Astronomers Can 'See' Invisible Dark Matter Through Faint Light In Galaxy Clusters


Much remains unknown about dark matter, the mysterious substance that makes up most of matter in the universe. Findings of a new research, however, could help scientists determine the distribution and eventually the true nature of dark matter.

The Invisible Dark Matter

Dark matter makes up about 85 percent of all matter in the universe, but it has remained invisible because it does not appear to interact with regular matter such as light. Astronomers cannot detect dark matter using current instruments. They only know it exists because of the visible effect of its gravity,

A new study by two astrophysicists from Australia and Spain, however, may bring science closer to figuring out where the mysterious substance may lie.

Intracluster Light In Galaxy Clusters

Mireia Montes, from the University of New South Wales in Australia, and Ignacio Trujillo, from Instituto de Astrofísica de Canarias in Spain, said that faint light in galaxy clusters known as intracluster light can map the distribution of dark matter and help astronomers understand this invisible source of gravity.

The researchers explained that intracluster light are a byproduct of galactic interactions. When galaxies interact, individual stars are ejected from their home galaxy and float within the galaxy cluster. These stars then end up where most of the mass of the cluster, mostly dark matter, resides.

Locating Dark Matter In Galaxy Clusters

The isolated stars and dark matter that form the intracluster light both follow the gravitational potential of the cluster itself. Because the two follow exactly the same gravity, the intracluster light can indicate the location of dark matter.

"We have found a new way to see the location where the dark matter should be, because you are tracing exactly the same gravitational potential. We can illuminate, with a very faint glow, the position of dark matter," Montes said.

The researchers said that the findings mean researchers can map where dark matter resides just by using deep imaging observations of galaxy clusters.

The findings were published in the journal Monthly Notices of the Royal Astronomical Society.

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