Zooming In on Dark Matter Haloes

Dark Matter Haloes

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An artist’s impression of dark matter haloes with numerous mass in the Universe. Credit: YU Jingchuan, Beijing Planetarium

Most matter in the Universe is dark and entirely various in nature from the matter that comprises stars, worlds and individuals. Galaxies kind and grow when gas cools and condenses at the center of huge clumps of this dark matter, the so-called dark matter haloes.

An worldwide research study group led by Prof. WANG Jie from the National Astronomical Observatories of the Chinese Academy of Sciences (NAOC) utilized supercomputers in China and Europe to focus on a common area of a virtual universe as if focusing on a picture of the Moon to see a flea on its surface area.

The research study was released in Nature on September 2, 2020.

The greatest dark matter haloes in today’s universe include big galaxy clusters, collections of numerous intense galaxies. The homes of such clusters, which weigh over a quadrillion (a million billion) times as much as our Sun, are well studied.

On the other hand, the masses of the tiniest dark matter haloes are unidentified. They are assumed to be about the mass of the Earth, according to presently popular theories.

Such little haloes would be incredibly many, including a significant portion of all the dark matter in deep space. However, they would stay dark throughout cosmic history due to the fact that stars and galaxies grow just in haloes more than a million times as huge as the Sun.

“These small haloes can only be studied by simulating the evolution of the Universe in a large supercomputer,” stated Prof. WANG.

Projected Dark Matter Density

Simulations of development of dark matter haloes varying in size from Earth mass to clusters of galaxies discover a universal halo density structure spanning 20 orders of magnitude in mass. Credit: Dr. Sownak Bose, Center for Astrophysics, Harvard University

The research study group, based at the National Observatory of the Chinese Academy of Sciences in China, Durham University in the UK, the Max Planck Institute for Astrophysics in Germany, and the Center for Astrophysics in the U.S.A., took 5 years to establish, test and perform their cosmic zoom.

It allowed them to study the structure of dark matter haloes of all masses in between that of the Earth which of a huge galaxy cluster. In number, the zoom covers a mass series of 10 to the power 30 (that is a one followed by 30 absolutely nos), which is comparable to the variety of kgs in the Sun.

By zooming-in on the virtual universe in such tiny information, the scientists had the ability to study the structure of dark matter haloes varying in mass from that of the Earth to a huge galaxy cluster.

“Surprisingly, we find that haloes of all sizes have a very similar internal structure, i.e., they are extremely dense at the center, become increasingly spread out, and have smaller clumps orbiting in their outer regions,” stated Prof. WANG. “Without a measure scale it was almost impossible to tell an image of a dark matter halo of a massive galaxy from one whose mass is a fraction of the Sun.”

Particles of dark matter can clash near the centers of haloes, and may, according to some theories, wipe out in a burst of energetic (gamma) radiation.

Co-author, Prof. Carlos Frenk from Durham University stated: “By zooming in on these relatively tiny dark matter haloes, we can calculate the amount of radiation expected to come from different sized haloes.”

Most of this radiation would be discharged by dark matter haloes too little to include stars and future gamma-ray observatories may be able to find these emissions, making these little items separately or jointly “visible.”

“This would confirm the hypothesized nature of the dark matter, which may not be entirely dark after all,” stated co-author Simon White from the Max Planck Institute of Astrophysics. “Our research sheds light on these small haloes as we seek to learn more about what dark matter is and the role it plays in the evolution of the universe.”

Read Zooming In Tight on Dark Matter for more on this research study.

Reference: “Universal structure of dark matter haloes over a mass range of 20 orders of magnitude” by J. Wang, S. Bose, C. S. Frenk, L. Gao, A. Jenkins, V. Springel and S. D. M. White, 2 September 2020, Nature.
DOI: 10.1038/s41586-020-2642-9

The simulations were performed in the Cosmology Machine supercomputers in Guangzhou, China, Durham, England of the UK, and Munich, Germany.