Mysterious explosion of energy first seen in millimeter wavelength radio astronomy

Mysterious explosion of energy first seen in millimeter wavelength radio astronomy

Mysterious explosion of energy first seen in millimeter wavelength radio astronomy

An artistic idea 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))

An artistic idea 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, the result of the collision of a star and a neutron star, was first observed by millimeter wavelength radio astronomy, offering an unprecedented insight into 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 radio telescope in Chile to capture the afterglow of GRB 211106A, a short gamma-ray burst (GRB) determined at originate in a galaxy 20 billion light years away.

“This brief gamma-ray burst was the first time we tried to observe such an event with ALMA,” Northwestern physics and astronomy professor Wen-fai Fong said in a statement. “It is very difficult to find residual flare for short bursts, so it was spectacular to see this event shine so brightly.

Dr. Fong is one of several authors of a study on observation to be published in an upcoming issue of Letters from the astrophysical diaryand is now available online in the arxiv.org academic preprint archive.

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 catastrophic event believed to forge the most of the heaviest elements in the universe such as gold and plutonium.

“These mergers occur due to radiation from gravitational waves which removes energy from the orbit of binary stars, causing the stars to spiral towards each other,” the astronomer said in a statement. of Radboud University and lead author of the article Tanmoy Laskar. “The resulting explosion is accompanied by jets moving at close to the speed of light. When one of these jets is pointed towards the Earth, we observe a short pulse of gamma-ray radiation or a short duration GRB ”.

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

Such was the case with GRB 211106A, the residual glow of which was first detected in X-ray light by NASA’s Neil Gehrels Swift Observatory, later found in infrared light by the Hubble Space Telescope and, more recently, in millimeter radio light from ALMA. It was only with the addition of the ALMA observation that the GRB was spotted in a distant galaxy.

“Hubble observations revealed an immutable galaxy field,” said Dr. Laskar in a statement. “ALMA’s unmatched sensitivity allowed us to pinpoint the location of the GRB in that field with greater accuracy, and it turned out to be in another faint galaxy, which is further away. This, in turn, means that this short-lived gamma-ray burst is even more powerful than we thought, making it one of the brightest and most 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. Fong, and even allowed the researchers to measure the apparent width of the jet that triggered the GRB. explosion at just over 15 degrees, one of the largest ever measured.

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

“In the future, we could also use JWST to capture infrared flares and study their chemical composition,” said Dr. Laskar in a statement. “I am thrilled with these upcoming breakthroughs in our field.”

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