Unveiling the distribution of dark matter around galaxies 12B years

Tue, 02 Aug 2022 05:32:57 GMT
Space Daily

Nagoya, Japan (SPX) Aug 02, 2022 A collaboration led by scientists at Nagoya University in Japan...

A collaboration led by scientists at Nagoya University in Japan has investigated the nature of dark matter surrounding galaxies seen as they were 12 billion years ago, billions of years further back in time than ever before.

Unable to detect enough distant source galaxies to measure the distortion, they could only analyze dark matter from no more than 8-10 billion years ago.

These limitations left open the question of the distribution of dark matter between this time and 13.7 billion years ago, around the beginning of our universe.

Using microwaves observed by the European Space Agency's Planck satellite, the team measured how the dark matter around the lens galaxies distorted the microwaves.

"Look at dark matter around distant galaxies?" asked Professor Masami Ouchi of the University of Tokyo, who made many of the observations.

"It was a crazy idea. No one realized we could do this. But after I gave a talk about a large distant galaxy sample, Hironao came to me and said it may be possible to look at dark matter around these galaxies with the CMB.".

"Most researchers use source galaxies to measure dark matter distribution from the present to eight billion years ago", added Assistant Professor Yuichi Harikane of the Institute for Cosmic Ray Research, University of Tokyo.

Combining the large distant galaxy sample and the lensing distortions in CMB, they detected dark matter even further back in time, from 12 billion years ago.

"12 billion years ago, things were very different. You see more galaxies that are in the process of formation than at the present; the first galaxy clusters are starting to form as well." Galaxy clusters comprise 100-1000 galaxies bound by gravity with large amounts of dark matter.

"This result gives a very consistent picture of galaxies and their evolution, as well as the dark matter in and around galaxies, and how this picture evolves with time," said Neta Bahcall, Eugene Higgins Professor of Astronomy, professor of astrophysical sciences, and director of undergraduate studies at Princeton University.