Scientists using South Africa's MeerKAT radio telescope have discovered a superpowered cosmic maser. The source was the most distant megamaser known today, located about five billion light years away and named Nkalakatha (Nkalakatha), which can be translated from Zulu as "big boss". The discovery is described in an article accepted for publication in The Astrophysical Journal Letters and is already available in the arXiv Preprints Library.
Some astronomical objects - usually molecular clouds - can be "pumped up" with energy and emit it as stimulated radiation. Some types of lasers operate in a similar way and because these cosmic sources are emitted in the microwave region of the spectrum, they are called masers. Some are orders of magnitude brighter than the Sun - megamasers, for instance, are thousands of times brighter.
The find was made by the MeerKAT telescope, during its LADUMA survey of molecular clouds in the early and distant Universe. The Nkalakath emission turned out to be quite distinctive, indicating that its source is an interstellar hydroxyl (OH) cloud located in a galaxy that is experiencing a merger with another galaxy. "When galaxies merge, the gas they contain becomes extremely dense and can emit concentrated beams of radiation," said Marcin Glowacki, one of the authors of the discovery.
The megamaser is located in the WISEA galaxy J033046.26-275518.3, which is brightly visible in the infrared and shows a long 'tail' of radio emission, apparently associated with matter pulled from the galaxy by its approaching neighbour. Scientists say it is the most distant hydroxyl megamaser known to date. For MeerKAT, this is the first such find, but scientists are confident it will soon discover other megamasers in deep space.
