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SPACE SCIENCES

Megamaser “Nkalakatha”

discovered by astronomers

using MeerKAT

sing the MeerKAT radio telescope, a team of researchers from the University of The Looking at the Distant Universe with
the Western Cape, the University of Cape Town, Rhodes University, the South the Meerkat Array (LADUMA) team leads
UAfrican Radio Astronomy Observatory and the South African Astronomical one of the big MeerKAT science experiments,
Observatory, together with colleagues from 12 other countries, have discovered a which is looking for neutral hydrogen gas in
powerful megamaser - a radio-wavelength laser indicative of colliding galaxies. This is galaxies in one area of the sky and looking
the most distant such megamaser found so far. for it very deeply - meaning very far from
Galaxies are vast islands of matter in the universe. They are made of hundreds us, both in space and in time. By measuring
of billions of stars, gas and dark matter. When galaxies merge in collisions of cosmic the neutral hydrogen gas in galaxies
proportions, the gas they contain becomes extremely dense. In particular, this can from the distant past to now, LADUMA
stimulate hydroxyl molecules, made of one atom of oxygen and one atom of hydrogen, will contribute to our understanding of
to emit a specific radio signal called a maser (a maser is like a laser but emits radio the evolution of the universe. This is no
waves instead of visible light). When that signal is exceedingly bright, it is called a minor exercise, and so the research team
megamaser. “When two galaxies like the Milky Way and the Andromeda Galaxy collide, comprises scientists from South Africa,
beams of light shoot out from the collision and can be seen at cosmological distances. Australia, Chile, France, Germany, India, Italy,
The OH megamasers act like bright lights that say: here is a collision of galaxies that is Japan, the Netherlands, South Korea, Spain,
making new stars and feeding massive black holes,” explains Prof. Jeremy Darling from the UK and the US. “LADUMA is probing
the University of Colorado in the United States, a megamaser expert and co-author of hydrogen within a single ‘cosmic vuvuzela’
the study. that extends to when the universe was only
Hydroxyl megamasers emit light at a wavelength of 18cm. This light belongs to the a third of its present age,” says Associate
radio part of the electromagnetic spectrum, and it is the type of light that the MeerKAT Professor Sarah Blyth from the University of
radio telescope in the Karoo is designed to capture exceptionally well. Cape Town.

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