Researchers, for the very first time, have managed to observe one of the most powerful flashes in the sky caused by the collision of a star and a neutron star, by a millimeter wavelength radio astronomy.
Reported first by The Independent, the discovery was made by researchers from Northwestern University in Illinois and Radboud University in the Netherlands. They made use of the Atacama Large Millimetre/Submillimetre Array radio telescope in Chile to capture the afterglow of GRB 211106A — a brief GRB (gamma-ray burst) which originated in a galaxy around 20 billion light years away.
Northwestern professor of physics and astronomy Wen-fai Fong said in a statement, “This short gamma-ray burst was the first time we tried to observe such an event with ALMA. Afterglows for short bursts are very difficult to come by, so it was spectacular to catch this event shining so brightly.”
What are GRBs?
To the unaware, GRBs are powerful bursts of gamma radiation that appear when large stars fall into black holes or neutron stars, especially dense ones in a binary system fuse with their companion stars in order to form a black hole.
Radboud University astronomer and lead author of the paper Tanmoy Laskar added, “These mergers occur because of gravitational wave radiation that removes energy from the orbit of the binary stars, causing the stars to spiral towards each other. The resulting explosion is accompanied by jets moving at close to the speed of light. When one of these jets is pointed at Earth, we observe a short pulse of gamma-ray radiation or a short-duration GRB.”
Short-duration GRBs could only last for a fraction of a second however, the afterglow it releases persists for longer, in less-energetic wavelengths of light that can last for minutes, even hours or days.
This is exactly what happened with GRB 211106A. Its afterglow was first spotted in X-ray light by NASA’s Geil Gehrels Swift Observatory and later found in IR light by the Hubble Space Telescope and recently spotted by ALMA as a radio light. The last discovery finally shed light on the fact that the GRB was originating in a distant galaxy.