Abstract
An international consortium is presently constructing a beamformer for the
Atacama Large Millimeter/submillimeter Array (ALMA) in Chile that will be
available as a facility instrument. The beamformer will aggregate the entire
collecting area of the array into a single, very large aperture. The
extraordinary sensitivity of phased ALMA, combined with the extremely fine
angular resolution available on baselines to the Northern Hemisphere, will
enable transformational new very long baseline interferometry (VLBI)
observations in Bands 6 and 7 (1.3 and 0.8 mm) and provide substantial
improvements to existing VLBI arrays in Bands 1 and 3 (7 and 3 mm). The ALMA
beamformer will have impact on a variety of scientific topics, including
accretion and outflow processes around black holes in active galactic nuclei
(AGN), tests of general relativity near black holes, jet launch and collimation
from AGN and microquasars, pulsar and magnetar emission processes, the chemical
history of the universe and the evolution of fundamental constants across
cosmic time, maser science, and astrometry.