The US National Science Foundation (NSF) announced recently that an international collaboration led by Academia Sinica’s Institute of Astronomy and Astrophysics (ASIAA) has been selected to receive a 12-meter radio antenna designed for submillimeter-wavelength astronomy. The ASIAA-CfA (Harvard-Smithsonian Center for Astrophysics: CfA) team was selected from 3 competing teams to receive the antenna. The antenna was one of the three antennas built as prototypes for the Atacama Large Millimeter/Submillimeter Array (ALMA), a huge radio observatory currently being constructed in Chile. ASIAA represents Taiwan in participating in the international ALMA project Via Japan and North America, ASIAA represents Taiwan in joining the international ALMA project.

ASIAA and the CfA are long-term partners on several projects, including the construction and operation of the Submillimeter Array (SMA) on Mauna Kea in Hawaii and the Taiwan American Occultation Survey on Lulin Mountain in Taiwan.  Besides ASIAA and CfA, other participants in the Prototype Antenna Project include the MIT Haystack Observatory and the US National Radio Astronomy Observatory.

The astrophysicists plan to use the antenna to provide an extremely sharp high-resolution  sharp and high-resolution look at targets of interest, through a process known as Global Very Long Baseline Interferometry (VLBI) at submillimeter wavelengths.  In order to do this, they will the newly acquired antenna to other millimeter/submillimeter telescopes like SMA and ALMA. The set up will provide angular resolution of 20 micro arc-second (1 micro arc-second = 1/3600000000 degree), which is equal to the apparent size of a NTD10 coin on the moon, the highest angular resolution astronomers have achieved so far.  

Using this submillimeter VLBI, the astrophysicists plan to produce images of supermassive black holes located at the center of galaxies. They hope to obtain direct proof of the existence of black holes, and make possible the testing of General Relativity in the presence of strong gravitational fields, which has been an exciting topic in modern astrophysics.  The project will also study the ultra-relativistic jets emanating from the supermassive black holes.  The telescope will also be used for single-dish observations at very short submillimeter wavelengths, or THz frequencies, to study diverse cosmic environments such as cold interstellar gas clouds, dusty star-forming regions, and the cores of giant elliptical galaxies. 

The ALMA Prototype Antenna is currently located in New Mexico in the US, but the new owners intend to move the antenna to a new location where the submillimeter VLBI performance and THz observations are most effective. The best site for the instrument will be typically in a cold and dry climate and at very high altitude.  One possible location, say the scientists, is a site known as the Summit Station in Greenland. ASIAA is already conducting site testing at a nearby location in Eureka (northern Canada), and hopes to deploy test equipment to Greenland this summer.  In the meantime, ASIAA and CfA are beginning the process of upgrading the performance of the prototype antenna.