Mysterious burst of energy seen in millimeter-wavelength radio astronomy for the first time

An artist’s conception of a collision between a star and a neutron star, triggering a gamma-ray burst, one of the most energetic phenomena in the universe. (ALMA (ESO/NAOJ/NRAO), M. Weiss (NRAO/AUI/NSF))

One of the most powerful flashes in the sky, a result of the collision of a star and a neutron star, has been observed by millimeter-wavelength radio astronomy for the first time, offering an unprecedented view of one of the most violent events in the cosmos.

A research team led by Northwestern University in Illinois and Radboud University in the Netherlands used the Atacama Large Millimeter/submillimeter Array, or ALMA radio telescope, in Chile to capture the afterglow of GRB 211106A, a short burst of gamma rays. (GRB) determined to originate in a galaxy 20 billion light-years away.

“This short gamma-ray burst was the first time we’ve attempted to observe such an event with ALMA,” Northwestern professor of physics and astronomy Wen-fai Fong said in a statement. “Short burst afterglows are very hard to find, so it was spectacular to see this event shine so brightly.

The Doctor. Fong is one of many authors of a study of observation to be published in the next issue of Letters from astrophysical journalsand is available online now at the academic prepress archive arxiv.org.

GRBs are powerful bursts of gamma radiation that occur when massive stars collapse into black holes, or dense neutron stars in a binary system merge with their companion stars to form a black hole, an intense cataclysmic event believed to forge most of the heaviest elements on the planet. universe, like gold and plutonium.

“These mergers occur because of gravitational wave radiation that removes energy from the orbit of binary stars, causing the stars to move closer together,” said Radboud University astronomer and lead author of the paper Tanmoy Laskar in a statement. “The resulting explosion is accompanied by jets moving close to the speed of light. When one of these jets is aimed at Earth, we observe a short pulse of gamma-ray radiation or a short-lived GRB.”

Short GRBs can last only a fraction of a second, but their afterglow can persist in longer, less energetic wavelengths of light for minutes or even days.

That was the case for GRB 211106A, whose afterglow was first detected in X-rays by NASA’s Neil Gehrels Swift Observatory, later found in infrared light by the Hubble Space Telescope, and more recently in millimeter radio light by ALMA. It was only with the addition of the ALMA observation that the GRB was located in a distant galaxy.

“Hubble observations revealed an unchanging field of galaxies,” Laskar said in a statement. “ALMA’s unparalleled sensitivity allowed us to pinpoint the location of the GRB in that field more precisely, and it turned out to be in another faint galaxy, which is farther away. This, in turn, means that this short-lived gamma-ray burst is even more powerful than we thought, making it one of the most luminous and energetic ever recorded.”

The millimeter wavelength also gave scientists a clearer picture of the structure and density of the environment around the GRB, according to Dr. one of the widest ever measured.

The study highlights the value of observing complex phenomena at multiple wavelengths using the most sophisticated tools available, which now include the newly operational James Webb Space Telescope.

“In the future, we could also use JWST to capture infrared glows and study their chemical composition,” Laskar said in a statement. “I am excited about these upcoming discoveries in our field.”

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