Nasa has captured two supermassive black holes photo bombing Milky Way's galactic neighbour, Andromeda, aka the M31 galaxy, in a new image. Research suggests the two black holes are drawing closer and could merge into one within 350 years.

The image, composed from Nasa's Chandra X-ray Observatory and a couple of ground-based telescopes, features a source of light or a system dubbed J0045+41.

Initially, this system was considered as a pair of orbiting stars located within Andromeda galaxy, which is some 2.5 million light-years away from the Earth.

However, the latest observations using Chandra, Gemini-North telescope in Hawaii and the Caltech's Palomar Transient Factory in California have suggested it might be about 2.6 million light-years away (1,000 times farther) and contains tightly bound supermassive black holes.

"We were looking for a special type of star in M31 and thought we had found one," said Trevor Dorn-Wallenstein, the lead author of the study published in The Astrophysical Journal. "We were surprised and excited to find something far stranger!"

While Chandra narrowed down what this source might contain — whether a neutron star, distant supermassive black hole, or a pair of orbiting black holes — Gemini-North telescope and Palomar Transient Factor provided more evidence that this is actually a tightly bound pair of two supermassive black holes.

"This is the first time such strong evidence has been found for a pair of orbiting giant black holes," says study co-author Emily Levesque.

The exact mass of these black holes is not clear, but is estimated to be two hundred million times the mass of the Sun, which is a more than that of Sagittarius A* — the black hole at the centre of Milky Way. Researchers believe the tightly bound pair might have formed billions of years ago following the merger of two galaxies.

As for the distance between the two black holes, they might just be less than a hundredth of a light-year apart or a few hundred times the distance between the Earth and the Sun, and are possibly drawing closer to each other, the researchers say.

"We think this pair will collide and merge into one black hole in as little as 350 years or as much as 360,000 years," says John Ruan, another author of the study.