NASA’s Chandra X-ray Observatory and Hubble Space Telescope gathered more clues on dark matter and its properties, as they captured a powerful collision of galaxy clusters two years after the Bullet Cluster was first revealed.

Just like the previous collision, the new cluster, known as MACS J0025.4-1222, provides crucial evidence on the mechanisms behind the Universe’s dark matter, highlighting the separation between dark and ordinary matter.

In August 2006, NASA reported that they had finally found evidence of the existence of dark matter, thanks to Chandra’s observations of two colliding clusters of galaxies. The clusters of galaxies are groups of galaxies held together by gravitational attraction.

NASA explained that MACS J0025.4-1222 formed after an incredibly energetic collision between two large clusters of galaxies. The phenomenon is believed to have occurred long before the Bullet Cluster.

With the help of data provided by Hubble’s optical images, scientists managed to infer the distribution of the dark and ordinary matter. By using the gravitational leasing technique, they managed to map the position of the ordinary matter, which mostly consists of hot gas.

MACS J0025.4-1222 seems to be very different from Bullet Cluster, in the sense that it does not contain a “bullet,” which is a visible X-ray bright core of gas moving through the Bullet Cluster.

The team of scientists estimated that the clusters in the MACS J0025.4-1222, each almost a million billion times the mass of the Sun, collided at speeds of millions of miles per hour. As the two began to merge, the hot gas in one cluster collided with the hot gas in the other cluster and slowed down, while the dark matter did not.

This observation revealed new details on the properties of the dark matter, namely that dark matter particles interact with each other only very weakly or not at all, apart from the pull of gravity, NASA explained.

“One of the great accomplishments of modern astronomy has been to establish a complete inventory of the matter and energy content of the Universe,” scientists from the Chandra observatory have said. “The so-called dark matter makes up approximately 23% of this content, five times more than the ordinary matter that can be detected by telescopes. The latest results with MACS J0025 once again confirm these findings.”