Using the James Webb Space Telescope (JWST), astronomers have traced an extremely bright gamma-ray burst (GRB) to its origin, a violent collision between two neutron stars.
The ring on your finger likely contains atoms produced in neutron star collisions like this, also known as «kilonova». That’s because, as well as blowing up the GRB over long periods of time, the kilonova is thought to be the forge of the universe’s heaviest elements, which cannot be synthesized in the nuclear furnaces at the heart of stars.
These elements are theoretically produced by a mechanism called «neutron capture» or r-process, which allows atomic nuclei to capture neutrons, creating new and heavier elements, including gold, white, and silver. metal and uranium. The r-process can only take place under extreme and intense conditions, such as those found around colliding neutron stars.
Related: Surprise! Colliding neutron stars create a perfectly spherical ‘kilonova’ explosion
This is the first time JWST has been used to detect emissions from such an event, and the powerful space telescope can also detect signs of heavy elements produced in the explosion. In particular, the team saw evidence of the heavy element tellurium and the creation of lanthanides – a group of 15 metals heavier than lead.
«These observations demonstrate that nuclear fusion in the GRB can generate r-process elements over a wide range of atomic masses and play a central role in elemental nuclei fusion. throughout the universe,» the team wrote in a paper detailing their findings.
The GRB’s track record of the group’s source of kilonova – led by Andrew Levan, a professor at Radboud University in the Netherlands – is also extraordinary in its own right. Designated GRB 230307A, it was first detected by NASA’s Fermi Gamma-ray Space Telescope on March 7, 2023 and is the second-brightest GRB ever seen.
GRB lasts about 34 seconds and is detected by many other telescopes, which is what allows astronomers to position it back to its source. Team member Brian Metzger, of Columbia University, discussed the achievement in a series of tweets on Thursday (July 6).
Metzger writes: “In research led by Andrew Levan, we detected kilonova emissions (for the first time!) with JWST, after GRB. «Perhaps in the biggest plot twist: the GRB — Monday morning of all time — lasts half a minute, i.e. a second ‘long’ explosion that accompanies the production r. Likely a crash neutron-star merger, but it is a case that challenges our ideas about how long the central engine will ‘jet’.»
JWST observed the kilonova twice, first at 29 days after GRB and then again at 61 days after the radiation burst, with a rapid decrease in luminosity and a blue-to-red transition between these observations giving see its kilonova nature.
The team identified several bright galaxies in the vicinity of the kilonova that could be the home of this neutron star collision and, therefore, the source of GRB 230307A. Their favorite galaxy is the brightest of these galaxies, about 8.3 million light-years from Earth and about 130,000 light-years away from the GRB source.
Kilonova can also be detected in a type of emission other than light. The collision of neutron stars causes the structure of space-time to «ring» in the form of gravitational waves. These ripples can be detected here on Earth with detectors like the Laser Interferometer Gravitational-Wave Observatory — but LIGO doesn’t work when GRB 230307A lights up. At the time, the facility had been decommissioned for three years, upgraded to make it more responsive, only to be operational again in May 2023.
Those are early days for the team’s discovery, which is currently being peer-reviewed before publication in a journal. The initial version of the paper, subject to revision, is published on the arXiv research archive.
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