Mystery of ghost space circles unravelled through shockwave simulation

Intrigued by the presence of enigmatic, ghostly circles within deep space, scientists have conducted a comprehensive analysis shedding light on these colossal celestial structures.

Initially detected in 2019, these luminous circles have now been identified as shockwaves formed by immense winds emanating from galaxies' cores undergoing or having experienced intense star formation.

The study, published in Nature, unveils the origins of these ethereal rings known as Odd Radio Circles (ORCs).

The research indicates that these mesmerising formations are a result of the intense interstellar activity within galaxies undergoing starburst events. During such periods, stars rapidly evolve, culminating in dramatic supernova explosions.

Astrophysicist Alison Coil from the University of California San Diego, leading the research, highlighted the complexity of these galaxies formed when two large galaxies collide. The collision compels gas to concentrate in a compact area, triggering an intense phase of star generation. The subsequent rapid burnout of massive stars leads to the expulsion of gas as powerful outflowing winds.

The analysis proposes that this expelled gas, driven outward from the galactic centre, gets entrapped within galactic winds, generating powerful shockwaves manifesting as ORCs.

Despite their resemblance to remnants of supernovae, scientists were surprised to uncover a galaxy situated at the heart of each ORC.

Using the WM Keck Observatory, the research team examined optical data concerning one of the ORCs. Their findings suggested that the stars within one ORC were approximately 6 billion years old, indicating a star-forming episode that concluded roughly a billion years in the past.

Employing high-performance computing, the scientists conducted data analysis to assess whether this burst of star formation could have produced an expanding bubble encircling the galaxy.

The simulations demonstrated that a galactic wind, propelled by a rapid rate of supernova explosions around 200 million years ago, travelled at approximately 450 kilometres per second. While the intensity of the wind diminished, the heated gas continued its outward trajectory, shaping a bubble around the galaxy.

The study concludes that the existence of ORCs is attributable to galactic outflows, potentially arising subsequent to a phase of vigorous starburst activity.