The Cerro Chajnantor Atacama Telescope (CCAT)
The CCAT Project
Submillimeter astronomy is a rapidly growing field. The ALMA interferometer will provide a powerful facility for detailed studies of individual projects. CCAT is designed to complement ALMA's capabilities. Its 25 m diameter and 20 arc minutes field of view will be optimized for wide field submillimeter imaging and survey, and with its high sensitivity continuum cameras, CAT will have a survey speed many times higher than any other facility. CCAT will be the largest and most sensitive facility of its class.
The site: Cerro Chajnantor, Chile
CCAT relies on superb submillimeter weather conditions. At 5612 m on Cerro Chajnantor, about 600 m above ALMA, the CCAT site has a median PWV of about 0.7 mm during the winter. The best water vapor conditions are around 0.2 mm, comparable tosouth pole conditions.
As well as being substantially larger and more sensitive than existing submillimeter telescopes, CCAT will be the first large submillimeter telescope designed specifically for wide field imaging. Hence it will provide an unparalleled abilityto address key astronomical questions by mapping large areas of the sky. The scientific priorities include:
- How did the first galaxies form? CCAT will detect hundreds of thousands of primeval galaxies from the era of galaxy formation and assembly, z = 2–4 or about 10–12 billion years ago, providing for the first time a complete picture of this process. In addition, CCAT will probe the earliest bursts of dusty star formation as far back as z ~ 10, less than 500 million years after the Big Bang when the Universe was ~ 4% of its current age.
- What is the nature of the dark matter and dark energy that fill the Universe? CCAT will image the Sunyaev-Zel’dovich effect in hundreds of clusters of galaxies selected from current and planned southern-hemisphere cluster searches. These images will be important for understanding how clusters form and evolve and for the interpretation of the survey data to constrain crucial cosmological parameters, i. e.,ΩM, ΩΛ, and the dark energy equation of state, independently of other techniques such as Type Ia supernova and direct CMB measurements.
- How do stars form? By surveying molecular clouds in our Galaxy, CCAT will detect cold dense cores that collapse to form stars, providing for the first time a complete census of star formation down to very low masses. In nearby molecular clouds, CCAT will be able to detect cold cores much smaller than the lowest mass stars (0.08 solar masses).
- How do conditions in circumstellar disks determine the nature of planetary systems and the possibilities for life? CCAT will image dust produced by collisional grinding of planetesimals around other stars to allow determination of the dynamical effects of planets on the dust distribution and, hence, the properties of planetary orbits. In concert with ALMA, CCAT will study disk evolution from early, Class I, to late, debris disk, stages.
- How did the Solar System form? Beyond Neptune, the Kuiper belt is a relic containing a record of the processes that operated in the early solar system, i.e., the accretion, migration, and clearing phases. CCAT will determine sizes and albedos for hundreds of Kuiper belt objects, thereby providing information to anchor models of planet formation in the early solar system.
The CCAT consortium
The CCAT consortium includes Cornell University, the California Institute of technology with the Jet Propulsion Laboratory, the University of Colorado, the University of British Columbia for a Canadian university consortium, the UK Astronomy Technology Centre on behalf of the UK community, and the Universities of Cologne and Bonn.