NRAO: New Insight into Galaxy Cluster's "Mini-Halo"

[bystander]

VLA Gives New Insight into Galaxy Cluster's Spectacular "Mini-Halo"
National Radio Astronomy Observatory | 2017 Jun 13

[img3="VLA image of radio-emitting mini-halo in the Perseus Cluster of galaxies.
Radio emission in red; optical in white.
Credit: Gendron-Marsolais et al.; NRAO/AUI/NSF; NASA; SDSS"]https://public.nrao.edu/wp-content/uplo ... 68x768.jpg[/img3][hr][/hr]

Astronomers using the National Science Foundation’s Karl G. Jansky Very Large Array (VLA) have discovered new details that are helping them decipher the mystery of how giant radio-emitting structures are formed at the center of a cluster of galaxies.

The scientists studied a cluster of thousands of galaxies more than 250 million light-years from Earth, named the Perseus Cluster after the constellation in which it appears. Embedded within the center, the Perseus Cluster hosts a pool of superfast particles that emit radio waves, creating a radio structure known as a “mini-halo.” Mini-haloes have been found in about 30 galaxy clusters, but the halo in the Perseus Cluster is the largest known, about 1.3 million light-years in diameter, or 10 times the size of our Milky Way Galaxy.

The sizes of the mini-haloes have presented a puzzle to astronomers. As the particles travel away from the cluster’s center, they should slow down and stop emitting radio waves long before they reach the distances observed, according to theory. ...

The new details indicate that the halo’s radio emission is caused by complex mechanisms that vary throughout the cluster. As theorized before, some radio emission is caused by particles being reaccelerated when small groups of galaxies collide with the cluster and give the particles a gravitational shove. In addition, however, the scientists now think that the radio emission is also caused by the powerful jets of particles generated by the supermassive black hole at the core of the central galaxy that give an extra “kick” of energy to the particles. ...

Deep 230-470 MHz VLA Observations of the Mini-Halo in the Perseus Cluster - M. Gendron-Marsolais et al

• Monthly Notices of the RAS 469(4):3872 (Aug 2017) DOI: 10.1093/mnras/stx1042
  arXiv.org > astro-ph > arXiv:1701.03791 > 13 Jan 2017