S347: Early Science with ELTs (EASE)


The Hubble Space Telescope increased the angular resolution of optical/infrared astronomical images by an order of magnitude over ground-based telescopes. The coming generation of ground-based extremely large telescopes (ELTs) will offer another order-of-magnitude increase in resolution thanks to their combination of giant aperture and state-of-the-art adaptive optics. (Fiorentino et al. 2018)

The next decade will see first light for three extremely large telescopes (ELTs): 30- to 40-metre-class reflectors that have the potential to truly transform our understanding of the Universe. IAU Symposium 347 will summarise the current status of these telescopes, their instrumentation and the planned early science.

The Extremely Large Telescope (ELT), the Giant Magellan Telescope (GMT) and the Thirty Meter Telescope (TMT) are well into their construction phases and will provide a collecting area larger than all current large ground-based telescopes put together. They will also provide uniquely high angular resolution thanks to adaptive optics (AO). These transformative facilities will be equipped with state-of-the-art instrumentation capable of covering a very broad range of science: from our Solar System to exoplanets, to stars and galaxies, to fundamental physics and cosmology. The first sets of instruments are now in an advanced design stage and will soon go into production. In parallel, comprehensive simulations are underway to quantify their scientific capabilities and to develop key cases for early science.

The three ELTs will have a huge impact on many open astrophysical and cosmological problems. Indeed, it is difficult to find a single field of modern astrophysical research that the ELTs are not going to completely revolutionise. The scientific goal of IAU Symposium 347 is to highlight the state-of-the-art facilities and the key outstanding questions across a wide range of fields. Topics covered will include:

  • ELTs in the context of other ground- and space-based facilities;
  • Characterisation of Earth-like planets;
  • Our Galaxy’s supermassive black hole;
  • From planets to stars;
  • Resolved stellar populations;
  • Galaxy evolution and active galactic nuclei;
  • Transients and extreme events; and
  • Fundamental constants and cosmology.

The symposium will provide a unique opportunity for the various scientific communities to strengthen their knowledge about these premier facilities, establish new collaborations for data handling and share their plans on how to exploit the discovery power of the ELTs.

This artist’s rendering of the European Extremely Large Telescope (E-ELT) is based on the detailed construction design for the telescope. The huge secondary mirror housing is clearly visible at the centre of this image, sitting at the top of the telescope structure, high above the enormous 39-metre primary mirror. On 25 May 2016, ESO signed a contract with the ACe Consortium, consisting of Astaldi, Cimolai and the nominated sub-contractor EIE Group to build the dome and telescope structure of the E-ELT.

The scientific context in which the symposium is organised appears very promising; Gaia has released the first set of very accurate parallax measurements. This is a quantum jump in the accuracy of the cosmic distance scale, since the Gaia parallaxes will impact both primary and secondary distance indicators and, in turn, cosmological parameter (e.g., H0, t0). In addition, the Atacama Large Millimeter/submillimeter Array (ALMA) has opened up new paths in many astrophysical fields ranging from stellar evolution to protoplanetary discs, and including such fields as the formation and evolution of galaxies.

The James Webb Space Telescope (JWST) should be launched in 2021. This space observatory will revolutionise our near-infrared and mid-infrared view of the Universe with its unprecedented sensitivity, and will provide scientific synergies with the ELTs. The Large Synoptic Survey Telescope (LSST) will start its commissioning and science verification within the next two years. This means that astronomers will have access to a wealth of new ground- and space-based data, together with an unprecedented set of simulations of the effects that the scientific capabilities of the ELTs will have on open astrophysical and cosmological problems. In addition, the astrophysical community is involved in an “alphabet soup” of photometric (Pan-STARRS, PTF, OGLE, VVVX, SkyMapper, DECaLS) and spectroscopic (GES, SEGUE, RAVE, APOGEE, LAMOST, 6dF, DESI) sky surveys. These represent a stepping-stone to future observing facilities that will be even more powerful and transformative.

Given the very broad range of scientific and technological topics covered by this symposium, we are bringing together experts with backgrounds in theory, observation and technology. Emphasis will be given to the key role that different flavours of adaptive optics are going to play during operations, including ground layer (GLAO), single conjugate (SCAO), laser tomography (LTAO), multi-conjugate (MCAO) and multi-object (MOAO).

We have also organised a one-day teacher training workshop during the symposium on using the world’s largest ground-based telescope as a context for teaching science. Also, the week after the General Assembly (2–7 September) we are holding an international school for graduate students and other early-career researchers in Belgrade, Serbia, on current and future observing facilities.

GIUSEPPE BONO is Professor of Astrophysics in the Department of Physics at the University of Rome Tor Vergata in Italy and serves as Chair of the Project Science Team for ESO’s Extremely Large Telescope. His research interests include stellar evolution and resolved stellar populations.