NGC 1316 galaxy, Meerkat

Like dust bunnies that lurk in corners and under beds, surprisingly complex loops and blobs of cosmic dust lie hidden in the giant elliptical galaxy NGC 1316. This image made from data obtained with the NASA/ESA Hubble Space Telescope reveals the dust lanes and star clusters of this giant galaxy that give evidence that it was formed from a past merger of two gas-rich galaxies. Photo: NASA, STScI, and ESA

SA’s MeerKAT telescope discovers missing gas in distant galaxy

An international team of astronomers discovered vast amounts of hydrogen gas in NGC 1316, a galaxy 60 million light-years from Earth.

NGC 1316 galaxy, Meerkat

Like dust bunnies that lurk in corners and under beds, surprisingly complex loops and blobs of cosmic dust lie hidden in the giant elliptical galaxy NGC 1316. This image made from data obtained with the NASA/ESA Hubble Space Telescope reveals the dust lanes and star clusters of this giant galaxy that give evidence that it was formed from a past merger of two gas-rich galaxies. Photo: NASA, STScI, and ESA

The SA Radio Astronomy Observatory (Sarao) announced this week that MeerKAT, the country’s radio telescope array, had made a major scientific discovery and solved an age-old astronomical riddle regarding the NGC 1316 galaxy.

The team of international astronomers published their findings in the Astronomy and Astrophysics journal. They discovered vast amounts of hydrogen gas in a galaxy 60 million light-years from Earth.

The NGC 1316 galaxy – abbreviated from ‘New General Catalogue of Nebulae and Clusters of Stars 1316’ – is the brightest visible-light and the most powerful radio wave-emission galaxy in Fornax constellation.

Picture this, when you look up at the night sky and see all those shining dots – those are galaxies, not stars – NGC 1316 is the fourth brightest radio wavelength out of everything you can see, if you had the proper equipment.

The research into NGC 1316 is funded in part by the European Research Council. Furthermore, it was carried out while the MeerKAT telescope was still in its commissioning phase. 

A decade-old space riddle

NGC 1316 was created a few billion years ago, when two galaxies collided. One of those galaxies was roughly the size of the Milky Way.

In addition, it absorbed several smaller satellite galaxies as well. The team explained in their paper:

“Galaxy merging is one of the cornerstones of modern cosmological theories. Examples such as NGC 1316 are of great importance because they allow astronomers to study in detail the physical processes at work during mergers; and their effect on galaxy evolution.”

The decades-long mystery is why NGC 1316 seemed to have so little hydrogen gas – the chemical element present in many galaxies alongside heavier dust grains – which ultimately makes up stars throughout the Universe.

Hydrogen hide-and-seek

The astronomers found that NGC1316 contained far less hydrogen gas than it should. Paolo Serra, the project lead author at the Italian Institute for Astrophysics Cagliari Observatory, said:

“NGC 1316 contains a very large amount of dust in its interstellar medium. In this article we show new radio images obtained with MeerKAT, which revealed where all the hydrogen was hiding; it’s distributed in two long, faint, gaseous tails, stretching to a large distance from the galaxy.”

He adds that the tails were generated by tidal forces in action during the creation of NGC 1316, when the two major galaxies and several satellite galaxies collided. Serra’s colleague, Chief Scientist Dr Fernando Camilo, adds:

“With this beautiful piece of work, Paolo and his colleagues, among whom are several young South Africans, have significantly advanced our knowledge of the formation and evolution of galaxies. This provides a wonderful taste of what MeerKAT will do in years to come.”

The Meerkat Telescope

MeerKAT, the South African precursor to the international Square Kilometre Array (SKA), consists of 64 dishes extremely sensitive to radio waves, spread over a diameter of eight kilometres in the Karoo.

However, the observations by the team of international astronomers were carried out in July last year. At the time, only 40 out of 64 dishes were available. Camilo concludes:

“Results like these show that MeerKAT has begun addressing some of the key open questions in modern astrophysics. We look forward to researchers in South Africa and from around the world joining us on a journey of scientific discovery.”

NGC 1316 galaxy, meerkat telescope
Hydrogen gas (represented by green blobs) detected with SARAO’s MeerKAT radio telescope within and around the galaxy NGC 1316, visible at the centre of the image. The two hydrogen tails newly discovered with MeerKAT are visible in the upper and lower parts of the image (the curved arcs are added to guide the eye). Additional hydrogen clouds near NGC 1316 are also visible.