ALMA Goes to New (Wave)lengths

First light has been achieved for a new set of receivers installed on the Atacama Large Millimetre/submillimetre Array (ALMA), in which ESO is a partner. The band 1 receivers pick up radio waves between 6 and 8.5 mm in length, setting a new record for the longest wavelengths that ALMA can observe. They will allow astronomers to view the early, distant Universe and to explore how planets form as never before.

To capture radiation from cosmic sources over a broad range of wavelengths, ALMA’s 66 antennas, located on the Chajnantor plateau in Chile, are equipped with precisely tuned receivers. Each receiver type is sensitive to a particular “band” or range of wavelengths of the electromagnetic spectrum. Until recently, eight out of a planned ten receivers had been mounted on the antennas, covering altogether the window between 0.3 and 3.6 mm (bands 10 to 3).

Now, thanks to band 1 receivers, ALMA will be equipped to observe at even longer wavelengths of light, opening a new window to explore the Universe. Scientists hope to be able to study gas in the reionisation epoch of the Universe, the time when the first stars and galaxies formed. In addition, as it is able to detect larger dust grains than the other ALMA bands, band 1 is ideal to look at the growth of such grains in discs around stars, allowing astronomers to gain more insight into how planets form.

The development of the ALMA band 1 receivers has been led by Taiwan’s Academia Sinica Institute of Astronomy and Astrophysics (ASIAA), accompanied by an international team comprising the National Astronomical Observatory of Japan (NAOJ), the University of Chile, the National Radio Astronomy Observatory (NRAO), the Herzberg Institute of Astrophysics in Canada and the National Chung-Shan Institute of Science and Technology in Taiwan. The University of Chile has been involved in the project since the beginning, helping to develop and produce optical elements such as the lenses and horn antennas for the band 1 receivers. 

Recently, the ALMA board signed a contract for the development of the final, band 2, set of ALMA receivers, which will be led by a consortium of European institutions. 

More Information

ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada), MOST and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO and NAOJ. 

The band 1 research project was supported in Taiwan by Academia Sinica and grants from the Ministry of Science and Technology of Taiwan.

Courtesy of European Southern Observatory