Texas Tech researcher is part of a team that has identified tellurium in the aftermath of the gamma-ray burst.
A team of scientists has used multiple space and ground-based telescopes, including NASA's James Webb Space Telescope, NASA's Fermi Gamma-ray Space Telescope, and NASA's Transiting Exoplanet Survey Satellite (TESS), to observe an exceptionally bright gamma-ray burst, GRB 230307A, and identify the neutron star merger that generated an explosion that created the burst. Webb also helped scientists detect the chemical element tellurium in the explosion's aftermath.
Other elements near tellurium on the periodic table – like iodine, which is needed for much of life on Earth – are also likely to be present among the kilonova's ejected material. A kilonova is an explosion produced by a neutron star merging with either a black hole or with another neutron star.
Michael Fausnaugh, an assistant professor in Texas Tech University's Department of Physics and Astronomy, is part of the research team. The findings, announced by NASA Oct. 25, have been published in the journal Nature.
“A key aspect for this event is that TESS was observing this part of the sky when the neutron stars merged,” Fausnaugh said. “This means we were able to observe the gamma-ray burst at the very earliest times, just as the heavy elements were synthesized. It is likely the elements are synthesized around a newly formed black holes, so the TESS observations are a unique way of peering into black hole formation and gamma-ray burst physics.”
While neutron star mergers have long been theorized as being the ideal “pressure cookers” to create some of the rarer elements substantially heavier than iron, astronomers have previously encountered a few obstacles in obtaining solid evidence.
“Just over 150 years since Dmitri Mendeleev wrote down the periodic table of elements, we are now finally in the position to start filling in those last blanks of understanding where everything was made, thanks to Webb,” said Andrew Levan of Radboud University in the Netherlands and the University of Warwick in the UK, lead author of the study.
Kilonovas are extremely rare, making it difficult to observe these events. Short gamma-ray bursts (GRBs), traditionally thought to be those that last less than two seconds, can be byproducts of these infrequent merger episodes. (In contrast, long gamma-ray bursts may last several minutes and are usually associated with the explosive death of a massive star.)
The case of GRB 230307A is particularly remarkable. First detected by NASA's Fermi Gamma-ray Space Telescope in March, it is the second brightest GRB observed in over 50 years of observations, about 1,000 times brighter than a typical gamma-ray burst that Fermi observes. It also lasted for 200 seconds, placing it firmly in the category of long duration gamma-ray bursts, despite its different origin.
After the first detection, an intensive series of observations from the ground and from space swung into action to pinpoint the source on the sky and track how its brightness changed. These observations in the gamma-ray, X-ray, optical, infrared, and radio showed that the optical/infrared counterpart was faint, evolved quickly, and became very red – the hallmarks of a kilonova.
In this case, the neutron stars remained as a binary system despite two explosive jolts and were kicked out of their home galaxy. The pair traveled approximately the equivalent of the Milky Way galaxy's diameter before merging several hundred million years later.