Using the Very Large Array telescope in New Mexico, astronomers led by Marie-Lou Gendron-Marsolay of the European Southern Observatory have studied a huge cluster of galaxies.
There, in low frequency radio waves, they saw complex halos that could be the result of intense galactic interactions.
The galaxy is much more than the visible light it emits. Many of them, including the Milky Way, have large-scale radio structures, huge bubbles or jets of radio emission that extend far above and below the galactic plane. In many cases, these lobes and streams are clearly defined and more or less symmetrical.
In the Perseus Cluster, about 240 million light-years from the Milky Way, a different picture emerges.
The Perseus Cluster is huge, one of the most massive objects in the known universe. It contains thousands of galaxies enveloped in a huge cloud of hot gas. And the new VLA images – the first in high resolution in the low frequency range of 230 to 470 megahertz – reveal previously unseen details in large-scale radio structures.
Galaxy NGC 1275, also known as Perseus A, sits right in the center of the cluster and is the brightest galaxy in it. In the inner lobes of observation, new substructures are found – thin fibers of radio emission and loop-like structures in the southern lobe. The observations also confirmed the presence of radio spurs in the outer lobes, first discovered in 2002.
Meanwhile, the galaxy NGC 1265 has two long jets, but they are bent at 90 degrees, forming a single comet-like tail that curves around. This structure is well known but puzzling; such tails are usually interpreted as indicators of movement through the intracluster environment caused by the pressure of the plate. Based on an analysis of the difference in tail brightness, the team interprets this shape as evidence of two separate electron populations.
Clusters of galaxies are strange places filled with interactions and objects that we do not fully understand.
“These images,” Gendron-Marsolais said, “show us previously unseen structures and details, and this helps our efforts to determine the nature of these objects.”
The team's research was included in the Royal Astronomical Society's Monthly Notices and is available on arXiv.
Sources: Photo: M. Gendron-Marsolais et al .; S. Dagnello, NRAO / AUI / NSF; Sloan Digital Sky Survey.
