The universe can be like a magic trick. When you move to see different wavelengths of light, you can see all kinds of objects, events, and interactions that are otherwise invisible to the human eye.
Astronomers led by Marie-Lou Gendron-Marsolais of the European Southern Observatory have entered a humble galaxy cluster, using the Very Large Array Telescope in New Mexico. There, in low-frequency radio wavelengths, they have seen complex invisible aura that can be the result of intense galactic interactions.
There is a lot more to the galaxy than the visible light that turns it off. Many, including the Milky Way, have large-scale radio structures, huge bubbles or jets of radio emission that extend above and below the galactic plane. In many cases, these lobes and jets are well defined and more or less symmetric.
A different picture emerges in the Perseus cluster, located in the constellation of Perseus, about 240 million light years from the Milky Way.
The Perseus cluster is very large, one of the largest objects in the known Universe. It consists of thousands of galaxies in a huge cloud of hot gas. And new VLA images – the first in high resolution in the low-frequency 230 to 470 Merghartz range – reveal previously undiscovered details in large-scale radio structures.
Galaxy NGC 1275, also known as Perseus A, sits right in the center of the cluster, and has the brightest galaxy. In its inner lobe, observations reveal new satellites – thin filaments of radio emission and loop-like structures in the southern lobe. Observations also confirmed the presence of radio spurs in the outer lobe, first discovered in 2002.
Meanwhile, the Galaxy NGC 1265 has two long jets – but they are bent at a 90-degree angle, rotating in a single, comet-like tail that curves around. This structure is well known, but esoteric; Such tails are usually interpreted as motion tracers through the intracluster medium, which is caused by the pressure of the ram. Based on an analysis of the difference in brightness in the tail, the team interprets this figure as evidence for two different electron populations.
They also identified new filaments of radio emission in the tail, although at this stage it is difficult to say what they produced. It could have been turbulence, or a magnetic field; More detailed analysis will require higher resolution images.
The galaxy IC 310 is also a tailed galaxy, although it has a straight tail, which is much more common, corresponding to a radio galaxy falling into a cluster. But recent research has revealed a blur of this galaxy, in which material is shot at near-light speed from the galactic nucleus in the direction of the observer.
Due to the viewing angle, the team was able to observe gamma radiation from the galactic center, as well as new structures in the tail jets – two separate, narrowly constricted jets at the base of the tail. According to their analysis, observations correspond to a bang, meaning that the Libra-Jet radio galaxy and the blazer are not mutually exclusive.
Galaxy clusters are strange places, full of interactions and objects that we do not understand well. These new observations are breadcrumbs on the trail of learning … but they also highlight the importance of being near us with the most powerful telescopes.
“These pictures,” Gendron-Marsolis said, “show us previously-unseen structures and details and that helps our effort to determine the nature of these objects.”
The team’s research has been accepted Monthly notice of the Royal Astronomical Society, And available on arXiv.