Two astrophysicists from Australia and Spain claim to have found a new method to 'see' invisible dark matter in the universe. This method relies on the faint starlight that lingers between massive clusters of galaxies and allows accurate mapping of the distribution of the dark matter, according to research team.
The concept of dark matter has perplexed scientists for decades. The invisible, elusive dark matter is believed to make up about 85 per cent of all the matter in the universe.
It is also thought to account for about 25 per cent of the universe's total energy density. Presence of dark matter has never been observed directly, and scientists predict its presence only on the basis of its gravitational effect on other objects in the universe.
"We have found a way to 'see ' dark matter," says Mireia Montes, from the University of New South Wales, Australia, and the lead author of the study.
"We have found that very faint light in galaxy clusters - the intracluster light - maps how dark matter is distributed."
In the current study, Montes and her teammate, Ignacio Trujillo, from the Instituto de Astrofísica de Canarias, Spain, used the data from the Frontier Fields programme of the NASA/ESA Hubble Space Telescope. In the Frontier Fields programme, six galaxy clusters were observed for more than 630 hours of Hubble's time.
In the Hubble data, Montes and Trujillo investigated isolated stars stripped from their galaxies. Such stars float freely within a galaxy cluster and eventually end up where the majority of the cluster mass - mostly dark matter - resides.
According to Montes, these isolated stars "have an identical distribution to the dark matter," as observed by using the latest technology.
Moreover, both dark matter and isolated stars act as collisionless components and form the intracluster light.
After thorough investigation of the Hubble data, both astronomers arrived at the conclusion that the intracluster light was aligned with the dark matter present in that region. According to them, the intracluster light enables tracing the distribution of dark matter more efficiently than any other method relying on luminous tracers.
Researchers also believe the new results "open up the possibility of exploring the distribution of dark matter in galaxy clusters in detail using deep imaging observations."
The findings of the study are published in the journal Monthly Notices of the Royal Astronomical Society.
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