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Tianlai joins pathfinder family
from Contact 17
BY ANNE DANIELS (SKAO)
China’s Tianlai, a hydrogen intensity mapping experiment, is the latest telescope to join the SKA pathfinder family.
Operated by the National Astronomical Observatories (NAOC) of the Chinese Academy of Sciences, the Tianlai experiment is located near Hongliuxia in the north-west of China. It consists of two telescope arrays: the Tianlai cylinder array, which has three adjacent cylindrical reflectors with a total of 96 receivers, and the Tianlai dish array, which consists of 16 dishes, each 6 m in diameter.
Though of relatively small scale, they were built to test the technique of hydrogen intensity mapping, which could be applied to larger arrays such as the SKA telescopes and is already the subject of pilot studies on South Africa’s MeerKAT radio telescope (see page 30).
Tianlai aims to shine a light on the mysterious dark energy, which is believed to make up 70% of the cosmos and drives the acceleration of the expansion of the Universe. Although it has never been detected directly, its properties can be derived from the change in the expansion rate of the Universe.
By studying the 21 cm line emitted by hydrogen atoms, the Tianlai experiment is building a 3D map of the largescale structures in the Universe. This map helps reveal the expansion rate by looking at the “baryon acoustic oscillations” that mark the imprint left behind by the “sound” of the Big Bang on the early Universe. The Chinese experiment was fittingly coined Tianlai which translates to “heavenly sound”.
