Do mysterious “radio circles” occur during galaxy explosions?

In the early 1960s, by successfully identifying a source’s optical counterpart radio powerful discovery by radio telescopes of the time and christened 3C 273, the astronomers notice that she looks like one star but that his spectrum the light is strongly redshifted. As a part of cosmology relativist of the time already pretty well developed, this would mean that it is on billions oflight years distance and that it therefore emits, to be visible from so far away, quantities ofenergies amazing and almost incredible because no normal star or even starburst can physically explain it.

Several hypotheses exotic proposed to explain the existence of this source and other similar ones that radio astronomers will discover during the same decade. A conservative hypothesis assumed that they were actually stars but very massive and therefore had a significant redshift due to their field of gravitya well-known prediction of general theory of relativity since its discovery of Einstein. These stars would then be close and theirs brightness inherent would then have nothing extraordinary.

Other researchers, during the same decade, where the theory of the Big Bang will quickly impose itself after the discovery of cosmic radiation in 1965, is more daring and exploring, as Igor Novikov and Yuval Ne’eman suggested it, the idea of ​​what we already call quasars could be parts ofUniverse if expansion at the time of big bang had been delayed (assumption of limping core). They would even go so far as to suggest that these cosmic phenomena are the other end of wormholes that emit fabric which they had recorded in the form of black holes in another part of the cosmos, or even in another universe.

We think we know that now quasars are active nuclei in galaxies containing one supermassive black hole accumulating substance, such as M87 *, now depicted by members of the collaboration Event Horizon Telescope.

From quasars to ORCs

Since 2019, however, British-Australian astronomer Ray Norris and his colleagues have been very confused about a handful of objects they have discovered usingAustralian Square Kilometer Array Pathfinder (Askap), the Australian radio telescope network that served as the prototype for the long-awaited Square Kilometer Array (SKA), a virtual giant radio telescope project, with a collection area equivalent to one square kilometer, underway and which combines several instruments.

The first unusual object revealed by Askap was named ORC 1, ORC for acronym of ” odd radio circuits “, which can be translated to” strange radio circuits “.

As their name suggests, they appeared on the radio in the form of rings, but with nothing connected to them in the visible domain, eliminating the hypothesis that they could be remnants of supernovae or planetary nebulae, which may also have this kind of aspect. It can also be dismissed as unlikely that they are radio patches associated with supermassive black hole jets because they are much more irregular.

The distance and therefore also the size of these circles were not yet determined in the beginning. But that has just changed and a publication in Monthly announcements from the Royal Astronomical Society (MNRAS), which can be freely consulted regarding arXiv, start giving some answers.

Astronomers have mobilized South African MeerKAT radio telescopealso a forerunner of SKA, which we already owe discoveriesto observe with a better solution ORC 1. It was then possible to find a new radio source in the center of the radio circle, a source that could be connected to a galaxy. Ultimately, the data collected now suggest that we are in the presence of a ring located one billion light-years from The Milky Way and correspondingly about one million light-years in diameter.

Similar conclusions were reached with MeerKAT, and it now appears that ORCs are giant bubbles of gas very hot if the contours seem brighter because in slices we can see a greater thickness of material containing electrons relativists form a plasma immersed in magnetic fields, and which radiate correspondingly. The presence of magnetic fields is detected by the polarization of radio waves measured with MeerKAT. This type of radiation called synchrotron, because it is observed in these particle accelerators on Earth, is well known in the Milky Way and also in crab fog.

The bubbles appear centered on galaxies discovered, and it therefore seems clear and established that they were blown by these galaxies, as if it were the front of the shock wave of a quasi-spherical explosion.

The artist’s impression of the formation of one of the strange radio circles from an explosion from a central galaxy. It is believed that it took 1 billion years for the bubble from the explosion to grow to the size we know today. The radio circles are so large (millions of light-years in diameter) that they have extended beyond their source galaxies. © Sam Moorfield / CSIRO

However, the nature of the explosion is still intangible. It can be an unforeseen and unobserved phenomenon when two supermassive black holes collide after the fusion of two galaxies.

It can also be a sudden formation by collapse the gravity of about one million stars in a galaxy, where the birth of these stars causes a sudden explosion of plasma leaving the galaxy.

We should know more with an extra gain in resolution when SKA is fully operational.

Support your independent scientific media: Discover our subscription formulas!

4 good reasons to subscribe to Futura on Patreon:

  1. A site without any advertising from 3.29 euros per month.
  2. It is without obligation.
  3. Access to priority content, in preview, just for you.
  4. You support our business in the best possible way. A true motivation for us!
I subscribe to Futura on Patreon

Interested in what you just read?

Leave a Comment