Scientific requirements of ALMA, and its capabilities for key-projects: Extragalactic

The Atacama Large Millimeter Array (ALMA) consists of 64 antennas of 12m diameter that will initially observe in 4 frequency bands between 84 and 720 GHz with spatial resolutions down to 0.01" and velocity resolutions as fine as 0.05 km/s. These technical requirements are based on three primary science goals. We illustrate two of these requirements: (i) the ability to detect spectral line emission from a Milky-Way type galaxy at z=3, and (ii) the ability to provide precise images at an angular resolution of 0.1". Finally, we present a possible large extragalactic project with ALMA: molecular line studies of submm galaxies.