area, equivalent to gathering together all the current large telescopes in use today. Multi-object spectroscopy will be a key capability of the observatory, immediately able to harness its unprecedented sensitivity to deliver unique surveys which address a broad range of important topics in contemporary astrophysics.


The conceptual design of MOSAIC, a powerful multi-object spectrograph for the E-ELT, will conclude in late 2017. The design combines high-multiplex near-IR and visible spectroscopy, together with AO-corrected spectroscopy in the near-IR that exploits the fantastic angular resolution of the E-ELT across a large field of view. Building on recent investments in cutting-edge instrumentation for GTC, VLT and other 8-10m class telescopes, MOSAIC will push back the observational barriers even further, tackling fundamental questions that demand the fantastic light-gathering power of the ELT. In cosmology, MOSAIC will lift the veil on how matter is distributed in distant galaxy haloes, including dark matter and missing baryons. It will also result in a leap forward in our understanding of how present-day galaxies assemble. This includes detecting nearby primordial stars and the very first galaxies at the epoch of reionisation, the most exhaustive dynamical survey of distant galaxies ever undertaken and the detailed study of the stellar populations.

This colloquium is timed to discuss the scientific opportunities of surveys with MOSAIC, focussing in particular on simulated performances from the conceptual design. It will also take stock of other developments that will influence surveys envisaged for the late 2020s.

Scientific topics covered by the colloquium:


  • Probing the stellar populations at the heart of the Milky Way
  • Dissecting the different structural components of the Milky Way
  • Unravelling the stellar components of galaxies in the Local Volume
  • Spectroscopy of luminous stars far beyond the Local Group
  • Evolution/universality of the initial mass function
  • Properties of high-z dwarfs and their role in galaxy assembly
  • Constraints on the dark matter properties of high-z galaxies
  • Dynamical properties and formation of galaxies
  • Tomography of the high-redshift intergalactic medium
  • Evolution and baryon content of galaxy halos
  • Surveys of high-z AGN
  • Spectroscopy of first-light galaxies & the era of reionisation