Discovery of ‘mini halo’ points to how the early universe was formed
Astronomers co-led by Professor Julie Hlavacek-Larrondo from the Center for Research in Astrophysics of Quebec detect a gigantic cloud of high-energy particles 10 billions light years away from Earth.
Astronomers have uncovered a vast cloud of energetic particles surrounding one of the most distant galaxy clusters ever observed, shedding new light on the evolution of galaxy clusters in the early universe.
The scientists, co-led by Julie Hlavacek-Larrondo from Université de Montréal, say their finding shows that entire galaxy clusters, among the largest structures in the Universe, have been immersed in high-energy particles for most of their existence.
The discovery, at a distance so great that it takes light 10 billion years to reach Earth, is the most distant ‘radio mini-halo’ ever found, doubling the previous record.
Such a mini-halo consists of highly energetic charged particles in the vacuum between galaxies in a cluster, which together emanate radio waves that can be detected from Earth.
Accepted for publication in Astrophysical Journal Letters, the discovery shows that even in the early universe, galaxy clusters were already shaped by energetic processes.
And understanding how energy moves through galaxy clusters will help in piecing together the story of cosmic evolution, the astronomers say.
Two likely explanations
There are two likely explanations behind the formation of the mini-halo.
One is that there are supermassive black holes which lie at the hearts of galaxies within a cluster and can eject streams of high-energy particles into space.
However, astronomers are still trying to understand how these particles would be able to migrate away from the black hole to create such a gigantic cloud of particles, while maintaining so much of their energy.
The second explanation is cosmic particle collisions.
This is when charged particles within the hot plasma of the galaxy cluster collide at near-light speeds, smashing apart into the highly energetic particles that make up the mini-halo.
The astronomers say their finding offers a rare look at what galaxy clusters were like just after they formed. It not only shows that galaxy clusters have been infused with high-energy particles for billions of years more than previously known, but also allows scientists to study where these high-energy particles come from.
“It’s astonishing to find such a strong radio signal at this distance,” said Roland Timmerman, a Durham University (U.K.) astronomer who co-led the discovery with Hlavacek-Larrondo. “It means these energetic particles and the processes creating them have been shaping galaxy clusters for nearly the entire history of the universe.”
About this study
”Discovery of Diffuse Radio Emission in a Massive z=1.709 Cool Core Cluster: A Candidate Radio Mini-Halo”, by Julie Hlavacek-Larrondo and her colleagues will be published in the Astrophysical Journal Letters.
About the Centre for Research in Astrophysics of Quebec
The Centre for Research in Astrophysics of Quebec brings together all the astrophysicists in Quebec. Nearly 150 people, including some fifty researchers and their students from Université de Montréal, McGill University, Université Laval, Bishop’s University, Cégep de Sherbrooke, Collège de Bois-de-Boulogne and a number of other collaborating institutions are part of the cluster. The Center is under the direction of David Lafrenière of the Université de Montréal and is one of the strategic clusters funded by the Fonds de recherche du Québec – Nature and Technologies (FRQNT).
Source and information:
Frédérique Baron
Media Relations
Centre for Research in Astrophysics of Quebec
Julie Hlavacek-Larrondo
Co-lead of the study
Centre for Research in Astrophysics of Quebec
Université de Montréal
j.larrondo@umontreal.ca