The Atacama Large Aperture Sub-mm Telescope (AtLAST): Science Cases and Design

The versatility of ALMA has made sub-mm observations of the cold Universe commonplace for a wide range of Astronomy science cases. The strength of ALMA is its high sensitivity and angular resolution, making it the ideal follow-up instrument to observe relatively compact sources. However, this comes at the expense of its small field of view and lack of sensitivity to more extended emission. In this talk I will introduce the proposed AtLAST 50m single dish facility. This telescope would be the ultimate complement to ALMA, by providing a high sensitivity to faint, extended emission and the possibility to host multiple instruments accessing its wide field of view with a diameter of 1 to 2 degrees. I will introduce the wide range of science cases that define the technical requirements of AtLAST, ranging from the Sun, the solar system, the Galactic interstellar medium, nearby and distant galaxies, and cosmology. As a single dish telescope, AtLAST will not only recover the total flux which can be over resolved by interferometers, but will also be ideal for time domain astronomy and flexible mm VLBI observations. Achieving these transformational goals requires a fast switching 50m telescope with a unique design to cover such a wide field of view. The dish will require a closed-loop metrology system to provide a surface accuracy to observe out to 350µm. An initial suite of 6 instruments hosted by AtLAST is currently being designed. It is foreseen that these instruments will be continuously upgraded to ensure optimal performance through the long lifetime of the facility.

AtLAST will be built on the 5000m high Chajnantor plane to allow it to cover the same sub-mm wavelengths as ALMA. An innovative distributed remote operations concept is being worked out to provide efficient and sustainable operations. From the start of the design phase, AtLAST has put a renewable and efficient energy generation as a core requirement, by investing resources into the development of a tailored renewable energy system that can team up with other observatories and/or civil users. Furthermore, the use of supercapacitors to recover and reuse kinetic energy of the telescope, much like what is already used in electrical cars, will further reduce the energy demands of the facility.