Powerful radio-wavelength laser light has been detected from the greatest distance yet in space.
It’s a type of massless cosmic object called a megamaser, and its light has traveled a staggering 5 billion light-years to reach us here on Earth. The astronomers who discovered it with the Radio telescope MeerKAT in South Africa called it Nkalakatha – an isiZulu word meaning “big boss”.
The discovery was accepted The Letters of the Astrophysical Journal and is available on the preprint server arXiv.
“It is impressive that we have already found a record-breaking megamaser with just one night of observation,” said astronomer Marcin Glowacki the Curtin University node of the International Center for Radio Astronomy Research (ICRAR) in Australia.
“That shows how good the telescope is.”
A maser is the microwave equivalent of a laser (light amplification by stimulated emission of radiation). Instead of emitting visible light, a maser emits microwave and radio wavelengths that are stimulated and amplified. For a astrophysical maser, the processes that amplify the Light are cosmic; Planets, comets, clouds, and stars can all produce burl.
Therefore, as you might have guessed, a megamaser is a maser with some momentum. In general, these emissions are produced by an object that is in some way absolutely bad; for example, active supermassive black holes can produce Megamaser.
When data arrived from the first night of a 3,000-hour survey, Glowacki and his team found the signature of a very specific type of megamaser, bright in wavelength, enhanced by stimulated hydroxyl molecules composed of one hydrogen atom and one oxygen atom.
Hydroxyl Megamasers have a known production mechanism. They are emitted by galaxies that are in the process of, or have recently suffered, a collision with another galaxy and are bursting with star formation as a result. The gravitational interactions of such a massive encounter compress star-forming gas, causing it to collapse into baby stars at tremendous speeds.
The source of the megamaser discovered by Glowacki and his colleagues is just that, a galaxy called WISEA J033046.26−275518.3 – now known as Nkalakatha.
“When two galaxies such as the Milky Way and Andromeda collide, rays of light shoot out from the collision and can be seen at cosmological distances,” said astrophysicist Jeremy Darling from the University of Colorado.
“The hydroxyl megamasers act like bright lights saying: Here is a collision of galaxies, making new stars and feeding massive black holes.”
The MeerKAT survey was not designed to search for megamasers. It’s called “Looking at the Distant Universe with the Meerkat Array” (LADUMA) and is looking for a 21-centimeter wavelength emitted by neutral hydrogen in the early Universe that has been stretched (redshifted) by the expansion of the Universe.
However, the wavelengths of a hydroxyl megamaser are 18 centimeters; They are even longer when redshifted, and this redshifted signal was within the range that could be picked up by the telescope array.
Because the region of the sky has been observed extensively at other wavelengths, tracking the signal to a host galaxy was fairly easy. Bright in the infrared, Nkalakatha has a long tail on one side that glows brightly on the radio, likely as a result of the gravitational attraction between the two now merged galaxies.
The team has already planned follow-up observations of the intriguing object and expect to find many more megamasers as the survey progresses.
“MeerKAT will likely double the known number of these rare phenomena,” darling said. “In the past it was thought that galaxies merged more frequently, and the newly discovered hydroxyl megamasers will allow us to test this hypothesis.”
The research was accepted The Letters of the Astrophysical Journal and is available on arXiv.