January 9, 2024 Astronomers may have unraveled the mystery behind the mysterious, ghostly circles in deep space that have puzzled scientists since their discovery in 2019. New analysis suggests that these odd radio circles, or ORCs, are shockwaves created by powerful winds emanating from galaxies undergoing or having undergone starbursting.
Starbursting galaxies are those experiencing an intense period of star formation due to the collision of two large galaxies. The collision pushes gas into a small region, leading to a burst of star formation, with massive stars expelling gas as outflowing winds when they die in supernovae.
The research, led by astrophysicist Alison Coil of the University of California San Diego, focused on one of the ORCs known as ORC 4. Optical data from the WM Keck Observatory revealed stars around 6 billion years old, indicating a burst of star formation ending about a billion years ago.
Computer simulations were then conducted to replicate the observed ORC, suggesting that galactic winds starting at a velocity of approximately 450 kilometers per second, lasting for about 200 million years, could create the observed shockfront. The simulations propose that ORCs are produced by galactic outflows following intense starburst periods.
The findings raise questions about the longevity and prevalence of ORCs, whether they occur in all starbursting galaxies, and the specific conditions required for their formation. This discovery offers a new avenue for understanding the evolution of the Universe. The research has been published in Nature.
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Reference: https://www.sciencealert.com/huge-mysterious-space-orcs-could-now-have-an-explanation
