How stars die: Astronomers detect magnetic fingerprint of a cosmic explosion for the first time
This illustration depicts Faraday rotation in the afterglow of a gamma-ray burst. A powerful jet (upper left) sends polarized radio waves through an H II region, a bubble of magnetized gas. The magnetic field twists the waves' polarization angle. Because the effect is stronger at longer wavelengths, the red and blue waves exit the bubble oscillating in different directions. By measuring this difference, astronomers mapped the magnetic environment surrounding GRB 260310A for the first time.
NSF/AUI/NSF NRAO/M.Weiss
An international team led by researchers at the University of Arizona and the University of Utah has made a series of landmark observations of one of the universe's most violent events.
Using the U.S. National Science Foundation Very Large Array radio telescope, operated by the National Radio Astronomy Observatory, the team detected polarized light from a gamma-ray burst afterglow for the first time at radio wavelengths. They also made the first detection of Faraday rotation in a gamma-ray burst – known as a GRB – a phenomenon in which magnetic fields cause the polarization of light to twist as it travels through space.
The findings, described in a paper submitted to The Astrophysical Journal and available on the open-access archive arXiv, offer a new window into the extreme physics behind gamma-ray bursts and may help astronomers better understand how the universe's most massive stars end their lives.
"We're effectively using the universe as our laboratory to test our understanding of how physics operates under such extreme conditions," said Kate Alexander, assistant professor of astronomy at the University of Arizona's Steward Observatory and co-author of the study.