Science
In recent decades, major advances have been made in our understanding of the evolution of galaxies, the formation of stars and planetary systems, and the nature and evolution of the Universe itself. We now know that galaxies grow at least partly through mergers, that many stars have planetary systems, and the baryonic, dark matter, and dark energy content of the Universe have been precisely measured. However, important questions remain. When did the first galaxies form? What is the history of star formation (and supermassive black hole formation) in galaxies and what is the origin of interstellar dust? How does the astrophysics of feedback in galaxy clusters affect their utility for precision cosmology? What determines the masses of stars when they form?
Submillimeter astronomy is poised to directly address these questions, and others. Submillimeter observations provide the only opportunity to measure the bolometric luminosities of star-forming galaxies from z ~ 1 to the epoch of reionization – and beyond – by measuring the emission from the very dust that obscures young and forming stars. Observations of submillimeter atomic and molecular transitions enable astronomers to model the detailed physics of the interstellar media in galaxies from the nearby universe to z > 5, and in clouds in the Milky Way. High spatial resolution millimeter-wave observations of the Sunyaev-Zel’dovich effect in galaxy clusters, coupled with submillimeter observations to remove contamination from cluster members and lensed galaxies, will enable precise measurements of cluster scaling relations utilized for cluster mass estimates and thereby provide strong constraints on non-gaussianity in the dark energy equation of state. Deep submillimeter surveys will measure the mass function of protostellar cloud cores down to substellar (brown) dwarf masses within two kpc of the Sun.
CCAT will be a versatile observatory with unique and transformational capabilities. The need for CCAT is driven by several themes: high-z galaxy formation and evolution, characterization of the atomic and molecular interstellar medium in nearby galaxies, censuses of star formation regions in the Milky Way, and the physical state of baryonic matter in galaxy clusters.