Astronomers have detected a very powerful laser emanating from space, whose light has been traveling to reach us here on Earth.
It’s a type of massless cosmic object called a megamaser, and its light has been traveling to reach us here on Earth, 5 billion light years away.
The astronomers who discovered it using the MeerKAT radio telescope in South Africa called it Nkalakatha — an isiZulu word meaning “big boss“.
The paper presenting the discovery has been accepted for publication in The Astrophysical Journal Letters and has been pre-published on the arXiv platform.
“It’s amazing that, with just one night of observations, we’ve already found a record megamaser,” said Marcin Glowacki, an astronomer at Curtin University at the International Center for Radio Astronomical Research (ICRAR) in Australia. “Shows how good the telescope is“.
A maser is the microwave equivalent of a laser — amplification of light by stimulated emission of radiation, explains Science Alert.
Instead of emitting visible light, a maser emits microwaves and radio wavelengths that are stimulated and amplified.
For an astrophysical maser, the processes that amplify light are cosmic: planets, comets, clouds and stars can all produce masers.
A megamaser is an extraordinarily energetic maser. Typically, these emissions are produced by an object that is trapped in some way. Black holes, for example, can produce megamasers.
Glowacki and the research team found a very specific type of megamaser, glowing in amplified wavelengths by stimulated hydroxyl molecules, consisting of a hydrogen atom and an oxygen atom.
Hydroxyl megamasers have a known production mechanism. They are emitted by galaxies that are in the process of, or have recently experienced, a collision with another galaxy, and form stars as a result.
The gravitational interactions of such a massive encounter compress the star-forming gas, causing its collapse to translate into newborn stars at enormous speed.
The source of the megamaser detected by Glowacki is precisely that, a galaxy called WISEA J033046.26-275518.3 — now known as Nkalakatha.
“When two galaxies like the Milky Way and the Andromeda Galaxy collide, beams of light come out of the collision and can be seen at cosmological distances,” explained astrophysicist Jeremy Darling of the University of Colorado.
“The hydroxyl megamasers act like bright lights that say: here is a collision of galaxies that is causing new stars to be created and feeding huge black holes,” he adds.
The MeerKAT survey is not designed to look for megamasers. It’s called “Looking at the Distant Universe with the Meerkat Array” (LADUMA), and it looks for a wavelength of 21 centimeters — dilated by the expansion of the Universe — emitted by the neutral hydrogen of the early Universe.
The wavelengths of a hydroxyl megamaser are, however, 18 centimeters. When dilated, they are even longer, and the space laser signal was within the range detectable by the telescopic array.
Since the sky region has been observed at other wavelengths, tracking the signal to a host galaxy was quite simple.
Nkalakatha is bright at infrared wavelengths, and has a long tail on one side that glows in the radio, likely as a result of being “pulled” by the gravitational interaction between the two now merged galaxies.
The team has already planned follow-up observations of the fascinating object, and hopes to find many more megamasers, as it continues.
“MeerKAT will likely double the known number of these rare phenomena,” said Darling. “In the past, it was thought that galaxies would merge more often, and hydroxyl megamasers recently discovered will allow us to test this hypothesis.”
Alice Carqueja, ZAP //