Using data from NSF’s Atacama Cosmology Telescope, astronomers have produced the most detailed map of dark matter distributed across one quarter of the sky. Their work provides further support to Einstein’s theory of general relativity, which has been the foundation of the Standard Model of cosmology for more than a century.
Astronomers from the ACT Collaboration used NSF’s Atacama Cosmology Telescope to create this new map of the dark matter; the orange regions show where there is more mass; purple where there is less or none; the typical features are hundreds of millions of light years across; the whitish band shows where contaminating light from dust in our Milky Way Galaxy, measured by ESA’s Planck satellite, obscures a deeper view. Image credit: ACT Collaboration.
Although dark matter makes up a large chunk of the Universe, approximately 85%, it has remained hard to detect because dark matter does not interact with light or other forms of electromagnetic radiation.
Scientists believe dark matter may only interact with gravity.
To track dark matter down, Stony Brook University astronomer Neelima Sehgal and more than 160 astronomers worldwide have built and gathered data from NSF’s Atacama Cosmology Telescope in the high Chilean Andes.
The astronomers focused the Cosmic Microwave Background (CMB) radiation — light emanating from the dawn of the Universe’s formation, the Big Bang, when the Universe was only 380,000 years old.
They tracked how the gravitational pull of large, heavy structures including dark matter warps the CMB on its 14-billion-year journey to us, like how a magnifying glass bends light as it passes through its lens. This phenomenon is called gravitational lensing.
The new ACT results provide further support to Einstein’s theory of general relativity. Image credit: Lucy Reading-Ikkanda / Simons Foundation.
“The ACT result showcases the precision that can be obtained with measurements of the gravitational lensing of the microwave background, as well as the promise of future more sensitive CMB experiments in terms of furthering our understanding of the physics of the Universe,” Dr. Sehgal said.
The work further supports Einstein’s theory about how massive structures grow and bend light, with a test that spans the entire age of the Universe.
“We’ve made a new mass map using distortions of light left over from the Big Bang,” said Dr. Mathew Madhavacheril, an astronomer at the University of Pennsylvania.
“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.”
“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 University of Cambridge Ph.D. student Frank Qu.
A set of team’s three papers will be published in the Astrophysical Journal.
