Astro2020 Science White Papers and the US ELT Program

Mark Dickinson, NOAO

Astronomers are rarely at a loss for words to describe the scientific ideas that excite them. In an outpouring of enthusiasm, the astronomical community wrote nearly 600 science white papers for the 2020 Decadal Survey on Astronomy and Astrophysics (Astro2020). These white papers discuss forefront problems in astronomy for the next decade and beyond. In many cases, the white papers also elaborate the measurements that will be required to advance our knowledge at the frontiers of research.

In the next decade, a new generation of Extremely Large Telescopes (ELTs) with primary mirrors larger than 20m in diameter will open new vistas in astronomical research. ELTs will achieve very high angular resolutions at infrared wavelengths with diffraction-limited adaptive optics systems, and their large collecting areas will enable very sensitive observations of objects beyond the limits of today’s 8m-class ground-based optical-infrared observatories.

Many white papers submitted to Astro2020 address scientific problems that require the angular resolution and sensitivity that the ELTs will offer. NOAO is compiling a collection of Astro2020 white papers on science for which ELTs will be particularly important. These white papers span nearly all areas of astronomical research, from our Solar System and extrasolar planetary systems to the early universe and cosmology. This list is still a work in progress: we have not yet read all 590 submissions! If you wrote an “ELT-relevant” white paper that is not yet on our list, or if you know of one that we’ve missed, please bring this to our attention by writing to useltp@noao.edu.

NOAO and the Giant Magellan Telescope (GMT) and Thirty Meter Telescope (TMT) organizations are collaborating to secure 25% or more of the observing time on the TMT and GMT to enable transformational research by the US national community. A US Extremely Large Telescope Program (US-ELTP) would permit scientists anywhere in the US to create and lead projects with the GMT and TMT, taking advantage of their combined full-sky coverage and diverse capabilities.

Some of the foremost scientific questions in the era of ELTs will require large observing programs, perhaps using multiple instruments and coordinating with other observational facilities. Key Science Programs (KSPs) are envisioned as a core component of the US ELT Program, motivated by problems that require large amounts of GMT and TMT observing time, and that are best addressed by coordinating scientists and resources throughout the community. KSPs will follow successful open-collaboration models that encourage broad, diverse participation by observers, data scientists, and theorists. This will enable scientists from a wide range of institutions to contribute to the KSP effort, and will ensure that the benefits of federal investment in GMT and TMT are widespread. Large, coherent investigations also typically produce large, coherent data sets with high legacy value, enabling new science that may lie beyond the scope envisioned by the original proposing teams.

More than 250 community members responded to NOAO’s call to participate in the development of Key Science Program concepts for the US ELT Program. The scientific discussions by these KSP teams motivated some of the white papers that were submitted to the Decadal Survey, and these are flagged in the table on NOAO’s US-ELTP Astro2020 web page.

Many more Astro2020 white papers refer to ways in which ELTs can make unique new measurements in a wide range of research projects. Smaller-scale, PI-led investigations with GMT and TMT will also have an important role to play: they can be nimble, exploratory, and responsive to new opportunities. To this end, the US ELT Program would also support Discovery Science Programs (DSPs), selected at regular intervals through open competition and peer review.

As the Decadal Survey conversation continues, the NOAO will continue to gather more useful information about US ELT Program science on its web site. Stay tuned!