Mysterious Ring In Space Could Be First Known Intergalactic Supernova

J0624–6948. (Filipovic et al., MNRAS, 2022)

The universe is not a chaotic free at all. Many stars are bound-up in galaxies separated by enormous, almost unimaginable distances.

The space between the galaxies, the intergalactic space, is sparsely populated but not completely empty; occasionally lone stars can also be found there.

For the first time, astronomers believe that they’ve found evidence of the death of one of these lone rogue stars. A mysterious & remarkably clean circle emitting radio waves has been discovered not far from the Large Magellanic Cloud, a satellite galaxy orbiting the Milky Way discovered, hanging in space and named J0624–6948.

If it sounds familiar, there is a reason for it. Recently, astronomers are puzzled by several mysterious radio emitting circles in space called Odd Radio Circles or ORCs.

The resemblance did not go unnoticed by astronomer Miroslav Filipovic of the University of Western Sydney in Australia.

“When we originally found this almost perfectly circular radio object, we thought it was yet some other ORC,” he says. “But after our further observations, it has become clear that this object is more likely to be something else.”

ORCs were first discovered with one of the world’s most powerful radio telescopes, the Australian Square Kilometre Array Pathfinder (ASKAP) in Australia. These objects appeared huge and distant, with several distinctive features, not the least of which is a galaxy dead center.

Scientists now believe the ORCs are a end result of an energetic process in those central galaxies, even though near exact nature of that process is unknown.

The location of J0624–6948. (Filipovic et al., MNRAS, 2022)

In fact, it’s likely that the ORCs are really spheres. The reason they seem as rings is because of perspective; at the edges, there is a higher emission density along our line of sight.

However, there are some key differences between J0624-6948 and the ORCs. The lack of an undeniable central galaxy in J0624-6948 is large, but by itself not decisive. The spectral index of radio emission is flatter than ORCs, and the apparent size of J0624–6948 is also different: very larger than that of the other ORCs.

Filipovic and his team taken into consideration various possibilities that would result in an object that resembles their observations. These covered a far large ORC, in addition to a super-flare originating in a star close to the galactic center, or jets from a far off active supermassive black hole.

In the end, one situation stood out as the many consistent with the observed phenomenon.

“The maximum plausible explanation is that the object is an intergalactic Supernova Remnant because of an exploded star that resided withinside the Large Magellanic Cloud outskirts that had passed through a single-degenerate kind Ia supernova which includes the explosion of stars orbiting every other,” Filipovic explains.

“What we have got potentially then observed is a completely unique remnant of [a] supernova that has expanded right into a rarefied, intergalactic environment – a surroundings that we did not assume to locate in such an object. Our estimates point to the age of approximately 2,200 to 7,100 years old.”

While supernova remnants do not have a tendency to be so fantastically circular, it would not be unprecedented. A handful of comparable examples, just like the stunning eye-shaped object SN 1987A withinside the Large Magellenic Cloud, had been documented.

If the scientists are right, J0624–6948 will be the first intergalactic supernova remnant ever identified, a bubble-like sphere of ejecta expanding outwards. Consistent with the team’s measurements, an association with the Large Magellanic Cloud might make J0624–6948 about 155 light-years across.

Follow-up observations could help solve the uncertainties. In addition, greater observations with instruments including ASKAP and its South African counterpart MeerKAT could help identify greater unusual radio circles withinside the sky.

Finding greater will provide us a greater complete picture in their range and diversity, which offers us a higher chance of identifying what they are.

“These new radio telescopes can pick up a number of spherical objects,” Filipovic says. “Due to the combined effects of high-sensitivity, top spatial sampling, and huge area coverage, they’re enriching our understanding of the Universe.”

This research was published in the Monthly Notices of the Royal Astronomical Society.