A new camera that will revolutionise the field of submillimetre astronomy has been unveiled on the James Clerk Maxwell Telescope (JCMT) in Hawaii.
SCUBA-2 (Superconducting Sub-mm Camera) is the most powerful instrument of its type ever built; able to detect light at “sub-mm” wavelengths that are 1,000 times longer than those which can be seen by the human eye. It is far more sensitive and powerful than previous instruments, mapping areas of the sky hundreds of times faster and providing unprecedented information on the early life of stars – normally obscured by the remains of the very dust and gas cloud that collapsed under its own gravity to form the star.
Researchers involved with the project; led by STFC’s UK Astronomy Technology Centre (UKATC) at the Royal Observatory in Edinburgh in collaboration with a world-wide consortium of laboratories, believe that the camera will help lay bare one of the most exciting phases in the whole history of the Universe. “The Milky Way Galaxy today only produces maybe two suns a year amid a population of 100 billion suns,” explains Prof James Dunlop from the University of Edinburgh. “We are looking back 10 billion years in time to see galaxies when they produced stars a thousand times faster than anything in the local cosmos today.”
The data obtained by these surveys will allow a new and precise understanding of star formation throughout the history of the universe, and complements research being carried out on other telescopes such as the Atacama Large Millimetre Array (ALMA), undergoing commissioning in Chile.
“Looking up at the stars, you only see the light they are emitting in the visible part of the spectrum,” explains Professor Gary Davis, Director of the JCMT. “Many galaxies, including our own Milky Way, contain huge amounts of cold dust that absorbs visible light and these dusty regions just look black when seen through an optical telescope. The absorbed energy is then re-radiated by the dust at longer, submillimetre, wavelengths.”
“SCUBA-2 has been designed to detect extremely low energy radiation in the submillimetre region of the spectrum. To do this, the instrument itself needs to be even colder. The SCUBA-2 detectors are cooled to only 0.1 degree above absolute zero (–273.05°C), making the interior of SCUBA-2 colder than anything in the Universe that we know of”.
Cryoconnect, a division of Tekdata interconnections Limited, manufactured the original SCUBA cryogenic harnesses and subsequently were selected to meet the challenge of providing the cryogenic harnesses for the SCUBA-2 Instrument. The harnesses were constructed in a planar form with Niobium Titanium (NbTi) alloys and introducing a very significant cost and mass saving by designing hermetic connectorless feedthroughs at the vacuum wall (1).
To be able to terminate the ultra fine tracks, pre-heaters were used at the cold end ceramic PCBs (2).
The detectors on SCUBA-2 are Transition Edge Sensor (TES) arrays developed by NIST and there are four 32×40 of these, each of 850 and 450 micron; in total 10240 detectors.
Commenting on the performance of the new instrument, Professor Wayne Holland of the UKATC, and the SCUBA-2 Project Scientist, said, “Cryoconnect’s support was critical to be able to have the full complement of eight arrays on the instrument. With SCUBA, it typically took 20 nights to image an area about the size of the full Moon. SCUBA-2 will be able to cover the same area in a couple of hours and go much deeper, allowing us to detect faint objects that have never been seen before.”
The increased mapping speed and sensitivity of SCUBA-2 make it ideal for large-scale surveys; no other instrument will be able to survey the submillimetre sky in such exquisite detail. Dr Antonio Chrysostomou, Associate Director of the JCMT said, “SCUBA-2′s first task is carrying out a series of surveys right across the heavens, mapping sites of star formation within our Galaxy, as well as planet formation around nearby stars. It will also survey our galactic neighbours and crucially, will look deep into space and sample the youngest galaxies in the Universe, which will be critical to understanding how galaxies have evolved since the Big Bang.”
A composite image of the Whirlpool Galaxy (also known as M51). The green image is from the Hubble Space Telescope and shows the optical wavelength. The submillimetre light detected by SCUBA-2 is shown in red (850 microns) and blue (450 microns). The Whirlpool Galaxy lies at an estimated distance of 31 million light years from Earth in the constellation Canes Venatici.