In a week that has included the announcement of the most distant single star observed and the most distant galaxy comes the announcement of a record-breaking funky space phenomenon called a "megamaser", a powerful radio-wave laser that is at least 1,000 times brighter than the Sun. Astronomers have now observed the most distant one, the light of which comes from 5 billion light-years, or 58 thousand billion billion kilometers, away.
The findings, accepted for publication in The Astrophysical Journal Letters, show the emission comes from compact gas, in particular, hydroxyl molecules, which are made of one hydrogen atom and one oxygen. These, when excited by some energetic process, emit light in a very specific wavelength creating a laser-like signal.
Hydroxyl megamasers are found in gas-rich galaxies that are bright in infrared. They are hallmarks of galaxy mergers so studying these megamasers opens up a new way to study galaxy evolution.
“When galaxies collide, the gas they contain becomes extremely dense and can trigger concentrated beams of light to shoot out,” lead author Dr Marcin Glowacki, from Curtin University, said in a statement. “This is the first hydroxyl megamaser of its kind to be observed by MeerKAT and the most distant seen by any telescope to date.”
The galaxy has been nicknamed "Nkalakatha" [pronounced ng-kuh-la-kuh-tah] which translates to “big boss” in the isiZulu language. It has an integrated luminosity of over 6,000 times that of our Sun.
The discovery was observed by the MeerKAT telescope in South Africa, as part of the Looking At the Distant Universe with the MeerKAT Array (LADUMA) survey. Interestingly, the discovery comes from the very first night of observations in the program that is scheduled to study the night sky for 3,424 hours.
“It’s impressive that, with just a single night of observations, we’ve already found a record-breaking megamaser. It shows just how good the telescope is,” Dr Glowacki, formerly at the University of the Western Cape in South Africa, added.
The LADUMA project aims to study a small region of the sky very deeply, focusing in particular on the emission of hydrogen and hydroxyl from very distant galaxies. The goal is to learn more about galaxies across the ages of the universe, and with this megamaser, they have an exciting candidate to do just that.
“We have follow-up observations of the megamaser planned and hope to make many more discoveries,” Dr Glowacki said.
MeerKAT is one of the two precursor radio telescopes of the Square Kilometer Array, which will be built across Australia and South Africa to become the world's largest radio telescope. Thanks to a quirk of physics, the further apart two radio antennas are the more precise the observations, so placing the many antennas in different countries far apart will create an incredible instrument.