WASHINGTON (Rahnuma): Astronomers revealed that a narrow jet of particles moving at nearly the speed of light broke out into interstellar space after a pair of neutron stars merged in a galaxy 130 million light-years from Earth.
The study published on Wednesday in the journal Nature showed that the neutron star merger in August of 2017 also sent gravitational waves rippling through space.
This is the first event ever to be detected both by gravitational waves and electromagnetic waves, including gamma rays, X-rays, visible light, and radio waves.
The aftermath of the merger was observed by orbiting and ground-based telescopes around the world. Scientists watched as the characteristics of the received waves changed with time, and used the changes as clues to reveal the nature of the phenomena that followed the merger.
According to the researchers from National Radio Astronomy Observatory (NRAO) in the United States, the fast-moving jet are required to produce the type of gamma ray bursts that theorists had said should be caused by the merger of neutron-star pairs.
They discovered that a region of radio emission from the merger had moved, and the motion was so fast that only a jet could explain its speed.
“We measured an apparent motion that is four times faster than light. That illusion, called superluminal motion, results when the jet is pointed nearly toward Earth and the material in the jet is moving close to the speed of light,” said Kunal Mooley with NRAO.
The astronomers observed the object 75 days after the merger, then again 230 days after.
“This jet most likely is very narrow, at most 5 degrees wide, and was pointed only 20 degrees away from the Earth’s direction,” said Adam Deller from the Swinburne University of Technology.
“But to match our observations, the material in the jet also has to be blasting outwards at over 97 percent of the speed of light,” said Deller.
It was an initial merger of the two superdense neutron stars caused an explosion that propelled a spherical shell of debris outward, according to the researchers.
The neutron stars collapsed into a black hole whose powerful gravity began pulling material toward it. That material formed a rapidly-spinning disk that generated a pair of jets moving outward from its poles.
Data from observations indicated that a jet had interacted with the debris, forming a broad “cocoon” of material expanding outward. Such a cocoon would expand more slowly than a jet.
“The cocoon dominated the radio emission until about 60 days after the merger, and at later times the emission was jet dominated,” said Ore Gottlieb from the Tel Aviv University, a leading theorist on the study.
The detection strengthened the connection between neutron star mergers and short-duration gamma-ray bursts, the scientists said.
