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wide-field spectroscopic telescope

An innovative 12-m class wide-field spectroscopic telescope (WST) with simultaneous operation of a large field-of-view (3 sq. degree) and high multiplex (30,000) multi-object spectrograph facility with both medium and high resolution modes (MOS), and a giant panoramic (3x3 sq. arcmin) integral field spectrograph (IFS).
WST will achieve transformative results in most areas of astrophysics: e.g. the nature and expansion of the dark Universe, the formation of first stars and galaxies and their role in the cosmic reionisation, the study of the dark and baryonic material in the cosmic web, the baryon cycle in galaxies, the formation history of the Milky Way and dwarf galaxies in the Local Group, characterization of exoplanet hosts, and the characterization of transient phenomena, including electromagnetic counterparts of gravitational wave events.

WST will be a revolutionary spectroscopic facility addressing many open questions in astrophysics over a large range in physical scales: from the formation of the large-scale structures in the early universe (100s of Mpc), to the interplay of galaxies in the cosmic web (10s of Mpc), to the formation of our own Galaxy (kpc scales), to the evolution of stars and the formation of planets around them (sub-pc scales) (Credit Rossella Spiga, INAF).

Objectives and ambition

Astrophysics is witnessing a golden era with a number of breakthrough discoveries achieved in the last decade or so, and a large variety of new instrumentation and programs planned for the next decade. Nonetheless, a comprehensive understanding of the formation and evolution of structures in the Universe is still missing.

Many key quests in modern astrophysics and cosmology are still in their infancy:

Is the accelerated expansion of the Universe due to an unknown form of energy or to a modification of General Relativity on large scales?
What is the interplay between dark, stellar, and gaseous material in galaxies and how does primordial and metal-enriched gas flow in and out of galaxies at various scales?
What is the detailed formation history of our own Galaxy, the Milky Way and of its satellites?
What is the origin of the various chemical elements that are crucial to trace galactic evolution?
What are the conditions that drive the formation and evolution of extra-solar planets?
What are the extreme physics conditions that govern transient events (explosions, eruptions, and disruptions)?
What do gravitational waves tell us about neutron star physics, heavy element production, and cosmology?

A vital element to answering these questions will be the availability of vast all-sky spectroscopic datasets of nearby and distant astrophysical sources at medium and high resolution delivering quantitative measurements of key physical parameters: examples include the redshift of galaxies, the kinematics of galaxies and stars, the physical and evolutionary properties of galaxies, the metal content and detailed chemical composition of stars. WST will be an innovative spectroscopic facility to provide this essential capability to the astronomical community.

This project has received funding from the European Union Horizon Europe Research and Innovation Action under grant agreement no. 101183153 -WST. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or European Research Executive Agency (REA). Neither the European Union nor the granting authority can be held responsible for them.