Brightest yet gamma-ray emission in space observed

In a cosmic first, researchers have observed the most powerful and luminous yet known energy release -- a trillion times more energetic than visible light -- in the brightest type of electromagnetic events known to occur in the universe called gamma-ray bursts (GRBs).

The study, published in the journal Nature, noted that the very high energy cosmic emission had been predicted earlier in theoretical studies, and thought to originate from collapsing stars or from the merging of two dying stars, but never directly observed until now.

The researchers, including those from George Washington University in the US, detected a burst on January 14 labeled GRB 190114C which led to a collaborative effort to observe the radiation coming from the source using more than 20 observatories and instruments around the world. An international team gathered information about GRB 190114C, capturing the evolution of the gamma-ray burst's afterglow emission.

The researchers found that this particular burst originated from a very dense environment in the middle of a bright galaxy at a distance that would take light 5 billion years to travel. "After over 45 years of observing GRBs, we just confirmed the existence of yet another unknown component in their afterglows, which increases the gamma-ray burst overall energy budget dramatically," said study co-author Chryssa Kouveliotou, a professor of physics at George Washington University.

The researchers said this type of GRBs last typically for only a few tens of seconds, and are generated by extremely energetic cosmic explosions. The electromagnetic spectrum consists of the lowest energy radio waves on one end, visible light in the middle, gamma rays at the other energy end, and X-rays closer to the high energy end, the researchers said, adding that GRBs are followed by an afterglow, mostly in the visible and X-ray spectral regions.

The researchers used the new MeerKAT radio telescope in South Africa to record the X-rays emission from the afterglow. According to the researchers, the shape of the observed spectrum of afterglow light was indicative of an emission process called inverse Compton emission, which they said is commonly produced in gamma-ray bursts.

"MeerKAT is a new radio observatory with very good sensitivity. It is a great facility to observe this kind of event. Our team is carrying out a multi-year program to observe many more gamma-ray bursts and other cosmic explosions in the coming years," said study co-author Alexander van der Horst. The researchers said the observations opened up a new window for research on gamma-ray bursts, and added that they plan to understand their physics with more detections in the future.