Detailed map of dark matter proves Einstein's theory of gravity

In a recent study, researchers have developed a detailed mass map of invisible dark matter distributed across a quarter of the entire sky.

New Delhi: Researchers have developed a detailed mass map of invisible dark matter distributed across a quarter of the entire sky, extending deep into the cosmos. The international team of researchers forming the Atacama Cosmology Telescope (ACT) collaboration further said that the map also confirmed Einstein's theory of how massive structures grow and bend light over the entire 14-billion-year life span of the universe.

The yet-to-be-published study which appears in the pre-print repository arXiv.org recently and have been submitted to the Astrophysical Journal. "We have mapped the invisible dark matter across the sky to the largest distances, and clearly see features of this invisible world that are hundreds of millions of light-years across," said Blake Sherwin, professor of cosmology at the University of Cambridge, where he leads a group of ACT researchers. "It looks just as our theories predict."

Despite making up 85 per cent of the universe along with influencing its evolution, dark matter is hard to detect because it does not interact with electromagnetic radiations such as light and is known to interact only with gravity. The team of researchers tracked how the gravitational pull exerted by large, heavy structures including dark matter bent the cosmic microwave background (CMB) radiations to produce a new mass map.

CMB radiations are the diffuse light emanating following the dawn of the universe's formation, the Big Bang, referred to by the cosmologists as the "baby picture of the universe" and are on their 14-billion-year journey to the Earth. The universe was only 3,80,000 years old then. "We've made a new mass map using distortions of light left over from the Big Bang," said Mathew Madhavacheril, assistant professor in the Department of Physics and Astronomy at the University of Pennsylvania.

The team built and gathered data from the National Science Foundation's Atacama Cosmology Telescope (ACT) located in the high Chilean Andes mountain range. "Remarkably, it provides measurements that show that both the 'lumpiness' of the universe, and the rate at which it is growing after 14 billion years of evolution, are just what you'd expect from our standard model of cosmology based on Einstein's theory of gravity," said Madhavacheril.

Recent measurements using background light emitted by stars in galaxies, different to the CMB, have sparked an ongoing debate, termed by some as the 'The Crisis in Cosmology'. These measurements produced results suggesting that dark matter was not lumpy enough under the standard model of cosmology, thereby, leading to concerns that the model may be broken. However, the team's latest results from ACT were able to precisely assess that the vast lumps seen in this image are the exact right size in accordance with the model.

"When I first saw them, our measurements were in such good agreement with the underlying theory that it took me a moment to process the results," said Cambridge PhD student Frank Qu, part of the research team. "It will be interesting to see how this possible discrepancy between different measurements will be resolved."

"The CMB lensing data rivals more conventional surveys of the visible light from galaxies in their ability to trace the sum of what is out there," said Suzanne Staggs, director of ACT and professor of Physics at Princeton University, US. "Together, the CMB lensing and the best optical surveys are clarifying the evolution of all the mass in the universe." (PTI)